The natural serow is a family of small stocky mountain deer found in Asia and Japan. The Yamaha model has similar aptitudes and habitat, although it can be found in the US and many have migrated to the UK. Note that US and Japanese specification bikes are subtly different from each other.
The Serow is one of the lowest dual purpose bikes around, which is why it is popular with newcomers to dirt. It is listed as suitable for a small beginner which can be seen by when you see the scale of the machine next to a Japanese rider. Of course good riders can ride any size of bike.
The 2006 US model can be seen here and the Japanese Yamaha site is here with links to a 360 degree viewer.
Japanese riders' pages:
Prices are clearly very variable and specific to your region and time of year. In mid-1990s Serows were rare in UK and prices high to reflect this. Now there are lots of used examples and so they have dropped in value, new prices following behind. Here are some guides (January 2002):
RecommendedSuppliers of JT sprockets for the Serow. A very helpful small company who really know their stuff, Ive been using them for years.
Hightown Industrial Estate
Crow Arch Lane
Tel: 01425 474800
Fax: 01425 461962
The Container Company LtdHave ceased trading, but I believe same people at:
Dirt WorldTheir spares line staff know Serows and their faults and can advise accordingly. Rapid delivery of parts with realistic P&P charges, although in many cases it's probably best to order direct from Fowlers.
Tel: 01226 2447700
|Unit B |
571 Stanningley Rd
Tel: 0113 2909878
Ellastone Off RoadHave the occasional Serow to break. Send what they say they will.
|Ashbourne Road |
Tel: 01889 590186
West Coast ImportsImporters of used trail bikes from Japan
|Unit 4 |
Tel: 01643 702511
Importers of bikes and parts. Also organise offroad days and corporate entertainment.
|Bogbusters International Imports
Yew Tree Farm, Newcastle Rd Betchton
Tel: 01477 500777
Service Exchange Parts
RecommendedThis firm of engineers specialise in specialised motorcycle and car engine work. Not cheap, not fast, but they do seem to have plentiful equipment and skilled staff to use it. Call to discuss your work, their carrier will collect and then they'll give a quote when they've inspected your parts.
|39 Sideley Road |
Tel: 01509 673295
Fax: 01509 673244
The Off Road Centre (formerly Notts Trail Bikes)Alasdair sells a variety of grey imports, UK spec bikes and accessories.
Oaktree Business Park
Tel: 01623 428777
Fax: 01623 626884
Motorcycle CentreImporters of used trail bikes from Japan
|Lambs Business Park |
Tel: 01342 892768
K&M Motorcycles Ltd.Importers of used trail bikes from Japan
|10 Dalestorth Road |
Tel: 01623 460700
Fax: 01623 460700
|Unit 9 |
Gilwilly Industrial Estate
Tel/Fax: 01768 891300
Moto-X MotorsImporters of used trail bikes from Japan
|29-31 Ashton Road |
Tel: 0161 652 7393 (Sales)
Tel: 0161 624 2313 (Spares)
Northern Trail BikesImporters of used trail bikes from Japan
Tel: 01904 673080
|Tel: 01273 726678|
|250 Oakleys Yard |
Tel: 0115 973 2466
|Bill Smith Motors Ltd |
30 - 36 Tarvin Road,
Tel : 01244 323845 / 320685 / 320699
Stores and Clothing : 01244 348515
Fax : 01244 350118
Email : Info@bill-smiths.co.uk
|Tel: 00 81 3 3928 0935 |
Fax: 00 81 3 5991 7062
|Yauncos Cottage |
Tel: 01531 890639
Fax: 01531 890250
Recommended10% discount for TRF members
The largest stockist of spares for imported Japanese Bikes including the Serow. The Yamaha parts line are happy to identify items on their Japanese-spec fiches and P&P is reasonable and rapid (i.e. often next day) for small orders. Have your frame number (the first 3 figure code in particular define model eg 4JG) ready but be prepared to find that your bike doesn't quite match the fiche! Be very careful with parts for rear wheel on rear disc models and front disc for twin-pot models. Don't bother requesting their catalogue though, it's not a great asset.
|2-12 Bath Road |
Tel: 0117 977 0466
|117 Brighton Road |
Tel: 0208 399 0630
Fax: 0208 296 0704
Riders of Yeovil
RecommendedCan get you any part for this bike. It is based on the XT125 frame, and many parts are the same apparently. They seem nice enough people to deal with and are often recommended by list members.
|Tel: 01935 421681|
Earl's Performance Parts Direct
RecommendedRapid construction and delivery of braided oil and brake hoses.
|4D Brent Mill Industrial Estate |
Tel: 01364 73956
Fax: 01364 73957
Tel: 01730 269817
Fax: 01730 260775
RecommendedExcellent telephone sales and mediocre WWW site for a wide range of gear at sensible prices.
Tel: 01597 851811
Fax: 01597 851962
|LED tail light (The fit has not been tested on a Serow yet).||109/111 Corporation Road|
Tel: 08700 660 393
Fax No: 08707 586 586
|Battery||The OEM battery is maintenance free. Check case for damage and that terminals are clean and coated with vaseline, maintenance charging is recommended.|
|Cylinder head and exhaust pipe nuts||check & tighten|
|Air cleaner element||clean||replace||clean||replace|
|Check and adjust when engine is cold and clean.|
Remove spark plug, rocker covers and flywheel case plugs and then turn crank to TDC (some engines have a 'T' on the flywheel) mark in the crankcase window by turning anticlockwise, both valves are closed every alternate rotation. Check gap with feeler gauge. If adjustment ios required loosen lock nut and then turn central square adjuster. Tighten locknut and recheck. To be safe, turn engine 2 complere rotations and observe correct functioning nd recheck.
Replace O-rings on rocker covers if they are compressed into square sections
NGK DR8EA or DR8ES-L
0.6 to 0.7mm
|The two NGK plugs are very similar. DR8EA is recommended in
the US manual, DR8ES-L in the Japanese. An NGK rep. explained to me that
the DR8ES-L is a little 'hotter' and might, in theory, give better
combustion without a risk of engine damage. Their relative merits are
likely to depend on the precise carburation of your bike. |
SPLITFIRE plug for Serow is SF-413B
|Fuel line||inspect frequently for cracks||replace|
|Engine oil and filter
1100ml of 20W40
10W30 in cold climates
but 10W40 seems fine
|Replace, hot if possible. Some riders change as often as
every 500 miles, using 'plain' oil as insurance against lubrication
Mobil 1 has been recommended. It may cost a fortune, but the Serow's sump is tiny. Runs a treat and never seems to get dirty or lose lubricity. Probably better to use specific M/C oil as Mobil 1 has been reported to cause clutch slippage.
The filter is made of metal gauze and can be washed out with petrol if an emergency oil change is required.
The O-rings on filter housing and sump do perish and get squashed and for total cost of £3 I recommend occasional replacement. The screws don't need to be as tight if the O-ring is good.
|Steering stem||check for smooth, notch-free operation with no fouling of
strip and re-grease annually
|Lever free play||Ensure that all controls have a spot of free play at
all times. |
Front brake 1mm at adjuster
Rear drum brake 20-30mm at pedal - don't forget stop light adjustment
Rear disc brake
Clutch lever 10-15mm at end of lever
Throttle 3mm at actuator, few degrees at twist
|Cam chain tensioner||This is automatic but on occasion you may wish to check it. Remove the plug bolt and insert a flat blade screwdriver. Rotate clockwise, and then release spring.|
|Chassis bolts||check & tighten|
10W 344-355ml per leg
|vent air pressure||replace||vent air pressure||replace|
The filter needs to be moist but not wet otherwise the oil gets sucked into the carb. Engine oil can be used but filter oil is better as it has a volatile solvent which aids penetration and it is 'sticky' when dry. Some are coloured so you can check for uniform oiling. Put the dry filter in a zip-seal poly bag and pour around 30ml oil onto it. Massage the oil into the filter, add a bit more oil if it is soaked up. Excess oil should be removed by repeatedly squeezing the filter between sheets of clean newspaper; this stage is critcial as excess oil strangles the engine. Remove the filter from the bag and leave 10 minutes to dry. The instructions on some product say to repeat the process but once is often enough. Slide the filter back onto its frame.
Clean inside the airbox with an oiled cloth. Lightly grease the periphery of the filter and airbox lid and replace them. The bike may be difficult to start as the pores of the foam may be blocked. Once it's running take it on a trip and it'll be OK then.
New OEM Yamaha filters are delivered in a few drops of light oil. I don't know if this is supposed to be adequate but I wouldn't chance it.
If you're doing a lot of riding I suggest you get a spare filter and keep it oiled in a bag so you can slot it in while the other one is being prepared. Some people recommend re-oiling a filter after every use - I suppose it depends on where and how you ride. After 1000km of Derbyshire trail riding, the drain was clear and the filter was still slightly moist and not dirty to the touch. After 2000km it had a few bits of foliage on it but the bike ran quite roughly in midrange. Cleaning and re-oiling the filter cured it so they need to be really clean.
Many parts of the Serow are standard to other Yamaha Trail bike models, in particular DT125R, XT125/250/350 and even the SR125. This is one reason that Fowlers can supply many parts from stock. If you take the part to a local dealer it's quite likely you'll find a suitable fitment.
In addition, the engine was first fitted to the "Forrester" Quad from the 1990s and many parts are much cheaper from the agricultural agents.
UK retail July 1999
|Part number |
Yamaha and/or pattern
Please note that this list is not be guaranteed to be accurate.
|Front brake discs||EBC MD6066D is 245mm diameter for XT225W (also DT200)|
EBC MD6067D is 220mm for 4JG frames Mk1&2 (also DT125LC)
|Front brake pads (for single piston calipers)
(almost rectangular with a lug at each short end)
|£15||EBC101, Ferodo FDB383, Dunlop DP406, SBS596, Brembo YA14 |
Sintered pads for XT350 fit and may be better than OE
|Front brake pads (for double piston calipers) as fitted to latest Japanese spec bikes||£12||EBC FA275, Dunlopad DP420, SBS 728 |
fit rear of Yamaha YZF600 R "R6" 1999-02 and Yamaha YZF 1000 R1 2002
|Rear brake shoes||£13||EBC Y503(possibly G suffix for grooved MX type), Ferodo VB229, SBS2028|
|Rear brake pads
(basically rectangular with a single large, pierced lug on long side, little tangs pointing from pad to lug)
Pattern part catalogues sometimes list the wrong part, so be
careful. However pads fit many UK import bikes including certain models of
YZ125&250, RM125&250, DR350&650, KX125&250, KLX250&650
|Front brake lever||£9||3FY-83922-00 |
WR200 or TTR 250 parts fit and are readily available
Dogleg type: 55Y-83922-00
|Front brake master cylinder service kit||£18|
|Complete front master cylinder||£45
|5CG-2583T-10 or 2KF-25850-00 |
Is there a difference between these?
|Brake discs||Take care with pattern parts as some are too thick and bind.
Always melt Loctite on the retaining screws before attempting to loosen them. This will need between 30s and a minute of gentle, carefully aimed use of a blow torch. An impact driver may save heads on fasteners. Whilst the screw is hot undo it a few turns.
|Clutch lever rubber boot||£2-50||Yamaha 1E6-26372-00|
|Clutch plate set (5+1)||£36|
|Clutch spring set (4)||£5||Minimum length for old springs is 35.3mm, nominal new length of 37mm.|
|Gearbox sprocket is somewhat "special" with Yamaha splines and Honda two bolt fixing, but is same as Yamaha RD/DT/GS fitment. Don't try to fit a Honda one as the splines will chatter and wear away.||£6||pattern 263-15 for RD-DT
Chains sell JT brand front sprockets:
|Rear chain wheel
Note that drum brake models have a dished chainwheel whereas rear disc models have a flat one.
|£13||pattern 842-45 for DT125F & XT350|
|Chain||£50||120 links 428V O-ring |
For larger tyres the rear wheel can be slid back, use a 122 link chain
|Chain and sprocket set||£90||Kits are available to convert to the more common 520 size. In this case 102 links used with 41/13 ratio.|
|Genuine cylinder head (incomplete)||£380||So you don't want to damage that!|
|Wire mesh oil filter||£7||5HO-13440-09 Make sure you get the right one. The box says it suits XT350and SR125. Filter for TT250 looks VERY similar but isn't! Check for 4 small holes around pressure relief valve.|
|Oil filter cover O-ring||£1-80||Yamaha 93210-54175|
|Oil filter drain screw O-ring||£0-60||Yamaha 93210-07135|
|Sump plug O-ring||£1||Yamaha 93210-35389|
|Copper washer for oil check screw||£0-50||Yamaha 90430-06014|
|Air filter element||£7|
|Inlet manifold (carb to engine)||£22|
|Petcock O rings||£5 for the set||3AJ-24534-00-00 is the O-ring |
3AJ-24523-00-00 is the 3 hole packing washer
4X8-24512-00-00 is the O-ring between tap and tank - it'll be obvious if this is leaking. May need replacing if you remove the tap.
The parts above can be replaced by taking off knob (very small lock screw) and then undoing the screw-retained plate underneath. Be ready for spring spacer!
|Clutch cover gasket||£7||The clutch cover is often hard to remove as the rear dowel gets rusty. The kickstart oil seal will withdraw from shaft with care but ensure you keep it in housing by tapping it back in if it starts to come out. A new gasket is very likely to be needed as you will damage it. Note also that the gasket has a 'bead' of sealant along the top edge where bolts are sparse so you may wish to use sealant along that length if you are attempting to reuse a gasket..|
|Retrofit kick start kit||£150 - £300||Grey importers can supply kits but delivery is long. Is it worth it?|
|Battery 12V 6AH no-spill, no maintenance||£64 Yuasa from Yamaha
£52 Yuasa from dealer
£30 No-name from dealer
|Yuasa YTX7L-BS have proven long life and reliability. Note that MF type batteries cannot be charged with conventional fixed-voltage chargers.|
|Headlight bulb||£2 upwards||OEM 35/35 halogen is difficult to source. Fit either 30/30 non-halogen or even more common H4 standard car fitment 55/60 halogen (housing doesn't seem to melt).|
|US model higher wattage bulb||55/60W Sylvania 9003 or equivalent fits perfectly in the Serow but you may want to disconnect your front turn signal *running lights* to preserve wattage.|
|Alternator rotor assembly||£150 to £170||Several riders have suffered from disintegrating rotors that rattle and then sieze engine as lumps fall off.|
|Master fuse carrier||£1-25 including 2 fuses||Pattern part from good bike shop specialising in Jap bikes. Fit heatshrink tubing to bullet connectors to bring upto O.E. specification and improve on this by adding heatshrink tubing at fuse end also.|
|Wheels and Bearings|
|Front wheel||identical to DT125LC mark III |
XT350 similar but disc of different diameter
|Rear drum brake wheel||one model (which?) of DT125R|
|Rear disc brake wheel||DT125 mark III|
|Wheel bearings||£3 to £5 each||6202-2RS |
6202-DDU (these are supposedly better sealed)
2 at front, 3 at rear
|Steering stem top cup & cone||£40||Yamaha 22F-23411-01 & 22F-23412-01 |
also needs 22 of 3/16" ball bearings
|Steering stem bottom taper roller||NTN part number 4T-32006X |
Bottom taper seal is part of the Yamaha bearing kit at a high £45. However a seal D.U.204/112 DSL can be made to fit with modification: Remove the inner lip completely so it is flush with the bottom of the inside of the seal (careful work with the scapel or whatever) so you open it up enough for it to just slip over nicely. Then you will find the outside lip fouls the cage on the bearing when fitted together. Again, a simple job to cut a little off the seal depth until it fits right. Not as good as OE but a lot cheaper.
Available from Mervin on 0116 251 4379
|Taper bearing set||£30||Moore International of Poole (UK) +44(0) 1202 462214 have had one of their suppliers make a taper bearing in the right dimensions (43 X 25 X 11) - ask them for Item Code 324305 and they will charge you £12.50 + VAT. The bottom bearing is a standard engineering type 32006, however this normally requires a separate seal. Better still, the motocross enthusiasts at Moore International can supply a sealed taper bearing - ask them for Item Code 32006RS, cost £11.00 + VAT.|
|Odds and Ends, Chassis and 'Bodywork'|
|Mirrors||£15||Who needs them?|
|Rear shock||£230 Hagon
|Speedo cable||£8||1KH-83550-04 inner and outer set|
|Model 1 rear light lens||£4||1Y1-84521-30 fits DTR125R & FS1EDX|
|Japanese model indicator lens||£2|
|Japanese model indicator body||£5 used
|3RW-83340-00 (note front and rear are different by virtue of lead length)|
|TTR250 Brushguards to fit Serow||$24-$35||Yamaha parts list
Please send me your experience with these or other fitments.What terrain do you use them on, how long do they last. how easy are they to fit, number of punctures, best air pressure to use etc?
The Serow has limited clearance at swing arm and some widths need to be checked before assuming any of these fit. One reader has fitted a 140/80 rear tyre by using a lengthened arm (I'm hoping to get details of this), longer chain and brake rod to move wheel back in swing arm. This might be beneficial for mud clearance and lengthened wheelbase even if standard tyre retained.
Tyres marked TESTED are known to fit as
I've a reliable report.
Front Wheel size is 21x1.60
Rear Wheel Size is 18x2.15
Comments and opinions from diverse sources
|Michelin Moose 90/90-21||Michelin Moose 120/80-18||TESTED Steve writes: Mooses fitted
front and back are excellent once fitted, they last quite a few years but
are very difficult to fit, it usually takes two people, sometimes three if
its a tough make of tyre. Michelins are one of the more pliable/easier
makes to fit, but still difficult. I have a friend who fits his own mooses
but I wouldn't, I think they are far too difficult. But I do help fit
them, mainly out of guilt. |
There is a lot of bad press flying around about mooses but a number of us have used them for quite a few years without any problems. They obviously wear out, but can last about 3-5 years in the UK. The mooses are made to an equivalent of about 14 psi.
|Michelin Baja 90/90-21||140/80-18 (Will it fit?)||Michelin say: Street-legal, desert-proven|
Baja tyres cost more than any other off-road,or semi-offroad tyre, but they last SO LONG, it is well worth it. I rate them very highly. I have used a number of sets on DR 350, DT200, WR,XTZ 660, and I will put a set on my Serow just as soon as I can get out and wear out the motocross tyres it came on.They are fully road legal, therefore OK for Cambrian Rally etc, but they look just as knobbly as any enduro tyre. They are radials, and because the side wall is so flexible, they can run a much harder compound than would be possible on a cross-ply. Hence the high mileage,even on the road.
|Bridgestone TW-302 4.10x18||TESTED Quite tarmac orientated. The prototype non-trials tyre tyre for MCC long distance trials since 6/2000. At 20psi they roll quite nicely on the road. For trials use I dropped to around 8psi. Initially they felt very loose and insecure but over a few hours I got used to them both on and off tarmac. At low pressures they seemed equal to MT21s until I encountered muddy grass and may have the edge on the road. The closer black pattern appears to give a longer road life. Sidewalls are soft and the tyres are easy to fit but front doesn't seat centrally on bead very easily.|
|Bridgestone ED661||Bridgestone ED660
|I think these are the ones used by Norwest Trails in Skye where ground is very wet and soft. Very knobbly, squirmy on the road, and they will wear rapidly on tarmac. Possibly not legal in US?|
|Cheng Shin C858
275x21 or 300x21
|Cheng Shin C858 'Cats Paw' 4.10x18||Made in Taiwan, the price is good. Don't look knobbly enough for use in the winter! Is the 300 too big?|
|Cheng Shin C6006||The OEM tyre on the 2000 U.S. model Serow.|
400R18 gives plenty of swingarm clearance
|TESTED Fairly open block design with
history of good use on bigger bikes such as BMW R1100GS.|
They are in a separate category inbetween the knobblies and the OE "trail" tyre. Reasonably good off-road, and amazingly good on-road for such a knobbly tyre. They give a good mileage on-road as well.You can ride to Spain, trail ride and get home,on a set of TKC80's, which you certainly can't on MT21's. In that respect I think they are in a class of one!
Enduro Comp II
|Enduro Comp IV
|TESTED A pair of these tyres fitted front and back are really pleasing due to the off road grip, so that the Serow now goes where it's pointed and climbs up all sorts of hills. They are excellent for trail riding on a mixture of terrain, including, mud, chalk and sand, but do tend to wear out rather quickly on the roads. You also have to treat them with caution on the road, due to the agressive tread pattern. The recommended/standard tyre size fits perfectly on the rim. The chain adjuster is set at about number 6, this clears the swinging arm ok, with still a lot of adjustment to go.|
80/90 P21 or 90/90 R21
|Pirelli MT-21 Enduro
110/80P 18 or 120/80P 18
TESTED The 120/80 rear is a much bigger and knobblier tyre than the 110/80 - far more than the slight size difference would suggest (check them out side by side). The smaller one is better on the road. Fitting a 120 section MT21 gives great grip, but it effectively raises the gearing quite a lot (much larger diameter than a 110). Most noticable effect is that it makes sixth gear on the road a bit breathless, necessitating a change down for hills and headwinds, where the smaller tyre would not have needed one. However the 120 is much better in serious mud, so it's my choice for the Welsh winter, even though it's also a tight fit in swing arm.
|Considered by many to be the ultimate dual-purpose tyre. Knobs can be
broken off by big bikes at high speeds - so no problem here then.... A review.
20psi is a suggested pressure to compromise between grip and puncture resistance although they feel more secure on rocks at 12psi.
MT21s are excellent on the dirt (except in deep mud, loose stones,
slippery tree roots), fair on the road. On tarmac they howl a bit and wear
fairly quickly, but they handle OK. As to life, the 110/80 rear I fitted
for my Picos trip
lasted about 2000 miles (still plenty road legal but losing its bite on
Rear Pirelli MT21 120 section shown here has lasted very well: about 2000 miles so far, including Iceland crossing and a mix of road and dirt. Initial wear is quite rapid, then slows down. The tyre is no longer much good in deep mud, however, but OK for hacking around.
|4.00 18||TESTED The standard road-legal trials tyre. Used by almost everyone on long-distance trials. Square blocked, soft compound with offset blocks at edge. Use at around 8psi off road and 20psi on tarmac. The rear tyre needs the wheel to be near the back of the swing arm, so try a combination of a longer chain or smaller front sprocket - the tyre has a large rolling circumference anyway.|
|M6001 4.10-18||Rarely seen in UK. An inconclusive review.|
2.75-21 or 90/90-21
|M6006 120/80-18||A street-biased tyre, available mail order in UK. Intended for big bikes, but small sizes available.|
|M7000 120/100-18||DualSport tyre, with not a lot of mud clearance.|
|Dunlop D604 90/90-21||D604 120/90-18 Trailmax is too wide for the rim.||These are basically road tyres.|
D905 (are these road legal?)
or K139 3.0-21
|This looks to be Dunlop's clone of the well known MT21 on the rear with choice of front fitment.|
|Dunlop D903 3.00-21||D903 120/80-18||A widely spaced, street legal (in US) enduro tyre. I can't imagine a long life if used on road although the Dunlop chart suggests more road-worthy than D606.|
|Avon AM24 80/90S21||Avon AM24 80/120S18||Street orientated. The tyre of choice for BMW GS machines that do miles of unpaved roads. Will these last forever on a Serow?|
Enduro 3 90/90-21S
|Metzeler Enduro 3
110/80-18 or 120/80-18
|Fitted OEM to BMW G/S and big KTMs, this is a soft-compound
street-worthy tyre which offers fair traction on unpaved tracks.
TESTED For the summer you might fit a 90/90 front and 80/120 set of Enduro 3 Saharas. They are superb on the road - grippy, stable, quiet, amazing lean angles. They make the bike quite a little scratcher. Very little wear in a couple of thousand miles. They belie their name too, as they put up a surprisingly good show in mud. A very good choice for someone who only occasionally ventures into boggy ground.
|Metzeler Enduro 1||TESTED Enduro 1 is similar in properties to the Sahara but is specifically intended for lighter motorcycles and has somewhat softer compound, to allow for proper warmup. My impression so far is that it is an excellent choice for both street and (dry Greek terrain) dirt usage.|
|Metzeler MCE 2 Front 90/90-21||Metzeler
Six Day Enduro 120/90-18R
and Six Days 2
|TESTED Very highly recommended. Rear only just clears the shock (higher profile) but it does fit. V.cheap too - just over £100 for the pair. They give enough grip for tarmac (they're road legal), and they really give good traction in the mud. We went through some nasty bogs last year, and they've never clogged up. Ten times better than the usual MT21 style option. Life may be only 1000 miles.|
|If you pull the carb apart, make sure you refit BOTH washers the right way round on the needle. There's a plain washer that goes underneath the circlip and a stepped collar that goes above it. I have never seen a similar set-up on any other carb, so it is easy to get it wrong. If the top collar is missed out, the spring does not seat over the needle to keep it in place and the bike will never run right. NEVER assume that the way the carb is assembled when you first take it apart is the right one. The diaphragm cover can be removed by rotating carb between loosened manifolds with all cables connected (seat and tank off).|
|A drill and sharp, full drill bit set 1/8th and up. A sharp x-acto knife (standard, sharp, one-sided blade #11). A Dremel or small grinder/sander and some 100 grit or lighter sandpaper for turning down the nylon part to size for the needle jet. Metric open, socket and Allen wrench sets, Phillips screwdriver, needle nose & regular pliers for removing seat, tank and carb.|
|Parts needed for the mod can be found at a local hobby shop in the model airplane area. Look for a product called "DU-BRO Large Nylon "T-Style" Control Horns" (DU-BRO Cat. No. 237) cost $1.00 US. The thickness of the product is spot-on. All you need to do is sand it to the same size/diameter as the one on the needle jet. More about this later.|
|1.||Take the carb off the bike. To make this easier, first remove the seat and gas tank. It's easier to take the choke off (just unscrew the black nylon fastener) after the carb is out. Take the carb to the bench with clean shop rags and lots of lighting.|
|2.||On a clean towel, lay the carb down with the front side up (the side the fits into the engine not the air box) and the top (black) away from you. Just above the float bowl you will see three tap/post looking items. The center one will has a brass plug in it (this brass plug is in the center one, Item #14 on the list). Now find a drill from your drill set that's smaller (about half the size of the brass plug hole - 11/64 works) and drill out. Use a low speed setting on the drill if you can. Be careful not to drill out the Pilot screw on the other side of the plug. The plug is about 3/16" thick and there is about 1/8" of space between it and the screw. Also make sure that you put some rags in/around the carb so metal will not fall into the carb. With the plug out you will see a flat head screw down in the hole that you can turn for low-end idle fuel mixing (this will help big-time for starting up the bike cold or hot - see more later).|
|3.||After loosening the 4 diaphragm cover screws, hold the carburetor upright and remove the diaphragm cover (Item #1 on the list). Rest the carburetor in an upright position. Inside the cover, where the flat top meets the angled side you will see a small hole that leads into/out of the diaphragm. This hole is for vacuum that raises and lowers the diaphragm assembly, Item #4. You will see that the hole leading into the diaphragm cover is larger than the one on the inside of the diaphragm cover. You will now make this the same size (open it up with a small drill bit (a light touch with the 11/64 works fine) or you can use the sharp x-acto knife. I use the x-acto knife; it took a little longer but the plastic was easy to cut away to enlarge the hole inside the diaphragm cover.|
|4.||Carefully lift out the diaphragm and attached spring and you will see the needle topped by a loose white nylon washer. This washer seats the spring on top of the needle. Now lift out the needle jet (Item #3 on the list); the spring is the only thing holding it down. You will see that there is a small white/grey plastic spacer secured near the top. You will now fit the DU-BRO piece (it's the flat sided, nylon square backing plate that holds the horn in place with just two holes. Its 75 thousands thick .0075"). Now take a drill and make a hole in the middle that's just a little smaller (3/32 or 7/64) than the needle jet (use the top of the needle jet as guide for picking out the right drill bit that's 2-4 thousands smaller. You are going to press-fit the part till it touches the white spacer. Make sure that you put the new spacer on the tapered side of the existing grey/white spacer, not on the top/spring side! Use a Dremel to shape the DU-BRO part to the same size/diameter as the white stock spacer. Take your time and check your work. Start by rounding off the corners with a Dremel and sanding cylinder. At some point the workpiece gets too small to hold in your hand. Slip it onto the needle jet and with thumb and forefinger hold it tightly against the existing spacer. With the Dremel set at low speed, very carefully continue to shape the new spacer (without touching the existing spacer) until its dimensions match the existing spacer. A little smaller is okay, but larger won't work. Lightly sand the new part to remove any debris or rough edges.|
|5.||Now reassemble the carb starting with the needle jet (now you should have two plastic spacers each the same size with the new spacer at the bottom and the OEM white spacer on top/spring side.). Make sure the needle jet moves up and down freely and that the new spacer seats properly in the recessed area. Make sure that the diaphragm is correctly oriented, the cover is seating flat and that you have a carb that looks the same as when you started.|
|6.||Put carb on bike and gas tank/bike seat. It's easier to attach the choke to the carb before reinstalling the carb.|
|7.||Now order a new air filter "UNI-Filter" from your dealer. (MSRP is $12.95 for the NU-3237ST). Follow the Notoil directions and install the new air filter, leaving the metal screen behind/under it off. Notoil filter oil and cleaner can be found at http://www.powerstart-systems.com/notoil.html|
|8.||You are now ready for starting it up!!! You will need to fine tune the carb for low end for best set up. Turn the Pilot Screw to the left to loosen (Item #14 on the list) that you exposed in the mod to richen it up! You will see that the bike starts so easy now and when you pull back on the throttle the bike snaps off. Now take it for a ride and you will feel it pull harder and smoother.|
|9.||To make the XT225 more sprightly still, change the sprockets. Stock sprockets in the US are geared up to meet EPA's MPG requirements. For offroad and around town you can try 14 teeth front and 47 to 50 teeth back. You'll need a new chain as well. Sprockets and chain ought to run around $130. One online California source is: http://www.sprocketspecialists.com/html/yamaha3.html SUN-Line sprockets look just like the OEM model, but there are a number of manufacturers. The XT225 comes alive with this set-up and a top speed it 65 MPH. Look it's not a street bike for long highway runs so make it work for you. Going 65 MPH on the dirt is scary fast and around town it's a little rocket with the gear change!! If you want to be cautious, start by changing the front sprocket from 15 to 14; it'll only cost $12-15 and you don't need a new chain.|
|Ken ((email@example.com)) and amended & edited 08/22/01 by Mike (firstname.lastname@example.org)|
Front fork settings and modifications
|Fork oil||Change fork oil for some new 15w or 25w (different riders suggest either but I am told that viscosity ratings are not consistent between brands). Higher viscoity increases damping and should be used if preload is increased. Remember that increasing the oil height tends to increase effective spring rate as there is less air column to compress. Excess oil will lock the forks solid and blow seals.|
Some riders recommend around 12psi to be added using a balance tube and a bicycle pump, although spec-sheet states 0-5.7psi correct. Here's Craig's set-up that balances pressure between the legs, which is ciritical, and allows rapid pressure modifications. Air assitance helps to overcome initial 'stiction' and provides 'progressive' spring rate behaviour.
|Some opinion seems to be that 5 to 25mm preload with a bit of pipe
or a pile of washers is better than air. Add washers one at once to
check that spring doesn't bind or become too tightly pressed together to
compress! On valved models enlist the help of a friend to prise the
circlips out while you push down on the caps. On others, just remember
to press as you unscrew. |
If you are going the solid preload route, remember to bleed air out of forks. Support the bike with forks fully extended and press valve or remove bleed screw. Pressure builds up due to pump action of forks and air leaking past oil seals.
|After market springs or forks||Pat reports: I let Racetech Suspension work over the forks on my TTR225 (same chassis as XT225). They put in "Progessive" p/n 1136 progressive springs and "Racetech" Gold Valve Emulators" adjusted by them per my riding type (casual trail with ocassional tough rocky sections). They have 15mm preload and 10wt oil. The ride is still plush, yet doesn't dive as much when I hit the brakes. I weigh 175 lbs. without gear.|
Rear shock adjustmentsFor general information see:
|Spring rate||The shock comes out with the rear wheel still in situ, just undo the tank bolt and lift it up a bit to get to the top mount. At 11 stone the preload needs to be wound up a few mm. One 13 stone rider found a breaker in South London who swapped the spring for something with a much firmer rate for thirty quid. Although this stopped the shock from bottoming the stock damping couldn't cope.|
|Preload, Rebound and Compression settings||This is a minefield for non-experts such as myself and I'd value
more input. Adjustment needs trial and error. So alter one setting, note
down what you do and go for a ride and see if you can feel a difference.
PreloadThe unloaded bike should sag a small percentage of its travel when unloaded. With a rider onboard, one third travel of sag is an oft-quoted rule of thumb. By increasing the preload the spring is made exert a larger constant upwards force to achieve this position. The problem of this is twofold. First it reduces the possible compression of the spring as it is already part compressed and second it tends to shorten the life of the spring as it gradually adopts its 'new' length. These problems can be overcome by fitting a 'stronger' higher rate spring so it has negligible preload to achieve correct sag and it will have enough movment left to absorb a big landing. Excessive preload or spring rate eliminates sag and removes the ability of the wheel to enter hollows and you will feel the loss of traction.
Rebound and compressionAs the spring compresses and relaxes its movement is damped hydraulically so that the bike doesn't pogo across the ground. Ideally the wheel should folow the terrain exactly. On many shocks (eg as fitted to US models) a single adjuster alters both at the same time. Slightly more upmarket shocks allow adjustment of both independently. These settings are also dependent on preload or spring rate as more force needs more damping for a given rate of movement.
|After market shocks||Hagon have recently set up a shock with optimised spring rate, damping and a 5mm longer stroke for a list member. Early reports suggest that the ride is improved dramatically. They will retail them at £230, call for details.|
|Polisport and other 'no-name' versions||Cheap but very limited clearance. You'll need to cut out around front brake hose. Mountings are plastic and tend to twist even when done up tight. Personal experience suggests that the plastic isn't very impact resistant either!|
|Acerbis guards||Acerbis do both a market-leader plastic model and an aluminium framed 'pro' version. You may not like the big logo on their front. The standard 'Rally' is around twice the price of a 'no-name' despite looking very similar. But it does have a better finish and has alloy, rather then nylon C-clamps. The C-clamps are quite malleable and can opened and closed once with reasonable force. The general feel is more solid when fitted to the bike. Also needs a cut-out around brake hose. Be sure to loosen brake and clutch perches so nothing terrible happens if guards twist.|
|Off Road Only Rally Pro (#75-108)||This company produces 'unbranded' guards very similar to the Acerbis models but at a reduced cost. This means that you can buy the Aluminium-framed model for the price of the plastic Acerbis. Although this model is quite heavy it offers good protection to the levers and the mounting hardware is far more sophisticated in that the bar-end mount is serrated to grip the bar and the mid-bar connector is in two parts so that it does not have to be stretched over the bars (unlike the usual 'C' mount). It does not need to be trimmed around brake master cylinder although the hose angle may need to be adjusted at the bajo bolt (Don't forget to bleed it afterwards - this may be a good time to replace that fluid!).|
posted by Roger
The new seat cost me $130.00US + 15.00 shipping. That was for a one-color vinyl cover (you choose the color) and saddlegel insert. They have a model that's $170.00 that has a 2-color seat, the other color being black spandura for breathability...I didn't get this one. You can call the company to order what you want. Their literature and sales staff will tell you that the XT225 seat they sell is for 1992-1994 year models but it fit on my 1995 OK. Does anyone know what differences between '94 and '95 there were?
The catch with their product is you have to re-cover your existing seat's backplate. You do not simply buy and bolt-on like you would think. I took mine to an upholstery shop to have it done right. That cost me $45.00US, but it looks better than I could have done it. No more Yamaha insignia, though :( Also, the purple is not an exact match to the Yamaha purple of my bike.
The new seat does feel nice. It adds about 1/2 inch to the seat height and is a little more firm than the original one (mine had crushed foam so really hurt my butt). If you ever double-head on the Serow, your passenger will be a little better off too.
I'm not sure it's $190.00 better, but it is better. My 30 mile dual-sport ride yesterday still left me with a small case of monkey-butt, to be expected with any seat, I guess. I will need to ride for a few more weeks to get used to it. I would like to be able to ride 120 mile dual-sport days without so much butt-pain.
|Welsh Seat posted by John||The original foam squashes and breaks up early. The covering
material is flimsy and the 'pillion' strap is literally a pain in the
I had my seat recovered in tough black vinyl by Menai Upholstery in Bangor, North Wales (01248 370067). They used denser foam than the original and made it wider. It initially feels hard, but it's much better than the OE over distance. Cost was £70 incl. VAT. They do different colours.
Cheap (about £20) underwater watch strapped to handlebar is better than most dedicated bike kit. Some are rated to 25-50m water depth and seem pressure-wash proof. Put closed cell foam (sleeping mat or pipe insulation material) under it to isolate vibration. Secure against casual theft with non-corroding wire (chandler or soft copper plant ties from garden centres).
Even with the highest rise Renthals I could find, the bars were too low, so down to the scrap yard for a pair of top handlebar clamps with the same bolt centres as the Serow and a nice flat upper surface (these were from a Kawasaki KLX). Add some longer Allen bolts (Note that these should be of high tensile steel) and voila - a cheap set of risers.
|The necessary materials are: 4 elbows, 4 T joints, about
6 feet of 1/2 inch white PVC pipe, and some PVC cement. You will need
a saw and maybe, a mitre box, to cut the pipe. The cost for piping and
glue was about 8 bucks. The dimensions can vary depending on what you
need; I made mine 10"x11".|
Just cut your pipe accordingly, and put the elbows on the corners and the Ts at the appropriate points along the front and back sides of the square. If you haven't used PVC glue before, be advised that it sets immediately, so it may be good to assemble the whole thing a few times first without glue, just for drill.
I mounted the rack to the bike with heavy rubber bungie cords. That way you don't need to drill holes in anything, and you can remove it easily. I picked up a little nylon pouch with pockets for different size stuff and strapped it onto the rack.
|Problem: how to use throwover bags without them burning on the exhaust.|
Answer: a wooden rack that slots over the rear lifting handles and rests on the rear mudguards. It takes about five seconds to fit (or demount) and weighs 4.5 lbs (2 kg). It could be lighter if I made cut-outs in it, but I like it strong.
Construction is 8mm marine ply (waterproof, light and very tough), screwed together and glued with marine epoxy resin, plus quadrant reinforcement at the joints. Various stainless loops (again, from any marine supplier) have been added to secure bags to rack, and rack to bike, using cable ties and/or straps.
The boat-building technology is simple and very effective. The rack
also doubles as a seat, picnic table etc. and a platform to carry a fuel
can - which I guess I will need for the 150 miles or so without petrol
Use good cam cleat straps. Thule are best (from Halfords). Most other cheapo cams slip. Loop them under the carry handles but make sure they don't crush the indicators. The guides screwed to the bracket here are stainless yachtie items and keep the straps in the right location, away from the lenses.
First strap the rack to the bike, then strap the bags to the rack. Use zip ties to get length right to fixing points for bags-to-bike (I use the loops behind the pillion rests, which are nicely positioned to secure the bags forward and downwards: stops them flapping about). Use stainless shackles to secure (more yachtie stuff). Easy to do up and undo, but be careful not to lose the pins!
Note that the pannier bags are supported underneath. This means that straps are for retention rather than weight bearing.
Straps are fitted through smooth holes in the rack. The straps from the top to bottom of the rack help to stop it falling towards the wheel as no side supports are included.
At present, zip-ties are used to hold it to the grab rails.
We've tried to make this information accurate but we cannot accept responsibility for errors. Check with a trained mechanic if unsure. Please let me know if you find a mistake or want to add your knowledge to the pages.