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Project CBX550


I looked for some time for a restoration challange. This all started with seeing Evan's 1977 CB400. I knew that any honda restoration will be hard as brilliant HONDA CEOs tend to think that parts or bikes older than 20 years should not be on available or on the street. I was faced with the same issue with my 1989 civic. But to make things worse, this is an '83 bike that I was considering and was only available in Canada for one year!
No matter what, the bike is beautiful. To me, It represents a change from the 70s into the new area of cycling. And so it began. My goal is to share some of my restoration findings on this site. Don't hesitate to email with any opinions you may have on the this subject. I'll try to include honda part numbers as well. For some reason, I cannot purchase honda part number catalogue for this bike. I can find it for any bike bike that's been made in the US for free. That makes a lot of sense Honda CEOs!


The oil was drained through a filter medium to analyze the condition of the motor. Oil filter was also taken apart and inspected for any metal or other kind of unwanted materials. No foreign particulates were found. Oil was dirty though so the leak down test will have to be performed later to get the over all shape of the motor.


Previous owner indicated to puchase some good "toyota" washers as there is a small leak at the drain bolt. Upon dropping the oil pan, I found that the oil drain hole was tapped and TIG welded! Have a peak!

Suffice it to say I had to get a replacement due to that superb TIG welding. The replacement oil pan was thoroughly cleaned and polished at the machine shop as there was a considerable aluminum sedimentation most likely due to looseing cam chain that kept on rubbing against the aluminum block. This is one of the reasons why these PC04E motors fail. It would not be a bad idea to have your oil pan checked every year. Here's what it looked like after cleaning.

I've opted to change all the bottom end O-rings as the motor is 25+ years old! Rubber with time deteriorates! Those O-rings are crucial for sufficient oil pressure. Have a peak at the image below for what you're after.

Pay particular attention on how you install the dowel and the O-ring for the oil cooler feed. If you're doing this with the motor still on the bike, install the dowel and the O-ring into the engine and NOT into the oil pan. A dab of assembly lube on the O-ring will keep is from falling down. Have a look what can happen if this is not done right.


Due to numerous reports from many CBX 400F/550F owners of loosing motors due to oil starvation, this issue has to be addressed. Stock unit delivers 28L/min at the engine side at 7K RPM. At this time, I will not take the pump out; BUT, next time the bottom end has to be rebuild, the oil pump will receive considerable massaging. i.e. it will be ported and polished. This modifications will reduce pump cavitation at high engine RPMs and increase output by reducing losses, and ultimately netting more power at the cank. This technique has be utilized extensively by Honda Civic/Integra enthusiasts in the past to gain valuble PSI. The B16/B18 Type R motor I'm refering to is an excellet example. Keep in mind that with that upgrade, your pressure relief valve has to be modified as well.


This was tested before installing the oil pan. The Honda shop manual does not describe how to perform the test nor does it give any specifications of the pressure relieve point. Test was simple; attach an air ressure hose to the end is see at what PSI will it open. It should be higher than 71 PSI.


I took it off and got very scared. There was so much metal and crap on the screen! Tried to get a new one but it's discontinued. So off to the machine shop I went to have it cleaned. The guys did a good job but indicated that there was still some material on the screen that the solvent cleaner could not remove. I also tried dipping it into a rust remover (POR-15) without much luck. With some tweezers and surgical needles, I got most of it off. The seal that goes over the neck is also disontinued. I found a close match, I think it even gives a better seal.


Due to oil strainer contamination, I decided to thoroughly clean and flush the cooler. No surprises there. I'll keep the stock cooler for now but will have a look at some aftermarket units in order to inclease overall Oil volume availability for lubrication and cooling purposes.


This is where most of the time and effort should be spent to gain any considerable performance. The head will sent off for port and polish and flow analysis.

Update: I've acquired a second head but unfortunately even at 12,000km, the head needs to fixed due to oil problems. I'll have to find a new one and that's Mucho Dimero!!!

Update: Found a replacement. I had it polished and ported, changed all the valve seals, lapped the valves. The head was decked. Machine shop had to take 8 thou of an inch. Valves where is such bad shape even for a motor that had only 16,000km. The only way to clean them is to glass bead. I'll post more pictures.

In the end, the head lost 15 thou, so compression is up by about 0.2. :)

Exhaust cam sprocket was slotted a little. Have a peak.

I did clay the motor, timing is all nice and even.


When a suitable dyno comes along, carbs will be tuned on an individual basis. I'll have to have EGT ports welded into the header and wide band O2 ports as well. Having some experience with MUGEN and SPOON products on my previous CIVIC project, I'll try to incorporate those design ideas into this custom CBX's exhaust. This bike will mostly be for street use so mid range to low top end is what I'm after. Consequently, two exausts will be utilized, one feeding off cylinders 1-4 and the other feeding 2-3.
Update: 2012 season.
In the end, I could not justify destroying the only set of exhaust I have. I took it for a 2 hour dyno tuning session. I'll scan the charts when I find time but the results where:

- Destroyed clutch :(
- Needles, stock with stock height.
- Slow jet (#35) stock.
- Main jet (#95) upgraded to #105.
- Stock air delivery system with an exception of removal of top air cleaner box cover/snorkel.
- Short exhaust causes a loss of torque and power in the 4K - 6K RPM range.


Countless times I see reports of CBX motors blowing due to oil problem issues in the head and in the bottom end.I decided to investigate and I found the reason for it!
The reason is a manufacturing mistake in one banjo bolt! If you look at the picture below, see what the oil feed is from the banjo bolt(the bolt with the oil pressure switch on top) to the top of the head. The hole feeding the tubing is so small! This is what the head is fed with!!!! The picute below shows original bolts. (the banjo bolt on the left is used to attached oil feed to the head).

I've enlaged the hole and drilled right through to create a second one on the opposite side. This is a common design of honda banjo bolts these days. Why Honda chose to create only one opening that is so small buffles me. I'm sure it's a supplier error.
This little hole worked OK for the majority of time but if you ride your motorcylce at LOW RPMs, the engine wouldn't last long and hence I suspect CBX owners that tend to keep their RPMs above 3000 RPM are still on the road today.

Here is a picture after the modification that I call the "Czarek Mod" :)

As you can see, I've opended up the 2 upper banjo bolts as well.(They are bolts #10 in the picture above)

I'm beginning to suspect that perhaps this bottle neck in oil feed throughout the system may be also what contributed to the crank failures. Time permitting I'll have a peak at the bottom end oil route.

UPDATE: I recently talked to a reputable motorcycle repair mechanic about the oiling issue and he said NOT to do the modification. Apparetly, if the oil pump is not strong, the bottom end will fail. The issue with these bikes according to him are:
1. valve lash too tight, so keep it in the middle to loose spec.
2. not checking oil level between oil changes.
Update: I've run into an avid CBX fan who used to race it. He said the problem with those bikes is the valves leaking oil. Thus oil starvation is brought about by poor oil seal on the valves along with the fact that the oil pickup is far back into the engine. With hard braking, the motor starves for oil.


So far I've done well over 1,000km and it's been a lot of fun! Have a peak at some


It took a while but I managed to get my hands on a new OEM original honda timing chain. I decided to split the chain and rivit it back with a link. There are 134 pins in a chain and it is 87.1cm long including the link.
UPDATE!!! I thought this chain was new, as claimed by ebayer. It was not new! I hate people like that. The chain I was replacing it with was 85.0 cm. I ended up getting one with 136 links and shortening it.

Here's a picture of a critical installation instruction which OEM Honda Service manual failed to mention.

You ablsolutely must compress the chain on the tensioner slipper in order to install the chain onto the exhaust cam sprocket. Otherwise, you'll think that the chain is waaay to short. So, the chain tensioner slipper flexes! Get a thin long screwdriver and compress it. I should also mention that the best way to do this is to install the exhaust cam sprocket by itself first onto the cam chain, and then feed the exhaust cam through the sprocket (with the cam chain already on it) and bolt it up. To make sure you have the timing right, before you take the old cam chain off, count the number of cam chain links from the intake cam top "dot" mark to the exhaust cam top "dot" mark. Please email me at with what you have on your motor. I'm very curious. Thanks! Here's what it looked on my motor at a point of valve lash setting (so not TDC, just slightly off).

Here's a picture how I opted out to break the chain. This was my first time doing it, so in retrospect, I could just use a big hammer and a pin.


Had to make them as there was nothing I could find ready for install...


I'm not placing any deadlines for this project. I'll keep progress log time permitting.