Rebuilding a 300 Hirth into a MOD motor
The air shroud on the right is the original. Note that the rear part has cracked and come off. * * * The red one is from a 53R and will need to be modified a bit. The lower 1/3rd of the back brace will need to be trimmed off.
Flywheel pulling lesson #2: I got the correct puller, screwed it on, tightened it up, and pop! It came right off. * * * Always use the correct puller for flywheels and drive clutches. It will make your life much easier!
The flywheel is in real good shape, save for some oil and dirt. * * * The early Hirth singles use the internal ignition coil and the point set without the post (post is part of the stator plate).
The points look to be the originals, and have burned quite deep into the stationary side. A new condenser will be installed along with the new points. * * * The plug wire that was on it (left) is a no-go, so a new one will be put on. I've got two to choose from but I'm not sure which one I will use. The larger one (lower right) looks more like the original Hirth style.
The cylinder head has carbon build-up but is otherwise in great shape. It will get milled to raise compression. * * * The piston looks good, too, but it will also get modified.
"Houston, we have a problem..." Some of the end plate screws were loose with one of them (lower right) falling out when the flywheel came off. The threads for that screw are messed up and an insert will need to be installed. * * * Finding Top Dead Center so the port timing can be measured. The cylinder will also be modified, and I will post the "before and after" specs.
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