rebuild engine

[motorbreath]

Are there any main thing took buy when rebuilding an engine, what are the main things to replace?

 

[5twins]

You'll want to replace the front cam chain guide, the valve guide seals, and probably the cam chain. Anything else like rings, pistons, valves, etc. will have to be decided once you can get a look at them.

Buy the complete engine gasket set. Besides the gaskets, that will give you all the valve guide seals and all the o-rings you need. Also get the brass or copper washers for the 4 outside acorn nuts.

 

[motorbreath]

so would you recommend honing the cylinder?

 

[bigpup]

If I were you I would replace the rings as long as your in there and yes hone the cylinder with new rings. also do a valve job it does not cost that much to do it then you have a fresh engine. $100 bucks around here for a valve job, or you could buy a kit and do it yourself, ecspecially if you plan on making this a hobby then you can do all your own heads.

 

[5twins]

Usually, the valves just need a hand lapping to seal minor leaks. The stick w/ rubber cup and lapping compound will set you back less than $20. Every one I've had apart so far has needed this.

 

[5twins]

You might also consider cleaning the ports up with a Dremel. They're just terrible from the factory, full of lumps, bumps, casting flaws, and machine marks from the valve seat install .....

A few hours spent cleaning them up and you can make them pretty nice. The intakes are smoothed all out to eliminate the bumps then roughed back up to aid in atomizing the fuel .....

The exhausts are left as smooth and polished as possible .....

 

[motorbreath]

thanks for the pics! really helpfull, what attachment did you use on your dremel to do that?

 

[5twins]

191 and 192 high speed cutters, 1/4" and 1/2" sanding rolls, and the midi wheel (rubber wheel impregnated with abrasive grit).