First 300ex top end rebuild

[cbrooks118]

I am going to tear down my 300ex on Sunday for the first time and put in a new piston, rings ect.... Any suggestions to make the job go nice and easy? Also Is there anything special i need to do after I get the jugg back from the machine shop? Went .020 with a high comp, also got new gasket kit

Thanks for your advice!

[Sjorge450R]

make sure that everything that is supposed to be greased with moly grease, does get greased. Other than that, just take your time and make sure the rings are lined up correctly when you slide the cylinder back on. And make sure to check the valves before you but the cover back on.

[ZeroLogic]

When you go to take out the vaulves, take a socket and put it ontop of the spring and hit the top of the socket to get the clips out. Thats the easly way to get them out. Make sure you get it honed also. Keep everything covered up with a clean rag or something to keep dirt from getting into the engine. Be carful, read instructions and take your time.:)

[Sjorge450R]

Originally posted by ZeroLogic
When you go to take out the vaulves, take a socket and put it ontop of the spring and hit the top of the socket to get the clips out. Thats the easly way to get them out. Make sure you get it honed also. Keep everything covered up with a clean rag or something to keep dirt from getting into the engine. Be carful, read instructions and take your time.:)

you dont need to remove the valves for a top end job.

[cbrooks118]

Is there somewhere i can find step by step instructions online?

[ZeroLogic]

Originally posted by Sjorge300EX
you dont need to remove the valves for a top end job.

Ah, what was I thinking? Well just incase you need to replace them now or in the future thats the easiest way to get them out.

[BlasterEaten250]

Originally posted by cbrooks118
Is there somewhere i can find step by step instructions online? get a clymer manual. they are sooo nice. you can find them for $20 if you look around on some sites. It takes no brains to understand them.

[Cody_300ex]

Originally posted by ZeroLogic
When you go to take out the vaulves, take a socket and put it ontop of the spring and hit the top of the socket to get the clips out. Thats the easly way to get them out. Make sure you get it honed also. Keep everything covered up with a clean rag or something to keep dirt from getting into the engine. Be carful, read instructions and take your time.:)

The easiet way is to use a valve spring compressor. Also make sure you put the piston in right, remember the arrow goes toward the exhaust.

[Sjorge450R]

Originally posted by Cody_300ex
The easiet way is to use a valve spring compressor. Also make sure you put the piston in right, remember the arrow goes toward the exhaust.

:eek2: arrow goes towards the intake on a 4 stroke!

arrow goes towards the exhaust on a 2 stroke.

[Cody_300ex]

Originally posted by Sjorge300EX
:eek2: arrow goes towards the intake on a 4 stroke!

arrow goes towards the exhaust on a 2 stroke.

That why I saw two intake valves get bent this past weekend by putting the arrow towards the intake? Do the research, the arrow goes toward the EXH on 2 and 4 stroke.

[Honda TRX250ex]

Cody is right, the arrow goes to the exhaust side.

[Sjorge450R]

im not trying to start any thing with any one, but my manual says arrow towards intake, and thats how it was when I took my old piston out. So are the aftermarket pistons supposed to face towards the exhaust. ****. That means that my piston is in backwards. So are you telling me that I have to open the motor up, change the rings and flip the piston. :mad: But its running fine.:huh

[Cody_300ex]

Originally posted by Sjorge300EX
im not trying to start any thing with any one, but my manual says arrow towards intake, and thats how it was when I took my old piston out. So are the aftermarket pistons supposed to face towards the exhaust. ****. That means that my piston is in backwards. So are you telling me that I have to open the motor up, change the rings and flip the piston. :mad: But its running fine.:huh

Yea i did it on my first rebuild, a .040 11:1 weisco piston, and it ran fine, but it was on a completely stock engine. The one I saw this past weekend had OS valves and a High lift cam.

[chapmanmd]

Im with Cody.

If I did that on my 13+:1 piston with big valves, Id have myself a nice mess on my hands.