Topend Rebuild ?'s

[jrm03]

I got screwed over by the guy who was supposed to install a cam and piston in my motor, so now it is up to me or a shop. Is this work capable of being done by a novice? I have the piston, cam, gasket, and manual. I'd like to hear from those that have done this in the past. The motor is not blown, I was just a bit tired of the same ol 4hundy, I wanted a lil more. I've been without a quad for nearly 4 months, and I need help, I want to ride.

[kalebarellano]

I am in the process of doing my own top end right now. I am replacing, piston, valve seals, and putting in a crf450 cam chain. This is my first top end.

If I were you I would go for it. You have all the parts and a lot of people on this forum that can help. You will never learn how to do a top end if you never try.

Once you start taking it apart you will realize that it is not as hard as it seems. Follow your manual.

Good Luck

[400eXr1d3rZ]

It's a TON easier than it sounds.

[dixon_cass]

i have done a couple 2 strokes. they are really easy. the hardest part is getting the rings and piston in the cylinder. not that its hard but i did bend a ring the first time. i saw a neat trick. if you assemble the rings on the piston then slip it half way in the cylinder on the bottom. then put jug on motor and put wrist pin and clips in. saves hassle of puttin it on rod first. and no bent rings. hope this helps

[dariusld]

Originally posted by dixon_cass
i have done a couple 2 strokes. they are really easy. the hardest part is getting the rings and piston in the cylinder. not that its hard but i did bend a ring the first time. i saw a neat trick. if you assemble the rings on the piston then slip it half way in the cylinder on the bottom. then put jug on motor and put wrist pin and clips in. saves hassle of puttin it on rod first. and no bent rings. hope this helps
Getting the piston, with the rings on, in the cylinder is a piece of cake on the 400.

[northwest Texas]

There's a first time for everything. It's really much easier than you think.

A couple tricks especially to keep the different length bolts straight on the head is to leave them in when you remove the cover and set it on a piece of cardboard. Take a sharpie and draw around it and then take a hammer and lightly tap each bolt so that it makes a hole or indention and you can keep your bolts straight that way.

I don't have a ring compressor so the last time I used a hose clamp to lightly hold the rings in while I slid the cylinder over the piston. Worked great, just be careful as that's metal on metal though and don't get overly rambunctous.

If you have any problems, come back here, seems like there's always someone that can answer your question almost immediately.

[dariusld]

Originally posted by northwest Texas


I don't have a ring compressor so the last time I used a hose clamp to lightly hold the rings in while I slid the cylinder over the piston.

I don't have a ring compressor or a hose clamp. I used my fingers and they went in easy as pie. And Iv'e done it more than once.

[northwest Texas]

I've used my fingers too, hose clamp is easier.

[jrm03]

Thanks to everybody for their words. I am looking at a stroker that I may buy, if not, this is my only option since I am tired of a stock motor. Thanks again.

[1brock69]

if you do it your self be carefull when installing a new cam you should replace shims and everyelse to be sure your new cam wers in rihgt make sure your clearances are right. it'ts very tricky so be carefull.

[4 shizzle]

Originally posted by 1brock69
replace shims ???????????????

[dondiesel444]

450's use shims on the cam....

[Ruby Soho]

umm...he went with the stroker obviously.. and got it all done... so why bring this up?

[4 shizzle]

Originally posted by dondiesel444
450's use shims on the cam.... Read the thread, do you know what we are talking about.