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02 400 scrambler 2-stroke rebuild

8250 Views 2 Replies 3 Participants Last post by  Bruce!
Hi, this is my first time on this forum and need some help. I need to rebuild at least my top end. I have everything tore apart and out except the crankcase. I'm trying to do it myself because I want to learn more about my bike and motor and add a few extras to it.

1. The rod on the crankshaft that holds the piston has no play in it except from side to side, maybe a 1/16" no more then that. Is that okay?

2.I was going to put a stage one kit on it once everything was rebuilt. I understand that clutching comes with the kit, where exactly does this go? Does it go where the drive clutch goes? If so, is that easy to put back on.

3.Once I have the cylinder honed and start putting back together is there anything I need to be very careful about? Like how tight I should be tightening the bolts down or the sequence I do it in? Should I be putting anything around the piston or in the motor to help the break in process?

4. Should I take the bottom end out as well? Is that fairly easy to do? The only thing that concerns me is taking the drive clutch off.

Any other information would be great, this is my first time doing this and really want to learn how without screwing up anything. I really appreciate your help and insight. Thanks
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Be a good time to invest in a haynes repair manual.

Make sure the head isn't warped,you can do that at home with a square and feeler guage, draw file it across, if you want to make sure.

Install head gasket with the tab ,facing the front.

Now would be a good time to clean the counter balance area out, refill with fresh oil.10w-30

Head bolt torquing sequence is like start at 12 o'clock bolt,jump to 6 o'clock bolt,2 o'clock,then 8................

Head bolts..18-20 ft.lbs
base bolts..25-29 ft.lbs

You'll need to remove the clutch cover ,if you haven't already and give it a tug. if there is any noticeable end play or up and down play to be felt at all ,it's time for a bottom end. Cause end play .008-.016

Anything else ,let us know.
The advise you get on here is worth exactly what you pay for............kidding , good luck
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Welcome to the board!:med:
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