Tight piston after rebuild XR200r 1994

[Fireatwill]

Hello there, this is my first post

I have just rebuilt the top end of my 1994 Honda XR200r engine including a new piston, gaskets, and doing a valve lapping job.  This bike was given to me by a friend that had it at his ranch here and Texas and thought it would be a great project for me, being an engineer.  This is my second bike rebuild and I am having an issue when I get all the bolts torqued up. I have the manual and everything has been torqued to the spec.  The issue seems to be with the ignition advance and pulse generator assembly bolts, and when I get them tightened up, the piston will not move. Once I loosen them up it moves freely no problem. Initially I thought it was the timing chain being too tight but isolated the problem to those two bolts.  I see the bolts attach one to the valve cover and one to the cylinder head which leads me to think it might be pulling the valve cover tight on that side. Has anyone else run into this issue or have any idea what I might be able to do to correct this?

Thank you

 

[chadzu]

From your description you are binding the camshaft for some reason.  Go back through your honda factory service manual, since your an engineering student I know you have the correct manual, and figure out where you went wrong.

[firstplacephoto]

is the back of the cover,and mating surface on head smooth and flat? any old gasket piece forcing it to flex/twist when tightened?

[Tbahr]

Are your valve rockers loose? Is the cam end seated in the groove properly? Locating pin cam end in the hole? Cam gear mounting bolts tightened properly? Cam chain slider in the proper place? 

Looks like you have a 10mm bolt head on the right of the cover, should be a matching 8mm. Wrong bolt causing an issue? Don't see the pin to fit the advancer, did it fall inside the engine?

[Daniel627]

You don't want the inside of your head looking like this from the can bearing dowel not staying in the hole when the ticket cover is tightened down... Then you'll be looking for a new head. 

[Chuck.]

If the right side cam bushing is not properly install you get what is in the above pictures, it has a pin that fits into the hole in the head. Something is amiss with the cam install. I'll add to what chadzu posted regarding the Honda manual; IMO it is the best for engine work.