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matthew smith

2002 honda recon 250 top end problems

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I have a honda recon 250 that i just bought. the compression is around 90 needs to be rebuilt. im getting into rebuilding it took apart the top end no problem except for the cylinder walls. as shown in the pictures. the way the piston sits in the cylinder is if you were sitting on the wheeler the skirt on the piston is left to right. so the wrist pin is front to back. which is where the two marks are in the cylinder. so that means the connecting rod is making the piston slap the cylinder on the wrist pin side which seems like a weird way for the cylinder to be moving. not natural. now the connecting rod has slight play left to right but not up and down. ive talked to a few people they say it might be the roller bearings in the connecting rod where it meets the crankshaft. but the play it has is not that much. im just looking for some more input before i start splitting the case. 




Piston diagram.jpg

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Welcome to Quadcrazy @matthew smith 

The movement left to right is perfectly fine. If there is up and down then there is a problem.  
Honestly if the compression is that low then a new piston and rings are in need. 
Also a honer VERY LIGHTLY ran through the cylinder jug would be good. 
Also a valve adjustment should be done as well.  
Other then that you should be good to go. 

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buddy of mine got the same bike that doesnt run good and smokes bad all the time.  are these motors hard to rebuild?  he was asking my about rebuilding his.

id say if your cylinder is gouged out from the skirt slap then your might be good to replace that cylinder.

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Skirt slap in the cylinder like that is not totally unusual when the rings are worn completely out.  Chevy 5.3's often have that same skirt slap.  I'd run a hone through it and see if they clean up.  If they don't and are deep enough to feel with your fingernail it either needs to be bored up a size or a new cylinder.  If i was flipping that thing i'd put a cheap cylinder and piston on it and send it on it's way.  If i was keeping it to ride for a while i'd either bore it or get a better quality Weisco kit or similar.

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so im replacing the cylinder , piston and rings brand new already have the parts. but that is not skirt slap. it is slapping on the wrist pin sides. which is an unnatural movement for the piston. the skirt side is fine. which is left to right inside the cylinder. so the gauges on the piston are on the same side that the connecting rode has play. i thought the slight movement in the connecting rod was normal. play up and down is not good which it is not doing. 

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Posted (edited)

i have also taken the valves and springs completly apart and cleaned them the carbon build up was crazy. will be setting the specs once its completely back together


Edited by matthew smith

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Left and right movement is normal because the cylinder and piston keep it from moving left to right once the piston is in. 
The only other reason i could think of would be the wrist pin and bearing at the piston? The bearing could be bad or check the top of the connecting rod where the wrist pin goes through and make sure its not egged. (Oval from a worn out bearing) 


Hopefully you are putting in new valve stem seals?

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