My friend owns a 86 250r and he haden't rode it for a little while. When he got it going he said he was riding around for half hour and then the engine blew. He says the piston shattered or something. Has anyone experianced this before or have an idea of what it may be or why it happened. Any advice including how to fix it would be greatly appreiciated. He's who I ride with and without a quad it's suck. Thanks

 

if you 'shatter' a piston its usually because the topend was worn out, and there was too much piston to cylinder wall clearance, and it was slapping around in the bore...the piston fatigued and went boom.

Tell your friend to do a topend job more often [img]i/expressions/face-icon-small-smile.gif[/img]

 

How old was the gas? if the gas is stale you'll pop a piston also.

 

He had it ported and polished a while ago, i'm not sure the specs on that but he has riden it since then. How fast can a top end be worn out because the piston and top end should have been farely new shouldn't they have? I may be wrong, tell me if I am. Also what does stale gas do to make that happen? Thanks for your help guys

 

If the quad has stale gas the gas won't fire right. A 250r needs high octane, stale gas won't give it that good octane it needs.

 

I really doubt it was stale gas.


The other possibility is when he had the new topend done, the machime shop set the piston up with too much clearance, with the same result as I mentioned above. The piston shattered correct? it does not have a hole in the dome

 

A engine can go bad for many reasons. Just to list a few;
1. Oil and gas ratio
2. wornout piston from riding all the time
3. piston and rings not cleaned when installed
4 bad airfilter or air leak
5. do you warm the engine up each time before you ride?
6. did not gap the rings
Don't aless blaim the engine builder when most of the time it is the rider or owner fault.

 

I will talk to him today and find out some more detail of exactly what happened. Thanks for your guys imput. I've never done much in the honda forum but you guys are great. Just because I own 2 polaris's doesn't mean I don't like honda. My quads need to be driven by family members and such so scramblers were the best way to go. I will always consider honda to be the most reliable machines ever. Anyway, just thought I would add that.