blown 125

[lukesh40]

Looks like I blew out the top end in my 01' YZ125 the other day out here in the Oregon sand dunes. Never ridin' sand before and I'm wondering if maybe it put too much of a load on my little small bore. I had a paddle on the rear. 6th gear pinned across the beach and the bike bogged and shut off. There was oil all over the swing arm that came out of the exhaust due to the blown piston rings. Pulled off the head and noticed there are some small carbon deposits on the very top side of the cylinder where the piston is totally shot. I had a similiar problem about 15 hours ago and I had the motor professionally rebuilt (top end) and the cylinder honed as well as some work done on the head. The mechanic said my head was warped, but i thought he was able to smooth it out. Maybe I need a new head? Im thinking this could be why I blew out the top end so quickly but I'm not sure. Are the dunes maybe just too much for a 125? Any opinions appreciated.

 

[Xtremesports445]

6th gear pinned across the beach

if you did that for long at all then thats why it blew so quickly.

 

[FloGreen245]

Dude, you've got to change your jetting before riding at sea level. When you pinned it on the beach, your bike's fuel-air mixture was lean and got way too much air for the amount of gas. You've got to jet it richer (less air, more fuel).

 

[lukesh40]

Yeah, i guess that makes sense and I thought about it before coming out to Oregon but I live near the shore on the east coast and figured it would be the same. I guess I should have looked into it more though. I replaced the top end and was told by the guys at the local shop out here that riding a 125 in the sand is just asking for a blown motor.

 

[Oldman125]

What do you mean its "Blown"? Is there a hole in the piston crown? Did the rod break? Are the rings cracked?

Or did it just seize?

Got any pics of the disassembled engine?

Sand...a 125 (WFO no less) and incorect jetting isn't a good combination pal.