burnt o-rings

[notsed]

well i was ot ridin the lake today and the shee started to run like crap and then it over heated. so i took it home and one spark plug was half out and on the other cylinder the o-ring for the dome was burnt out so i was burning coolant. it obviosly boiled over because of the o-ring but what causes them to do that? 21cc domes at 600' +4 timing on 94 octane 17 f jetted a lil rich. bad gas maybe? it was running at 120 f before it burnt all the coolant.

[Wildcardracing]

Detonation will cause the plugs to back out and cause the o-rings to burn. How old was the fuel? Bad gas will cause detonation because as it ages it slowly looses it's octane level. What are your other mods, temp and what size jets do you currently have in it? How do your piston crowns look? Both detonation and burning coolant will tear the pistons apart.

[brian]

Fuel slowly loses its octane level ?

Never heard of that before.

I have always noticed that it becomes slower burning and slower igniting.

It loses it's light ends over time.

 

I am not saying he doesn't have a detonation problem, just not convinced

that old fuel is the reason.

[SAVAGE420]

Takes atleast 6 months for fuel to 'go off' and it becomes really thick and gluey in consistency. It will also smell very different to good petrol.

 

Also, add a little bit of metho in your petrol to remove any water condensation that could be in the fuel after a month.

[notsed]

the fuel was only a week old, the jetting is 290 mains and 30 pilots on middle clip, plugs are black, i was running 260 27.5 in the summer and its about 20 f right now, everything looks good on the pistons so far im gonna tear it all down today