why detonation?

[MagicJames]

What is detonation?

I have a 85 250r, cut head and all the goodies and I ran out of gas last weekend. I got towed to the next parking lot and while we were there, some guys asked me if I wanted to barrow some fuel. I knew that I ran 110 octane with synthetic MC1 and the guy had R50 with 93 octane fuel. I was iffy on taking it but decided to run with it.

20 minutes later riding down the trail every time I got to the top of the revs I could hear detonation. I didn't ride wide open very much because my buddy in front of me had a cracked frame and was worried about crashing.

When we got back to the trucks, I drained all the fuel out of my tank and carb and refilled it with my 110 fuel and ran it back up and down the trail and the detonation was gone, so I was like phew.

What kind of things might I damaged? Should I change the rings?

I am investing in an oversize tank to keep from this problem.

Apparently I can't ride for 6 hours without running out of gas. Hahahahaha

[fabiodriven]

I'm pretty sure detonation is the sound of the expanding burning fuel slapping off the top of the piston before the piston has reached TDC (top dead center). This condition is called "Pre ignition". It is very bad for your engine because it is like smacking the top of the piston with a as it's on its way up. It is very common in engines with higher compression, that's why you have to run race gas. Exactly why the lower octane gas ignites prematurely I could not tell you. That's a bit above my paygrade. I know I have heard it before, but I can't think of it.

[Dammit!]

The lower the octane, the lower the ignition point. The added heat created by increased compression causes lower octane fuel to ignite before it's supposed to.

[fabiodriven]

The lower the octane, the lower the ignition point. The added heat created by increased compression causes lower octane fuel to ignite before it's supposed to.

Thank you . There ya go.

[MagicJames]

So I should tear my top end apart and look at the piston or just say freebird and keep riding ???

[fabiodriven]

If it were mine I'd just run it. A little detonation here and there isn't going to just blow it up. You might just wanna peek in the spark plug hole right quick.

[dcreel]

If it were mine I'd just run it. A little detonation here and there isn't going to just blow it up. You might just wanna peek in the spark plug hole right quick.

I agree with fabiodriven. Take a peak in the exhaust port or the spark plug hole if you want to. If its doing alright now.. no weird noises. run it.