83 xlr600 detonating

hi there

my 83 xlr600 detonates when under heavy load as in trying to accelerate from cruising in a higher gear or when pulling wheelies does anybody know wat the problem may be i run it on 91 octane fuel and it has a dpr8ea-9 which is the best ive tryed with it, it also starts and runs perfectly except under heavy load the noise is a heavy knocking like the piston trying to slap and was wondering if anyone had experienced this and had a fix for it thanks

Casey lyons

'83 xlr600



My first thought is to check your timing.

Has the bike just started doing this?

I'd check the jetting first, sounds lean. You're on the right track a cooler spark plug does help.

i have checked both cam and ignition timing and are all fine, it may be the mixture but would usualy lean out all the time not just under extreme load ill put a gas analyser on it to check jetting also i was going to run some avgas(avaiation fuel) in it to see if it runs better on a higher octane fuel as the head could have been machined before i bought it any other help or ideas would be much appreciated


casey lyons

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