My 2000 XRL has the typical mods, I recently put a big bore piston in and all seems well, it starts well cold or hot, it idles great, motor is quiet and smooth, its running super until I really horse on it. If I give throttle a crack the motor is still good, it will maintain speed slow or fast but when I go full twist on the throttle I can hear the motor pinging, this only happens when full or almost full throttle. I am running high test fuel, piston is 10 1/2 compression(103mm). I am going to try some octane boost next, not sure of jetting from PO but plug looks great and its running fantastic until wide open throttle. Any suggestions? Also running factory cam.       Don

Stock CDI module?  I haven't heard any timing issues with them but I have with some of the aftermarket replacements.

carb too lean. do a search on the topic in this forum. lots of discussion.

What main jet to you have in there?


I have a 10.5:1 compression piston in mine and run a 158 main, which is one step richer than I would use with lower compression.  I haven't heard any pinging from it using the 87 octane stuff we get in California.

If you try octane booster get the Klotz booster , it is one of the few that is petroleum based and not just alcohol . I believe Lucas is also petroleum based. It takes quite a bit of the stuff to really add any % to a tank of gas with all boosters , thus why it's better to use one that is actually gas not just alcohol (which absorbs water).

Edited by jjktmrider

Shouldn't need octane booster with a 10.5 piston. I'd go with running lean.

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