Attachment 1718107855
Here is the plug. I have jetted the engine as fat as I could before it would loose power. I drill my jets so i dont know what size they are. Much larger than stock.
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Attachment 1718107855
Here is the plug. I have jetted the engine as fat as I could before it would loose power. I drill my jets so i dont know what size they are. Much larger than stock.
wow.from the pic that plug looks lean.it should be a tan/light brown color but that looks really clean,almost gray.what size carb are you running? when we had our malossi big bore 90 we had a 28mm with 140/45 combo and our ngk iridium 10eixplugs were always good.i always went a little fat on the fuel mix.rather replace plugs than rebuild engines.
It is the stock carb.. It is on the grey side. It does look lean. The quad has been driven on long trips before but this time was 3 min at best. Higher elevation at that . I I have tuned turbo cars and have lots of knowledge on tuning carbs but It does look lean. I don't know, as i stated I drilled the jets quite large and when it started to run worse I went back to the last jet. Perhaps I need to re tune, after I get a new cylinder and piston.
dump the stock carb.the stocker is 19mm and parts are non existent.i have a 28mm and a bunch of jets and I also have the malossi big bore 90 that's complete if you're interested.it's in the mini parts for sale section. make me an offer I can't refuse!!!!! it's just sitting btw,what pipe are you running??
I've seen this before.
IMO, compression dictates octane. You said it had high compression. 91 is crap for octane (let alone 89) when you have high comp.
Not enough octane and it detonated, thus the hole.
BIG debate on AV gas (100LL). Some love it. I doubt I'd run it.
I blew holes in pistons with AV gas on 12 lbs boost. Granted the tune was not right but when I got it right I run 94 and boost 17 lbs on a VW bug.
I have a hetric stage 2 pipe.
lt80 is right about compression but with the garbage in the pump gas today we ran 100 just for that fact.don't forget;if you can lessen the chance of detonation with a higher octane you can add more timing and with more timing comes more power so it's not necessarily just the fuel that's going to make the power.it's all in the tune
how do you advance the timing on a quad? I think i have a aftermarket CDI but don't remember.
Well I put on a new top end and it runs good. I removed the oil tank and premixd the fuel also put in 104 octane. I put in a new CDI box with high rev. I just need to tune the engine now. This time I will make the mix nice and fat.