Comments on plug color

Zingzing29

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Oct 26, 2021
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I have checked for air leaks, but haven't checked the float level yet. That's a tomorrow job.

It has a tendency to idle high after long periods of 3/4 throttle. But if I do short runs (500ft / 1000ft) it drops back to normal idle. It's only after long runs of maybe 3 or 4 miles at 3/4 throttle the idle stays high for awhile. Idk. I've shoved the damn carb into the intake tube using a pry bar while tightening it down so I doubt there's and air leak there. Also I made my own intake gasket and applied alight coating of gasket sealer. Like I've done with almost every car I've ever owned and never had intake problems so I doubt that's it.

EDIT: I also check the torque of the intake bolts and exhaust bolts before I take her out to make sure they're not loose.
How long have. You been riding the bike check your fuel filter and line I always change them out for black rubber hoes check the screen in you gas tank to. Bikes have a hot cold thing to if you run hot wot open that's how it'll runn you run it ccold and rich in mids it idle fine. Probably has something to do with crank case volume and stuff.
 

Zingzing29

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So what's with the knocking Im getting after prolonged WOT. My plug fouls out from the 30 pilot. So it takes about a mile for it to burn it all off before I start get power. It'll run good for about 15mins a few miles before I start getting some knocking. Only around 3/4 throttle and more at higher speeds once it hot it doesn't have much trouble getting there but no fast than 35. The main 70 and reads rich carbon fouled dark enough for the smoke ring not to show and far enough in to not be visible. Dark brown with carbon on the prongs. My guess is heat and carbon build up or a combination of a. Colder plug and a leaner jet. I do know you all take some timing out but I'm not try to do that not yet. I think the stock exhaust isn't let exaust gas and heat out quick enough and being rich and carbon foul?
 

Zingzing29

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Oct 26, 2021
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That about how the plug looks after the main. I dropped the needle and it seems to stall a bit now acceleration is nice and smooth to 1/4 then gets a bit blubbery if I don't continue a little goes away almost entirely after that with the needle lower. I'll have. To increase the idle a. Bit more I turned it down a tad because it idled slightly higher. That a plug the from running under 1/2 throttle for a couple minutes. 30 pilot annd 70 main. That main check looks similar to below if I let it idle for a few minutes it cools and fouls out it still runs fine just loose top end power until I run it a mile or so. Remarks?
 

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Karl Snarl

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Sep 20, 2019
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So what's with the knocking Im getting after prolonged WOT. My plug fouls out from the 30 pilot. So it takes about a mile for it to burn it all off before I start get power. It'll run good for about 15mins a few miles before I start getting some knocking. Only around 3/4 throttle and more at higher speeds once it hot it doesn't have much trouble getting there but no fast than 35. The main 70 and reads rich carbon fouled dark enough for the smoke ring not to show and far enough in to not be visible. Dark brown with carbon on the prongs. My guess is heat and carbon build up or a combination of a. Colder plug and a leaner jet. I do know you all take some timing out but I'm not try to do that not yet. I think the stock exhaust isn't let exaust gas and heat out quick enough and being rich and carbon foul?
If it is knocking, you are hitting the head gasket, the head, or have a bad bearing on the con rod somewhere. You won't hear detonation on these engines unless you know what to listen for. An that takes years of experience to nail down. These engines are just way to loud to hear detonation on without a ton of engine experience under your belt. You may be hearing the intake sound. The intake on these bikes is just loud as heck, sounds like popcorn. Build an air box and it will go away if that's what you are hearing.
 

Zingzing29

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You know I've noticed weed whips make the same noise when under light load short string. It's not a rapid knock. If I go to 3/4 throttle then back to full it goes away until the load levels out and the engine and. The engine is under constant load at constant. Rpm
 

Zingzing29

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Oct 26, 2021
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285
I can't see it hitting the head unless the squish needs to be reworked or enlarged. Even then I dont think the problem would only occur then and there would be more knocking other than during prolonged throttle. Just saying
 

Karl Snarl

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You know I've noticed weed whips make the same noise when under light load short string. It's not a rapid knock. If I go to 3/4 throttle then back to full it goes away until the load levels out and the engine and. The engine is under constant load at constant. Rpm
It's called four stroking and normal on a 2 stroke, and needed. I highly suggest you study the operation of a two stoke further before doing any more changes on your engine.
 

ImpulseRocket89

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Apr 16, 2014
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Just my 2 cents to start with, all carb tuning and adjustments need to be done with the engine at operating temp. Trying to judge fueling on a cool motor is a waste of time.

I would suggest you go back and sort out the pilot jet first. Get the idle fueling dialed in and then the pilot jet fueling (up to but not beyond 1/4 throttle" figured out.

Once you have the idle mixture and pilot jet sorted, leave the needle where it is for now and then sort out the main jet. Why? It's the second easiest jet to figure out since it only majorly affects the fueling beyond 3/4 to wide open, especially 7/8 to wide open.

It's a good idea to have a few clean, new plugs handy for doing this type of work. Not because they go bad, but because starting with a clean plug when doing a plug chop to check fueling helps ensure you eliminate many of the other variables. A Proper plug chop also means you hold it in that throttle position for several seconds. Some people say minutes, but I have found that, at least for wide open tuning, is a bit unreasonable. 10-20 seconds is often enough to get a good idea if you cut the ignition and throttle properly. Obviously the longer you can hold it the better.

Once you have the pilot and main sorted now you can finish with tweaking the part throttle tune with the needle position.

Whatever you do, be very mindful of how tight you tighten the plug on a hot engine. Stick to finger tight plus 1/8th of a turn so you don't strip the threads in the aluminum.
 
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