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01cr80

pinging at 1/4 throttle roll on

9 posts in this topic

i got my 1993 cr250 out for the first time this weekend and it was running good but was a little boggy off idle. I have the jd kit and according to it all you should ever change is the needle and maybe the main. So i changed the blue needle 3rd pos clip to the red one which is leaner 0-1/4 throttle, 3rd clip pos, and air screw best at 2 turns out. And now the bike runs amazing! no bogging anywhere and very very crisp through all rpms. But, when the motor is under load it pings 7-15 times like when you are going up a hill in too high of a gear. At least im 90% sure its pinging. It sounds like a metallic sound but i have to listen hard to hear it. No power difference or any difference in the way it runs, just the noise. So i went back to the needle it had before which is slightly richer and it runs like crap but the pinging is mostly gone, very boggy and cannot get the air screw set right, it needs to be 4+ turns out to even idle. So i went back to the red (leaner) needle and tried some 110 sunoco race fuel from my grandpas late model. Its not there as much but it still pings a little. So idk if i need to change the main jet or what but im lost. Any help will be appreciated!!

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You may have an air leak. Check your stator side crankshaft seal. My 125 was doing that when the crankshaft seal was blown.

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Main jet is barely coming in at 1/4 throttle so I don't think that's it. Did you try the stock needle? I would give that a shot and play with the needle clip.

KeihinPJPWKCircuit_Needle.jpg

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i forgot to mention it has a pwk airstryker off a 99 cr250 and the jetting was very far off with the stock jetting so i bought the jd kit and have it pretty close now besides the pinging

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Maybe leave the blue needle in but go i clip position down, richening the mixture just a little but enough?

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tried that and it still runs like crap...i rode it yesterday for a while and there was no pinging so i might just leave it alone for a while

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thats what i just did, half 110 octaine sunoco and half 91 pump gas, no pinging yet!!

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Have you checked timing? If timing is right, and it sounds like your jetting is pretty close, then I would reduce compression with a little head work. Pre-detonation is hard on bearings, and running race gas is inconvenient imo.

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