Thread size for fuel screw

What is the thread size for the fuel mixture screw? I want to get a tap to clean out the threads, I removed an old alloy screw and am installing a new brass one from JD Jetting and it feels really tight and I want to clean out the treads, I think the alloy one may have left some material behind.

Thanks,

Jake

You should be able to measure the thread diameter of the new screw easily enough. After that, it's safe to assume it's an ISO thread. I can check one tonight if I remember. If I don't post it here, send me a PM to remind me of it.

Well, my metric thread gauge has gone for a walk, but what it looks like is an M6x0.75 fine thread. Double check it to be safe.

Alright gray, you got me to drag my sorry butt out to the shop and actually measure a fuel screw.

0.5 X 6 mm but the fit did not seem perfect to my bad eyes. A .6 was def. wrong as was a .4

Alright gray, you got me to drag my sorry butt out to the shop and actually measure a fuel screw.

0.5 X 6 mm but the fit did not seem perfect to my bad eyes. A .6 was def. wrong as was a .4

I was thinking it looked more like a 0.5 pitch than an 0.75, but that would make it a "special" thread (not that it couldn't be). Using a magnifier and calipers to gauge the pitch, it did look like about 0.5, but the 36 TPI gauge was pretty close, too.

I think you may be right. M6x0.5. Tough to find a tap, most likely.

Thanks everybody, I might just live with it being a little tight, better than too loose! :thumbsup:

Jake

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