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pro 785 plug fouling??

2281 Views 4 Replies 2 Participants Last post by  gsxr1216
my pro never fouled plugs till this season.. i finally got it running right after chasing a exhust manifold leak all season, now it runs GREAT pulls 7700+rpm but i have now fouled three plugs in the back cylinder??? i adjusted the high speed screws a little early season and my wash looks very good when i had the head off last week, but this no wake zone keeps fouling my rear plug. funny part is when i head out to the lake it doesnt foul, when i come back in at the end of the ride is when its fouling?? any ideas on how to solve this? i dont even remember if theres a low speed screws on these carbs??? i assume the screws on these carbs are air screws( IE turn screw open allows more air, runs leaner?) any help would be appreciated!
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You have a low speed fuel lean, out rich.

How's your throttle response? Just got mine running this weekend and I am still a little rich on the bottom, but not fouling plugs.

You might try leaning out the pto low speed a tad and see if that clears up that cylinder.
out is lean really?? find that funny since everyone says the pros are setup on the rich side from the factory and they have the screw in all the way on the high needle, so that means you could only go richer never leaner, thats odd.....

anyway my throttle response is pretty good once the water is blown out of the pipes from idling or wake zones, ETC. if you going along good clip and chop the throttle and get back on it after it slows down then it takes right off. I'll have to give that low speed a little turn.... just wondering why this problem is now arising after 4 seasons riding the same channel to the lake with no fouls..... compression is good on all cylinders, i have clipped the ends off my plug wires and "re-threaded" the boots on to make sure i had a good connection on all three. is leaner.

Pro's have fuel screws......not air screws.

Do you know what you have in for jetting?
Mine had stock jetting
170, 165, 170
85 pilots

high speeds were almost half turn out, and the low speeds were 1 3/4 out.

I put in 95 pilots per Randy's advice and turned the low speed in to 1 turn out, and it's awesome, just a touch rich.
stock jetting, but it has Vforce reeds and a hotseat billet head....
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