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Post by rcq92130 on Sept 12, 2014 20:08:10 GMT -5
OK. have the new 30mm pumper carb set up with 38 pilot and 120 main (that's all I have - except for a smaller 35 pilot and a huge 130 main (plus smaller mains).
Will install it tomorrow and just for yuks see what happens, though i don't expect any improvement till the new coil arrives on Tuesday.
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New Rider
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Joined: Mar 4, 2013 3:38:11 GMT -5
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Post by Moat on Sept 13, 2014 1:08:27 GMT -5
Will install it tomorrow and just for yuks see what happens... Well, ya never know... could very well cure it! Please keep us posted on how it does... Bob |
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Post by rcq92130 on Sept 13, 2014 9:51:35 GMT -5
Thanks, Moat & GEH!
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Post by rcq92130 on Sept 13, 2014 17:31:58 GMT -5
OK I'm hoping Moat , or geh3333, JerryScript or alleyoop, will still help out 'cause i think things have changed (for the better)! New (30mm) carb is in and working. Do not yet have the new coil. Much, much better! Have not done a thing to tune, but it just might be that tuning is all that is now needed. Starts OK. Sudden WOT (on the stand) gives good, rapid, smooth RPM climb ---- up till about 5000 RPM. Then it bogs and does not want to go higher. BUT ~~~~ if I back off to about 3/4 throttle the thing get's it's legs back and accellerates suddenly to 7000 (where i stop - new piston rings). Slight pop or two when throttle is released and engine coasts back to idle. Too rich? Have 38 pilot and 120 main. I have a 35 pilot and a 120 main if those are what is needed. |
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Post by JerryScript on Sept 13, 2014 20:57:00 GMT -5
If you are accelerating, and it bogs, and you let off a bit on the throttle, and then it picks up (not settles down), it is too lean. Backfiring is also often an indication of too lean. The larger carb automatically sucks in more air, so you need to be sure it is feeding more fuel. Alleyoop has written an excellent tutorial on tuning a 4 stroke carb: Alleyoop's 4T carb tuning instructions |
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Post by rcq92130 on Sept 13, 2014 22:09:57 GMT -5
Thanks, Jerry.
Alley sent that to me last week when I was playing with the old 24mm carb (unsuccessfully).
Before doing these fine adjustments, I was wondering if I should rejet the carb with bigger or smaller jets.
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Post by JerryScript on Sept 13, 2014 22:18:34 GMT -5
I would recommend you begin by adjusting the a/f screw. If that doesn't work, try raising the needle (lowering the clip), and then re-adjust your a/f screw. If you raise the needle all the way and it still seems lean, then it's time to upjet.
BTW- Alleyoop and several others here are very good at diagnosing based on sounds. If you can post a video with decent sound while revving the engine, they may be able to help.
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