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Post by magoconnor on Jul 15, 2019 23:56:32 GMT -5
Hello. How does this spark plug look to you? The bike runs okay, with only slight hesitation between 6k and 7k rpms. The needle is in the middle position, I've tried moving the clip all the way down, but then I could not get the bike to idle. It was waaay too rich. Main jet 110 idle jet 28 The picture was taken right after a 30min trip. Spark plug type : c8rhsa Setup 90cc + bvh 20mm carb pod filter leovince exhaust  |
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lupo76
Scoot Enthusiast
Posts: 157
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Post by lupo76 on Jul 16, 2019 3:56:30 GMT -5
Hard to tell. Black outside is indicator for good jetting, but white isolator is indicator for too lean.
Ride WOT for a while and then check again. Then adjust main jet.
Ride a while half to 3/4 throttle, then adjust needle position.
There is no "mixed riding" for jetting if you want to do it properly.
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Post by magoconnor on Jul 16, 2019 9:00:16 GMT -5
Yes its hard to tell. On one site I looked up, it said that if the base ring was black all the way around, it meant it was running rich, regardles of the insolator being bone white. But im not sure... I tried poppin in a 116 main jet, and the bike just felt weird, like it needed an extra set of teeth, to chew that much fuel.  I just want it to make sure i did not run with an extreamly lean setting, that would damage the engine. The picture was taken after a wot run, at the end of a 30min trip. |
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Post by dexameth on Jul 16, 2019 9:31:04 GMT -5
If you moved the needle clip down, and it wouldn't idle... could you then turn the A/F screw in to re-adjust the idle?
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Post by magoconnor on Jul 16, 2019 9:52:10 GMT -5
Yes, when I moved all the way down, now its in the middle.
I had the A/F screw out 2 turns, but the idle was crazy high, and the idle screw did not do much.
Its now 1 turn out.
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Post by GrumpyUnk on Jul 16, 2019 13:47:41 GMT -5
MAG:"I had the A/F screw out 2 turns, but the idle was crazy high, and the idle screw did not do much."
I suspect you were into the 'bottom end' of the midrange carb circuits. 90GT has a series on how to adjust carb settings if you were unaware.
When you have a too-high idle, my suggestion would be to back off the 'hard stop' screw for the throttle plate, engine running. The idle should drop, and the carb start to feed from the idle circuit. A LOT easier to slow down into the idle circuit than trying to get a cold engine to start and run on idle when it needs adjustment. A warmed engine will run more readily on 'goofed' idle mix/airflow settings than a cold one. It lets you get started on adjusting without having to re-start all the time. In my opinion.
tom
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