cardinalsfan
Scoot Member
Still learning and working on my scoot
Posts: 59 
Location: OKC
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Post by cardinalsfan on Apr 6, 2017 16:44:34 GMT -5
Got my new keihin carb installed the other day - went with 85 jet and pod air filter. Now it won't start. Was running fine with old carb. I could get it to start and run (after lots of tries) if I held the throttle at about 3k rpm but as soon as I let off it would die - and it wasn't dying from the idle setting.
When it did die I saw a puff of smoke from the air filter and it sounded like it backfired.
I did some research and I can think of 2 issues - valve adjustment or too much air. I will check the valves and I'll try running the stock air filter and see if that fixes anything.
Can anyone else think of anything to check?
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Post by spaz12 on Apr 6, 2017 16:48:29 GMT -5
Timing could be one tooth off. Not that I know anything about 4 strokes.
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Post by badpumpkin on Apr 6, 2017 16:53:12 GMT -5
First, is it a real keihin? If there is any doubt check out human shields thread on fake carbs. And now, is there gas getting to the carb,is spark plug wet. Is fuse good, run switch on, is plug sparking.
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Post by knobby on Apr 6, 2017 18:11:45 GMT -5
There are a lot carbs out there that say Keihin on them but aren't. I've seen some pilots that weren't even drilled all the way through. No hole at all.
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cardinalsfan
Scoot Member
Still learning and working on my scoot
Posts: 59
Location: OKC
|
Post by cardinalsfan on Apr 7, 2017 9:27:21 GMT -5
it's real, i bought it from one of the certified vendor guys that's been tested on the forum. I'm getting spark because I CAN get it to start eventually. Timing wouldn't have changed as I never messed with it.
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Post by matt2015taotao on Apr 7, 2017 9:54:50 GMT -5
I would put the stock intake/airbox back on. Its very easy to get too much air into these tiny engines and they will not run like that.
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cardinalsfan
Scoot Member
Still learning and working on my scoot
Posts: 59
Location: OKC
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Post by cardinalsfan on Apr 11, 2017 18:43:06 GMT -5
Ok I got some time to work on it today and I put the stock airbox back on and it was easier to start but as soon as I would let it from 3k rpm down to idle it would die.
I wonder if it's jetted too high? Gonna try the stock jet when I get a chance and if none of that works, back to the original carb and I'll just deal with it.
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Post by badpumpkin on Apr 13, 2017 8:49:48 GMT -5
What size engine, what size carb,what size jets. Oh I'm glad you got a real keihin and not fake.
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Post by oakleyscoot on Apr 13, 2017 11:34:48 GMT -5
The symptoms you mention IMHO suggest intake air leak.
Check from carb to head, with it running spray area with wd40 or some other aerosol and listen for engine speed change.
If rpms change this means intake leak.
Main jet size really has nothing to do with idle no matter its size, main jets come into play at around the 1/3 throttle area.
Pilot jet size does have effect on starting and below 1/3 throttle.
Airbox should not be an issue at idle either, it does / can cause issues at higher speeds by allowing too much air to be drawn in through the carb unless carb is jetted to accommodate the extra air allowed in.
my .02¢
P.S. The "puff" / pop you spoke of coming from the carb is also another symptom of a lean condition
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