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Post by mojo89 on May 9, 2014 19:48:14 GMT -5
My scooter ran great for about a mile after I started it the night this issue cropped up. I stopped at a light, and when I pulled the throttle on the green light, the engine died.
It starts up just fine with electric and kick starter, idles beautifully, but once I give it throttle to rev up and go, it bogs down and cuts out right around the rpm where my clutch engages if I don't lay off the gas.
I disassembled the carb itself and also air box to check jets and passages for any gunk or blockage; valves are set at .05; vacuum and fuel lines are all good.
I'm running aftermarket cdi, coil, cvt, exhaust, and upgraded from 50cc to 60cc cylinder, but the rest of it is stock. Put about 15,000 km on it since last feb.
I will recheck the valves, as they are still fairly new. Also will recheck the accelerator pump and main fuel jet.
Any other ideas?
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Post by JerryScript on May 9, 2014 23:14:26 GMT -5
Shot in the dark here, did you check your diaphragm when you disassembled the carb?
What happens when you have it on the stand and you give it throttle and hold it? Can you do quick twist & release on the throttle and have fast response in RPM going up and back down?
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Post by mojo89 on May 10, 2014 19:04:59 GMT -5
Diaphragm seemed ok, no rips holes or hardening. Anything else to watch out for?
If I open throttle all the way for even a second it dies right away, rpm drop off once I give enough gas for more than 1000(guess) but if I let go before it dies it will get back up to idle.
Think I'll try using a different carb to process-of-elimination the whole thing but if it is I still want to fix it.
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Post by JerryScript on May 10, 2014 20:23:34 GMT -5
Generally speaking, if you bog while increasing throttle, then let off the throttle a bit and it picks back up, that's a lean condition. Since this came on all of a sudden, I would suspect an air leak somewhere.
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Post by alleyoop on May 10, 2014 20:29:49 GMT -5
Turn your fuel ratio mixture screw Clockwise until it stops then turn it out 2 1/2 turns and see if it is better. Your lean for some reason and you may have put the carb back together wrong. Check to see if the Needle Guide is sticking up in the Venture about 1/8 of an inch.
Alleyoop
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Post by mojo89 on May 14, 2014 15:49:42 GMT -5
I'm about to check my intake manifold and vacuum system, check valves, and check my carb's settings and integrity; if it doesn't run after that, I will begin replacing the air filter, then the carb. This thing WILL work again.
Here's a video of the problem, look forward to posting one of the solution!
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Post by mojo89 on May 14, 2014 18:33:08 GMT -5
Valve gaps good at .05mm, vacuum lines and intake manifold still good, my carb is taotao atm50 stock and has no fuel/air mixture screw, replaced entire air filter housing.
Nothing helping performance so far. I'm a little loathe to put on a brand new carb in case I'm missing something, I'm disassembling and reassembling my old one once more first.
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Post by mojo89 on May 14, 2014 18:44:17 GMT -5
I mispoke earlier; if I pull my throttle all the way open and release it immediately, it revs like normal and goes back to idle just like it would when it's running correctly. Only when I hold throttle open does it bog. Where else can air leak? Or fuel blockage? Fuel and vacuum lines, fuel filter, and carb have a good 15k km on them, they are original stock parts.
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Post by alleyoop on May 14, 2014 20:22:55 GMT -5
Check the Diaphgarm it may have rips in it.
Alleyoop
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Post by mojo89 on May 15, 2014 20:32:54 GMT -5
Cleaned my carb, only issues I saw were the float bowl and autochoke gaskets being somewhat old. I reassembled and ran my bike, no changes. Have to see what a whole new carb will do if I don't have any other ideas by tomorrow.
If it matters, I upgraded my piston, cylinder, and head a couple hundred miles ago, used a 60cc cylinder and piston. Transmission upgraded slightly last november. It ran great with the upgrades; I replaced the exhaust, cdi, coil, and spark plug early last year as well. Got 100 mpg and cruised at 35(no hill or wind, ~75% throttle) with the 60cc. It's not even fully broken in yet.
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Post by alleyoop on May 15, 2014 20:57:51 GMT -5
You need more gas and your carb has the fuel ratio plugged so you cannot adjust anything. So either drill out the plug and turn the fuel ratio counter clockwise to feed it more fuel and also you need to up jet the carbs main jet if you slapped in a 63bbk. The motor needs more fuel.
Alleyoop
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Post by alleyoop on May 15, 2014 20:59:06 GMT -5
You need more gas and your carb has the fuel ratio plugged so you cannot adjust anything. So either drill out the plug and turn the fuel ratio counter clockwise to feed it more fuel or buy a carb the same size with the screw available and also you need to up jet the carbs main jet if you slapped in a 63bbk, the motor needs more fuel at WOT.
Alleyoop
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Post by mojo89 on May 16, 2014 12:07:08 GMT -5
My new carb has the fuel screw. I'll throw it on and hope that does it
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Post by mojo89 on May 18, 2014 18:17:15 GMT -5
Put the new carb on and it runs great again. Same size as my stock carb, got it from my local taotao distribution center; it has a better throttle cable guide and a fuel/air screw that isn't sealed, though I don't know if jets are the same inside. The reason I put a 60cc piston on was because my original one lost compression one day, I posted about it back in january. Had to use a 60 because the distribution center didn't have any 50's for some reason. I didn't have to change the carb at all when I got the 60 for it to run.
Thanks for all the advice, knowledge, and wisdom, much respect and love for you all and your bikes. Ride on
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Post by mojo89 on May 19, 2014 7:28:12 GMT -5
I'm getting lots more power out of my scoot now, it's taking off faster than most traffic and keeping up all the way to 30. It'll pull pretty well to 35 and slowly up to 40, people are asking what I did lol
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..BAD TO THE BONE..