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Engine turns over but no start

Use this area to post problems that may arise, if you could use some help in figuring out what is wrong with your bicycle motor and what needs to be done to achieve top performance.


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  #1  
Old 03-02-2013, 12:46 PM
Damian84 Damian84 is offline
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Default Engine turns over but no start

I have the GT-5 Skyhawk with the cns carb and HD Shift kit. I am Having issues with the motor starting. I can get it to turn over repeatedly with clutch lever out, but will not fire up. I checked the CDI and checked for spark, no issues there. I am pretty good at tuning the CNS carb, so i do not believe that it is the issue. I know you have to pedal through with the shift kit. I am at a loss. Any suggestions?
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Old 03-02-2013, 01:48 PM
crassius crassius is offline
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Default Re: Engine turns over but no start

If this motor is new, it may take some pretty fast pedaling and some choke to get the first start out of it.
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Old 03-02-2013, 01:54 PM
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Kioshk Kioshk is offline
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Default Re: Engine turns over but no start

It's probably the CNS...throw it out and get an NT Speed.


kiddin'...just trying to cause a $#!+storm!

Is this a brand new engine? Never run at all? Buncha different things could be going on here. You sure the bowl's getting fuel? Enrichment jet position? Standard mainjet? Compression good? Head-nuts tight?
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Old 03-02-2013, 03:30 PM
nightcruiser nightcruiser is offline
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Default Re: Engine turns over but no start

I would start out by pulling the plug and looking for evidence of fuel. If none then look for reasons fuel would not be flowing. If the plug is wet with fuel then dry it off and reinstall and give her another try. After that I would check for spark. If you have spark and fuel, that's half the battle, now you just need compression and air... If this isn't your first motorized bicycle you should be able to tell if you have compression by listening/feeling the resistance of the motor when you turn it over.

It never hurts to try a different spark plug, most kits come with a spare, or even better try an NGK BP6HS or there is an E3 plug that Home Depot carries that works pretty good too.... I forget the E3 number, but if you need it I can dig up the plug I have in the garage that I tested and found it to run well, IMHO it was not quite as good as the NGK BP6HS so I changed back, but it did run well. I had to mail order the NGK plugs, so the E3 from home depot or the lawn mower section of any good hardware store may be the easiest plug to source....
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Old 03-02-2013, 11:36 PM
Damian84 Damian84 is offline
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Default Re: Engine turns over but no start

Thanks for feed back. finally home from work. now to get this mutha runnin!! All components are bran' spankin new! I got it to start once. Had it on a center mount double kick stand and a rear axle bike stand so the rear wheel is free. Pedaling like a mad man and one hella down trust and release of the clutch got it going with some follow through pedaling! The back tire kept spinning a little, and was reving high. So i got off and tried to tune in the idle with the idle screw. almost had it, then it died... Its brand new and got it started once. now i can not repeat it.

I have spark on the plug NGK B8S, its band new its petty dry, but i can smell gas inside the piston head walls. pretty sure compression is good, makes the chug chug sound when cluth is released. I have the high compression performance slant head from pirate cycles made for the GT-5. but had to add another gasket to get the piston to turn over with the spark plug in. I have gas in the float bowl, i know because of so many triest start it, i was worried i would flood the motor, so i emptied it from the bottom drain. due to my frame and mounting options i am using an offset intake. I had it modified and rewelded so that the carb sat pretty level. And had the reworked intake vaccume checked for leaks...no leaks. still stumped! gonna mess with carb setting tonight. when i tried to start it with cluth lever released it sounded more throaty than with the clutch pulled in. and when i gave it a little throttle with the cluth lever released it got even more throaty. haha. dont know if that makes sense to anyone else.
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Old 03-03-2013, 02:24 AM
Damian84 Damian84 is offline
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Default Re: Engine turns over but no start

So I went back through everything through process of elimination. What got it going was removing the kill switch. Fired right up. but i want the kill switch!! i had the black wire from the kill switch connected to the black wire of the CDI and the black wire from the motor. the red wire from the kill switch connected to the blue wire from the CDI and blue wire from the motor. I got this wiring method from another post. I also tried it with the black wires together and the red connected to the white, per manufacture manual, this was not workin either. I really want the kill switch workin'!! Any ideas anyone?? Sweet thing is...she sounds awesome!! purrin like a lion!
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  #7  
Old 03-03-2013, 03:25 AM
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Kioshk Kioshk is offline
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Default Re: Engine turns over but no start

If your motor's working now, and your kill-switch was connected to the CDI's terminals, then the kill-switch is shorted. Invest in a multimeter and check the switch; split the throttle housing and inspect the switch's soldered terminals. The kill-switch's wire-colors mean nothing (they shoulda just made 'em both black IMHO). Now, you stated that you HAD a spark...if the kill-switch was shorted, you WOULDN'T have. Did you insulate the CDI/Mag/Switch connection-points? Is it possible the blue-wire point was exposed and touching the ground, or your frame, and by disconnecting the switch you inadvertently corrected it? Judging by your pimped-out ground-effects lighting, I have to assume you have a least enough electrical marbles to figure out the KS.
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  #8  
Old 03-03-2013, 03:37 AM
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Kioshk Kioshk is offline
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Default Re: Engine turns over but no start

I just re-read your last post: when you connected the KS to the mag's white-wire, was the CDI still connected to the blue/blue? If so, even if the KS is defective, the engine should still have started = crappy wiring job elsewhere. Get those wires away from the exhaust-header, and protect 'em from your mounting-clamp; that's got "HI! I'M A GROUND!" all over it.
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Old 03-03-2013, 07:56 AM
Damian84 Damian84 is offline
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Default Re: Engine turns over but no start

word. thanks for all the info and tips. everyone and this site is very helpful!!
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