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Motorized Bicycle Trouble Shooting Use this area to post problems that may arise that you could use some help in figuring out what is wrong with their bicycle motor and what needs to be done to achieve top performance.

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  #1  
Old 06-27-2008, 01:46 PM
oldmanpaintball oldmanpaintball is offline
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Default jerking under 7 mph

when i engage the engine to turn over .it starts up but it jerks back and forth . i give it gas and its fine after 7mph .i can disengage the clutch and keep the motor in idle and rev it up fine .
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  #2  
Old 06-27-2008, 03:29 PM
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Bikeguy Joe Bikeguy Joe is offline
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Default Re: jerking under 7 mph

That's because 7 mph is too slow, go to ten or better before you let the engine do the work.
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Last edited by Bikeguy Joe; 06-27-2008 at 03:31 PM.
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Old 06-27-2008, 03:35 PM
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MrLarkins MrLarkins is offline
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Default Re: jerking under 7 mph

or get a larger rear sprocket
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Old 06-27-2008, 03:43 PM
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Default Re: jerking under 7 mph

I have one for sale...48T.
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Old 06-27-2008, 04:03 PM
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Default Re: jerking under 7 mph

7 mph is too slow? Crap, I was hoping to hardly have to pedal at all...
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Old 06-27-2008, 04:11 PM
oldmanpaintball oldmanpaintball is offline
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Default Re: jerking under 7 mph

if iam going down a hill and iam freewheeling down with the engine on .iam at the bottom now going around coasting when do i engage the motor .do i need to slow to 3-5 mph . whats the best way to approach this ?
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Old 06-27-2008, 09:29 PM
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Bikeguy Joe Bikeguy Joe is offline
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Default Re: jerking under 7 mph

I almost always coast going downhill (clutch pulled). I would just rev it up to meet the wheel speed when I was ready to re-engage the clutch. It's something you get a feel for, start at lower speeds when practicing.
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Old 06-29-2008, 12:46 PM
Skyliner70cc Skyliner70cc is offline
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Default Re: jerking under 7 mph

I don't recommend coasting downhill. Most bikes have some partial clutch engagement when the clutch is locked-you'll notice that the locked clutch position is not at the maximum point of clutch engagement. To check if this is your situation, start your bike and lock out your clutch. Pick up the rear of the bike to lift the tire off the ground and rev the engine. If the tire spins ever so slightly and it probably will while locked, it means that you may increase wear or glaze the clutch friction pucks if you coast down hill with it in the locked position. Check to see if the wheel spins with the clutch fully depressed by hand (not locked) and you'll see that it usually doesn't.

Yes, this occurs with a well adjusted clutch. If you try to completely disengage the clutch in the locked position, odds it won't fully engage or possibly slip when it is released for a start. THe situation worsens if you use one of those extra long levers.

There is no harm done in coasting down hill with engine engaged. If you need to go slower while in gear, then a 48, 50, or 55 tooth sprocket is your best bet.
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Old 06-29-2008, 01:20 PM
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Pablo Pablo is offline
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Default Re: jerking under 7 mph

Quote:
Originally Posted by jasonh View Post
7 mph is too slow? Crap, I was hoping to hardly have to pedal at all...
http://motorbicycling.com/f6/elimina...ocket-434.html
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Old 06-29-2008, 04:00 PM
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Bikeguy Joe Bikeguy Joe is offline
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Default Re: jerking under 7 mph

I've never had any problems with coasting- just pull in your well adjusted clutch and let gravity do the work. It doesn't hurt the clutch pads.

Now if your clutch is not adjusted right, it may cause a tiny microscopic amount of wear.

What is not recommended is prolonged periods of downhill, throttle off, clutch engaged "coasting".

...and why is that Mr. Skyliner?
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