80cc bicycle kit "knocking sound" HELP

kevin2100 · #1 09-06-2010, 02:56 PM

i have a 80cc bicycle engine kit, and i noticed then when i ride the bike in neutral or engaged their is a loud "knocking" sound comming from the motor. It sounds like the sound is comming from the back of the motor where the clutch essambly is or the sprocket is. Im not sure what to do, i tried taking off the sprocket cover but to no avail. Who ever assembled the motor put the screws on way to tight and i cannot get the screws off, so i went to the clutch side with the gears and got that cover off but dont know where to go from their. I have a feeling that something is loose and needs to be tightened but not sure how to do it or what to do.

Nougat · #2 09-06-2010, 03:23 PM

Could be the drive chain banging on the inside of the left side cover, where the engine sprocket is. Get your hands on an impact driver, the kind you strike with a hammer, to get those loose.

kevin2100 · #3 09-06-2010, 04:01 PM

i think i will try that, i need to get those screws out either way. Thankyou for your response.

In the meen time i tried lubing up the chain and that seemed to help cut down on the noise.

Nougat · #4 09-06-2010, 07:27 PM

Might also be some sticky chain links, which could be banging in there too.

Once you get it off, you can dremel or file down the place where it's banging. Use a good chain lube and be liberal with spraying it on. Do it over a cardboard box or something, or you'll have a slippery spot in your driveway for a while.

Kevlarr · #5 09-06-2010, 08:44 PM

It's all that extra power wanting to get out.

How is your chain tension?

kevin2100 · #6 09-07-2010, 09:54 AM

i looked inside the sprocket cover and i see aluminum shavings i think the sprocket is hitting somwhere inside, i have a dremel so once i get it off im gunna try that idea, thankx for the response

kevin2100 · #7 09-07-2010, 09:56 AM

my chain tension is pretty good at the most the chain moves 1/2"

Allen_Wrench · #8 09-14-2010, 12:36 AM

Quote:

Originally Posted by kevin2100

i looked inside the sprocket cover and i see aluminum shavings i think the sprocket is hitting somwhere inside, i have a dremel so once i get it off im gunna try that idea, thankx for the response

I don't think it's the sprocket itself hitting anything (of course, if it were, that would be really bad). And it probably isn't Opportunity knocking either. I think it's your chain knocking around in there. Lubing the chain will help a little. Making sure the engine and drive sprocket are mounted in perfect allignment with the rear wheel (or as close as humanly possible) will help more. But you may have to get that cover off and examine it, see the place(s) where the chain is banging it, and maybe find a way to file or grind the "in-the-way" area back a bit, or down a bit, or whatever. Don't ruin the cover doing it, but you may be able to gain needed clearance this way.
(ADDITION

Oh, now I see the dremel suggestion. Well, yeah. Like he said

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