Problems with "80cc" Clutch

[Halifaxcycles]

I have a Zoom Bicycles Stealth Black 80cc kit. The Clutch isn't engaging properly after 400km of ridding on it, The Engine will start but oddly I don't have to pedal then drop the clutch to engage it, While the bike is stationary I can drop the clutch and it will start but the throttle has no impacted on it and it's a quiet spitting noise that the engine makes. I took the clutch cover off and removed the set screw and the star nut and checked the pads and everything looks in order to the best of my knowledge, the problem I think it's having is the small cog is slipping I can wheel the bike around with out holding in the clutch and and the larger cog obviously is turning because it's not locked by the small cog. So some advice on what to do asides from biffing it.

I am a bicycle mechanic and have access to all the tools of the non motorized trade, but My knowledge of motors and terminology isn't the greatest so apologies for that.

-Adam

[DudeZXT]

Sounds like you need to adjust your throttle cable. I would start with taking the throttle tube off the handlebar and inspect the plastic for damage.

If no damage then reassemble and take the top off the carb, where the throttle cable goes into it. Turn the throttle and watch for the plunger to go up and down. You should make sure the plunger is assembled correctly with the cable, that the needle is fixed to the plunger and that your c-clip is held down inside the top of the plunger.

Here's all the info you should ever need regarding the stock carburetor:
http://motorbicycling.com/f4/motoriz...stall-195.html

Thanks to Norman for his tutorials!

[GearNut]

After DudeZXT's post, I gotta ask: Will the engine rev up?

I think you were saying that is does start and rev fine, only the power is not getting to the rear wheel and the engine makes a funny sound.
Please clarify this?

[Halifaxcycles]

The engine starts it won't rev, and there's no power getting to the back wheel, both cogs under the cluch cover can be turned by hand without holding the clutch lever in, is that normal?

[GearNut]

It is possible to turn or wiggle the gears a little. If you can easily turn them around and around I don't see how they could transfer enough torque to start the engine.
The no revving problem is most likely carburetor related. Are you turning the choke off (lever down) before trying to rev up the engine?

[bairdco]

it doesn't sound like it's starting at all.

i don't understand the "...While the bike is stationary I can drop the clutch and it will start..." part.

the bike needs to be rolling, or at least the wheel needs to be spinning. it's like push starting a car.

when you say "...it's a quiet spitting noise that the engine makes..." are you sure it's not just the compression of the motor without running?

with the bike off and without the clutch lever pulled in, does the bike roll smoothly? it shouldn't. the wheel should skid, as it's fighting the resistance of the compression. with the lever pulled, it should roll, then "catch" as you release the lever.

if that's the case, you need to re-adjust your clutch cable till it grabs with the lever released.

[Halifaxcycles]

I don't think its a cable tension issue, the cable was working fine, and nothings changed or been altered. The bicycle can roll with the clutch not pulled in. So the part that stops this from happening is the issue and from the sounds of the feedback here is also the part that ...starts it as well. I suspect it has something to do with the small cog, does it have some adjustment, or is there some part that can strip or break behind it. The bicycle should have the rear wheel fully locked and skidding with the clutch not engaged, but it rolls and both larger cog and smaller one turn while rolling/ridding.

[Kevlarr]

Do you have a pull start because what you're describing is impossible unless you're starting the engine with a pull start. It sounds like you've had the key fall out of the small gear on the crank.

Either that or you've lost all compression and the motor will roll over with no resistance but then it wouldn't start.

Got pictures?

[Halifaxcycles]

I can get pictures, even video I suppose, what pictures would help?

[Halifaxcycles]

It's not a pull start, it's just a stock zoombicycles kit