Jerky clutch

[nightcruiser]

DO you have any problems with the chain/sprocket at higher speeds, or is it just when you are moving slow?
I once had a jerky slow ride on my bike, had the original cheap chain, changed to a quality #41 chain, that didn't fix the rough ride. It did stop my chain problems, but slow riding was still jerky.
You had commented about having a hard time maintaining idle on this motor, once again I will say, if your motor is not running smooth then your ride will be rough! When my motor ran like crap at low RPM my ride was all kinds of jerky, at higher speeds the motor ran smoother and jerkyness went away. Think about it, your motor sprocket is chained directly to your wheel sprocket, if the motor sprocket is spinning rough (not turning at a smooth steady speed) then it is gonna jerk on your wheel and make your ride jerky. Once I got my motor running right at low RPM all the jerking stopped for me, if your bike sounds like it is snapping and poping until it reaches a higher RPM (then it smooths out) your ride is gonna be rough.

 

[vincent713]

DO you have any problems with the chain/sprocket at higher speeds, or is it just when you are moving slow?
I once had a jerky slow ride on my bike, had the original cheap chain, changed to a quality #41 chain, that didn't fix the rough ride. It did stop my chain problems, but slow riding was still jerky.
You had commented about having a hard time maintaining idle on this motor, once again I will say, if your motor is not running smooth then your ride will be rough! When my motor ran like crap at low RPM my ride was all kinds of jerky, at higher speeds the motor ran smoother and jerkyness went away. Think about it, your motor sprocket is chained directly to your wheel sprocket, if the motor sprocket is spinning rough (not turning at a smooth steady speed) then it is gonna jerk on your wheel and make your ride jerky. Once I got my motor running right at low RPM all the jerking stopped for me, if your bike sounds like it is snapping and poping until it reaches a higher RPM (then it smooths out) your ride is gonna be rough.

I don't have any issues when I'm at high speed, only jerks when I'm at low speed. I Will take out the drive sprocket cover and see if there are issues. Thanks for the help.

 

[DuctTapedGoat]

Actually - another thing you can do is richen to the fuel to air mix by adjusting the needle clip and/or rejetting.

 

[nightcruiser]

Getting these little motors running right can be tricky sometimes, more so if you have the CNS carb. Since you have the more basic carb yours should need less tuning, but if she runs rough then tuning should be done...
The whole air/fuel system is quite a balance, picture this. The piston pulls down making suction, the suction draws air and fuel through little holes and jets that are all balanced so the right amount of air and fuel come through each orface. The air filter and muffler dampen the whole system, one little change in any of it (or a little air leak or spec of debres in a jet) and the whole system is out of whack.
It seems your carb needs to be tuned better for the lower throttle range, to do this we need to figure out what cause of the rough running is in that throttle range. I would warm the bike up, then run it a bit in that rough throttle range and do a plug chop. (Simultaniously kill motor, pull clutch and let go of throttle) After the motor has cooled pull the plug and take a look at it, let us know if it is white, or brown, wet or dry etc. From there you can figure out how to give it less or more fuel, or air, whatever it is needing in that throttle range.
Since you have only one jet in the NT carb you could just kinda guess at whether you are lean or rich and adjust the needle, move toward the pointed end to richen the mix and away to lean it up. You also want to make sure you dont have any air leaks on the exhaust/intake manifold, and where the carb mates with the intake. Make sure your air fillter is clean and not oil soaked.
The solution to your problem most likely lies in some minor tweaks to the air/fuel system.
On the clutch, I didn't follow all that stuff very closely cause I dont have the centrifical clutch myself, but if the three screws on the clutch wheel are rubbing on the gear cover plate then you might need to crank down the nut the holds your drive sprocket on the motor. I had problems with a clutch once, had that rubbing, when I tightened that nut the whole clutch shaft pulled out a bit. The rubbing stopped and the clutch action got lots better. Do yourself a favor and go buy a big socket that fits that nut instead of using the spark plug tool, when I put a real socket wrench on there I got quite a bit more turns on that nut....

 

[nightcruiser]

I don't have any issues when I'm at high speed, only jerks when I'm at low speed. I Will take out the drive sprocket cover and see if there are issues. Thanks for the help.

Hey man, I dont know how many ways I can say this to you. I really think your drive sprocket, chain, clutch, all that stuff, probably has nothing at all to do with why your ride is jerky.....

I suspect your ride is jerky because the motor is not running smoothly, the only way you are going to make your ride smooth out is to make your motor run smoother.

Think of it this way, when your ride is jerking you around it is your motor dying/starting/dying/starting cough cough cough, very rapidly. The motor is pulling you, then dragging you, then pulling you, then dragging you, over and over in a rapid fashion until you rev the motor high enough that it starts to run smoothly. Since there is no transmission between the motor and the drive wheel every cough of the engine is going to be felt in the drive wheel, when the motor doesn't fire it drags on your wheel and jerks you about.....

 

[DuctTapedGoat]

I know I can speak from experience in that it's going to be alignment, sprocket teeth, or small chain as I've had this problem and solved it. If none of that solves it, increased fuel to air will eliminate the symptoms at least.

 

[nightcruiser]

Actually - another thing you can do is richen to the fuel to air mix by adjusting the needle clip and/or rejetting.

I read people talking about leaning up the NT carbs, I had to richen up my CNS carb, it has 3 jets with a more complicated balance going on. So I am not sure whether he needs to lean or richen the mix with the needle? Without looking at the plug or exhaust etc its hard to tell... Trial an error works too...

 

[DuctTapedGoat]

There's a lot of variables to consider when adjusting the carb, such as elevation, oil mix/viscosity and ethanol content.

There's no sense it tuning it to performance before break in, as it could always stand to be running rich during break in, and once it breaks in your settings will need to change to adapt.

 

[nightcruiser]

I know I can speak from experience in that it's going to be alignment, sprocket teeth, or small chain as I've had this problem and solved it. If none of that solves it, increased fuel to air will eliminate the symptoms at least.

When you had this chain alignment problem did it only exist at low speeds, or was there still a problem at higher speeds???
I have had cheap chain, bad alignment etc cause lots of chain noise, and chain slap on the cover plate and motor, even rode home with 1/2 a link missing without knowing it one time before I got a real #41 chain. Even with 1/2 a link missing and the chain wanting to jump there was some roughness in the ride but it didnt make the ride unbearably rough. When my bike wouldnt idle and ran rough in the low RPM range the low speed ride was jerky as **** and pull was weak until my speed built up, then things smoothed out. Since he says the problem goes away at higher speeds I was thinking the roughness might be more with the motor....
****, what do I know, I guess I'll let you guys puzzle it out...

 

[DuctTapedGoat]

When I had this problem it was ONLY at low speeds, we're talking near idle. It's not like chain noise - if this guys got happening what I think he's got happening, it's an incredibly violent kick! Imagine the sprocket not being centered and the alignment being off - the chain will catch a tooth and snap down. This causes the bike to violently jerk, derail the drive chain, and can even break the chain or sprocket.

Once you get some speed, it's not an issue, because the slack in the chain is being pulled so taut, it almost auto corrects itself. But once that slack is back in the chain at low throttle/idle, it's back again.

I solved mine by using my tried and true nondished sprocket. It's wider than the dished sprockets, and has shorter teeth - this way I didn't have to file the teeth down, and I was already on 415 chain.

Anything smaller than 415 or #41 is going to be seriously near impossible to align perfectly - especially given the width of the roller tensioner.

Motor alignment is an easy thing to mess up too - so you've gotta adjust the motor's position, the tensioner, and the sprocket in turn to get it set where you need it to be.

 

[vincent713]

Ok guys, I took out my carb and cleaned it, it wasn't really dirty or clogged so it wasn't the carb. I recently installed a centrifugal clutch and now I am able to ride at slow speed 5mph with no jerks! I think it was my old clutch that was slipping at slow speed. This new CC clutch eliminated all that problem. Thanks to Rohmell for suggesting the CC and all you guys for your help.