What clutch and belt drive is this? Does an upgrade to the Grubee 4G make sense? 4 Stroke fake?

[Nirve]

Hello gasoline mates,

I recently finished my Chopper 4 Stroke built. So far I’ve ridden maybe 50 miles and it works great.
Then i noticed a new dangling noise and found out, that my belt wheel and the clutch bell is wobbling and therefore touch each other every now and then.
I tried to see if i can fix it and thought i have to remove the outer black metal ring around the belt wheel. That worked, but that’s freely spinning now making even more noises. I also believe that the belt wheels wobbling causes most of the vibrations.
I’ve read a lot about clutch wheels, but mine doesn’t seem to have springs? Im confused what i have.

Then i found the 4G belt drive from grubee. I thought i might just buy the hole thing from them to make sure i definitely get rid of all the problems at once.
Now they offer like a 1A 1B 1C kit, and i really don’t know what i could get.

Can anyone help me in choosing the right one, or does someone has tips for my current belt drive?

Also my engine does not say Honda or Huasheng anywhere. Is that more common now? Would a 4G belt drive still fit?

Thank you! And now some picture for you guys

 

[5-7HEAVEN]

Methinks your belt needs tightening.
When you do so, it'll move the large driven pulley away from the crank pulley, eliminating your problem.

 

[Scott81]

I have the exact same setup on my kit I had the same problem you are having with the rubbing the clutch bell was warped so I tapt the high sides with a hammer tell it was flat a nuff to to clear the big pulley.

 

[Scott81]

If that bushing is the same as mine it's not a oillite bushing and you will have to oil it a lot I drilled a small hole inbutwen two of the small teeth on the clutch bell to squirt oil in

 

[Scott81]

If iny one has more information on this transmission please help for all us new guys

 

[Nirve]

I found out more about this transmission.
It is a straight shaft. Most information i find about it is it should be 5/8“ (15.875mm) wide, however, my shaft is at least where the clutch and the clutch bell sits 15mm wide. Its ratio is 1:5.
With a straight shaft, we can not just buy one of the grubee ones, because they are based on a tapered shaft (like a cone).

For the clutch i found that the springs are inside the pads and can be easily removed.

For the clutch bell: The bell sits on what’s it’s called an olite bushing. Its screwed into the straight shaft and therefore always spins when the engine is on. In theory it is lubricated enough in its pores to be freely spinning from the clutch bell. In real life this technique is just bulls**t, needs a lot of maintenance and still does not work. To undo the screw in the shaft you can try to hold the fan wheel on the other side, or what i did, jam a piece of big soft string between one of the two magnetic bigger parts of the fan wheel and the CDI (where there is very little clearance).

Fix:
I’ve read that people soak this bushing in 30w engine oil for 24 hours and then oil it weekly with a drop. That should have been done by everybody before running the engine at all. I of course didn’t know and messed up the inside of the clutch bell. It’s supposed to be smooth, mine looks like this now:

I will get some fine grit sandpaper and try to fix it like this. The oilite bushing luckily doesn’t seem to have taken damage. For other people I’ve read it happened that the bell baked to the bushing, not being able to idle anymore at all.

I soaked my bushing in oil for a day and it did improve the idling by much. But it didn’t last long, i guess its because of the rough clutch bell. Let’s see if sanding it fixes that. But it did not fix a smooth start.

Smooth start: I’ve compared a lot of other peoples 4 stroke starting behavior on youtube. They seem to just be able to throttle it and then gain speed, and it looks and sounds healthy.
If i try that, my bike shakes and wobbles and it sounds awful. I always have to get going by pedaling only.
I experimented with two drops of grease directly on the clutch. I know you shouldn’t do this but if you’re already unhappy with it, why not.
It worked perfectly for 5 or 10 starts and then went back to the old behavior. It also started smelling more burnt and for what i understand, the smoother the start the more heat and wear for the clutch. But that’s a later problem if i ever fix the other ones.

Mod:
Apparently years ago this dude called called cobrafreak modded his shaft so that he could substitute the bushing with ball bearings. To do so he sanded down one mm from his shaft. I am not going to do this. The source is here: https://motorbicycling.com/threads/4g-t-drive-bearing-conversion.37410/ It is a tempting approach tho.
This whole topic got discussed here already in this thread: https://motoredbikes.com/threads/centrifugal-clutch-problem-help.49354/
To my surprise the user KCvale on post nine apparently did this and named it an expensive fail. But he uploaded a picture from cobraheads thread from 5 years before from another forum.



And here are the only replacement parts i found:
Oilite bushing: https://www.bicycle-engines.com/oillite-bushing-for-5-8-centrifugal-clutch-33/
This could be the big pulley:

4G Solid Transmission Pulley/Sprocket For Grubee 4 Stroke T Belt Drive Kits

Your source for 2-Stroke and 4-Stroke Bicycle Engine Kits, Performance Parts, and Accessories!

www.bicycle-engines.com

Clutch: https://mbrebel.com/product/4-stroke-clutch-flyweight-58-straight-shaft-engines/
My Belt: https://mbrebel.com/product/transmission-belt-7g-htd575-5m/
Clutch bell, looks like it but they don’t say dimensions: https://www.gasbike.net/collections/4-stroke-parts/products/clutch-bell-for-ghost-racer

Tempting mod:
I could imagine sanding the bell down half a mm so it is 21mm wide. And then put a couple of bearings in: https://bearingsdirect.com/ball-bea...02-2rs-ball-bearing-15x21x4-sealed-61702-2rs1

Tragedy:
But at this point I am still deciding to get a new engine with a tapered shaft and a proper 4G grubee transmission.
I informed myself before buying one, and everybody said get a belt drive. If it's a belt drive with a straight shaft, its a waste of money IMO. Unfortunately

Oiling that bushing once a week is a joke. I got a 4 stroke to have something reliable, low maintenance once set up properly.

 

[mark20]

i have a straight shaft belt drive myself.
i oil it once every few months now (when it starts acting up i oil it up)

there pretty reliable once the bushing can spin freely.
but there are NO upgrades with this belt drive. so what you get is what your stuck with.
the bearing mod is probably worth doing, since it can make the clutch a lot smoother and a overall a better feel.

overall, its reliable enough for me, but some people prefer the more expensive options.

 

[Wrench]

I would put a little Red and tacky grease on the bushing too. It shouldn't fling off and get on the clutch shoes.

 

[mccauleypm1]

I found out more about this transmission.
It is a straight shaft. Most information i find about it is it should be 5/8“ (15.875mm) wide, however, my shaft is at least where the clutch and the clutch bell sits 15mm wide. Its ratio is 1:5.
With a straight shaft, we can not just buy one of the grubee ones, because they are based on a tapered shaft (like a cone).

For the clutch i found that the springs are inside the pads and can be easily removed.

For the clutch bell: The bell sits on what’s it’s called an olite bushing. Its screwed into the straight shaft and therefore always spins when the engine is on. In theory it is lubricated enough in its pores to be freely spinning from the clutch bell. In real life this technique is just bulls**t, needs a lot of maintenance and still does not work. To undo the screw in the shaft you can try to hold the fan wheel on the other side, or what i did, jam a piece of big soft string between one of the two magnetic bigger parts of the fan wheel and the CDI (where there is very little clearance).

Fix:
I’ve read that people soak this bushing in 30w engine oil for 24 hours and then oil it weekly with a drop. That should have been done by everybody before running the engine at all. I of course didn’t know and messed up the inside of the clutch bell. It’s supposed to be smooth, mine looks like this now:

View attachment 96882

I will get some fine grit sandpaper and try to fix it like this. The oilite bushing luckily doesn’t seem to have taken damage. For other people I’ve read it happened that the bell baked to the bushing, not being able to idle anymore at all.

I soaked my bushing in oil for a day and it did improve the idling by much. But it didn’t last long, i guess its because of the rough clutch bell. Let’s see if sanding it fixes that. But it did not fix a smooth start.

Smooth start: I’ve compared a lot of other peoples 4 stroke starting behavior on youtube. They seem to just be able to throttle it and then gain speed, and it looks and sounds healthy.
If i try that, my bike shakes and wobbles and it sounds awful. I always have to get going by pedaling only.
I experimented with two drops of grease directly on the clutch. I know you shouldn’t do this but if you’re already unhappy with it, why not.
It worked perfectly for 5 or 10 starts and then went back to the old behavior. It also started smelling more burnt and for what i understand, the smoother the start the more heat and wear for the clutch. But that’s a later problem if i ever fix the other ones.

Mod:
Apparently years ago this dude called called cobrafreak modded his shaft so that he could substitute the bushing with ball bearings. To do so he sanded down one mm from his shaft. I am not going to do this. The source is here: https://motorbicycling.com/threads/4g-t-drive-bearing-conversion.37410/ It is a tempting approach tho.
This whole topic got discussed here already in this thread: https://motoredbikes.com/threads/centrifugal-clutch-problem-help.49354/
To my surprise the user KCvale on post nine apparently did this and named it an expensive fail. But he uploaded a picture from cobraheads thread from 5 years before from another forum.
i can find the oilite bushing but not the beraing that is supposed to go inside that buhing. Any help?


And here are the only replacement parts i found:
Oilite bushing: https://www.bicycle-engines.com/oillite-bushing-for-5-8-centrifugal-clutch-33/
This could be the big pulley:

4G Solid Transmission Pulley/Sprocket For Grubee 4 Stroke T Belt Drive Kits

Your source for 2-Stroke and 4-Stroke Bicycle Engine Kits, Performance Parts, and Accessories!

www.bicycle-engines.com

Clutch: https://mbrebel.com/product/4-stroke-clutch-flyweight-58-straight-shaft-engines/
My Belt: https://mbrebel.com/product/transmission-belt-7g-htd575-5m/
Clutch bell, looks like it but they don’t say dimensions: https://www.gasbike.net/collections/4-stroke-parts/products/clutch-bell-for-ghost-racer

Tempting mod:
I could imagine sanding the bell down half a mm so it is 21mm wide. And then put a couple of bearings in: https://bearingsdirect.com/ball-bea...02-2rs-ball-bearing-15x21x4-sealed-61702-2rs1

Tragedy:
But at this point I am still deciding to get a new engine with a tapered shaft and a proper 4G grubee transmission.
I informed myself before buying one, and everybody said get a belt drive. If it's a belt drive with a straight shaft, its a waste of money IMO. Unfortunately

Oiling that bushing once a week is a joke. I got a 4 stroke to have something reliable, low maintenance once set up properly.


View attachment 96882View attachment 96883View attachment 96884View attachment 96887

 

[Deleted Member 4613]

You have the Chinese ebay 4 stroke with a belt drive and
15mm shaft. I have this kit. It is not compatible with Grubee
belt drives and can only be used with a clutch that fits the
15mm shaft. Looking at the photos, I suspect that your
bushing is bronze not Oilite like mine before I modded it
to an Oilite bushing. The bronze bushing works with
grease, and the belt tension has to be just right. Your
options would be:
1. If it's a bronze bushing, polish the clutch housing, grease it, adjust
the belt tension and large pulley and see what happens.
2. If the large pulley is serously wobbling, there is a bigtime
problem. It could be you failed to use loctite on the center
bolt holding the pulley and it came loose and caused damage
that can't be fixed. You would have to inspect the parts and
maybe even order a new belt drive from BGF, about $106.
3. Convert to a oilite bushing.
4. I can advise you how to convert to sealed bearings
if you wish to try, but it requires taking some material off
the motor shaft and removing about 1mm off the clutch
housing.
It's difficult to know what to do without seeing the
drive running and inspecting the parts. There are
limited options with this kit because the parts
are not readily available. Everything has to fit
a 15mm motor shaft.
If you have the cash, go with the Grubee tapered
shaft and his belt drive which uses two sealed
bearings.