Clutch Help

MrFastFox666

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Apr 28, 2021
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Hello everyone, I'm fairly new to this forum so I apologize if this has already been discussed, I couldn't find much of anything. If anyone could either help me or direct me to the relevant thread I'd greatly appreciate it.

I recently built a motorized bike with a kit from Amazon and so far it has worked well, but I think the clutch is worn out already. This is only after about 2 hours of riding max, I haven't even gone through half a fuel tank. Engine is Huasheng 142f with tapered clutch shaft, by the way.

On my last ride I noticed that the engine would vibrate very violently under acceleration, so I stopped riding. I solved this by cleaning the clutch and clutch bell housing. Also, I noted that in general I need to rev up the engine pretty high for the clutch to engage at all, and even at 25mph it isn't fully engaged. After I took off the transmission I noticed there is only about 1-2mm of pad left on either side of the clutch, and there is a huge gap between the bell and the clutch. After some digging I was able to find that it is common for the clutch bell to be oversized, but I can't find any replacements. I did find this clutch: https://www.amazon.com/gp/product/B08XLZ6QDX/ref=ox_sc_act_title_1?smid=A200MF86H5LIR7&psc=1 and was wondering if anyone had any experience with it. Is it any good, and if not, what are people doing to solve this issue?
 


Wrench

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Nov 14, 2018
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3,118
Try weaker springs, They should be available in different sizes for clutch engagement RPMs
1,500 RPM
2,000 RPM
2,500 RPM

Yes centrifugal Clutch shoes are the weight,
Some clutches offer Clutch shoes in different weights for different engagement RPM
While other clutch shoes have weights that can be bolted on to the shoes to change the engagement RPMs

Me personally on my Whizzer M/B clutch shoes, I shave some weight off the shoe metal for a higher RPM engagement.
 


Wrench

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Nov 14, 2018
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3,118
I feel like more gear reduction would certainly help.

I've only gotten the bike up to maybe 30-33 mph since I only had the weak sauce coaster brake and no wide crank assembly (included one didn't fit), but even at that speed it didn't sound like the clutch engaged completely

Edit: forgot to mention clutch is the 2 leaf type. It doesn't seem to have any weights attached to it
Look at the clutch shoes, the contact shoes to drum might not be broken in yet,
The shoe pad should show signs of full contact to drum

New Centrifugal clutch
If not full contact of shoe pad to drum. Sand off the contact area on the shoe. Test ride bike and check contact of pad to drum keep doing that until the shoe pad makes full contact to the drum.
 

MrFastFox666

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Apr 28, 2021
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8
Update: I just got a new clutch in the mail and installed it and I could immediately tell a huge difference. now the engine only needs to rev up a little to engage the clutch. From the moment I built it, the old clutch needed to rev up a ton before engaging, so I wonder if I got sent a worn out clutch or something, or if it just had stiffer springs. I measured it and it's only 70mm!

Still, I have to get to 20-25 mph before I can hear the engine start to rev up with the new clutch, so I think that the super long gearing isn't going to help much in terms of lifespan.
 

MrFastFox666

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Joined
Apr 28, 2021
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Update: I got 2 clutches now, one is the same style as the one I had, the other is the BGF clutch I linked (I just received it). The new 2 leaf clutch is way better than the one my bike came with. The engine does rev up a bit, but the clutch engages much sooner. the BGF clutch is even better, the engine barely speeds up before the clutch engages. It does have one issue, and that is that it's super jerky when it engages. Rather than engage smoothly, it jerks the bike forward rhythmically and isn't smooth at all. Only at about 10-15mph the vibrations start to go down, and at about 30mph they disappear completely. Any Ideas? BTW, I am pedaling to start.
 

MrFastFox666

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Apr 28, 2021
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8
Ride it a bit and then check the wear pattern on the shoes. The center of the shoes might be too high and grab sooner.
Just came back from doing that lol. Yesterday I rode for about 10 minutes, then checked the wear pattern and noticed only the outer edge of the shoe was grabbing, so I rode an extra 45 mins to break in the clutch. I just checked it and there's still very little wear, but mostly the outer edge is what's making contact, and it seems that 2 of the 4 shoes are a bit taller and make contact first
IMG_20210503_155434117_HDR.jpg


I'm really glad with the wear, or lack thereof. With about 50 mins there's less visible wear than 10 mins on the 2 leaf clutch.
IMG_20210503_160702168_HDR.jpg
 

Wrench

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Nov 14, 2018
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3,118
The 4 shoe clutch has a garter spring It's gonna disengage the clutch at a certain RPM with no load This is why the clutch feels jerky
The 4 shoe clutch, the shoes press out to the drum while the 2 shoe clutch the shoes fold out to the drum
 

Chainlube

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Jan 5, 2020
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3,610
It will be a little jumpy until the shoes wear down to the shape of the bell. Did you sand the inside of the bell clean while you had it off. I clean the driver on my race cart after each weekend. The rams and the bell get dirty.
 
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