Motorized Bicycle Engine Kit Forum  

Sponsors



Go Back   Motorized Bicycle Engine Kit Forum > Bicycle Motor > 2 Stroke Bicycle Engines & Kits

2 Stroke Bicycle Engines & Kits 2 stroke engine kits need careful installation and setup, find out how from our professionals here!

Reply
 
Thread Tools Display Modes
  #1  
Old 01-01-2017, 01:19 AM
StevenMain StevenMain is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2016
Location: Texas
Posts: 104
Default Overpowering the Clutch no matter what.

So I have been tweaking the engine im going to use on my scratch built suspension shifter bike build

Fully built China Doll reed valve motor I built, stuffed, ported, arrow kit, YZ85 Expansion chamber... I have had it now to 41.5 mph on a 44 Tooth !!! The thing screams and turns 10,000 RPMS.. but the clutch is slipping, I replaced the friction material, ruffed the crap out of the clutch plate, and cranked the **** out of the preload spring (the big spring in the case) No matter what I do the motor will overpower the clutch and it will start slipping. Any help ?
Reply With Quote
  #2  
Old 01-01-2017, 08:28 AM
Agreen's Avatar
Agreen Agreen is offline
Motorized Bicycle Elite Member
 
Join Date: Feb 2013
Location: Goose Creek, SC
Posts: 757
Default Re: Overpowering the Clutch no matter what.

http://motorbicycling.com/showthread.php?t=8392

This may help?
__________________
Never stop wrenching
Reply With Quote
  #3  
Old 01-01-2017, 12:23 PM
crassius crassius is offline
Motorized Bicycle Elite Member
 
Join Date: Sep 2012
Location: USA
Posts: 2,966
Default Re: Overpowering the Clutch no matter what.

how much grab the clutch has depends on the distance between the locked and unlocked positions of the hand lever - many of the longer levers do not have enough room there, so one needs to abandon free spinning at the lock position and just adjust for best grab (sometimes this can be fixed by filing down the frame of the lever to move where it stops when released so that it is farther from the handlebar)

another fix is to get a different lever
__________________
Sometimes I sets and thinks, sometimes I jes sets.
Reply With Quote
  #4  
Old 01-01-2017, 08:23 PM
StevenMain StevenMain is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2016
Location: Texas
Posts: 104
Default Re: Overpowering the Clutch no matter what.

There are 3 clutch adjustments preload, slack, and airgap which is typically incorrectly referred to as preload. The flower nut controls only airgap, which you want as tight as possible to the extent that the clutch is just barely dragging the motor idle rpm down a nearly imperceptible ammount when the clutch is in the locked lever position. Slack is in reference to cable slack you want just enough slack as to not be depressing the clutch arm when the clutch lever is released, But the moment you begin moving the lever the clutch arm starts depressing the main clutch spring. Clutch preload is adjusted on the big giant spring on the clutch shaft via the spanner nut... it controls the amount of pressure the clutch can squeeze the friction pads with.. This I have set very tight... the clutch lever is really stiff, if I adjust the spring any tighter, squeezing the clutch will simply coil bind the mainspring and not allow the clutch to disengage.

Adjusting the flower nut too tight to the point that there is no airgap and the clutch is still grabbing with the lever fully depressed does not make the clutch grab harder than proper adjustment. I did this just to humor a friend.

What I need is a stiffer replacement spring for the clutch main shaft like maybe a smallblock chevrolet valvespring. Or a better type of friction material. Like that of an automotive dry clutch. Does anyone else have experience with doing something like this?

Last edited by StevenMain; 01-01-2017 at 08:27 PM.
Reply With Quote
  #5  
Old 01-01-2017, 11:01 PM
Agreen's Avatar
Agreen Agreen is offline
Motorized Bicycle Elite Member
 
Join Date: Feb 2013
Location: Goose Creek, SC
Posts: 757
Default Re: Overpowering the Clutch no matter what.

This may be a silly question, but you're not trying to take off with the clutch are you?
__________________
Never stop wrenching
Reply With Quote
  #6  
Old 01-01-2017, 11:30 PM
StevenMain StevenMain is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2016
Location: Texas
Posts: 104
Default Re: Overpowering the Clutch no matter what.

Always have.. no reason it shouldn't be able to. I have replaced the friction pucks and they are brand new.
Reply With Quote
  #7  
Old 01-02-2017, 12:00 AM
Agreen's Avatar
Agreen Agreen is offline
Motorized Bicycle Elite Member
 
Join Date: Feb 2013
Location: Goose Creek, SC
Posts: 757
Default Re: Overpowering the Clutch no matter what.

On a 44 tooth sprocket, it's like taking off in 3rd gear always. No wonder it slips.
__________________
Never stop wrenching
Reply With Quote
  #8  
Old 01-05-2017, 01:17 PM
StevenMain StevenMain is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2016
Location: Texas
Posts: 104
Default Re: Overpowering the Clutch no matter what.

It doesn't slip on takeoff ... it slips at around 25 mph when the motor starts hitting the powerband. Hits so hard it sounds like a downshifted. Either way I've adjusted all that can be adjusted, replaced the clutch main spring, and clutch pads, the clutch isn't glazed and looks great. All adjusted right, pressure plate good and roughed up. The clutch can't hold the power.. I'll have to source my own stronger clutch spring and a different clutch material and make my own pucks.
Reply With Quote
  #9  
Old 01-05-2017, 02:11 PM
crassius crassius is offline
Motorized Bicycle Elite Member
 
Join Date: Sep 2012
Location: USA
Posts: 2,966
Default Re: Overpowering the Clutch no matter what.

never heard of such a thing with all parts aligned & seated, except when bottom of flower nut is hitting against outer lip of shaft - one fix is to trim off a bit of flower nut, other fix is to put pressure plate across vise, put large socket in center of plate, smack **** out of it with big hammer to get the dome of the plate a bit farther from shaft

see if that fixes it for you
__________________
Sometimes I sets and thinks, sometimes I jes sets.
Reply With Quote
  #10  
Old 01-05-2017, 02:25 PM
StevenMain StevenMain is offline
Motorized Bicycle Elite Member
 
Join Date: Jul 2016
Location: Texas
Posts: 104
Default Re: Overpowering the Clutch no matter what.

That's a good tip, I'll be sure to try it before I got making some clutch lining.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 10:36 PM.


Sponsors

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
MotorBicycling.com