Clutch Help

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kyle3194

New Member
Sep 8, 2011
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Kansas
Ok, so im using an old 25cc featherlite weed eater motor for my first build. I'm at the point now, where i need help deciding whether to put a clutch on it or not. As my friend pointed out, there has to be some kind of centrifugal clutch on it because the weed eater head does not spin when the throttle is completely out. This being said, would this work for me while starting? As in a pull start? Or do you think i should try and roll start?

Ill have pics coming up later :)

Your help is appreciated.

Kyle
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
What kind of drive are you planning to use. If you are going to attach a drive roller to the motor how are you going to do that. Most of the time i just pull my clutch off a weed eater and attach the roller to the drive shaft against the fly wheel. then use a lift or gravity clutch to start the motor and to lift if off the tire so that it can idle/
 
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kyle3194

New Member
Sep 8, 2011
5
0
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Kansas
Well i was really hoping to run a direct drive. with straight bicycle chain throughout the build. Does this change things much?
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
to be honest you should ask someone else I think that 25cc is a bit small for chain drive. Plus how did you plan to attach your sprocket to the engine. I don't know anyone who has done that to be honest at least not with the clutch. Someone probably has but I don't know about it.

The problem of having chain drive without a centrifugal clutch with any engine is what happens at the stop light or stop sign.. Some of the other guys can give you better advice I never build with those clutches myself. Cannonball2 has but i think with bigger engines.
 
cannonball2

cannonball2

Well-Known Member
Oct 28, 2010
3,682
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Colonial Coast USA.
Honestly, the Featherlite doesnt make much power. I see you are from Kansas, if its as flat as I hear it is then it might work out. I would look around for something at least 30ccs. Not trying to throw a damper your build. If you use the Featherlite, try to make the build universal enough to accept another brand/cc of WE engine so a swap out can be made later.
 
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kyle3194

New Member
Sep 8, 2011
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Kansas
So you are saying that i would get more power out of running a friction drive build? I'm not sure if its true or not, but i would think it wouldn't be as good because of the efficiency decrease between the two. I don't know much about this though, so feel free to criticize me... :D
 
cannonball2

cannonball2

Well-Known Member
Oct 28, 2010
3,682
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Colonial Coast USA.
Wasnt really leaning either way on the drive, was just commenting on the low power output of the featherlight. Most WE engines are FD, probably just due to the simplicity. A chain shoud be more efficient, but the complexity is considerate compared to FD.
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
9
0
north carolina
gonna weigh in on this even though I am no expert on chain drive at all. On friction drive the lower hp engines that have good rpm do well because they can be tensioned to slip over the wheel instead of bogging down. with a chain I thing you would need a clutch that would slip to get the same effect. So I don't know about efficiency.
 
NormO

NormO

New Member
Jun 15, 2011
197
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New Brunswick,Canada
I'm no expert on chain drive, but i'll throw in my two cents anyway. If you can find a high stall speed clutch and gear it properly it should be ok. Maybe even some sort of manual clutch. Something in the 30:1 range should do the trick, but forget about anything resembling top speed though.
 
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