Does a centrifugal clutch require a pull start?

MaxPower · Jul 25, 2009

I'm thinking about buying a centrifugal clutch from zoom bicycles. Do I also need to buy a pull start or can I pedal start it? I was thinking that the regular clutch could be used to start the motor and then the centrifugal clutch would take over.

Zoombicycles Motor Bicycle Gas Engine Kits Addon - Centrifugal Clutch (5-3) | 14-Addons (10) | 6-Parts and Accessories | RuiHong Enterprises Ltd.

Zoombicycles Motor Bicycle Gas Engine Kits Addon - Pull Start (5-1) | 14-Addons (10) | 6-Parts and Accessories | RuiHong Enterprises Ltd.

Cabinfever1977 · Jul 25, 2009

i dont know if you can peddal start it or if you have to use a pullstart.
The clutch would have to have over running clutch lock up to pedal start.

btw adding a cent clutch and a pullstart adds around a 1 1/2" on each side to the engine width.

did you ask zoombicycles if you need a pull start to go with the cent clutch.

MaxPower · Jul 25, 2009

I just tried to call zoom again. no answer. no email reply either. I'll try again on Monday.

how efficient is a centrifugal clutch compared to a manual clutch? can I expect a large preformance drop? my user name IS .wee.

"maxpower" .wee.

Rockenstein · Jul 25, 2009

The centi clutch kit from zoom does not require a pull start...you pedal start as normal. I use Zoom's clutch kit on my Tsunami 80 engine, works well after a couple mods that locked the clutch adapter to the crankshaft. I basically keyed it...

how efficient is a centrifugal clutch compared to a manual clutch? can I expect a large preformance drop?

I found that the added rotating weight of centrifugal clutch was a welcome addition, smoother idle and a better feeling throttle "roll on" once the engine was up to speed. I wouldn't mind a little stiffer spring so as to raise the engagement point a little but all in all it's good as it is.

Rockenstein · Jul 25, 2009

Cabinfever1977 said:
once you add the centrifugal clutch the manual one no longer works.

Not so...the manual clutch is still used and required, with the Zoom kit anyway...don't know about the other version(s).

MaxPower · Jul 25, 2009

thanks for the info rokenstien. You don't happen to have pictures of your mod. What tools are required to do your mod. I have a limited tool selection but I do however have a drimel tool. Is that enough?

donuts31 · Jul 26, 2009

I've got two centrifigual clutch engines. Once has pull start and the 2nd one doesn't. Not needed but very nice to have.

fall_down_stand_up · Jul 26, 2009

Gasbikeshop has the kit for 29 99....This post has answered alot of the same questions I had....I would think the kit would make alot more torque on take off....Is this true????

Rockenstein · Jul 26, 2009

granbury_man said:
I would think the kit would make alot more torque on take off....Is this true????

I don't know if you'd call it "more torque" but my engine is much smoother at idle and like I said when you roll on the throttle when your cruising at say 20 km\h it picks up and gets going smoother than it did without the centrifugal upgrade.

Rockenstein · Jul 26, 2009

MaxPower said:
thanks for the info rokenstien. You don't happen to have pictures of your mod. What tools are required to do your mod. I have a limited tool selection but I do however have a drimel tool. Is that enough?

I pretty much used a file and a dremel to do the mod MaxPower...I also had to shorten the mounting bolt that was included in the kit, I used my belt sander for that. The mounting bolt included in my kit was bottoming out in the crankshaft hole and would not allow me to tighten things down properly...pay attention to that note if you get one!

I filed about 2/3 of the half moon key so it would be flush with the crankshaft when placed in the keyway and left the remaining 1/3 as is. I dremel'ed a notch in the clutch shaft adapter to fit the part of the key that was not filed. This picture shows the notch I made in the shaft adapter...the adapter is hardened and the dremel bits I used were the diamond coated types...the bits were about 3/32 - 1/8 diameter.

.

Humsuckler · Dec 30, 2009

very nice info here

Russell · Dec 30, 2009

Rockstien,
Seems that locking the c-clutch bell/drum to the shaft negates the c-clutch operation.
My train of thought was that the c-clutch drum or bell with the gear attached was supposed to freewheel on the shaft until the shoes engaged driving the gear/drive?

Russ

silverbear · Dec 30, 2009

Mine is a bgf which came as a pull start slant head with centrifugal clutch. You can either pull start it or bump start. Very smooth motor.
SB

Rockenstein · Dec 31, 2009

Russell said:
Rockstien,
Seems that locking the c-clutch bell/drum to the shaft negates the c-clutch operation.
My train of thought was that the c-clutch drum or bell with the gear attached was supposed to freewheel on the shaft until the shoes engaged driving the gear/drive?

Russ

My mod does not lock the clutch drum to the crankshaft but rather locks the crankshaft adapter that clutch drum + roller clutch bearing runs on to the crankshaft. I locked the crankshaft adapter to the crankshaft because it, the crankshaft adapter, was slipping and sometimes that would cause the fixing bolt to back out a little which would cause even more slippage...when that happened the bike of course went nowhere.

Russell · Dec 31, 2009

Ro0ckenstein,
Thank you for setting me straight on the adapter setup. And thank you for comming up with the A-juice tank, it has worked out well for me.

leborico · Feb 28, 2010

Hi everyone, I made an installation guide the centrifugal clutch, it's on my blog :
leborico.blogspot

Someone said that you still need the clutch lever even with the centi-clutch ?
why that ?

I was planning to remove it.

thx

Ricco

Cabinfever1977 · Feb 28, 2010

leborico said:
Hi everyone, I made an installation guide the centrifugal clutch, it's on my blog :
leborico.blogspot

Someone said that you still need the clutch lever even with the centi-clutch ?
why that ?

I was planning to remove it.

thx

Ricco

You will want to keep the manual clutch lever. you disengage the clutch using the lever so if you use the pullstart and start the engine,if it was engaged the bike might take off on you, especially when its still new and not broken in yet.

Its mainly used for starting the engine but also clutch is pulled in when going down a hill.

leborico · Feb 28, 2010

Oh ok I understand

i have a stand that prenvent the wheel from touching the ground so it might be ok to removethe lever.

thank you for your answer !

Russell · Feb 28, 2010

In a panic stop it is good to have the manual clutch to disconnect the engine quickly(as the engine RPM does not drop fast enough). The hair spring in the c-clutch keeps the cam rollers engaged(when the rear wheel is moving faster than the engine output). That is why you can bump start the engine and does not require a pull start(but it is a good option).
It also comes in handy when going down a long hill(Turning the throttle down starves the engine of fuel and lube, as rpm is held hi by the hair spring cam rollers).

diceman2004 · Mar 7, 2010

cool , i was just reading the thread and was confused as to how a centrifugal clutch could be pedal started .
I didn,t realize the clutch in the kit had a one way sprag clutch .
that is pretty convenient .

Does a centrifugal clutch require a pull start?

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