Manual Clutch for 3/4" Crankshaft (Replacement for Centrifugal)

GoldenMotor.com
D

ddowns46

New Member
Sep 30, 2013
1
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0
San Jose
Hi all,

My name is Danny Downs and I have been working on a project over the last year with my brother (we're both engineers) to design and manufacture a manual clutch that can replace the standard centrifugal clutch. We have been posting our progress on various mini bike and go kart forums, and we've realized that motorized bikes could particularly benefit from a manually actuated clutch. You can check out our website at www.downsbrosracing.com

-We are still in the process of posting videos of our newest production clutch, and the kit that we are offering will feature everything necessary to mount a manual clutch onto a 3/4" crankshaft engine. The kid will include the clutch, the cable, a clutch lever, and all necessary mounting hardware. Please check out the photos section of our website for more information of the production clutch.

-Currently we have 100 production clutches in stock, but we are giving priority for the sales to the original forum guys that have shown interest. When everyone has had a chance to order, we will open up to the general public sometime next week.

Check out our other forums here for more information:

http://www.oldminibikes.com/forum/e...19-manual-clutch-horizontal-shaft-engine.html

http://www.diygokarts.com/vb/showthread.php?t=19841

We would really love to hear any input you all might have, so please keep us posted!
 

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maurtis

maurtis

New Member
Dec 14, 2011
707
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Kyle, TX
Excellent! I assume this could be used with a 5/8" shaft using a bushing? Definitely an interesting alternative! Great to see you guys made it into production, grats!
 
M

msrfan

Well-Known Member
Sep 17, 2010
1,808
120
63
Southern California
That's a great clutch. I would like to modify one with a larger sprocket for jack shaft mounting, as the four stroke engines are really wide.
 
Ratt_Bones

Ratt_Bones

New Member
Aug 2, 2013
153
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Appleton, Wi.
I couldn't help but notice some of the main components are basically that of a brake detangler. Sort a very mass produced item, and reproduced by many companies all of which are available for under $30.00

I'm not trying to be Mr. Negative, but I'm sort of failing to see the benefit for the price. Yes, the China Girl's stock clutches aren't great, but it only takes about $20.00 (at most, if at all) to get them butter smooth. This clutch assembly is nearly $40.00 more than the Girl herself.

I guess I am just curious how China Girl motorized bikes could benefit from this particular manually actuated clutch.
 
mapbike

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Ratt_Bones said:
I couldn't help but notice some of the main components are basically that of a brake detangler. Sort a very mass produced item, and reproduced by many companies all of which are available for under $30.00

I'm not trying to be Mr. Negative, but I'm sort of failing to see the benefit for the price. Yes, the China Girl's stock clutches aren't great, but it only takes about $20.00 (at most, if at all) to get them butter smooth. This clutch assembly is nearly $40.00 more than the Girl herself.

I guess I am just curious how China Girl motorized bikes could benefit from this particular manually actuated clutch.
Click to expand...
The clutch isn't for the china girl/HT engines this clutch is for the larger 4 stroke engines like a Predator 212cc, GX200 196cc Honda clone or 5hp Briggs, those all have a 3/4" crankshaft, completely different set up.

I see what you mean about the look being simular, but the detangler and a clutch is two very different things.





Map
reddd
 
Last edited:
J

Jim C

Member
Jul 11, 2010
200
6
18
Long Beach Calif
I am not really interested in putting another $175.00 into my bike at this time but I am really glad to see a manual clutch for the HS 4 stroke motors. I have built a 29 inch Onyx bike using a 49 cc HS 142 motor. The cent. clutch and the 29 inch wheels are just wrong for this bike. The clutch engages too quick and the engine just will not pull the tall gearing of the 29 inch wheels even with a 48 tooth rear sprocket. I am glad to see you guys here and see your product.
 
RicksRides

RicksRides

Member
Feb 22, 2012
864
6
18
osceola IN
I 'd like to see an abuse test on that clutch, pull the front of a kart or mini to a building and dump it. heat the clutch up, basically im looking to see how much abuse it will put up with.
are they rebuildable (by me) ?
 
LabRat

LabRat

New Member
Dec 24, 2011
596
20
0
Ruston, Washington
Glad to see you made it here and I do believe I am one of the first 100 according to a text I received. Looking for the ordering portal on Wednesday. That's in the morning! Its time (almost)!!!!
 
Scott.D.Lang

Scott.D.Lang

Member
Jan 1, 2013
406
2
16
Chicago
the biggest reason I have not done a 4 stroke other then looks is the fact I cant stand a centrifugal clutch. now that you have come up with this there is a good chance that Ill be building a 4 stroke or 2 come the new year.
 
mapbike

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Im thinkng a 4 stroke shifter bike withe the 79cc predator, dumping the clutch under higher rpms is likely to trash ever the heavy duty bike chains left and right but if it was handled righ it might make a nice cruiser.

Map
.wee.
 
Velodrome

Velodrome

Well-Known Member
May 27, 2011
2,387
271
63
Phoenix-ish
How exactly would one convert this to work on a 5/8 inch drive shaft? Like on a 49cc HS motor. I got a build coming up I REALLY want to use this clutch on but I'm staying AZ legal at 49cc four stroker.
 
LabRat

LabRat

New Member
Dec 24, 2011
596
20
0
Ruston, Washington
So excited! Notification on Wednesday of shipment. Arrived USPS today! (Monday) Two for the price of two! SWEET!

I have an engine and I have an idea of where to put it..... still undecided this will be a new build. The thought had occurred to cobble this clutch into the puma twin.... idk.
 
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