Harbor Freight Greyhound 79cc engine

GoldenMotor.com
Dan

Dan

Staff
May 25, 2008
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oh cool Jim. Please let us know how it goes.

I think they snail-mail it to ya so would be a while and HF seems to close up every thing but the stores on weekends. But don't really know and am saying that due to their not answering the phones on weekends and holidays.
 
A

atombikes

New Member
Feb 14, 2010
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Northern VA
I'm trying to size a centrifugal clutch to use with the HF 79cc engine. Does anyone know what the idle speed for this engine is? What should the engagement speed for the clutch be?
 
Dan

Dan

Staff
May 25, 2008
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missed this. The idle speed is 1150 to 1500 RPM Not sure what clutch/spring you have but on an old MaxTourq clutch I abused badly, the HF starts to engage at 1550 to 1600 RPM
 
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4950cycle

New Member
Sep 8, 2010
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Dunnellon,FL.
This is why I don't post here very much. Every time I write something that takes me a while, it kicks me out right before I submit and looses my reply in the process making me very p%#*ssed. And wasting a lot of my time and energies. Anyway, I'm done pissing and moaning now. I was going to put a mini torque converter (CVT) from a Catseye 49cc 2 stroke pocketbike on my HF Greyhound I just bought for $94 (missed the coupon thingy). To To To much modification needed though once I went over the coversion in my head. From finding a 3 1/2 inch cen. clutch to fit in the recess in the belt drive housing ( yes this little cvt uses a centrifical clutch also) Most CVTs don't need them. To hopeing I can find the right springs for said clutch that would deal with the completely differentrpm torque caracteristics of the HF 4stroke vs. the 49cc 2 stroke it was designed to operate with.
 
Quenton Guenther

Quenton Guenther

Dealer
Feb 21, 2008
686
1
0
Outer Banks of North Carolina
Hi 4950cycle,

The Max Torque clutch is 4 3/8" across. There are many versions of the clutch including #35 or #41 chain and a special v-belt output version. The clutch is also available with 5/8" and larger bore sizes.

Max Torque makes a special version for our Q-Matic drive system, however in order to reduce vibration, and the un-needed additional flywheel weight, we locate the clutch at the rear of the drive. Because the clutch is mounted on a dual supported shaft at the rear we make the primary reduction needed to bring the "ticking" speed within the range of the specially designed Max Torque clutch.

You can purchase Max Torque clutches to connect at different speeds and the most common is 1875 RPMs [would work on the HF motor], but it's size will not fit within the 3" size on your CVT. You can purchase a clutch to fit, but a little research will tell you the smaller clutch isn't holding up well and has many issues as it wasn't designed to engage smoothly, but "all of a sudden". I fear the additional torque and HP of the HF motor would be even more destructive on the small [weedeater] clutch.


Hope this information is helpful,
 
Dan

Dan

Staff
May 25, 2008
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Moosylvania
Bummer about the "kick out"s 4950. Is it the site or your connection? I know how infuriating that is. Then when you do retype it, loses your train of thought and being POed, makes ya come off angry, well I do. (happened to me today due to bloatware of this over priced laptop that is soon to be flight tested, lol. But hope ya keep trying.

Your build sounds really interesting.
 
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4950cycle

New Member
Sep 8, 2010
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Dunnellon,FL.
Thanks Quenton, I'm glad you told me guys have messed with this Catseye CVT before. Didn't take much to talk me out of that brain storm. to many mods needed. Gives me a good excuse to make my Lefty derailer for my 3 speed idea (not 3 speed hub). $67 to my door is the best price I have come up with for a Maxtorque belt style 5/8 bore cen. clutch. That was from Gokartsupply.com I believe. Hilliard (Northern Tool) has one but it's even more pricey. Also 3 1/2 inch pulley. Makes it even harder to drop the ratio. But looks like a bit better quality than Max torque. I think the Max torque is only 3 inches. If I can can get a doggone break from all this Holiday crapola I can get down to business. Thanks again, always open to ideas and opinions from guys that actually know how things work ! dance1 OH, That vid of you on your MB is cool. Man ! that thing flys ! BTW Thanks Dan for the encouragment.
 
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4950cycle

New Member
Sep 8, 2010
111
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Dunnellon,FL.
Thanks Dan, I must have more than one gear ! I'm over the minibike thing. I don't even care if it's only a 2 speed,as long as I have more than one ratio.
 
Dan

Dan

Staff
May 25, 2008
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Absolutely 4950! Know wut ya mean. I am waiting on parts to do a multi speed. Is more of an experiment.
 
4

4950cycle

New Member
Sep 8, 2010
111
1
0
Dunnellon,FL.
I'm thinking of maybe even going with mutipullys like in the top of a drillpress. But it "MUST" be light. I built a rack (rear) mount with a 3 1/2 HP about 10 years back. This sucker went faster than you ever wanted to go on a 26'' bicycle. The big problem with it was it was very heavy. The goal is to keep that super light feel of a bicycle. If you lose that you might as well get a motorcycle as far as I'm concerned. That's the way I see it. That's the only reason I like these noisy 2 strokes. They are lighter than 4 strokes for the HP you get. I went 4 stroke again just because of noise though.xct2
 
Dan

Dan

Staff
May 25, 2008
12,765
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Moosylvania
Yeppers, the 4 smokes have that throaty sound. I have a rubber muffler that works almost to good. Is funny dogs, squirrels and kids seem to like it.

That is a really interesting thought, drill press spindles...

How would you derail? lol, suicide shifter comes to mind but that would be bad. emmkay. (Mr. Mackey)

Wouldn't be that hard. Would take up a lot of room though.... hmmmm

Edit; went below for a smoke and thought about it. That is uber cool! Would not be hard to do at all. Use a devise like a front derailleur and spring tension the belt!
 

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Quenton Guenther

Quenton Guenther

Dealer
Feb 21, 2008
686
1
0
Outer Banks of North Carolina
Hi 4950cycle,


We [EZM] are currently testing a 2 speed drive and getting ready to accept bids for fabrication. We are currently working with Max Torque, as they agreed to help us in our effort to reduce cost on the project. I will be testing the latest proto-type on a HF 79 CC motor. The drive is designed to take advantage of 4 stroke low RPM motors [B & S, Lifan, HF, Honda, etc]

We hope to start production by mid 2011.

Have fun,
 
silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
8,325
670
113
northeastern Minnesota
Quenton Guenther said:
Hi 4950cycle,


We [EZM] are currently testing a 2 speed drive and getting ready to accept bids for fabrication. We are currently working with Max Torque, as they agreed to help us in our effort to reduce cost on the project. I will be testing the latest proto-type on a HF 79 CC motor. The drive is designed to take advantage of 4 stroke low RPM motors [B & S, Lifan, HF, Honda, etc]

We hope to start production by mid 2011.

Have fun,
Click to expand...
That, Sir, will be the cat's meow. Sign me up. I'll be very interested in your Greyhound test results.
SB
 
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