Harbor Freight Greyhound 79cc engine

tyrslider said:
KilRoy, Are you running the engine/oil switch or did you bypass it? Stock carb? Also were you guessing on the 4500 rpm or did ya check? Thanks, Evan
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Evan, the 4500rpm is an estimate arrived by us through crunching numbers. We are running the engine/oil switch and using the stock carb but disconnected the governor. The Whizzer WC-1 air cleaner was modified to fit the stock carb.
 
Thanks Kilroy,
The 1st few times I ran the motor it died mysteriously 2 times, instantly restarted so I thought maybe the switch was killing it from cornering. Hasn't happened since. I would agree w/ you after some similar crunching, 4500 rpm is prolly pretty close. Was also thinking that an HS carb might provide a wider power band, maybe I'll give it a try! Thanks again, Hope all is well, Evan.
 
I read on a thread on motoredbikes that Loquin was told by a HF tech that the torque for the HF 79cc was 4.0 N.m at 3000rpm's. Then I found some specs on the 98cc that said it had 3.8 N.m at 3600 rpm's. Does this sound right to anyone who knows more about this than me.
 
Don't know why everyone's so up on those Harbor freight engines. My 49cc Hueshang EZ is faster than the harbor freight EZ's. RusticoRay built a harbor Freight EZ & changed it to a Hueshang. Bigger isn't always faster. would a big diesel engine in a Corvette be faster than a 350 in a Corvette? I rode both at the Rally in Delaware so I'm not just blowing smoke. I figure the 79cc is good if you're a really big guy & need low end torque. They're only good for about 4500 RPM's. My hueshang cruises nice at 7500 RPM's.
Jay
 
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jbcruisin said:
Don't know why everyone's so up on those Harbor freight engines. I figure the 79cc is good if you're a really big guy & need low end torque. They're only good for about 4500 RPM's. My hueshang cruises nice at 7500 RPM's.
Jay
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You answered your own question Jay. I did it because I'm a large guy and live in a hilly area. Another reason is not many other people had done an in frame mount of this engine. Some even said it couldn't be done so I had to try. I also don't need to go mach 2 on a bicycle but I do need the power to climb hills. 25-30 MPH is just fine for me. Lastly it was a proof of concept build to see if the Q-Matic would function correctly on this engine.
It was a win win win for me. I can't wait for spring so I can ride it more. I may get a chrome frame so then the whole bike would be chrome. Cool...

Jim
 
Glack,

That could be right. The Honda 50 reaches peak torque at 4500 rpms w 2.7 nm (2ft-lbs) and tapers off from there; Net power is reached at 7000 rpm's 2.1 HP w a max recommended speed of 7700 rpms. Comparibly the Honda 100 States 2.8 hp and 5.7 nm (4.2 ft-lbs) at 3600 w/ a max recommended eng speed of 4000. And while the torque curve tapers off the power curve continues up past 3 hp at 4000 rpm's.

It really depends on the motors design and I used these 2 examples because their specs are widely published. Notice how the 100 is rated at 2.8 hp but actually puts out more that is because it is rated at 3600 rpms but continues to climb up past 4000. It has 50% more Hp and 110% more torque.

Most of the honda/clone motors are geared 16:1 to 20:1 giving a top speed of 25-35 mph w 26" wheels, If you mount the hf motor to the same gb's your top speed is going to be about 15-25mph

The HF at 4500 rpms and 9.688:1 will do 35 mph (w 26" wheels)
8.72:1=40 mph
7.927:1=45 mph

So if you change out the transmission in the Corvette to maximize the power and torque of the diesel engine it will go way faster than the 350 engine. More power equals more speed potential, there's no replacement for displacement. W/ the proper transmission ratios engine speed is barely relevent; you don't need your rear wheel to spin 4500 rpms let alone 8000 (more like 500) so you use different reductions depending on the engines max speed to get your rear wheel to spin 500ish times per min.

I'll try and find more specific info on these engines for you glack. If you follow this thread there has been many erroneous comparisons. Don't be afraid to do the math!
 
Tyrslider: Your so smart, and thorough. That's why I like it when you reply to my inquiries.
 
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I did find a gear ratio calculator on one of the threads. I guess the best thing is to put it to the streets and find a ratio that works best overall then, like you said, go up or down one tooth with the final drive sprocket for quick and cheap alterations if needed.
 
Glack heres specs from Lifan on the 98cc

Model: 152F(CE/EC, EPA/CARB)(2.5PS)
Engine type: 4-stroke single-cylinder forced air-cooled valve-sided
Bore*stroke: 52mm*46mm
Displacement: 97.7ml
Compression ratio: 5.6:1
Max power output: 1.8kw/4200rpm
Recommded power using: 1.4kw/3600rpm
Max torque: 3.8N.m/3000rpm
Ignition system: Non-contact transistorized ignition(TCI)
Start model: Recoil and hand-operated
Air cleaner: Semi-dry type
Fuel tank capacity: 1.4L
Fuel consumption: 450g/kw.h
Engine oil capacity: 0.35L
Dimension(L*W*H mm): 270*268*345
Dry weight: 9.0kg
Carton dimension(L*W*H mm): 325*315*410

The HF

Gasoline Engine(XR152F)
Model: XR152F
Engine Type: Air-cooled 4-stroke OHV inclined single cylinder
Bore x Stroke: 52x38 mm
Displacement: 80cm3
Compression Ratio: 8. 5: 1
Maximum Power Output: 3PS(2. 2KW)/3600rpm
Recommended Power Output: 2. 5PS(1. 8KW)/3600rpm
Maximum Torque: 0. 6kg. M(5. 9N. M)/2500rpm
Ignition system: Transistorized magneto
Starting System: Recoil
Fuel Tank Capacity: 3. 6L
Aircleaner: Semi-dry; Oil bath; Dual; Silent; Cyclone
Oil Capacity: 0. 6L
Fuel Consumption: 290g/PS-hr(395g/KWh)
Dimensions(L x W x H): 315x275x320 mm
Dry Weight: 10kg

Looks like the HF is a more powerful motor! at max 3hp and 4.3 ft lbs. The 98cc is lower compression and side valve, stands to reason.
 
NEAT TIMES said:
I Have Been Told That A Ford Deisel Pick Up With A Chip Will Blow Off A Vette . Ron
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77 Vette? Sure. I believe that. They were smogged out dogs. A 77 Vette ran the 1/4 mile in about 16.5 seconds.

2009 Vette? I don't think so. 1/4 mile is 11.3 seconds found here

Fastest Nearly stock truck I have ever heard of was this: Syclone It can run the 1/4 as fast as 13.4 and will beat a Ferrari 348ts

Don't get me wrong. I like diesels just fine and they can be fast too. This one runs a 7.77 1/4. Banks S-10 Diesel But as you can see it is a bit more than 'just a chip'

The biggest problem with making a truck fast is the aerodynamics. Aerodynamic drag is a logarithmic progression. Traction can be dealt with via 4 wheel drive but if it is still shaped like a brick it is going to need much much more power to go the same speed as the Vette at the top end.

Aerodynamic drag is the primary reason it is very difficult to get past 40mph on our bikes. If someone says they can go faster look for a fairing or some serious hp and gears.

I really like the work you have done on this Tyrslider. I looked up the manual for the greyhound motor and it looks decent. I was looking for ways to improve performance but I didn't see much that was easily doable. Porting and polishing the head may help a bit. You already opened it up with the exhaust and intake so thats done. You may be able to find a longer rod or different piston for more compression but I don't think the head could be shaved much based on the OHV design. You may be able to shave it a hair and get a little more lift on the valves too but if you go too far it will wreak havoc on the valves. The compression ratio is pretty low so you could definitely gain some hp there. A custom ground camshaft would be pretty difficult. Depending on how the ignition is set up you may be able to advance it a bit and use higher octane gas.
 
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You know what would be awesome? A self adjusting pulley that either opens or closes with centrifugal force, depending on it's placement in the system. Do they make something that would work for either belt drive systems. I have heard something about cvt's before, but is that in reference to the Nuvinci hubs.
 
jbcruisin said:
Don't know why everyone's so up on those Harbor freight engines. My 49cc Hueshang EZ is faster than the harbor freight EZ's. RusticoRay built a harbor Freight EZ & changed it to a Hueshang. Bigger isn't always faster. would a big diesel engine in a Corvette be faster than a 350 in a Corvette? I rode both at the Rally in Delaware so I'm not just blowing smoke. I figure the 79cc is good if you're a really big guy & need low end torque. They're only good for about 4500 RPM's. My hueshang cruises nice at 7500 RPM's.
Jay
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I think the thing that interests me most about the HF motor is that I think it has much more potential than the Hueshang for performance upgrades. It may not be faster now but I'm pretty sure it could be made to be much faster. Will take some work tho. The fact that it is dirt cheap is a bonus. You can afford to blow up a few figuring things out.
 
glacknoid said:
You know what would be awesome? A self adjusting pulley that either opens or closes with centrifugal force
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That is a CVT. A Nuvinci hub uses an entirely different principle. CVT's are wonderful. They provide tremendous bottom end torque and still give you max top end plus they adjust themselves based on rpm (CVT = Continuously Variable Transmission). The only problem with them is they tend to be a bit inefficient. This is fine if your motor is making 40hp but if it is only making 2hp it becomes more of a challenge. It means you have to be very careful to match the CVT to the size of the motor.
 
Just got a speedo today so we'll see if my math is correct in the next few days. CVT's work great! Lookin into it. Good points clotho, totally agree, lots o potential! I'm happy w/ the power though! Evan FBC
 
$ 20 for a 27 month full replacement warranty which can be extended for 27 more months on a new engine swap makes it more of a sweet deal.
 
I have a tomtom gps that worked great as an accurate way to gauge the speed of my bikes. It was dead on with my car so I knew it would be accurate. The mechanical speedo I got from bikeworld usa was way off. I thought I was going over 40 with a 56 tooth sprocket and the skyhawk stage 3.
 
I have faith that all the knowledge and ingenuity combined in this forum, will lead to some giant leaps in developement towards a variety of American made systems that will work for everyone.
 
I got a Garmin GPS speedometer & a digital tach. RusticoRay Gave me the tach last summer when he was at my place with his wife for a rally I had here. So I know how fast my bike goes & the RPM's. There are only a few of us that ever rode & raced each other with the HF's & Hueshangs. That was at the Delaware Rally in September. We all rode each others HF's & Hueshangs, raced each other & had a great time. I was surprised at how many HF's & Hueshangs were there. Check out the Rally pictures under rides & events in this forum. You guys, I'm sure , are right with your tech onfo, but hands on riding is still the best & we did it. Fossil hit the nail on the head a few posts back when he said he likes the HF because he's a really big guy & likes the low end torque & doesn't want to go fast anyway. Ask Ray why he went from HF back to the Hueshang. Be sure when you buy an engine it's going to give you the performance you want, not just "oh boy, this is a really big engine"
 
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Jay, forgive me but think your missing the ratio thing. The gearing being discussed is different from what was available last year.

(PS, race ya in CT this spring! lol) ((Really looking forward to seeing you folks again))
 
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