HF 6.5 (200cc) motor on a bike?

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oldtimer54

Member
May 15, 2010
540
6
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On a bike
I just bought a HF 6.5 motor for $59.98 (at that price I just couldnt help myself lol) and I want to put it on a bike. But other then the indian 1911 thread I havent been able to fing anyone who is using this motor to motorize a bike? My grandfather rode one of those indian bikes in his day and filled my head with visions of tooling down the road on my own indian but this is as close to one as Ill ever get. Now just getting to town and back is ok but I need something a little more reliable then our HT motors. Then I could maybe go to the nearest city once in a while or maybe go exploring. Can I use this motor with a bike is there any info here that would get me up to speed? If I can use this motor how would my SBP heavy duty shift kit hold up to that kind of horse power? Do I need a tranny and if so where would I get one and what one should I get? Looks like Iam going to need some help with this project is there anyone here that has tried this and would be willing to give me any advice? Thanks guys.
 
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agk

New Member
Oct 2, 2010
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Santa Barbara CA
I put a 6.5hp engine in a cruiser bicycle several years ago. I left the engine completely stock except for building a header that routed the exhaust toward the ground. I even left the govenor in the engine which limits rpm to 3600. I welded a slotted motor plate in the frame. I setup a jackshaft. And I mounted a sprocket to a 6 bolt mountain bike hub. I used a hydraulic front disc brake from a pit bike. With a stock engine this bike went 46mph at 3600 rpm. This cruiser could climb the steepest hill in my town at 46mph just riding on the govenor. These engines will run at 3600 rpm all day long.

The down side is the size and weight of the engine. The engine alone weighs 36lbs dry. The engine will not fit in most bike frames. It's pretty darn wide for a bike too. Despite these problems and after building about 20 mb's now, the 6.5hp bike is still my favorite.

I'm not familiar with the SBP heavy duty shift kit, but if it runs through bicycle chain, the torque of the 6.5hp engine will more than likely break that chain.
 
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oldtimer54

Member
May 15, 2010
540
6
18
On a bike
agk said:
I put a 6.5hp engine in a cruiser bicycle several years ago. I left the engine completely stock except for building a header that routed the exhaust toward the ground. I even left the govenor in the engine which limits rpm to 3600. I welded a slotted motor plate in the frame. I setup a jackshaft. And I mounted a sprocket to a 6 bolt mountain bike hub. I used a hydraulic front disc brake from a pit bike. With a stock engine this bike went 46mph at 3600 rpm. This cruiser could climb the steepest hill in my town at 46mph just riding on the govenor. These engines will run at 3600 rpm all day long.

The down side is the size and weight of the engine. The engine alone weighs 36lbs dry. The engine will not fit in most bike frames. It's pretty darn wide for a bike too. Despite these problems and after building about 20 mb's now, the 6.5hp bike is still my favorite.

I'm not familiar with the SBP heavy duty shift kit, but if it runs through bicycle chain, the torque of the 6.5hp engine will more than likely break that chain.
Click to expand...
What did you do for a clutch?
 
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agk

New Member
Oct 2, 2010
151
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Santa Barbara CA
I just used a basic MaxTorque clutch ($38). I ran the clutch inboard. I welded bearing hangers on the motor plate behind the engine. This is where I setup the jackshaft. I just used ideas from my go kart and mini bike experience to get it done. This was my first mb so I kept it simple. There are a couple forum members currently building bikes with the 6.5hp engine. Look around the the forum and check out their work.
 
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sketchman

New Member
Mar 23, 2011
168
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WV, USA
I got one too. Like you say, $60 knocking on 200cc, how could you not buy it?

Even if you were to use a common 44t sprocket in back and the stock 10t max torque up front and hook it up straight, you'd be flying and have mountains of oomph away from stop lights and such.
 
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agk

New Member
Oct 2, 2010
151
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Santa Barbara CA
chainmaker said:
Can anyone tell Me the dimensions of this motor?
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The engine is 13.5" from front to back.
The width is 12" from the recoil starter to the end of the output shaft.
The height is 12.5" with the stock tank, air filter box and exhaust.
If you remove the tank, build a custom header and replace the stock air filter box with a high flow filter and adapter it will be about 9.5" tall.
 
NEAT TIMES

NEAT TIMES

New Member
May 28, 2008
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PENSACOLA, FL
How would the 6.5 work in a stretch cruiser with the pedal crank forward ? Then i could use the special creative engineering sprocket for my wheels with many spokes.
 
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sketchman

New Member
Mar 23, 2011
168
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WV, USA
chainmaker said:
Can anyone tell Me the dimensions of this motor?
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Added to what agk said, it doesn't weigh quite so much when you take off all the "extra" stuff. With just what it absolutely has to have to run, mine weighs in at around 25lbs. Not bad at all IMO.

That's no fuel tank, air filter and housing, sheet metal stuff, pull starter, governor linkage, or exhaust heat shield. Probably another 1/2-1lb could come off when I take off the pull starter "cup" bolted to the crank and the blower wheel, along with the internal governor parts and low oil shutdown system.

It really isn't as heavy as it would seem.
 
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agk

New Member
Oct 2, 2010
151
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Santa Barbara CA
oldtimer54 said:
Can you try posting your pic again. What would you say would be the size and style bike frame this motor would fit in? How did you get your cranks around this wide (12") motor? What do you think would wouk better a jack shaft or a CVT? Thanks
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I'll try to post some photobucket links. Just remember, this is the first motorized bike I ever built. I didn't know much at all about motorized bikes. This bike was built about 6 or 7 years ago.

http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-13.gif
http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-12.gif
http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-10.gif
http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-7-1.gif
http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-6.gif
http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-4.gif
http://i126.photobucket.com/albums/p109/agk409/Clone-Beach-Cruiser-2.gif

I used a jackshaft. The jackshaft will multiply the torque of the engine which is necessary for turning the tall 26" tires. This bike will pull very strong from a dead stop. I can leave right with traffic without the car next to me pulling away. The power is nice and strong all the way to the top end. The cars usually pull away from me at about 30mph, but they are looking over at me the whole time because it's really unusual for a bicycle to keep up with a car like that.

The CVT that Cobrafreak is using is far superior to a jackshaft. With a jackshaft you are stuck with whatever gear ratio you choose. The CVT is a continuous variable transmission. So Cobrafreaks bike, by using the CVT, benefits from a nice low gear ratio for taking off and accelerating. The CVT will smoothly change gear ratios with torque and rpm. So Cobrafreaks bike is going to benefit from multiple gear ratios as he accelerates to top end. With my single gear ratio, my bike will go 46mph. I can't imagine what top speed Cobrafreaks bike will obtain.

With such a big engine in a bicycle a jackshaft is more than sufficient. If I wanted a higher top speed I could pull the govenor out of my engine and install 18lb valve springs. This would increase the engines rpm from the factory 3600 to 6500. This additional rpm will give me a higher top speed. The great thing about using the CVT is you can leave the engine completely stock and obtain a really high top speed simply due to the changing gear ratios that the CVT offers.

I'm not trying to compare my bike to Cobrafreaks as there simply is no comparison. I'm just trying to use these two bikes as examples to help you decide how you want to move forward with your bike build.

To answer a couple of your other questions, I used the same wide pedal cranks that Cobrafreak posted a link to in his thread. The bike I used for my 6.5hp engine was advertised as, "relaxed fit". The frame is stretched 4" to 5" between the bottom bracket and the seat tube. You may be able to see this in one of the pictures.
 
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oldtimer54

Member
May 15, 2010
540
6
18
On a bike
Cant seem to find anyone I would trust to mod a bike frame for this big motor so Iam stuck. I think Ill keep trying to find a 79cc HF. Wonder if anyone has got the new HF 99cc working with a CVT or jack shaft? What say you has anyone had any luck with the new HF 99cc engine?
 
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matthurd

New Member
Dec 13, 2010
817
2
0
manchester NH
a nice worksman bicycle with a straight bar style frame, should give you plenty of clearance, just gotta weld in some mounts for the motor, but worksman makes awesome bikes, and i think you'd have plenty of room for the motor.

No BULL Worksman/Pirate Roadster Bike

also has the cb-110 hub, so you could use already existing sprocket adapters, along with a 56 tooth sprocket, and bolt it right on.
 
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