After starting to build a motorized bicycle I realized I actually wanted to build an early motorcycle replica. I did not want to pedal this cycle. I tried a 49cc 2 cycle and a 66cc 2 cycle and neither gave me the power to climb hills. I tried 3 speed rear hubs which worked great but I could not keep them from falling apart after half a trip around the block. I rebuilt them several times. I was about to give up and I got a Harbor Freight 79cc 4 cycle. It has the power I was looking for to climb hills. It putts along at 20 mph and will probably go over 30mph if I wind it out. I have a 10 tooth centifical clutch that goes to a 25 tooth input jackshaft. That goes to a 8 tooth sprocket on the jackshaft output. That goes to a 50 tooth sprocket on the wheel. I have a disc brake on the jackshaft but it put much stress on the chain tensioner. I put a rear wheel brake and ran them both to a double brake lever. I have a disc brake on the front wheel. Attached are some pictures.
79cc harbor freight predator
- Thread starter Dulcijo
- Start date
silverbear
The Boy Who Never Grew Up
Dulcijo,
What a nice surprise when I clicked on the first photo and saw your bike... and each photo after revealed more surprises. You've done yourself proud, sir! A lot of clever thought has gone into that build from the purely cosmetic to the mechanically practical.
And I agree that the 79cc Predator is a good choice for a motored bike. Lot's of reliable grunt. I see you have changed the carb over as I did mine on a 99cc Predator. Lots more throttle response I find. I'm guessing the exhaust is pretty loud, or is it not so bad? It looks great!
This past week I drug out a bike with a 50cc china girl on it to get it going again and pass it along to one of my sons, who wants it for some reason. What a pain in the orsch those are. I had almost forgotten how much better my experience has been with four strokes. I have a couple of vintage 2 stroke bikes with well made engines, but those China girls are a pain in my opinion.
Anyway, great job on your Flying Fox!
SB
What a nice surprise when I clicked on the first photo and saw your bike... and each photo after revealed more surprises. You've done yourself proud, sir! A lot of clever thought has gone into that build from the purely cosmetic to the mechanically practical.
And I agree that the 79cc Predator is a good choice for a motored bike. Lot's of reliable grunt. I see you have changed the carb over as I did mine on a 99cc Predator. Lots more throttle response I find. I'm guessing the exhaust is pretty loud, or is it not so bad? It looks great!
This past week I drug out a bike with a 50cc china girl on it to get it going again and pass it along to one of my sons, who wants it for some reason. What a pain in the orsch those are. I had almost forgotten how much better my experience has been with four strokes. I have a couple of vintage 2 stroke bikes with well made engines, but those China girls are a pain in my opinion.
Anyway, great job on your Flying Fox!
SB
Thanks for your response and kind words. The exhaust has a 1/2 inch galvanized pipe inside a cosmetic outside chrome pipe. It is pretty loud but sounds kind of like the old board trackers. I have a fitting in the end of the galvanized pipe so I can screw in a small muffler if I am going somewhere I want to make less noise. It seems to have more power without the muffler.
Sidewinder Jerry
Well-Known Member
I live in Tennessee so I know what you mean about hills. I solved my issues with a shift kit.
Hawaiikelly
New Member
That's a very clean build
dirtwarrior
New Member
an awesome bike. Question who makes the HF engine
I am not sure but at this site it is discussed
http://weldingweb.com/showthread.php?207441-Harbor-Freight-Predator-Engines
http://weldingweb.com/showthread.php?207441-Harbor-Freight-Predator-Engines
dirtwarrior
New Member
thanks for the link
Robin Russell
New Member
i would like to run 79cc predator with SBP shift kit and grubee box. are there any problems mating motor and gear box, any suggestions