Thinking about 79 or 99cc predator bike.

LongboardMalinois

LongboardMalinois

Member
I've been wanting a second bike for a very long time, and soon i'm actually going to build one. My question is what is the bare minimum of things i will have to buy and make to put a Predator 99 or 79cc engine onto a bike? I was thinking of a simple drive system of a centrifugal clutch on the shaft with a chain going straight to a regular MB sprocket on the back wheel. Will that work? What i am mainly concerned about though is mounting the engine into the frame in such a way that i don't have to deal with a jackshaft. I also still need to find a frame, so and ideas about that would be great.
Thanks!
 
You must reduce the overall ratio to around 12:1(give or take). To direct drive(engine to wheel) would require a huge sprocket. The only way generally is a jackshaft. There are bolt on reductions/jackshafts as well as torque converters.

Check AGK go karts they have a nice bolt on unit.
 
Cannonball, is there any chance you could provide a link to the bolt on kit from AGK? I've looked all through their website and i can't find a bolt on unit which says it fits the 79 or 99 predator. Also, I've heard that torque converters on these engines eat up belts. Is that true?
 
Now i'm really getting somewhere with this build. I bought a 99cc predator yesterday, and i already had a 79cc pred, so i'll use whichever one works best with my setup. I can get the clutch, mounting plate and jackshaft kit from AGK, and i'll use a regular 56t MB sprocket on the back wheel. Now i just need to find a frame which will take the large engine, and i'll be ready to start building! Does anyone have an idea of top speed with the AGK jackshaft kit?
 
ElGallo, i went to my local Harbor Freight and just bought one. They were in stock.
Scotto, thanks for the link, i'll read that thread. I'll look into the Dyno Glide.
 
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scotto- said:
Here is a link to how I built my favorite 99cc Pred.

http://motorbicycling.com/showthread.php?t=44847

This bike is a blast to ride .wee.
Click to expand...


That is one incredible bike. Unfortunately i don't believe that i'm capable of doing a build anything like that, since i had trouble installing my first 66cc 2 stroke... I was thinking more of mounting the engine in its intended orientation, with the cylinder more or less horizontal, and using a regular 4 stroke mounting plate to attach it to the frame. Do you think that that method of mounting would work, or will i have to make or buy a mounting plate similar to the one that you used?
 
.That awesome that you found a 99cc, tried the HF website they don't sell them anymore. Then I tried looking for a used one but no luck there.

I would buy all you can of the 99cc and then sell them for profit later.
 
If i was using the AGK jackshaft and a centrifugal clutch could i decrease the wheel sprocket size a bit, like to 50t or even 44t without burning up the clutch? I'm not too keen on having my top speed be 25 mph at 4000 engine rpm, since i can do better than that on my china girl! I'm OK with having to pedal up to 5 or 10 mph before engaging the engine.

Edit: obviously i'm not going 25mph at 4000 engine rpm on my china girl, what i meant is that i have a top speed of more than 25 on it.
 
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If you run a 10:1 your top speed will be in the 31 mph range @4000. Much below 10:1 and the bottom end suffers. If hills are an issue in your area it wont climb as well as say a 12:1. There will be clutch chatter if you pull from stop. Its nice to have a larger engine bike pull from stop.
I have run the HF engines well above 4000 with no bad results, just be sensible with a stocker. With a lower rpm motor multi speed gearing is a nice thing. For road use 3speeds work well.
 
cannonball2 said:
If you run a 10:1 your top speed will be in the 31 mph range @4000. Much below 10:1 and the bottom end suffers. If hills are an issue in your area it wont climb as well as say a 12:1. There will be clutch chatter if you pull from stop. Its nice to have a larger engine bike pull from stop.
I have run the HF engines well above 4000 with no bad results, just be sensible with a stocker. With a lower rpm motor multi speed gearing is a nice thing. For road use 3speeds work well.
Click to expand...

31mph is more like what i'm hoping for! Is there any way to make it have multiple gears that is not too hard? Like i said, i'm not too experienced building bikes, since all i've done is build two china girl kits.
 
Search the forum for shifter builds.

There are derailleur types and internally geared hubs(IGH). While not hard to do they do require a bit of mechanical skill to accomplish, and the right type of bike/frame to start with.

Do some reading and see if it fits your skill set.
 
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