Building Michael's OCC with a 79cc Predator

[michael whiteman]

It seems there has been a lot of past interest in this particular build, and again at this time late 2023. With the help of all the knowledgable folks on this forum and multiple You-Tube Videos I have a more clear understanding of what's involved. I hope by sharing what I have discovered will help those who follow and reduce their frustration level. By no means am I saying this is the only way to do it........so just pick and choose my discoveries that may help you. Thanks to all again for your help.

 

[michael whiteman]

The low rpm Predator is quite the opposite of my other 142f engine and requires one to rethink the complete drive system. I spent a month researching CVT constant velocity transmissions verses jackshaft transmissions. Although others have used CVT straight to the wheel, I found for my speed and torque range I would also need a jackshaft for further reduction. I 'm not sure all this will fit in the frame and I didn't want to spend all the extra $$. I also like the compression braking that you get with a clutch and not with the CVT.

There are more CVT units available than you can imagine. As with all China knock offs you get what you pay for. Looking for complete Jackshaft Kits proved to be more challenging. There were only a couple I could find before I gave up looking.
1. The unit made by Coleman for minibikes has a stamped steel plate and a roller tensioner that most everyone feels to be very week and bends easily. Many reviews state the kit arrived bent in the box. Not very reassuring.
2. PMR made a very impressive kit with an aluminum plate using dual bearings. Advertised through Oldminibikes.com (no longer in business) and sold by Hent who does not stock them any longer. Bummer!
3.

Jackshaft Kit, Go Kart Mini Bike Gear Reduction, Inline Operation

This Jackshaft Gear Reduction kit bolts right onto your engine and is all fully self contained. In-line operation means the final drive sprocket is on the same side as the engine crankshaft, making it much easier if converting from a straight clutch

gokartsusa.com

This is the only quality jackshaft kit I could find but the $162 price took my breath away. Not mutch of a selection to choose from.

So I have decided to make my own kit and save some money doing it. Not counting shipping, cost will be $98

Plate https://www.bmikarts.com/Jackshaft-Plate-for-79cc-196cc-212cc-Engine_p_20833.html
Shaft https://www.amazon.com/Azusa-10-Long-Threaded-Jackshaft/dp/B07956DLDR
#35 sprockets https://www.bmikarts.com/35-Sprocket-with-58-Bore-B-Type_p_1053.html
#415 sprocket https://www.staton-inc.com/store/index.php?p=product&id=1959

 

[GW's Motorized]

Hey Michael. I didn't get a chance to make it to the PO yesterday. I was doing alot of running around and the PO closes at 5 every day. With my school schedule during the week I get home at 4 and I have trouble making it to the PO in time during the week. I will try tomorrow. Thanks!

 

[Chainlube]

You won't get any compression braking with either systems. When you let off the gas, they both go into freewheel mode.

 

[GW's Motorized]

The only way to get compression braking with a 4 stroke bike is one of the expensive manual clutches.

 

[cloakedvillain]

Clutch drag can do some braking but not the same as compression braking

 

[DieselTech]

Put a Blue Ox on it!!!

 

[michael whiteman]

You won't get any compression braking with either systems. When you let off the gas, they both go into freewheel mode.

If you come over I'll let you ride my rat bike with the 142F and you could see for yourself that the engine slows me down to where I hardly use the brake at all when coming to a stop. As long as my clutch is locked up the compression acts against the momentum of the wheel when decellerating.

 

[Chainlube]

If you come over I'll let you ride my rat bike with the 142F and you could see for yourself that the engine slows me down to where I hardly use the brake at all when coming to a stop. As long as my clutch is locked up the compression acts against the momentum of the wheel when decellerating.

As long as the engine has a higher rpm than the kick in rpm of the clutch you will get some engine braking. After that it's looses momentum from friction in the drive train, so yea you have that. Not engine braking like a diesel.

 

[michael whiteman]

As long as the engine has a higher rpm than the kick in rpm of the clutch you will get some engine braking. After that it's looses momentum from friction in the drive train, so yea you have that. Not engine braking like a diesel.

OK now you understand. It's definitely not like a Jake Brake. LOL