advice on 79cc transmission

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obesepolice

Member
Apr 5, 2012
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irving, texas
Im rebuilding my bike again with a 79cc predator. I need a transmission for it, but im not sure what to use. It will have the governor removed, 18lb valve springs, ported and milled head, exhaust and a 19mm carb.

Do I just use the standard clutch and jackshaft set up that comes with the kits, or make my own from better parts? Help with a parts list would be fantastic.

Grubee also makes a drive belt setup that looks like a quality piece of kit. allbet the gear ratio is abit steep. but i can change the ratios around

EZ motorbikes also has one but i cant seem to find any info for it.

there is a torque convertor but everything im finding is for a 3/4" shaft, i know you can use an adapter but i dont know what all that involves.

any help you guys can give me would be great
 
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curtisfox

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Dec 29, 2008
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Simple 3/4" to 5/8" reducer bushing and a 3/16 " by 1/4 " keyway is all the adapter you need...........Curt
 
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obesepolice

Member
Apr 5, 2012
114
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irving, texas
Tom from Rubicon said:
Did you try this? Dealer Locator - EZ MotorbikeEZ Motorbike To save typing I modified the inner clutch shaft support bracket. Replacements are roughly $35.00 shipping. You got a photo of your build to verify compatibility? I know this transmission mounting plate is right only with the engine configured one way. By the way. You got a real Christian name?
Tom
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Hey Tom Im Pete.
I ended up going with Grubees belt set up for it. Here is a picture of my bike so far. 20210228_152510.jpg 20210301_195724.jpg 20210301_200052.jpg
20210228_152510.jpg
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20210301_200052.jpg
 
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Tom from Rubicon

Tom from Rubicon

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Apr 4, 2016
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Hey Pete, coming together good. I have long thought about a Grubee Trans for my 49cc ride. I didn't know one was made for a 5/8" straight shaft. That shorty exhaust pipe will get some attention.
Tom
 
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user54508

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Feb 3, 2021
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So I'm tired of all the Torque converter Rants on the forums all over lol! So much advice yet never see people show it in action or working! 5/8 to 3/4 issues and it's to wide the back plate on smaller motors. How you get the sprocket on other side. that one is my favorite! Lots of beer used in some of those conclusions. going to use all simple tools with parts that function safely that don't look like a 4 year old made it. These are old easy things done for 100's years by hand. Just a matter of knowing what works and does not. When you secondary key your shaft 1 inch section must be in the adaptor to maintain correct holding of the key. After that not much to it. Mind you half of your main drive clutch key will be inside the main shafts keyway to start with ! So secondary key acts like a buffer/stop for the main keyway!



Part 1 Making the Bearing Holder correct Size:


Part 2 Jack Shaft to back side sprocket


Part 3 Secondary keying of Main 5/8 Shaft with second key for 3/4 adaptor use


Part 4 250 miles later

 
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user54508

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MotoMagz said:
Tav does work well with the 79cc or 212 but your not getting all the power the motor(a) has to offer.
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Okay you don't make sense.... works perfectly fine... zero lose compaired to centrifugal clutch setup. If anything the bike now has more more lower end take off power and will run the same speed the bike did before with clutch setup. How exactly is there a lose again? You just need the proper springs and weights for your motors power range. This bike will go 50mph. How exactly is there even a need to surpass that on a bicycle lol? Only thing that changed was the speed to which it hits 50mph from a dead stop. Not a lose in power though. Just time of the torque converter changing ratios as you speed up. Bike goes from 0 to 20 in 5 seconds. Takes about 20 to hit 45. Clutch took like 20 seconds to hit 45 but also shock like a crack who're trying to get up to speed
 
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Tony01

Tony01

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Nov 28, 2012
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TheEvilCareBear said:
Okay you don't make sense.... works perfectly fine... zero lose compaired to centrifugal clutch setup. If anything the bike now has more more lower end take off power and will run the same speed the bike did before with clutch setup. How exactly is there a lose again? You just need the proper springs and weights for your motors power range. This bike will go 50mph. How exactly is there even a need to surpass that on a bicycle lol? Only thing that changed was the speed to which it hits 50mph from a dead stop. Not a lose in power though. Just time of the torque converter changing ratios as you speed up. Bike goes from 0 to 20 in 5 seconds. Takes about 20 to hit 45. Clutch took like 20 seconds to hit 45 but also shock like a crack who're trying to get up to speed
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Okay you don't make sense.... works perfectly horribly... zero lose compaired to a bicycle. If anything the bike now has more more break down power and will run the same speed the bicycle did before with no engine setup. How exactly is there a lose again? You just need the proper springs and weights for your motors weakness range. This bike will go 150mph. How exactly is there even a need to surpass that on a bicycle lol? Only thing that changed was the speed to which it hits 150mph from a dead roll. Not a lose in bullcrap though. Just time of the torque converter changing strength as you wake up. Bike goes from 0 to 20 in .5 seconds. Takes about 20 dollars to hit a 45yo around here. My buddy paid like 20 dollars to hit the 45yo but also got shocked by the crack who're when she said shes pregnant
 
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