questions about non kit 79 cc predator build

[Cazziuz83]

Ok so i have been having issues lately with my bt 80 engine, and my back up china girl engine...so at my wifes suggestion im looking into what all is needed for a 79cc 4 stroke engine.from waht i have been told a 79cc will fit on my OCC stingray frame, so that shouldnt be a issue unless i was told wrong,which is always possible

from what all i can tell ( from reading in various places and my weak google-fu) i need the engine its self( can be bought for less than 100 usd at local harbor frieght), and a the very least a torque converter.

now my question is is that all i need? i mean i have the tank and can make the exhaust so thats not a issue, from what i read i can rig a throttle linkage fairly easily as well .

so what else is needed? and is the converter the best way to go , as in cheapest? cause im on a budget.
from what i have read on go kart sites ( which seem to be the only place i can find info for the 3.5 hp engines ) a series 30 converter is what i need, but the one they link on amazon says in the Q/A section that it wont work on a predator engine..so any suggestions ?

 

[Deleted member 26224]

Clutch, 9 or 10:1. Clutch good cvt bad.

 

[Cazziuz83]

Clutch, 9 or 10:1.

clutch 9 or 10:1 ? means what exactly? that i need a clutch in stead of a torque converter?

and the attachment is a bit unnecessary, i freely admit my google fu is weak AF ...so dont be a smart ass , its not funny nor does it do much to make you seem like a helpful person

 

[mark20]

clutch 9 or 10:1 ? means what exactly? that i need a clutch in stead of a torque converter?

and the attachment is a bit unnecessary, i freely admit my google fu is weak AF ...so dont be a smart ass , its not funny nor does it do much to make you seem like a helpful person

well, you need a 10:1 gear reduction. (basically, the wheel rotates 10 times every 1 complete turn of the engine)

id use a torque converter rather than a clutch, as there easier to get right the first time.
torque converters will give you about a 3-5:1 gear ratio (depends on what model you get). so you will need to get the rear sprocket to be around 44t or so (50t might be better for hills)

the engine has a smaller 5/8 shaft, so to use a torque converter you need s step up key (makes the shaft size a more standard 3/4)
this thing https://www.ebay.com/i/401958318183...72lh9eS2Dovnv4kxRy3SisF_TNSCCqDRoCquEQAvD_BwE

a engine plate (will need to redrill holes for the bigger engine)
https://www.bicycle-engines.com/black-v-frame-mounting-plate-kit/

and then work your way up (chain, sprocket, tank, throttle, etc)

hope this helps some!

 

[Cazziuz83]

well, you need a 10:1 gear reduction. (basically, the wheel rotates 10 times every 1 complete turn of the engine)

id use a torque converter rather than a clutch, as there easier to get right the first time.
torque converters will give you about a 5:1 gear ratio. so you will need to get the rear sprocket to be around 44t or so (50t might be better for hills)

the engine has a smaller 5/8 shaft, so to use a torque converter you need s step up key (makes the shaft size a more standard 3/4)
this thing https://www.ebay.com/i/401958318183...72lh9eS2Dovnv4kxRy3SisF_TNSCCqDRoCquEQAvD_BwE

a engine plate (will need to redrill holes for the bigger engine)
https://www.bicycle-engines.com/black-v-frame-mounting-plate-kit/

and then work your way up (chain, sprocket, tank, throttle, etc)

hope this helps some!

that helps massively , thank you

 

[mark20]

that helps massively , thank you

welcome! if you have some hickups just let us know, those predators are great for cruising around town!

 

[Cazziuz83]

so im looking around fora torque converter, and im having a issue on figuring out which one i need to get fora 79cc..assuming the shift size is correct, what should i be looking at to pick the proper one ? the engage rpm's? or something else ?
harbor freights website says the 79cc has a max rpm of 3600, so im assuming i want something that engages a fair amount lower than that.

the one im looking at is :

https://www.amazon.com/MOOSUN-GO-KA...4QN6NZS2S2F&psc=1&refRID=5ZMCPB5CG4QN6NZS2S2F


from what i understand if ia mreading it correctly it says it fits most engines 2 -11 hp , the 79 cc is 3.5 hp so it should in theory fit, correct?

 

[FNTPuck]

If you are riding on paved roads and streets then definitely go clutch on a 79cc. Torque converters are more for big power builds that don't mind the drivetrain loss, off road riding, and heavy setups that need the extra gearing down low. They add a lot of width to your build, will eat a lot of your hp, limit your top speed, and need more maintenance than a clutch (belts, cleaning, dry lube, etc).

If you will be doing trails and big hills, the TQ converter is awesome - tons of pulling and climbing power.

 

[Cazziuz83]

If you are riding on paved roads and streets then definitely go clutch on a 79cc. Torque converters are more for big power builds that don't mind the drivetrain loss, off road riding, and heavy setups that need the extra gearing down low. They add a lot of width to your build, will eat a lot of your hp, limit your top speed, and need more maintenance than a clutch (belts, cleaning, dry lube, etc).

If you will be doing trails and big hills, the TQ converter is awesome - tons of pulling and climbing power.

from what i understand, the weight is a factor in what im wanting to do, i mean i carry a 50 lb backpack ( tools/work uniform/emergency supply's ect ect) and i weigh in around 270 myself , speed isnt really a factor for me( assuming i can hit at least 30 mph which is the fastest i can go on my 2 stroke set up), and while most of what i ride is fairly flat, at this time there is a massive hill on my way to work ( to be honest probably the only hill on my side of town ,lol ) so not counting engine bike frame ,other add ons like my battery for my electronics and such im already sitting at 320 lbs.

im not overly worried about width added to the bike either,before i switched to my back up chinagirl engine i was using a bt-80 bullet train, thing is stupid wide, so pedals were mostly just for show and footpegs,lol.

 

[Deleted member 26224]

clutch 9 or 10:1 ? means what exactly? that i need a clutch in stead of a torque converter?

and the attachment is a bit unnecessary, i freely admit my google fu is weak AF ...so dont be a smart ass , its not funny nor does it do much to make you seem like a helpful person

I gave you the info specific to your query; 79cc and 20” rear wheel. Now you go do the research, search this site and other side, google whatever, until you understand what I’m talking about. Put the work in