Dennis I like your spirit of try it and .see. I haven't built a 4 stroke with CVT on a bike yet, but have done various go karts using both. The CVT is a game changer for final drive sprocket size though. I'm pulling for the 20 tooth to work for you, but that's pretty small.
I bought a Lifan 4 stroke vertical engine, think it's a 99cc, 3.5 hp about a year ago and put a comet CVT on it...bolted the thing down on a work bench and ran it for a couple of hours over the course of a few days to break it in. It's been waiting for me to get back to it ever since. I thought a 44 tooth would work with the CVT, my 175 lbs. & our hills, so I'm interested in what you find to work with the 212cc.though the Lifan has much less power and torque than the Predator 212.
Rick C.
Rick, I had some time off and went ahead and put the 20-tooth sprocket on Sunday. The thing was a real bugger to get the
chain to align with the sprockets. I finally got it as close as I could and couldn't try the bike till Monday night. The engine
wasn't fazed by it even taking off from a dead stop. The sprocket is a little slow building up and I suspect that the CVT
wasn't fully engaging with the belt. I revved the engine up and the engine was slipping the CVT belt. I could ease into the
throttle and it was alright. Normal cruise speed of 25 mph was wanting to climb over 35 mph. The engine can pull the
sprocket but the CVT doesn't like it.
I am thinking the belt has a little wear on it and I think it is stretched a little to slip
like that. My opinion on using a 20-tooth sprocket, don't do it, it's hard on belts and acceleration isn't there since there is
belt slippage. The sprocket also isn't easy to align. I put the brandnew belt on and it is better quality and fits tighter. I went
ahead and remounted the 32-tooth sprocket and a 30 or 28-tooth might be a compromise? The 32-tooth is wicked as it is.
You have good acceleration plus 30+ cruise speed. Running 30+ the bike will set you back and climb way past 50 mph.
My mechanical speedometer has been right since I put that engine on this bike. I doubt if a steep incline would bother the
bike. I know the 49cc can pull a hill over here but acceleration on the hill running about 25 mph it was sluggish whereas
the 212cc isn't fazed by the hill and accelerates with very little throttle applied to the engine on the hill.
I wouldn't run a 44-tooth on the 212cc and I doubt on a 79cc coupled to a CVT. The 36 and 40-tooth sprockets are
dangerous on the 212cc and will tear things up on the bike. The first time I came down on the throttle on the 212cc
and it was nowhere near top end of the throttle running 25 mph, the bike lifted the front wheel. These bike frames
won't take that! I've never opened this engine up full throttle since I removed the governor and the low-oil sensor
on the engine. I figure, if a fella can run 60 mph with a stock 212cc with 26" wheels and a 40-tooth sprocket, it's
fast enough! The Predator engines have the torque and rpm to get you down the road. I've got the Stage 1 kit on
this engine and I wouldn't go any higher. You have to have heavier hardware to go any higher in HP. What would
be fun would be to go with a "TrainMaster MB200-2 mini dirt bike" and a 212cc Tillotson Hemi 10 hp engine.
If I was you, I would go ahead and bolt that 79cc and CVT on a bike to try it. A good starting point would be a
40-tooth sprocket although since you already have the 44 give it a try.
Dennis
