Drag mini bike-Predator RPM issue??

[Havasu Dave]

Nice... Math for baseline, track for fine-tuning
These engines have been done to death and back, so fairly accurate curve characteristics can be extrapolated from the specs. Again, for baseline.
Belt stick at high ratio sucks, but I doubt he's near that. A Sharpie mark on the sheaves would tell how much sheave he's using.
I haven't seen an RPM rating on the TAV, but it's on a lot of my big Comet 102/108 stuff. I'd love to see what the mfg says on the TAV
Racer types should likely get a better, more tuneable setup like a Polar or other Jr Dragster stuff, even a 340.

Agree with that. Snow machine or dragster, done. I've seen anything from 3800 to 6000 RPM limits in the web. Of course warranty and normal driving issues come in to play with those numbers. I believe it was David Wulf who commented on belt sticking, but I think he was closer to 9K.

I like the sharpie idea, because that quickly answers the gearing question.

I'll crawl back into my flat head hole now. :laugh:

 

[massacre]

Thanks for posting Dave, i always look forward to your posts and the wisdom they contain.
I didn't think the TAVs had an RPM limit, thanks for setting me straight. Always glad to learn, i am far from an expert.

Only reason i commented in this thread is because I have done extensive testing in 100 foot drag racing. Between my Dad's bike and mine i bet over 500 passes easy. Gearing was something that we obviously tested, and got it down to the tooth. The shorter track means high high gearing, at least 6 or 7 to 1.
Also, a 60 tooth rear sprocket on a 12" tall tire is not helping you either. I was using a 11" tall tire with a 72 tooth sprocket and it still would not launch as hard as i needed it to.

Again this is just my experience, FWIW.

 

[Havasu Dave]

Thanks for posting Dave, i always look forward to your posts and the wisdom they contain.
I didn't think the TAVs had an RPM limit, thanks for setting me straight. Always glad to learn, i am far from an expert..

Thanks and I am NO expert. I just have a lot of experience moving rubber dog shit out of Hong Kong. Those standard TAV's are made for Yerf Dogs and old machines like I ride. It stands to reason that if you're running 30 HP at 9000 RPM some of that rubber is going to do bad things. It wears out quickly enough at 2000 RPM. lol

 

[Newoldstock]

Thanks and I am NO expert. I just have a lot of experience moving rubber dog shit out of Hong Kong. Those standard TAV's are made for Yerf Dogs and old machines like I ride. It stands to reason that if you're running 30 HP at 9000 RPM some of that rubber is going to do bad things. It wears out quickly enough at 2000 RPM. lol

Those PIX belts for the 30 series are really soft.
I can wear one out in an hour.
They hook up well but the rubber wears out fast and the kevlar belt will cut a groove in the primary at the base near the bushing because they just .... suck.

The right belt, with the right set up and tuning will work better and last longer but as Dave puts it you have to understand the limits of the system .