T20 input rpm?

[truckinwagen]

Hey guys and gals,
I'm wondering what the maximum input rpm is for a t20?
I'm doing a complete refurb on a max2 and am looking at using a large four stroke motorcycle engine(since I have an atk 605 in parts in my shed)
I am going to need to run a jackshaft to convert the chain drive to the primary clutch, but don't want to spin the clutch so fast that it damages it, or the trans.

Anyone have any input on how fast is too fast?

[dirtdobber]

So, are you going to run a chain from the motorcycle engine transmission to a jackshaft, and then a CVT setup from the jackshaft to the T20? Or will you use the motorcycle engine/trans for clutching purposes?

If you are going to use a CVT clutch setup, then just plan on having the drive clutch spin no faster than it would if it were attached to a typical 2 cylinder Briggs engine or similiar (what... 3,500 RPMs or so max?) That way you can enjoy normal speed ranges while trail riding or on the zipping along in open territory. The drive clutches have a max rpm rating also. If you are trying to build a super-fast racing buggy, then that's a different story!

[truckinwagen]

Yes, I intend to keep the CVT.
I see some people running 4000rpm on modded motors, I guess my question is, as long as I keep within the parameters of the primary clutch, will the t20 be ok?

For instance, I can get a clutch set up for 5k rpm from a snowmachine, would the t20 be ok turning that fast?

The engine spins 10k and I believe 5th gear is 1:1 so I need to be sure what reduction to put in the jackshaft to not tear stuff up.

[philipatmaxfour]

The army of two stroke race guys on this site almost exclusively run t20 trannys and they don't talk about their engines over revving the t20. Kohler 4 strokes don't need to be "modded" to turn 4,000 rpm in a Max iv.

[truckinwagen]

Correct me if I'm wrong, but most if the two stroke engines guys are using run quite a bit less than 10k rpm.

I'd like to run as high as I can to get the most out of the motor, but don't want to go too crazy and break things.

I've tried to find an rpm spec for the t20, but can't seem to find one.

[dirtdobber]

I don't think a high input rpm is going to hurt the transmission. It's what you intend to do with all that speed and built up inertia that may hurt something. Tell us about the driving conditions you intend to encounter and that will shed a little more light on things.

When you say you have a large four stroke motor to use, how large are you talking about?

[truckinwagen]

600cc single, air cooled rotax out of an atk 605.

Mostly winter with tracks.
I want to get as much wheel speed as is reasonable to stay on top of the snow.
Might run tracks as wide as 20"

[countrybumpkin]

Our racer t-20's are taking 8500 to 9000 rpm down the straightaways, you should not have any problem, especially with tracks.

[truckinwagen]

Good to know.
I just took a good look at the motor on the motorcycle and it looks pretty doable.
I priced out the parts for the jackshaft and I can have that together for less than $100.

I'll need a new primary clutch(don't think the 12hp Briggs one will like the added power and rpm) and I'll be on my way!