Top speed much lower after TAV install

[matthewlswanson]

Predator 212 Stock w/ straight pipe and performance filter
420 chain with 54 tooth rear sprocket
This TAV

I recently added the TAV and my top speed went way down. Is this due to gearing? Do I need to go down in rear sprocket tooth count? I chatted with someone at OldMiniBikes and they have a way to adapt my wheel for a sprocket with fewer teeth, but I wanted to make sure it would actually increase my speed or if I need to go back to the centrifugal clutch. Is the tooth count really limited to 40 or is that just all OldMiniBikes carries?

Here is the chat with OldMiniBikes:
Hi Matthew,
Someone did a great job of drilling that old sprocket! That was done as the options for the small 6 bolt pattern are limited!
Here is what we can do
Use this sprocket adapter
https://www.OldMiniBikes.com/doodlebug-sprocket-adapter-4.html
You may need longer screws
https://www.OldMiniBikes.com/mounting-bolt-kit-for-db3-db4-sprocket-adapter.html
and you can use this sprocket
https://www.OldMiniBikes.com/sprock...-6-holes-5_25-bolt-circle-p5245-40-tooth.html
You will need 6 bolts and nuts to attach the sprocket to the adapter. The only kits that we have bolts that are too long as they are made for use with sprocket guards!
https://www.OldMiniBikes.com/sprocket-hub-bolt-kit-for-split-sprockets.html

The sprocket choices for that size chain is limited to 40, 54, and 60 teeth

Here is my current sprocket:

 

[chrisr]

What was the clutch tooth and the rear wheel sprocket tooth before your conversion to the TC and TC tooth and rear sprocket after your conversion?

 

[toomanytoys]

Typically your top speed goes up a little bit due to the over drive of the tav.

Is the tav driver opening all the way up?

 

[matthewlswanson]

What was the clutch tooth and the rear wheel sprocket tooth before your conversion to the TC and TC tooth and rear sprocket after your conversion?

The centrifugal clutch had a 10 tooth sprocket before. The TAV has a 10 tooth as well. Rear sprocket is the same.

 

[matthewlswanson]

Typically your top speed goes up a little bit due to the over drive of the tav.

Is the tav driver opening all the way up?

I believe so. When I pull the throttle is opens wide so that makes me think it is gearing? The rear sprocket is basically as big as the wheel.

 

[SAS289]

If you want nearly identical gearing near top speed that you had with a 10 tooth clutch, put a 9 tooth on the TAV. When the TAV belt shifts all the way to "high" you will have 5.4/1 gearing with a 9/54.

Using a 40 tooth with the 10 tooth on the TAV is not a good idea unless you have twice the engine power and are using a Juggernaut drive pulley.

 

[Strigoi]

I have never seen an increase in top speed after installing a TAV on a small tire bike (ones running a 6" wheel). I always lose some mph compared to running a clutch. This is on bikes that have the power to pull those speeds too.

 

[massacre]

That rear sprocket is pretty big for that tire. A taller tire would increase your top speed. Running a 9 tooth like was mentioned would help as well.
There is an adjustment for the spring on the driven pulley, have you looked into it?

 

[matthewlswanson]

Thanks for the replies! I might look for a taller rear tire then and a 9 tooth for the TAV and see if that makes a difference! If I am still getting low speeds I may switch back to the centrifugal clutch and keep the TAV for a Coleman.

 

[massacre]

Have you adjusted the spring on the driven pulley?

 

[matthewlswanson]

Have you adjusted the spring on the driven pulley?

I'm not familiar with adjusting that but I'm willing to try. I'll do some googling and look for instructions.