Sprocket Recommendations?

[Frisco57]

I'm building a Bonanza BA1200 with a stock rebuilt 1969 5-horse Briggs flat head minus the governor for cruising the pits at the drag races. I'm a good sized (old) kid at 6'-3" and 290 lbs. I'm planning on using a 12 tooth clutch and the Bonanza has already got a 60 tooth sprocket at the wheel. What should I use for jack shaft gears? I want the Bonanza to have good street manors. I don't need big top speed and I have no need to lift the front wheel.

 

[I74]

If you went with a 12, 19, 12, 60 set up, that would give you a ratio of 7.917 - 1
I think with your size & the output of the engine, that it would be good all around gearing, & also take stress off the crank ect.

 

[chipper]

For cruising 7.5 to 8 range is good !

 

[Frisco57]

If you went with a 12, 19, 12, 60 set up, that would give you a ratio of 7.917 - 1
I think with your size & the output of the engine, that it would be good all around gearing, & also take stress off the crank ect.

Thanks for the info. 174 & chipper.

 

[Frisco57]

OldMiniBikes is out of stock on the 19 tooth sprocket. I’m considering an 18 tooth.

 

[I74]

OldMiniBikes is out of stock on the 19 tooth sprocket. I’m considering an 18 tooth.

USA bearing & belts out of Fla. has really good quality finished bore B type 19t sprockets.
I would still go with the 19t.
Ian

 

[Frisco57]

USA bearing & belts out of Fla. has really good quality finished bore B type 19t sprockets.
I would still go with the 19t.
Ian

Thanks 174,
I just placed an order with USA Bearing & Belt for a 12t and 19t #35 5/8" B type sprockets.

 

[Frisco57]

Question: Does anyone know how much/ how long a #35 chain would be for this 12t (clutch) to 19t, 12t to 60t (rear sprocket), jack shaft set-up? Would 120 link chain be long enough?

 

[Charles S]

I would buy 10' with 4 master links, have some extra on hand.

https://www.bmikarts.com/35-RLV-Extreme-Chain-Black-on-Black--10-Roll_p_5363.html

https://www.bmikarts.com/35-RLV-Extreme-Chain-Gold-on-Gold--10-Roll-_p_7450.html

https://www.bmikarts.com/Go-Kart-Chain-and-Racing-Chain

 

[I74]

I recently purchased some ''killer'' #35 chain from Theisens .
It is DID #35, -10ft roll ,, made in Japan.
Quality is the best I have ever seen for lower cost # 35 chain.
Price is 20 bucks, & comes with 1 master link.
4 pk. of DID master links is around 2.50
I highly recommend it !

 

[Frisco57]

I'm waking up an old post/question here... a year later, I've finally got my Bonanza BC-1200 up and running pretty well. As recommended I installed a 12 tooth SS Max Torque clutch (#35 chain) to a 19 tooth jack shaft in, to a 12 tooth jack shaft out. to a 60 tooth at the rear wheel. Everything seems to be working well but I was hoping for a bit more top end. I'm running a 5 horse Briggs with the governor deleted but it has a billet rod & billet flywheel from ARC Racing. The mini seems to have a lot of torque at take off but lacks a bit of top end speed but seem to have good top end rev. A little more top end speed would be good. Recommendations for altering the jack shaft gearing a bit?

 

[I74]

If you go to a 13t on your output from a 12t,, that would give you a ratio around 7.3 -1, from 7.9,, & give you a bit more top end.

Think that would be pretty good.

I

 

[Charles S]

As @I74 said, a 13T jackshaft out sprocket will get you around 7.3:1. A 14T jackshaft out will get you around 6.8:1, and a 15T jackshaft out will get you around 6.3:1. What to try would depend on how much of a change you want but I think a larger jackshaft out sprocket would be the best way to achieve the desired result. Of course, you could go with a smaller jackshaft in sprocket but smaller sprockets are harder on the chain and sprocket.