Gear Ratios ??

[Ed Powell]

Hi all
I am in the process of fitting my Montesa 250 engine onto my Dino and need some advise! re gear ratios for both short and long circuit, whilst I know this engine is not very common I am looking for a ball park idea of what gearing I should be fitting, what are you guys running on your Villiers etc as there cannot be too much difference??
Cheers
Ed

[Skid_53]

Hi Ed

On my Villiers for Strubby, Teeside and Rowrah I was running a 19 primary sprocket and a 30 final sprocket.

I hope that helps

Martin

[Ed Powell]

Thanks Martin,
Any info is of great help and much appreciated
Many thanks
Ed

[classic Ed]

just to add my input. At Strubby I ran 15/30 on an iron barrel Villiers with I guess a top rpm of 8500. This also worked for Kimbolton and the Shenington short circuit. If the long circuit were to be used i would drop down to 28 at the back. If I were to run an alloy barrel with a high exhaust port i would expect it would run a tooth or two bigger at the back and still get the same if not slightly higher top speed. Please bear in mind that all engines make power and torque in different patterns so your longest gearing will be based on what the engine will pull.
When it comes to Cadwell demo i would gear long for it as we are running old engines and the back straight is very long to be at maximum revs for any length of time. Just not too long that it dies going up the hill. I will be running 15/26 for this event.
Any use to you all?