sprocket sizes

[sidevalvedave50]

Thanks for your answers to my previous posts as it is reasurring to know there are fellow enthusiasts willing to help out with their own take on certain subjects so here's one which might get a good response.
 As the k7 based cr750 is in bits i thought it about time to sort the gearing out. When i bought the bike the previous owner said he had the bike geared high for more emphasis on top end speed, i have never felt the bike to be all that fast on accelleration but being a RG500 owner i may have been spoiled in that department. When the bike is in top gear at a indicated 70-75 mph the scitsu tacho is reading 4000 rpm. The bike has a Nova gear cluster fitted and a 15 tooth front sprocket and a 35 tooth rear sprocket fitted. What is the best combination for fast road work   i.e  accelleration ?    David Silvers state 15 tooth front and 41 tooth rear as standard so i imagine i will have to go up on the rear one . 

[Yoshi823]

With your existing sprockets you'd get a ratio of 2.333333.
With DS's suggestion you'd get 2.733.

On my 750F2 the standard sprockets were 15 & 43, where the bike would only ever rev to 9200rpm.
For better acceleration I went to a 14 front (& 43), giving a ratio of 3.07 where the bike would rev to 10,000...well into the red line.
So I dropped the rear to 41 which, together with the 14 front gave me a ratio of 2.93 & allowed the engine to rev to 9600...right where I wanted it. This gave me the best for acceleration & top end.

Hope this helps to work out what you need for the road.

[sidevalvedave50]

Cheers Yoshi,
                   this sounds about spot on for the bike, i just need to put it back together,get the Swarbrick exhaust fitted and do some speed trials down the local bypass (purely research officer ) !  I will keep you informed on my research