TS1 225 swept compression ratio.

[Storkfoot]

17.8 & 5.4 = 23.2cc giving a corrected compression ratio of 10.63 and an uncorrected of 6.55.

Thanks for your help

[Storkfoot]

Downsizing the front sprocket will make it more difficult to kick over especially if you have a light flywheel.
Change it back to an 18 and see what difference it makes and go from there.

I’m going to follow your advice now, F&F. My injury weakened left leg, even with heavy work boots, can’t cope with kicking this TS1 over. So, back to 18 front sprocket, push up tensioner CST3. Hopefully, that’ll work.

[Adam_Winstone]

17.8 & 5.4 = 23.2cc giving a corrected compression ratio of 10.63 and an uncorrected of 6.55.

Thanks for your help

Other way around..

[Storkfoot]

Minor detail

[dickie]

You could change to a gp200 box and use 20/47 sprockets to get a similar final drive.

If you want to keep the exhaust characteristic.

[Adam_Winstone]

Minor detail

^... LIKE

[Adam_Winstone]

Both the geometric and corrected are a tad too high IMO.

Whilst high compression can bring back power lost through the rev range by raising exhaust duration, it can actually stifle over-rev (thereby top speed) because it opposes piston rotating past TDC. It'll also cause running temps to rise and require that you reduce ignition advance, losing some of the grunt that it just regained... but bringing back the ability to rev / spin over TDC.

It's all about balance of factors that influence the overall performance of the motor, rather than considering compression, or any other factor, in isolation.