Has anyone any idea if it is possible to incorporate a decompression system to aid ease of kick starting on a 650 with compression ratio of 9.45 ?
I have the same issue with my 99 . I have no doubt a good engineer could rig up something for one cylinder .other options are a compression plate under the cylinder , a softer cam from an 88/99 , and a change of engine and gearbox sprockets ( a bigger engine sprocket will reduce kickstart gearing but would need a smaller box sprocket to retain the final drive ratio . Get the piston crowns turned to form a dish , If you are very tall a longer kickstart lever would help.and fit 18" wheels, Do the lot and tell me how it works !.
A wilder cam with more overlap like a Combat cam will drop compression at kickover speeds, counter intuitive.
Other option is a chainsaw decompressor on each cylinder which is used on hi compression 850's and 920's but it must be done with care.
I agree in theory a wilder cam should help , but I have a full race cam on my 250 single and you can stand on the KS or lock the wheel bumpstarting and thats only 9 to 1 comp. Chainsaw decomps sounds a good option.
I've not tried...but is it possible to put it in an intermediate gear and roll it back onto compression before the first kick? Like bump starting a big single
Hi David , thats basically what I do, I just ease it over compression first . But with a twin you dont get much momentum before the next cycle.
Thanks for ideas from Robert Tuck about a decompression valve but I failed to say that the 650 SS is twin cylinder and therefore maybe I cannot incorporate a valve and maybe a longer kick start peddle would be a good idea..Any idea where I could get such a thing?
Hi Roger ,I understood that your bike is a twin. Never seen a decompressor on one but it sounds like it has been done with a chainsaw device . In theory it should be possible to build a lever job into one of the exhaust covers (like a Ducati 350 scrambler of the 70's). Still only a partial job if only on one cylinder . A longer KS would have to be welded up from a couple of std ones. Would only work if you can get a foot on it !!
..looks like this. Very simple and effective.
RGM do the longest kickstart lever, it folds and is based on the T160 Trident kickstart. You need to check it does not foul anything, it fits a standard Commando but needs any rear sets to be moved backwards, well mine did.