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Valve lifter

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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 ?

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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 !.

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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.

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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.

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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

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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.

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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?

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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 !!  

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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. 

https://www.rgmnorton.co.uk/buy/kickstart-our-own-design-swivels-at-base_728.htm

 

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