Quote:
Originally Posted by
Kev
The XT660 standard compression ratio is 10:1, I fitted a 11:1 with a 2mm bigger bore 2 years ago, the piston alone gave around a 1.5 to 2hp gain across the whole rev range.
To get HP like the KTM on the XT you need a combination of mods, high lift cam, bigger inlet valves, bigger throttle body, bigger bore with a higher compression ratio ETC.
The new 2010 KTM690R produces 70HP.
http://hellforleathermagazine.com/20...90cc-of-s.html
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Hi Kev,
in wich way you calculate the compression (from 10:1 to 11:1). I think that only a bigger bore don't change the compression. I think that compression is a ratio between the two volume (minimum for compression, maximum at the end of stroke). So, if you don't change the stroke of piston, according to me, you have the same compression independently by the piston diameter. Unless you have pull down the head (machining plane or changing gasket system).
Can you explain me ??? Tank you in advance.
Ciao.
