compression help

[joshbot007]

On my bike if i pull out the kick start and put a consistant small force on it and hold the kick starter will slowly go down all the way. When kicking the bick it feels good and I feel like the bike has good compression. It was rebuilt with about 6-7 hours on it. Starts on firts kick. I was wondering if This is a 2 stroke thing with the exaust ports no valves. Like i said kick starting has good compression. It is a ktm 300

 

[High Lord Gomer]

They all will do that to some extent. The only way to really measure it is to get a compression tester and check it. I like to check it immediately after a rebuild, after an hour of running, and then periodically to see if/when the compression starts to drop.

 

[joshbot007]

The reson i ask this is because my 350 4stroke can barely do this at all when the auto decompressor is not on. It is very hard topress down even slowly. I asume this is because of valves. Thats why i would like to know if this is normal for 2 strokes.

 

[2strokerfun]

You have intake porting and exhaust porting on the cylinder walls of a 2 stroke. There is just a small area above the ports where you don't have any ingress or egress of air. Having said that, it doesn't mean you don't need fresh rings, but there is always a ring gap that will allow pressure to escape doing what you describe.