compression

shortassrider · Post by **shortassrider** » Sun Sep 23, 2007 8:01 pm

would my sump pan need to be on for me to get compression,
iv just rebuilt the engine for a fzr 600. but no compression. tdc is spot on . im at a loss . anyone any ideas. much thanks in advance

Gismo · Post by **Gismo** » Sun Sep 23, 2007 8:06 pm

Sump pan not required, but, i would worry that insufficient oil is circulating around the engine.
The piston rings provide the combustion in the bores, so, if they are significantly worn or broken etc then the pressure would simply disappear into the sump, sounds unlikely in your case though.
How about the valve timing, is that right, even at TDC if the valves are not set to coincide with the pistons you won't get the compression

shortassrider · Post by **shortassrider** » Sun Sep 23, 2007 8:16 pm

even though the valves were not removed or altered.could this still be the case?

baldy · Post by **baldy** » Mon Sep 24, 2007 8:15 am

Did you remove the timing chain ? If Exhaust valves are open when they should be closed then you wont get compression best to check the timing is correct

Gismo · Post by **Gismo** » Mon Sep 24, 2007 8:31 am

shortassrider wrote:even though the valves were not removed or altered.could this still be the case?

Nope, but, as baldy mentioned, did you remove the timing chain??
If not, then i think you have a serious problem, unless, you are not getting a tight fit for your type of compression tester, you should be pushing the rubber part hard into the spark plug hole.

Hmm, just thought, are you cranking the engine over with the starter, or just by hand and how many revolutions are you going through.
It could take at least 2 complete rotations on each bore to achieve compression as one of the cycles allows the burnt gases to exit the bore, so, depends from which position you start the rotation.

What was the reason the engine was stripped down for in the first place??

Are the valves actually opening and closing whilst cramking the engine??

CBRXX · Post by **CBRXX** » Mon Sep 24, 2007 10:41 am

Why are you checkiing for compression with no sump/oil?
and how are you checking?
have you refitted the spark plugs?

shortassrider · Post by **shortassrider** » Mon Sep 24, 2007 8:24 pm

THe egine was stripped down so i could replace the gearing shaft and bearings. i was advised by a Yamaha mech i would have to strip from the top down rather than just going in from the bottom.before there was no problem with the engine, the bike run fine .
should i need to have the sump pan on and fill up the eng oil to get the desired compression reading.?

Gismo · Post by **Gismo** » Mon Sep 24, 2007 8:30 pm

shortassrider wrote:THe egine was stripped down so i could replace the gearing shaft and bearings. i was advised by a Yamaha mech i would have to strip from the top down rather than just going in from the bottom.before there was no problem with the engine, the bike run fine .
should i need to have the sump pan on and fill up the eng oil to get the desired compression reading.?

Ok, compression is all above the pistons, so, in theory no, you don't need the sump pan on.
But, the compression readings are taken after several rotations of the engine, so, in this case i would advise that the pan is on and the recommended amount of oil is in.

But, i'm not sure of the engine that you stripped down and therefore cannot say whether you've altered the timing of the valves in relation to the piston stroke or not.

shortassrider · Post by **shortassrider** » Tue Sep 25, 2007 6:58 pm

Engine is from a fzr 600 genesis .

blagger · Post by **blagger** » Tue Sep 25, 2007 8:40 pm

shortassrider wrote:Engine is FOOKED.

I can't believe it's not butter! sorry couldn't help it

baldy · Post by **baldy** » Fri Oct 05, 2007 7:48 am

Any news on the Engine ?

shortassrider · Post by **shortassrider** » Fri Oct 05, 2007 7:56 am

Thants me off my ten days so im going to strip it down and offset those rings. picked up a compression gauge and hopefully that will do the trick . according to the guy at jops lane iv been expecting too much resistance and its probably been ok , but im going to do the rings anyway , may even replace them cost pending. but thanks to all for all the advice ,its a learning thing , slow but im learning I can't believe it's not butter!.