I need to know what the compression should be on an F3, and what it could be for it to start. im at 120 pounds and its burning the gas, but not firing off of it.

Also i really need to find someone who used to or still does race the F3. If thats you i would like to get in contact with you and ask some questions!

Thanks much,

 

take a look at this forum
https://cbrforum.com/forum/cbr-600f3...numbers-82653/

 

yeah i found the 185-191 in my manual after i posted that . But i still would like to know what kind of compression it would take to start. im struggling with my timing and cant get the compression i need.

 

did you take the engine apart?

 

i did yes, and the lower half of the engine ( transmission, and lower case, oil pan etc) is from a different engine than the upper half ( cylinders, pistons, head, cams, crankshaft). but everything that has to do with compression is from the same engine. so i dont think that would have any effect on compression.

 

Is it from an F3 of some other bike?

 

it was an F3, and after some fiddling around with the timing, moving it one tooth over on the intake cam and one on the exhaust ( from where the timing mark are) i am able to get it to 150 psi in cylinder 1, 120 in cylinders 2 and 4, and 130 in cylinder 3. But it still didnt fire enough to start it when i tried. Any ideas on what could be causing the compression loss?

 

Maybe a bad valve or a bad Valve spring?

 

if your compression is low it could either be a bad piston ring, hopefully not that, or you might have a bent valve. When you start the bike was it ticking at all?

 

Sounds like its time for a leak-down test, find out exactly where your losing air at... Either valves, rings or head-gasket.