my KLR 650 1990 has very hard starting. When i press the starter button, the battery dies after several times of engine spin. The battery is new ( tryed at other KLR, everything forks fine). First of all i inspected the KACR.
I'm totaly confused where to look next.
Any thougths where could be my problem? What to check next?
I'm suspecting a dirty or loose battery cable connection or worn-out starter brushes. So first order of business, do you have a proper Service Manual? What is the, minimum starter brush length??
6mm, by the manual!
Have you removed, scrubbed/scratched and re-installed Both Ends of all THREE of the battery cables? Tightened them with a wrench or socket, not just a Screw-Driver!
As to the engine compression. If the battery and starter motor Can NOT turn the engine fast enough and long enough for a 'well-worn' 1990 engine to develop the Minimum of 530kPa / 5.4 kg/cm2 / 77 PSI, you have an electrical issue which needs repaired.
If the starter motor/cables and battery can crank the engine for 1 Full minute/continuously and the engine Can NOT Develop at least 530kPa / 5.4 kg/cm2 / 77 PSI, then you have an engine mechanical problem. ie, tight valve tappets, worn valves, worn rings.
The KLR650 engine starts great, with 90+ PSI (with an Active KACR) at any temperature which I care to ride. And fairly well at 75 PSI. If you feel the need to 'experiment', I can Only Suggest that 100-110 PSI with the KACR DEFEATED may be near the absolute bottom of cold (0c./32f.) "start-ability". Tom Schmitz has shown us, about 175 PSI with the KACR Defeated! Toms bike had about 110-120psi, with active KACR, if I remember correctly.