Hi,
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. My thought was that KACR is not working and when the pressure builds, battery has no more juice to spin it. the KACR seems to work fine, during sping the pin presses the exhaust valve a little ( of course the KACR has some loose). When i tryed to spin engine without spark plug ( to reduce the compression more) i had the same result. The valve clearence is within normal range by the manual. Also when the engine is running at idle speed ( 1.3- 1.5 RPM) sometimes i have a misfire and the engine stops, so ,my idle speed must be > 1.5 RPM. Cleaned carb 5 times. I'm totaly confused where to look next.

Any thougths where could be my problem? What to check next?

Take your starter out and rebuild it, clean up all connections etc etc, I bet it's that.....

The starter looks fine, cleaned. Now sometimes it spins normal, sometimes hard.

IF it spins anything but perfect while out I would be taking it apart again just to be 1000% sure that is as long as you are supplying it with 12 volts but when out it should spin with almost nothing...... IF it isn't the starter think about taking the left side cover off to inspect the gears running to the rotor and make sure they have both washers on each gear and the shaft hasn't pulled out of it's dowel hle in the case....some are known to have what we call the deep hole issue where they drilled or milled out the case too far and we simply need to slip in a 1/4" dowel in to make up their mistake or the shaft can wear itself out. I didn't read what year you have so this may not apply, sorry.... But I would check everything about those two gears to make sure they are OK, one has bearings on a simple shaft pin but they both have two very thin washers.

He has a 1990 so the deep hole wouldn't be a problem as that only affected 08's and early 09's.

Does almost sound like a bad connection if it's intermittent though... Sometimes that stuff can be pesky to track down!

Testing with the spark plug removed was a good idea. It eliminates compression as the problem.

Does the starter relay (solenoid) ever chatter or buzz when the problem occurs?

Did you just clean the outside of the starter or did you remove it and disassemble it and check the condition of the brushes, the commutator strips that the brushes rub on and the bearings?

zulas,
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.

GoMotor and DPelletier,

I would cross link this posting over to klr650.net, if I could!

I think Tom has a video with compression numbers with and with-out the KACR and Before and After MC MOD. But I couldn't find it.
Ya' might could find it under "sooperdoo" on klr650.net or youtube.

Doubt the KACR is the culprit; have read of KLRistas jettisoning the KACR entirely without serious consequences.

Two questions arise: Is the starter motor receiving adequate current/voltage, and if so, is the starter motor/gearing fully operational?

I'd suggest starting with the battery circuit; even a new battery can break down under load, while showing adequate voltage. Then, all CONNECTIONS as mentioned above remain critical. If intervening switchgear is suspect, you can JUMP the starter motor positive lug directly to the battery positive terminal with a large-diameter cable to see if any difference exists.

I'd look at this simple/easy stuff first, before I'd tackle inspection of the starter motor innards, but your call--good luck!

Try load testing your battery. The voltage drop shouldn't be excessive while cranking the starter.