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KLX250 turns over slowly

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Hi all

after sitting for about a year, my friend's 2009 KLX250S turns over very slowly when you hit the starter button. It does eventually start and run, but since the bike has no kickstarter he's concerned about getting stuck in the woods.

  • Battery and regulator are almost brand new (18 months old).
  • We checked all the wiring to the starter motor - it's OK.
  • Checked the starter solenoid by bypassing it - no change.
  • Had a shop remove, disassemble, and check the starter motor itself. OK.

Now we're wondering what to look at next. Any suggestions?

I understand that this bike has an automatic compression release for starting - is that something we should check? If so, how?

I should mention that this bike has a Bill Blue 351cc big bore kit on it. But I don't think that is the source of the problem, the kit has been on it for about 4,000 kilometers and never had trouble starting until now.

Thanks in advance for any help you can provide!

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I would load test the battery.  18 months is old enough to be junk. I have had them last month's or years. Just never know with them nowadays. 

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Forgot to mention - we jumped the bike from another battery and it still did the same thing. So I don't think the battery is the problem, but you're right it's worth another look just to make sure. Thanks!

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So, we took a look the bike today. Battery ground connection looked OK, but we took it off and cleaned it up anyway. Sanded the terminal and the mounting point on the engine case with some emory paper and put it all back together. Guess what - problem solved! You called it S10gto! Thanks for the help.

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Two words, trickle charger. Will make a 2 year motorcycle battery last forever if used when parked. Walmart has cheap smart ones for around $20, I use them on all my small engines with batteries and my Model A I dont drive often. Glad you found the problem. Next time you have that apart use some dielectric grease where you had to sand it and it will not corrode again unless you powerwash this area often.

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So... it turns out we didn't really fix the problem, we just got lucky and it started relatively quickly. We put a brand new battery in it, and we went back and cleaned up ALL the electrical connections in the battery / solenoid / starter motor circuit just to be sure. No improvement - still cranks slowly. Checked all the cables, they are in great shape with no fraying or corrosion.

So now I think it's down to either the starter motor, or the auto compression release. Anything else we should be looking at?

We turned it over with and without the spark plug installed. Here are the videos:

KLX250s turns over slowly with spark plug installed

KLX250s turns over normally with spark plug removed

What do you guys think? Did we learn anything from these tests?

Edited by VI_DirtRider

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Starter sounds like it may be the issue but I would pull the valve cover off and check the ACR. Check the cam timing too just to be sure. 

Valve clearance can also be an issue.  If the exhaust valve at the ACR is too loose out of spec the ACR won't be able to release compression. 

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