Once Again...KLX 250S Cold Start...Help! - Kawasaki Motorcycle Forums
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post #1 of 2 (permalink) Old 04-10-2019, 02:14 PM Thread Starter
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Join Date: Apr 2019
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Once Again...KLX 250S Cold Start...Help!

So, I bought a 2009 KLX 250S with a CVK carb. It didn't run bad, but not great either. I added 87 with 10% ethanol and some Seafoam. It started running like crap, and upon removing the carb (who the **** designed that setup!) found green grime throughout the carb.

According to the local Kawasaki service guys, Seafoam doesn't do well for my situation. So, I cleaned the grime out of it, put a .038 pilot jet (original is .035) to address the cold start issue (per suggestions on this forum).

It is still really finicky about starting, but once it does, it doesn't even need to warm up. It just idles at about 1100 RPM. It's quick, responsive and when I let off the throttle doesn't sputter, stall, and it's great at high RPMs too!

I've check my spark plug (OEM NGK CB8E) and it's dry, nice brown and sparks well. I'm going to put a new one in it just in case.

I've tried the lean the bike to the left to let the bowl fill.

Ironically, it seems to start when the choke is in, but I've tried both ways.

It's about 60 degrees in the Seattle area right now, so it's not too cold.

Because it idles and runs so well, once it starts, and the plug is clean, I think my air/fuel mixture is good.

I also added the wire from the battery to a solid frame ground to get good cranking (again, a forum suggestion) and have the bike connected to a battery charger while trying to start it, just to help keep the battery up. Oh, yeah, new battery too.

I haven't added a switch to turn off the lights while starting, because I don't think it's a spark issue, but I well just because the lights drain the battery so much during the starting process/attempts.

So, all you KLX CVK Gods...what say you??



Last edited by sforeaker; 04-10-2019 at 02:18 PM.
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post #2 of 2 (permalink) Old 04-10-2019, 09:10 PM Thread Starter
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Join Date: Apr 2019
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Update: Starting fluid helped...

Update: I squirted a little starter fluid in via the air cleaner outlet towards the carb, choke on, just a tiny amount of throttle and it slowly fired until it ran. Now it's purring like a kitten running the gas out of the bowl. I know these bikes run lean. I hate to mess with any of the settings because once it fires and starts it runs great.

What's happening once it fires with the starting fluid? Is there more of a vacuum to pull fuel in? Does the extra kick of the engine firing give it just that much more to keep firing?

I put in a new NGK OEM plug gapped at .029" (.028 - .031 is spec). Since it fires with the starting fluid and then catches and runs, I think I can rule out spark? Or could I be lacking in spark during the cranking, and the spark is enough to ignite the starting fluid but not the actual fuel until the engine catches and somehow increases the spark?

Grabbing at straws here. I just don't have enough knowledge of how the system functions during starting vs. running.


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