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TOPIC: Hard to start when hot

Hard to start when hot 02 Feb 2020 17:04 #818442

  • Kz81
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My 81 kz1000j starts instantly when it's cold. Pull choke, press start button, 1/2 second later, bike is running. 10 seconds later, push choke halfway in, 15 seconds later, push choke off. Bike runs great on the road. But, after the bike warms up, it doesn't start as easily. Sometimes, I have to slightly open the throttle and it will start after cranking 1-4 seconds. Once started it idles and runs perfectly again. Fuel adjustment screws are 1.5 turns out. I've also tried them at 1.25 (factory recommend) and 2.25 turns out. A couple of the valves were on the tight side so I adjusted them slightly. Bike only has 9000 miles on it and looks brand new. It bums me out that it won't start instantly when warm/hot because when someone is looking at it when I'm out for a ride, I want to impress them by starting it up for them. Any ideas? Thanks!

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Last edit: by Kz81. Reason: Spelling

Hard to start when hot 02 Feb 2020 17:13 #818444

  • Nessism
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Hot start problems are often caused by tight valves. I know you said you adjusted them but this bears mentioning regardless. It's best to target the high end of the range.

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Hard to start when hot 02 Feb 2020 17:23 #818445

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Thanks! I wondered about that. It did seem to help slightly after I loosened 3 of the valves. Overall, I wouldn't describe all 8 valves as being on the high end. Next time I have the tank off, I may go back to 1.25 turns on the fuel screws.

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Hard to start when hot 02 Feb 2020 18:55 #818451

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1.25 is lean. Did you tune for highest idle?

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Hard to start when hot 02 Feb 2020 19:02 #818452

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No, I need to get a remote fuel bottle so I can keep the bike running with the tank off while I adjust the fuel adjustment screws.

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Hard to start when hot 03 Feb 2020 07:23 #818467

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By Kz81: ... Sometimes, I have to slightly open the throttle and it will start after cranking 1-4 seconds. Once started it idles and runs perfectly again. ...

From my 81 650 OM: when the engine is already warm or on hot days, open the throttle part way instead of using the choke.
Something else I do is set the petcock to PRI for a few seconds before starting, then move it back to ON >> in case there was fuel evaporation in the carburetor bowls, either because of a hot engine or from sitting a couple of weeks.

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Last edit: by martin_csr.

Hard to start when hot 03 Feb 2020 07:41 #818471

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That's very interesting that the owners manual says that. I'll start doing it from now on. I will check my om; it may have the same recommendation. My 05 vstrom om recommends doing the same thing when cold because it doesn't have a choke or fuel enricher. I'll try the prime position as well when starting warm engine. Thanks!

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Hard to start when hot 03 Feb 2020 10:45 #818485

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Many Kawasakis were jetted lean from the factory, so opening the throttle part way probably allows for the uptake of more fuel to compensate for the lean condition. That's my theory anyway. hee. As for the fuel tap, I switch the petcock to PRI, put on my gloves & mount the motorcycle & maybe do other stuff, then switch it back to ON. This usually allows plenty of time for the float bowls to fill, if needed.

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Last edit: by martin_csr.

Hard to start when hot 03 Feb 2020 19:22 #818509

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You were right! My om recommends opening the throttle part way to start the bike when its warm. Thanks again.

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