Hesitation on Acceleration - Kawasaki KLR 650 Forum
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post #1 of 15 Old 01-14-2012, 10:41 PM Thread Starter
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Hesitation on Acceleration

Hey Folks,

Just took the bike for a short 80 mile ride and noticed some hesitant throttle response on two or three occasions. My first thought is "time for a carb clean", however, I ride this thing regularly, and it doesn't sit without use for longer than 4 days at a time. Could the hesitation be signaling another problem or should I clean and/or rebuild the carb?

Possibly related: I've got a backfire on deceleration that I've had since I bought the bike, which I've been told could be the result of the idle mixture screws being "off", which, furthermore, could contribute to this new-found sporadic lack of throttle response.

Any insight/advice?
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post #2 of 15 Old 01-15-2012, 09:34 AM
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Quote:
Originally Posted by Mr. Junior View Post
Hey Folks,

Just took the bike for a short 80 mile ride and noticed some hesitant throttle response on two or three occasions. My first thought is "time for a carb clean", however, I ride this thing regularly, and it doesn't sit without use for longer than 4 days at a time. Could the hesitation be signaling another problem or should I clean and/or rebuild the carb?

Possibly related: I've got a backfire on deceleration that I've had since I bought the bike, which I've been told could be the result of the idle mixture screws being "off", which, furthermore, could contribute to this new-found sporadic lack of throttle response.

Any insight/advice?

Have you done the .22 mod? How's the air cleaner? Do you have any play in your throttle cable?

The backfire is a lean condition on the low speed card circuit (pilot/fuel screw) The .22 mod will help that and the off throttle response. If the air cleaner is excessively dirty throttle response will be affected. If the throttle cable has slack it will create a lag.

One more thing have you checked the valves? When they start to get tight the bike will get harder to start when cold and the motor will feel sluggish.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
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post #3 of 15 Old 01-15-2012, 09:45 AM Thread Starter
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Thanks for the response. I need to check all three of these things. I'm at 7000 miles, so I know it's time for a valve check. There's a slight amount of play in the throttle, but I got this hesitation while it was twisted back already, going about 60. This morning I'm going to reset the mixture screw and idle speed in case the guy who had it before me messed with it. Thanks again for the help!
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post #4 of 15 Old 01-15-2012, 07:28 PM
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Check these items:
1. Fuel tank vent line pinched
2. Vacuum petcock not working properly
3. Water in carb bowl
4. Intermittent short in wiring harness, excited by engine rpm at 60 mph.
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post #5 of 15 Old 01-16-2012, 05:02 PM
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check air cleaner first and foremost. Check it often. The klr air cleaner is quite small for a 650 and will get dirty much quicker than you'd think. It'll contribute to hesitation when opening the throttle and if it gets really dirty you'll experience surging at WOT - passing, etc.
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post #6 of 15 Old 01-16-2012, 07:20 PM Thread Starter
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Just cleaned that air filter, and it certainly needed it.

Did the .22 cent mod to the carb, but it didn't "fix" the pop/backfire on deceleration. instead, it just changed the popping frequency and timbre. prior to the mod, the pops were quick in succession, sometimes followed by a loud pop. now, it's about 2 or 3 muted pops, followed by a loud, low frequency pop. the mod did something, but it didn't fix it. perhaps a valve check is in order. I also noticed that the choke plunger cap was missing a little piece. looks like a previous owner chipped the piece off trying to mess with the carb. i'll have to switch that out, but i doubt that would settle the popping issue.

i second-guessed my work, and took everything apart again to make sure everything was tight. everything was exactly as it should be.

the GOOD news is that i've got my throttle back, which is nice.

Ever known anyone to run into the same problem after doing the .22 cent mod?
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post #7 of 15 Old 01-17-2012, 06:31 PM
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how many turns out on the idle mixture screw?
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post #8 of 15 Old 01-17-2012, 06:35 PM Thread Starter
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Originally Posted by Whitebread117 View Post
how many turns out on the idle mixture screw?
I went with 2 1/2 turns out after turning it in, based on conventional wisdom here on the forum. Perhaps that's a bit much for my particular KLR. I also read about 2 1/4 and 2 1/8. I may give 2 1/8 a go because the afterfire pops are a bit more substantial now than before the mod.

How many turns when you did the mod?
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post #9 of 15 Old 01-17-2012, 07:39 PM
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I'm 2 turns out but I'm stock jet, no .22, and spend most of my time at 2,000 to 5,000 ft. Elevation plays a factor. I get mild popping on downhill closed throttle deceleration but nothing serious. My solution - stay on the throttle whenever possible

Also check your header nuts. Loose header pipe can cause decel popping as well.
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post #10 of 15 Old 01-18-2012, 12:40 PM Thread Starter
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Good to know. I'll take this into consideration when I re-tweak the mixture screw in a day or so. I'm determined to get this right!
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