carb problem? - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 20 Old 06-07-2014, 03:48 PM Thread Starter
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carb problem?

Hey guys, newbie here. I acquired a 2003 KLR 650 that was sitting for a number of years. I cleaned it all up and now have a specific problem. Everything runs perfect except at 4500 rpm and around 60 mph this bike is maxed out! It's almost as if it's governed at that rpm. I have checked everything multiple times to the best of my ability, cleanded carb, replaced petcock, spark plug, filters ect. Any ideas?
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post #2 of 20 Old 06-07-2014, 04:43 PM
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Originally Posted by kiddeasy View Post
Hey guys, newbie here. I acquired a 2003 KLR 650 that was sitting for a number of years. I cleaned it all up and now have a specific problem. Everything runs perfect except at 4500 rpm and around 60 mph this bike is maxed out! It's almost as if it's governed at that rpm. I have checked everything multiple times to the best of my ability, cleanded carb, replaced petcock, spark plug, filters ect. Any ideas?

Have you checked the valves?

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 20 Old 06-07-2014, 06:06 PM Thread Starter
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nope, but after checking the carb 3 times and reading 4 hours of posts I decided to take the brand new air filter off and run it, 90 mph unlimited rpm no problem! guess I need to find a decent air filter besides the factory set up...
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post #4 of 20 Old 06-07-2014, 06:31 PM
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Might consider CLEANING the factory air cleaner, kiddeasy!
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post #5 of 20 Old 06-07-2014, 06:35 PM Thread Starter
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hey man, it's brand new!
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post #6 of 20 Old 06-07-2014, 06:41 PM Thread Starter
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this bike was previously modified with Dynojet carb kit and Laser pro enduro exhaust, maybe stock air flow is insufficient?
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post #7 of 20 Old 06-07-2014, 07:09 PM
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It doesn't make sense that somebody who had done these mods would put a new stock air filter in the thing right before a sale unless they were unaware it would cause problems.

As far as I know, the stock filter is reputed to give pretty good flow, especially a brand-new clean one. I can't imagine a "high flow" aftermarket filter would work any better than a stock filter once it starts getting dirty. If the setup is that persnickety and sensitive to airflow, I personally would ditch it for more reliable stock components.

I can tell the difference when my stock air filter is caked with a thick layer of filter oil and limestone dust and is way beyond needing a cleaning, but never the degradation of performance you seem to have experienced.



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post #8 of 20 Old 06-07-2014, 07:36 PM
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In my experience, stock air filter, clean and properly oiled, flows pretty good; bike runs up to redline with no problem. Like planalp, can't imagine the subtle changes of "trick" jetting and aftermarket exhaust sensitive to the miniscule difference in air flow between stock and aftermarket air filters.

But, maybe so! A few bucks for an aftermarket filter might tell the tale, but . . . I'd suggest a "control" baseline run with the stock filter once more, deliberately confirming any advantage from an aftermarket filter.
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post #9 of 20 Old 06-07-2014, 09:24 PM Thread Starter
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Ok, the guy that owned this bike previously died and I bought it from his son after it sat for 3 years. Needless to say it needed quite a bit of cleaning to even get to the point where it would run. With no history on what modifications have been attempted, and this being my first KLR, I'm learning as best I can here. I have quite a bit of experience turning wrenches but this thing has been getting the better of me. I feel the same as y'all about the filter, I've never had situation where a restriction in airflow has caused this big of a performance issue. What I know though is it won't run past 4500 rpm at 60 mph with the filter on and it runs perfect when removed. I'm open to suggestions on what else may be causing this issue, otherwise it looks like I'll be modifying the air box and trying a freer flowing filter I suppose...Thanks for the help!
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post #10 of 20 Old 06-07-2014, 10:56 PM
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Possibly, the "modifications," i.e. the jet kit, trick needle, and who knows what else, created a seriously fuel-rich mixture. Thus, any intake air restriction (even a clean, properly-oiled, stock air filter) exacerbates the air/fuel ratio's fuel-richness and inhibits higher-rpm running.

As planalp above suggests, restoring the carburetor to stock condition (i.e., stock main jet, stock needle) and running with the stock air filter, might allow higher-rpm operation.

The aftermarket exhaust may want slightly larger jetting, but probably will run fine on stock jets.

I'd consider going back to a stock carb, stock air filter, and modifying from there, if that's your pleasure.

So, don't know the cause or cure for your problem, only--jillions of KLR650s in production for 28 inclusive years ('87-'14), run fine with stock air filters. Unless your carburetor has been jiggered to an overly fuel-rich mixture condition, seems like it oughta run o.k. also, with a stock air filter, IMHO. Doubt an aftermarket air filter or air box modification will solve your problem.
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