Mysterious low RPM """Lean""" surging (Yes I already tried KLX needle and adjusted air mix screw) PLEASE HELP!! - 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 34 Old 06-19-2018, 01:02 PM Thread Starter
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Mysterious low RPM """Lean""" surging (Yes I already tried KLX needle and adjusted air mix screw) PLEASE HELP!!

Posted this on reddit and klr650net already but haven't been able to find a solution that worked
Basically I'm getting a really annoying surge/jerkiness/seat of the pants bad feeling below 4000 rpm up through the gears until I get to 4th where it starts to smooth out a bit and can not for the life of me figure out what it could be. Also feels like a loss of power in that range. When I crank the throttle the surging goes away but the bike still does not feel 100%

Here are some details
2001 KLR 650. No air box mods, stock exhaust, Gen 2 header, chain and sprockets have low miles
~10,000 miles
Problem started when the bike was bone stock except with a uni air filter and manual petcock, since then I have tried a few mods that I listed below


Since the problem started I have:
  • Got tires replaced and wheels trued by dealership (both spacers appear to be in place on the axel)
  • Replaced the stock tank with an IMS 6.6
  • Drilled the slide on the carb
  • Put KLX needle 2nd slot with a shim under clip
  • Tried 145 and 142 mains (145 was maybe slightly better, not much)
  • Adjusted the air mix screw as far in as 1.5 turns and as far out as 3.5 turns, no noticeable affect
  • Cleaned the heck out of the jets until every tiny hole in each of them was clear, also blasted the ports of the carb with cleaner and air
  • Checked Diaphragm and rubber parts of the carb to make sure they were seated and undamaged
  • Replaced stock gen 1 header with a gen 2
  • Loosened the chain until I was able to push it up onto the rubber piece under the swingarm
  • Replaced the gnarled stock plastic choke cable housing with a pull knob for a Harley

I know someone will suggest valve clearance check which I have not done yet, but the bike has 0 issues starting so I wouldn't think it's an issue. Possibly unrelated to fuel? electical issue? I am losing my mind trying to get this fixed. I just want to be able to cruise like it used to. Please someone be a hero and tell me what the hell is going on with my bike

Last edited by omfgtimmy; 06-19-2018 at 01:04 PM.
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post #2 of 34 Old 06-19-2018, 03:24 PM
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My first thought is a sticking slide or pin hole in the diaphragm, but others with more time on this carb can advise better.

Knowing When the problem started could lend some clues.

2016 KLR 650
2017 BMW S1000RR (traded in for
2018 Ducati V4S
1983 GL1100 Goldwing
2017 Yamaha R1
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post #3 of 34 Old 06-19-2018, 03:40 PM
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Yeah, I can't get past the diaphragm since that is kinda what regulates how much gas flows on the way up through the gears by creating a vacuum that lets the needle rise to let more fuel in. If that vacuum isn't totally sealed or there is blockage in a passage then it would do exactly what you described. Take that carb off and the diaphram and all the jets and squirt the heck out of ALL passages. Soak it in that stuff.

Check this awesome video out.

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post #4 of 34 Old 06-19-2018, 05:13 PM
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I'm going to suggest that either 1 or all 3 of the tiny little low speed mixture holes at the bottom edge of the throttle plate is restricted.
Use a wire bent 90 degrees to poke down thru them and back-flush the passage way (pilot jet removed, of course).

Throttle diaphragm problems are primarily from 4000rpm & up.

pdwestman
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Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #5 of 34 Old 06-19-2018, 06:49 PM Thread Starter
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Here's something interesting (or not) I took the carb apart -again- and this time I took the KLX needle clip and moved it down to the 3rd position, also went back to the 145 main which is stock size as far as I'm aware.
it solved the low RPM surging by moving the surging higher in the RPM range. Now it has the same feeling except at 4-5k rpms and I have to really crack the throttle to make it stop now.

I did check the diaphragm for tears or holes, did not see any. I've made sure it's stuck down in the groove every time with a small bit of silicone grease also.
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post #6 of 34 Old 06-19-2018, 07:00 PM Thread Starter
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Quote:
Originally Posted by dan filipi View Post
My first thought is a sticking slide or pin hole in the diaphragm, but others with more time on this carb can advise better.

Knowing When the problem started could lend some clues.
I can't pinpoint exactly when it happened, but here are some things that happened AROUND the time I started noticing it:
Dumped the bike into a foot of mud water during offroad
Switched to full synthetic oil (this completely solved my oil consumption issue and also made shifting a bit better)
Had an issue with my gas boiling (vaccuum in the tank, probably clogged fuel cap from mud water. Since then I have a different gas tank)
Put new tires on and had them trued
Ran really low on oil at one point without noticing, probably had like 1/2 quart of oil running in the bike at some point
spent time abusing the clutch learning to wheelie in parking lots (I stopped doing that after dumping the clutch in first gear shot the front wheel up to 2 o clock)

so yeah, take your pick on what could have possibly done something
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post #7 of 34 Old 06-19-2018, 08:02 PM
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Again I'll suggest that you triple check the 3 tiny pilot outlets at the bottom edge of the throttle butterfly plate. And lean your mid-range needle back down, probably even leave the shim off of the needle. (You do have brass spacer on top of the e-clip, correct?)

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #8 of 34 Old 06-19-2018, 08:18 PM Thread Starter
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Quote:
Originally Posted by pdwestman View Post
Again I'll suggest that you triple check the 3 tiny pilot outlets at the bottom edge of the throttle butterfly plate. And lean your mid-range needle back down, probably even leave the shim off of the needle. (You do have brass spacer on top of the e-clip, correct?)
You might be right about this. My jets were gunked up the first time I gutted the carb and cleaned the hell out of them, but didn't do as good a job with the ports in the carb housing. Once I have the will to take it out again I'll do that. Anything else I should check with the bike apart and the carb out?
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post #9 of 34 Old 06-19-2018, 08:35 PM
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Quote:
Originally Posted by omfgtimmy View Post
Ran really low on oil at one point without noticing, probably had like 1/2 quart of oil running in the bike at some point
spent time abusing the clutch learning to wheelie in parking lots (I stopped doing that after dumping the clutch in first gear shot the front wheel up to 2 o clock)

so yeah, take your pick on what could have possibly done something
Well with only a mere 1/2 quart of oil in the engine and popping wheelies, maybe you ought to check that you didn't damage the RH exhaust camshaft bearing and possibly all of the camshaft bearings.
The RH exhaust cam bearing is the absolute last bearing in the entire lubrication system, so it is the 1st to be damaged!

But that is not the cause of its current poor running.
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pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #10 of 34 Old 06-20-2018, 11:02 AM
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Quote:
Originally Posted by omfgtimmy View Post
I can't pinpoint exactly when it happened, but here are some things that happened AROUND the time I started noticing it:
Dumped the bike into a foot of mud water during offroad

Ran really low on oil at one point without noticing, probably had like 1/2 quart of oil running in the bike at some point
spent time abusing the clutch learning to wheelie in parking lots (I stopped doing that after dumping the clutch in first gear shot the front wheel up to 2 o clock)

so yeah, take your pick on what could have possibly done something
Wow, your bike has cause to be unhappy! I second Paul's comments about checking for damage due to the low oil but the most likely cause of your current problem is water/dirt in the carb.

Dave
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