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Discussion Starter #1 (Edited)
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
 

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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.
 

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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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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.
 

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Discussion Starter #5
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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Discussion Starter #6
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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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?)
 

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Discussion Starter #8
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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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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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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If that were my bike I'd try to return everything (jets, needle, slider hole) to stock and getting it running right from there before making any mods.

They do run just fine stock. You're in a situation now where you don't know whether your mods have broken it more or helped. Return to stock then change one thing at a time.
 

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If that were my bike I'd try to return everything (jets, needle, slider hole) to stock and getting it running right from there before making any mods.

They do run just fine stock. You're in a situation now where you don't know whether your mods have broken it more or helped. Return to stock then change one thing at a time.
The rationale is fine but he's said it had the same problem before the jetting, etc.

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


Dave
 

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Yeah, saw that, but why add additional variables to the equation? There was obviously something wrong before the mods started. I like to see stuff working perfectly before I start changing things. I get confused easily if I change too many things at once.
 

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Yeah, saw that, but why add additional variables to the equation? There was obviously something wrong before the mods started. I like to see stuff working perfectly before I start changing things. I get confused easily if I change too many things at once.
Yep, always a good idea to do things one at a time.

Dave
 

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Discussion Starter #16
If that were my bike I'd try to return everything (jets, needle, slider hole) to stock and getting it running right from there before making any mods.

They do run just fine stock. You're in a situation now where you don't know whether your mods have broken it more or helped. Return to stock then change one thing at a time.
True, I got lazy and did the '2 birds with 1 stone' approach since I knew these bikes are lean from the factory I figured a KLX needle wouldn't hurt anything while I cleaned the carb. I assumed I was chasing down a lean issue


I hope that you at least pulled the snorkle as recommended by Eaglemike

Dave
I did not remove the snorkle

Would it be worth to run some star tron through it or should I just skip that and gut the carb again?
 

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You can always try Seafoam or something similar; it won't hurt anything. If you stick with the KLX kit, pull the snorkle out or you're running too rich......though I doubt jetting is your main issue.

Dave
 

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Discussion Starter #18
Does anyone have a good explanation as to why it extended the surging higher in the RPM range when I raised up the needle? It's probably obvious to those of you who know things about carburetors but I don't have a clue
 

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Discussion Starter #19
Alright so you guys convinced me to take the whole thing apart again and check all the small fuel passages in the carb - and what do you know, one of them looked completely gummed up and inoperative.
I'm giving it a bath in pine sol overnight for now, I assume to clear out the passages I just need to use a piece of wire?
 

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Discussion Starter #20
You can always try Seafoam or something similar; it won't hurt anything. If you stick with the KLX kit, pull the snorkle out or you're running too rich......though I doubt jetting is your main issue.

Dave
I opted to pull out the snorkel as well, which turned out to be only like 2 inches long, is that normal? doesn't seem like something that small would even restrict intake that much
 
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