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Discussion Starter #1
About a year ago I was riding on the interstate and suddenly the engine on my 2008 KLR started "bucking". The only way to describe it is like at the beginning of low fuel. It got to the point where I needed to pull off the interstate because of low speed. I sat for a minute or two and tried going again...still bucking but got a little more speed. Then all of a sudden the issue stopped and all was well. I thought maybe it was bad fuel or somthing. I rode several other times including interstate speeds and no further problem until...

A few weeks later the same thing happened. Again...all of a sudden on the interstate. This time I switched to reserve thinking maybe I was out of gas or it was bad gas again but no difference. I stopped and filled up with more gas. No change. This was not the same tank of gas as previously anyways. This day it was worse than the first time above and the problem didn't go away for 40 miles. I had to stop once because it died. It gets even more weird...I got home and discovered a stone in behind the linkage on the side of the carb. I removed it but the problem had stopped. I thought maybe the linkage and the throttle were not cooperating. Rode the bike some 300 miles without another problem after that and assumed the stone was the culprit...

Then...a month or so later...again at about 60 mph, it started. This time not as severe but just as sudden. When I say sudden I mean that I am cruising at speed with holding throttle steady and it happened...it's like a coughing feel. It didn't slow me down much but I could feel the slight bucking for the remaining 50 miles I had to get home. No new stones in the linkage in case you were wondering.

Off and on for the rest of the year....more of the same. Light bucking in Utah in the canyons and I went down hard and after I got back up and started again it had stopped. 200 or so miles later it starts again and is now bucking with a vengence.

I am baffled. Some of you guys are master wrenches I know. I would appreciate any advise.

Here's what I have done thus far...

Changed petcock to gravity feed. Emptied the carb bowl like 15 times including immediately after the bucking started. Ran 3 cans of Seafoam through. Tried all types of gasoline including non ethanol.


What next?

Thoughts?
 

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twohawks -

Intermittent problems are a sumbitch to troubleshoot.

Next time it happens, stop and open the gas cap. If it is a vent issue, that will stop the bucking.

If that doesn't work right away, stop and pull the seat off. Find the pinkish vent hose and give it a good blow to clear it.

I suggest these two things because it sounds like a fuel delivery issue and these are both common causes. You've eliminated another, the vacuum petcock.

If neither of these work, you may have an intermittent ignition issue, in which case I would suggest you stock up on rum, cigars, and a live chicken to sacrifice to Electrocutus, the demi-god of motorcycle ignition...

T
 

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Discussion Starter #3
twohawks -

Intermittent problems are a sumbitch to troubleshoot.

Next time it happens, stop and open the gas cap. If it is a vent issue, that will stop the bucking.

If that doesn't work right away, stop and pull the seat off. Find the pinkish vent hose and give it a good blow to clear it.

I suggest these two things because it sounds like a fuel delivery issue and these are both common causes. You've eliminated another, the vacuum petcock.

If neither of these work, you may have an intermittent ignition issue, in which case I would suggest you stock up on rum, cigars, and a live chicken to sacrifice to Electrocutus, the demi-god of motorcycle ignition...

T
Thanks Tom...

I forgot to mention already trying the gas cap opening strategy...to no avail....BUT...I did not try checking the under seat breather vent hose...but I assure you...I WILL.

I also forgot to mention that the first winter I bought the bike I had to have the dealer do a factory recommended mod to grind .020 inches off of a pin in the KACR that hits a tappet so it would start in the cold.Not sure if it's related.
 

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Thanks Tom...

I forgot to mention already trying the gas cap opening strategy...to no avail....BUT...I did not try checking the under seat breather vent hose...but I assure you...I WILL.

I also forgot to mention that the first winter I bought the bike I had to have the dealer do a factory recommended mod to grind .020 inches off of a pin in the KACR that hits a tappet so it would start in the cold.Not sure if it's related.
The KACR is not part of your current issue. It is most likely the vacuum operated petcock. The smaller line going to the back of it may be getting pinched causing the petcock to partially close. Check the vacuum lines carefully for any place that might kink or leak. If this doesn't resolve the issue try removing the diaphram from the petcock and replace it with a piece of heavy fuel gasket material. Cap the vacuum port on it and plug the rubber vacuum line. Now the petcock will no longer be dependant on vacuum to operate.
 

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twohawks -

On the Gen2 bikes the carb vent got re-routed. It now goes up and out towards the back of the tank. This routing tends to make a bit of a dip in the line where fluid can accumulate. In my case it was gas from letting the pig take a dirt nap.

It is possible for that fluid in the vent line to block the vent line at some times and not at others. I found (this is speculation in hind sight) that as long as I was bouncing along in the desert the fluid would stay separated enough to not block the line. As soon as I hit the slab and things smoothed out, the fluid ran together and crated a dam, blocking the tube. as soon as the vent is blocked pressure builds in the bowl and gas can't come in and she runs like a cat hacking up a fur ball.

It's a long shot, I know, but it might keep you from going to the store for rum, cigars, and chicken....

T
 

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Good luck, dude. You already tried all the things I would have. Keep us posted.
 

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The KACR is not part of your current issue. It is most likely the vacuum operated petcock. The smaller line going to the back of it may be getting pinched causing the petcock to partially close. Check the vacuum lines carefully for any place that might kink or leak. If this doesn't resolve the issue try removing the diaphram from the petcock and replace it with a piece of heavy fuel gasket material. Cap the vacuum port on it and plug the rubber vacuum line. Now the petcock will no longer be dependant on vacuum to operate.
It's most likely not. The petcock has been converted to gravity feed.


twohawks, post #1
Changed petcock to gravity feed. Emptied the carb bowl like 15 times including immediately after the bucking started. Ran 3 cans of Seafoam through. Tried all types of gasoline including non ethanol.
The reference to the KACR was to bring to the table all information of all work performed by owner and / or shops. While the symptoms may or may not indicate a KACR issue, it needs to be said that the dealer was in there. The issue was present before the KACR repair, and has continued since the repair.

Internet Diagnostics are hard enough without having a considerable amount of pertinent information withheld. Like, "someone else was in thar workin'". Good to know, sometimes.
 

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twohawks -

On the Gen2 bikes the carb vent got re-routed. It now goes up and out towards the back of the tank. This routing tends to make a bit of a dip in the line where fluid can accumulate. In my case it was gas from letting the pig take a dirt nap.

It is possible for that fluid in the vent line to block the vent line at some times and not at others. I found (this is speculation in hind sight) that as long as I was bouncing along in the desert the fluid would stay separated enough to not block the line. As soon as I hit the slab and things smoothed out, the fluid ran together and crated a dam, blocking the tube. as soon as the vent is blocked pressure builds in the bowl and gas can't come in and she runs like a cat hacking up a fur ball.

It's a long shot, I know, but it might keep you from going to the store for rum, cigars, and chicken....

T
Tom, can you clear that line by just blowing through it, or do you find it best to remove and drain it?
 

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Discussion Starter #9
twohawks -

On the Gen2 bikes the carb vent got re-routed. It now goes up and out towards the back of the tank. This routing tends to make a bit of a dip in the line where fluid can accumulate. In my case it was gas from letting the pig take a dirt nap.

It is possible for that fluid in the vent line to block the vent line at some times and not at others. I found (this is speculation in hind sight) that as long as I was bouncing along in the desert the fluid would stay separated enough to not block the line. As soon as I hit the slab and things smoothed out, the fluid ran together and crated a dam, blocking the tube. as soon as the vent is blocked pressure builds in the bowl and gas can't come in and she runs like a cat hacking up a fur ball.

It's a long shot, I know, but it might keep you from going to the store for rum, cigars, and chicken....

T
Right...I already put rum, cigars, and chicken on the list but..I gotta tell you...your suggestion and solution sound more plausable than some suggestions i've gotten! Will try it out when I am back home this weekend...
 

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It's most likely not. The petcock has been converted to gravity feed.


twohawks, post #1


The reference to the KACR was to bring to the table all information of all work performed by owner and / or shops. While the symptoms may or may not indicate a KACR issue, it needs to be said that the dealer was in there. The issue was present before the KACR repair, and has continued since the repair.

Internet Diagnostics are hard enough without having a considerable amount of pertinent information withheld. Like, "someone else was in thar workin'". Good to know, sometimes.
Sorry, missed that.

The vent line sounds very plausable. The T-mod is still a good idea for the gen-2.
 

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Discussion Starter #11
It's most likely not. The petcock has been converted to gravity feed.


twohawks, post #1


The reference to the KACR was to bring to the table all information of all work performed by owner and / or shops. While the symptoms may or may not indicate a KACR issue, it needs to be said that the dealer was in there. The issue was present before the KACR repair, and has continued since the repair.

Internet Diagnostics are hard enough without having a considerable amount of pertinent information withheld. Like, "someone else was in thar workin'". Good to know, sometimes.

Actually....the problem was NOT there before the KACR fix....
 

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Tom, can you clear that line by just blowing through it, or do you find it best to remove and drain it?
vatrader -

If it is really full of stuff you can't blow it out. You'd be blowing into a closed system.

What I have seen happen is just a small amount of liquid will, due to surface tension, create a dam of liquid sufficient enough to block the tube. Blowing on it will break the surface tension and open the tube.

It is best to remove the tube and do a T-Mod. Good catch;I should have been more complete.

Thanks!

Tom
 

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I'm asking out of ignorance - is there a way that the KACR can suddenly get stuck in the 'on' position and crack an exhaust valve?

I wouldn't think so, as it was my impression there was some sort of centrifugal chingadera that retracted once the cam got spun up.

T
 

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I dont remeber exactly how it is Tom. ( have not been in one for a few years.)
[talking to self] The weights pull w/springs, down on slow rpms and then spin out of the way on higher rpms. What I remember. I dont think it could engage the the shim flying down the highway. It would have to lock up first, before the engine is started.[/talking to self]

If someone at the Techday opens one up I'll take a better look at it and see if it can happen out of the blue on sustained RPms.
 

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Discussion Starter #15
Well...here's an update. Had Wayne Cycle look for electrical gremlins...and after completely tearing down and cleaning the carb, etc....the problem is gone. No gremplins actually found anywhere either electricall of fule process. It's running better than from when it came from the factory ( they set things very lean apparently) BUT...time will tell...the problem would dissapear on its own before.

The breather tube (pink) was clear.

Will report back after 400 miles...thats the farthest I went in between problems last time!
 
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