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Old 11-28-2012, 12:54 PM   #1
David_in_TX OP
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1997 KLR650 surges and cuts out just like it's out of gas

My 1997 KLR650 surges and cuts out just like it's out of gas when using partial throttle in windy conditions. I can always get it back running by adding more throttle. This happens while I am riding at about 3,750 RPM - about 55 MPH. I've been trying to figure out what's going on for awhile and I'm still stumped. It may be my imagination, but this issue seems worse on a windy day. I recently trimmed the carb vent line, before I trimmed it it was hanging down below the swing arm about 4 inches. Could that have caused it? I cannot tell yet because I haven't been able to ride much since trimming the vent. I haven't done the T mod...yet.

Here's the details on my KLR:
17,000 miles, I'm the second owner.
22 cent mod, drilled the slide, shimmed the main needle, set the air screw to 1.75 turns (should it be further out?).
Carb has been cleaned recently and has new parts in it everywhere they can be replaced (except for slide and diaphragm, which are in good shape).
Vacuum petcock, recently overhauled.
Sintered brass type fuel filter, which is high flow.
OEM oiled air filter with Notoil oil, recently cleaned and not over oiled.
IMS tank, with a vent hose that's not clogged or kinked.
New Eagle Mike/Wyman Winn 688 piston, rings, and valve job 400 miles ago.
New chain and sprockets.
Eagle Mike doohickey and torsion spring.
Valve clearances set to max clearance 400 miles ago.
OEM exhaust, fresh gaskets with no leakage.
Removed the snorkle.

Some more details: it doesn't pop a lot under deceleration but does have a slight popping. When I start it on a cold day the enrichener doesn't work. I can always start it by twisting the throttle until it fires and I need to keep a little throttle for about 30 seconds until it idles on it's own. If I use the enrichener, it just won't start and I'm afraid I'll flood it. I recently replaced the enrichener plunger with a new OEM one, the one I replaced had a gouge on the outside diameter of the larger part of it. Looked like someone had grabbed it with pliers.
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Old 11-28-2012, 03:46 PM   #2
RandoCommando
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Petcock

I'm gonna venture a guess on the petcock.
I had a similar issue.
Replaced the petcock and it was fixed.
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Old 11-28-2012, 05:57 PM   #3
Hektoglider
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stuff like this is hard to diagnose online. Drain your carb float bowl, capture the fuel in a clear clean glass. Inspect for beads of water. Problems like you describe are usually very simple. Remove your fuel line, apply vacuum to the other smaller line at the petcock. Verify a good fuel delivery. Reconnect the vacuum line to carb. With the float bowl filled up, start the bike and see that the fuel flows out of the line(petcock diapragm ok) and if so reconnect the line.
Next time it does it , look in the mirror for black smoke, or the rider behind you notice , or pull your spark plug and read it for mixture...lean/rich.....
Check your airbox for a rodent nest. Your bike should not start that easily without the enrichener being engaged. Is the cable set up with correct free play? Sounds like its getting a rich condition......Could be as simple as a new spark plug.........but I am guessing it has something to do with recent work(enrichener )
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Old 11-28-2012, 06:38 PM   #4
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Does this happen literally when it's windy/when the bike is getting hit with wind...?
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Old 11-29-2012, 08:53 AM   #5
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Thanks for all the suggestions. I've already covered all of that and was searching for something else to try. It seems more pronounced in windy conditions, When a gust hits me it cuts out.
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Old 11-29-2012, 09:03 AM   #6
miguelitro
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This may sound stupid but when hit with a gust of wind you will tend to squeeze a little harder with your legs which could be pinching a wire.
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Old 11-29-2012, 09:04 AM   #7
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Had this on a rented KLR once. In gusts of wind or when passing an oncoming truck, it would act like it wasn't getting fuel. It was fine at low speed and never stalled, so we didn't worry about it. Not that that's helpful to you at all, but it might mean you're not crazy.
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Old 11-29-2012, 09:20 AM   #8
elsalvadorklr
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Quote:
Originally Posted by David_in_TX View Post
Thanks for all the suggestions. I've already covered all of that and was searching for something else to try. It seems more pronounced in windy conditions, When a gust hits me it cuts out.
a lot of bikes with POD filters have this issue(street trackers, cafe racers, etc...)

the turbulent air that the filters suck causes the carb to bog...

thats the reason most bikes have airboxes...they are there to create a steady flow and a non tubulent air space that the filter can suck through, obviously protect against water and dust...but also a lot to do with airflow.

having said that my klr didnt do this even when removing the backfire screen(uni filter and snorkle out)

so cant help much

sorry

EDIT i just read you trimmed your carb vent lines
yes this might possibly be the reason you are having issues

vent lines need to be capped and under the swingarm with those funnly looking duckbill caps...they prevent water and air from going in yet let the water and or gas or air flow out...

so yes

in windy conditions all vents will be exposed more...including the carb vents

I guarantee almost that by going back to stock you will get rid if this issue

those duckbill caps are worth gold

in the meantime if you cant find them anywhere you can put a small foam filter or even pantyhose on the ends of the tubes to help...

please let us know if this helps

christian

elsalvadorklr screwed with this post 11-29-2012 at 09:25 AM
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Old 11-29-2012, 09:32 AM   #9
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Wrong size pilot with mods? May need to bump up a size or two. Sounds like it wants to cut out in your transition from slow speed circuit (IE, pilot circuit) to high speed circuit (main). Maybe try raising your needle clip one position?

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Old 11-29-2012, 10:26 AM   #10
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ah.... the carb vent line has to be open or the engine will not run without full choke, and then runs poorly (not your problem)

you can take the vent line off... it's only there because when you dump the bike sometimes fuel will come out & the line is supposed to let it go somewhere else besides you crotch (with the bike in you lap) but I don't see how. anyway, you should have the T mod if you keep the vent

try running with the air box door off just to see

are all the carb parts Kehin? Dynajet uses different hole size for same part number jets and the needles have a different taper... so does the KLX needle
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Old 11-29-2012, 11:03 AM   #11
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Mine did this after the 705 kit after running high speeds for a long time. About 70-75, and it would start to act like I was out of gas. Checked the valves the other day, and noticed my cams were both set off by one tooth (to the rear). Have not had a chance to see if that solved it yet. You have a 685 kit, might be worth double checking.
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Old 11-29-2012, 11:17 AM   #12
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Did you do the carb work? The 22 cent mod is adding two small washers as shims under the needle, so I'm a little concerned that you mentioned that and shimming the needle. Any chance the diaphragm spring got left out when the carb was put back together? I would take the fuel filter out and see if that helps. Aftermarket fuel filters have been known to cause issues on the KLR. I know you say it's a high-flow part, but it's an easy test to see if it is causing the problem. Also, check the vacuum hose to the petcock, that has been known to get soft and collapse, but I'm doubt that's your issue. As for the fuel screw adjustment, setting it to some arbitrary number of turns is just a starting point. You need to warm the bike up and turn the fuel screw in until it starts to stumble, then out until it idles faster and set it at some point in between. Blip the throttle and make sure it revs up and then idles back down right away. If the engine hangs at a higher RPM, turn the fuel screw out. If it revs up than drops down below normal idle speed, turn the fuel screw back in.

I don't have any experience with removing the snorkel on a KLR, but that could be causing an issue. The bike shouldn't backfire on decel with the carb settings you have and the stock intake and exhaust.You also need to figure out what's going on with the choke. If it's not installed properly and letting in extra air, that will cause problems too. It's a real bear to get in there and tightened properly, hence the plier marks on the old one. BTDT.
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Old 11-29-2012, 12:22 PM   #13
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I've read here and elsewhere about people having issues with wind pushing air up their carb vent and causing stumbling (KLRs specifically). I'm not sure what the fix would be for that but that was the only wind-specific issue like this that I've read about ever.

Otherwise, fuel starvation at higher speeds is often linked to a kinked tank vent hose or a bad tank cap vent which can be cleaned out. I'd remove the tank vent and ride (being careful not to drop the bike). Then if that doesn't fix your problem, re-install that vent and ride with the tank cap off. That should help find potential culprits. Also, pull the vacuum line off the petcock and make sure there's no gas in it at all. If there is, you need a new diaphram for the vacuum operated valve part of the petcock. In that case there would probably be fuel that leaked to the outside of the petcock also which will be easy to spot/feel. I've read about those leaky diaphrams causing all sorts of problems for people of course including simple failure leading to a completely useless petcock (no vacuum, no fuel).
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Old 11-29-2012, 07:58 PM   #14
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Quote:
Originally Posted by Myfuture_yourdebt View Post
I've read here and elsewhere about people having issues with wind pushing air up their carb vent and causing stumbling (KLRs specifically). I'm not sure what the fix would be for that but that was the only wind-specific issue like this that I've read about ever.

Otherwise, fuel starvation at higher speeds is often linked to a kinked tank vent hose or a bad tank cap vent which can be cleaned out. I'd remove the tank vent and ride (being careful not to drop the bike). Then if that doesn't fix your problem, re-install that vent and ride with the tank cap off. That should help find potential culprits. Also, pull the vacuum line off the petcock and make sure there's no gas in it at all. If there is, you need a new diaphram for the vacuum operated valve part of the petcock. In that case there would probably be fuel that leaked to the outside of the petcock also which will be easy to spot/feel. I've read about those leaky diaphrams causing all sorts of problems for people of course including simple failure leading to a completely useless petcock (no vacuum, no fuel).
thats what I was trying to say

its a wind related thing issue so I dont see how any of the standard carb mod, fixes has anything to do with it

he also the op said he trimmed the vent klines for a reason

if no body beleives me try blowing in the vent lines of the carb while the bike is running and see how tbe bike reacts

just sayin

hope the op fixes the issue but Im betting its related to this

cheers
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Old 03-13-2014, 09:59 AM   #15
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better late than never??

I had a similar problem with my last bike. Turned out it was an exhaust leak boiling the gas as it went through the carb. I'm guessing you have yours fixed now but thought I'd throw this in anyways.
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