Oil in my carb???!!! - Kawasaki KLR 650 Forum
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post #1 of 20 Old 06-18-2019, 01:50 AM Thread Starter
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Oil in my carb???!!!

Hi everybody,

Hoping for some help from people wiser than myself (everyone) to help get me home.

I've been traveling on an 07 KLR for two years now, California to Ushuaia, and back. 45k miles on this trip, although the bike has about 60k total. Now, I'm 450 miles from the final destination (Boston) and it's really died on me. Stuck in Pennsylvania.

Here's the shortest version I can provide:

Bike starts and idles fine. But under load, it cannot maintain high RPMs. Even in neutral, if I open the throttle, it starts to sputter and die above 4k RPM. Can't go above 2k or 3k RPM while riding.

Today, I changed spark plug (ngk iridium), swapped in a spare ignition coil, visually inspected wires for damage, checked that gas is flowing to carb, cleaned main and pilot jets, cleaned air filter, and checked breather and vacuum hoses. All look fine to me. Problem is unchanged.

In cleaning the carb, I notice oil behind the small, air cut off diaphragm on the side of the CVK. Oil in my carb? Which reminds me that it's been drinking more oil than usual recently.

No unusual smoke from exhaust.

Obviously, I'm leaving out a ton of other stuff that's happened since California. That'd be a novel.

Anyone got any ideas or tests I can run on the side of the road? I've been searching for 'oil in carb', but everything seems to be about oil in the airbox. There may have been more oil in the air filter than I expected. But I oil that filter, so I can't say.

Any help is greatly, greatly appreciated. I'm so freaking close to the end. Just want to go home.
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post #2 of 20 Old 06-18-2019, 08:57 AM
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That small diaphragm is the decel valve. I imagine it could get oil behind it from oil coming from the airbox. I don't' think that is the main problem.

What you describe are the classic symptoms of bogging under load. That indicates that the main diaphragm may be torn. Remove it, inspect it for holes.

While you are at it, remove the idle et and check it again. You should be able to see daylight through the axial hole.

Tom [email protected]

“I lit a cigarette and dragged a smoking stand beside the chair. The minutes went by on tiptoe, with their fingers to their lips.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.
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post #3 of 20 Old 06-18-2019, 09:16 AM Thread Starter
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Hi Tom,

First off, thank you so much for everything you contribute on this forum. I've been reading your posts for years. Huge fan.

I just out the carb back in five minutes ago. I'd read people mention the large diaphragm as a suspect, so I checked it against a light pretty thoroughly. Looked fine. Couldn't see any damage or light passing through.

Also pulled both jets. No blockage and plenty of light coming through the tunnel. Holes through the sides also clean and clear.

Anything else you'd recommend checking??
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post #4 of 20 Old 06-18-2019, 11:20 AM
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The throttle slide diaphragm is my thought also.

Are there any nicks on the outer perimeter sealing lip? Are there any impressions from imperfections on the top plastic cap?
Is there any corrosion in the groove that the sealing lip seats into?

Tucker Rocky / Bikers Choice #482841 TP Keihin Membrane Seal, (Diaphragm) only about $17. Or a complete Harley Sportster CV 40 throttle slide assembly.

pdwestman
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Still riding my 1987 KL650-A1. 83,000+ miles & counting
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post #5 of 20 Old 06-18-2019, 11:20 AM
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A lack of ability to rev usually indicates that the engine is not getting enough air, fuel, or both.

You say that you have checked the breather hose, but I'm not sure if you mean the big rubber hose going from the crankcase to the airbox or if you mean the vent line. If you meant the big rubber hose, then disconnect the vent line at the carb. If the vent line is blocked the carb can't flow gas to the bowl. You could also pull the vent elbow out of the carb and make sure it is clear. Some of the earlier vent elbows were restricted. It wouldn't take much of a critter's crap to block it. I know the '08 elbows were restricted and the '07's might have been as well.

The air filter may be dirty and not flowing air. In your case, that seems simplistic. Still worth checking.

The fact that it runs well at idle would indicate that the ignition system is working fairly well. Usually, they either work or they don't. There is a remote possibility that the pick-up coil's wires are broken, usually down by the case where they exit the case near the front sprocket. Increased vibration may cause an intermittent connection. This is really grasping at straws, but the wires down there do tend to get brittle. If it begins to run rough and sputters a bit as you try to increase RPM then that would support the idea. If it simply won't rev but runs smoothly up to that point, not so much. I suppose that the exciter coil's wires could be suspect as well.

If the slide won't lift it won't have power and won't rev well (most common and why I thought the diaphragm might be compromised). Blast the decel valve passageways with some carb cleaner to clear any oil; perhaps the oil is a culprit here. Again, grasping at straws.

If the floats are stuck in a raised position then the inlet valve won't allow enough gas in to support higher RPMs. Without starting the engine beforehand, remove the drain screw from the bottom of the bowl. At least an ounce of gas or so should come out. You could remove the bowl, gently, and see if they are in the dropped position as they should be when the bowl is off. Move the float up and down to check for free and easy motion.

You say that the fuel flow to the carb is good, but the tank really needs to be able to flow a couple of ounces a minute. Figure it should have a good, healthy stream rather than just a dribble. The stock, vacuum operated petcock, has a couple of extra opportunities to reduce flow. The selector gasket can degrade and block flow and the diaphragm can degrade and reduce flow as well. These are age-related and if the petcock is original then it might be a good candidate.

Tom [email protected]

“I lit a cigarette and dragged a smoking stand beside the chair. The minutes went by on tiptoe, with their fingers to their lips.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.

Last edited by Tom Schmitz; 06-18-2019 at 11:26 AM.
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post #6 of 20 Old 06-18-2019, 02:39 PM Thread Starter
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Thanks for all the feedback guys. Third test drive of the day, but still no joy.

Short Version: I've tested everything recommended except pulling the petcock. One thing I notice on these test rides is the bike is backfiring more on deceleration than I'm used to. And there seems to be more engine noise up front than I'd expect, compared to at the exhaust.

Could I be looking at a head gasket issue?


Long Version:

I've been over the large diaphragm with a fine tough comb. There's some visible wear, a slight texture to the rubber in some places. But no holes, no cracks or nicks, and no corrosion or malfeasance on the plastic cap or carb itself. Shucks.

Big breather hose (to crank case) and vent line (to carb) are clear, and hold pressure when I block the other end with my thumb. I checked the elbows yesterday when I cleaned the carb, and they also are clear. Also blew out all passages in the dismantled carb while I had it apart. Float moved smooth and easily with gravity as I tilt carb back and forth, and the little rubber tip on the plunger that moves with it is clean and soft, no cracks.

Wires at the front sprocket and to the coil look good. Air filter is spiffy clean, and when I drained gas from tank yesterday (by sucking on vacuum hose) I filled a small soup bowl in a minute no sweat.

Petcock I haven't pulled yet. No place to empty the tank. But it's on the list.
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post #7 of 20 Old 06-18-2019, 03:06 PM
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If the petcock diaphragm hose holds suction on your tongue and the fuel screens on both the ON & Reserve inlets can flow a soup bowl full per minute, I see No Reason to remove or dismantle the petcock, unless the automatic OFF is non-functional.

The 'after-fire' out the tail pipe on deceleration and the increased noise Up Front could easily be caused by the same thing, a BAD exhaust Header pipe to head Gasket. Part # 11060-1108. Possibly caused by missing or loose nuts.

Do you have access to a straight edge? It could be possible that the plastic carb top has Warped and that could cause the vacuum loss to prevent full lift of the diaphragm & slide!

pdwestman
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post #8 of 20 Old 06-18-2019, 03:32 PM
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I agree with Paul on the header pipe gasket issue, though I don't see how that would affect running. Sometimes simply tightening the nuts will fix that issue. If not, a new gasket will.

As much as I hate to say it, I'm leaning toward an idle circuit issue. That would be the idle jet itself (you wouldn't believe how many 'ok' idle jets wind up being clogged. And, not to put to fine a point on it, the same goes for 'good' diaphragms. These things can be beastly.) and/or the idle circuit passages themselves. There are three small holes at the leading edge of the butterfly plate. These all need to be clear. The problem is that the idle jet hole is less than .015" and the passages in the carb body are not a lot larger.

The saying "... when you have eliminated the impossible, whatever remains, however improbable, must be the truth...". Check the idle jet again, making sure that you can see daylight. Better if you can pass a small wire through.



The passageways in the carb body can be confirmed to be clear by spraying a fluid through them and witnessing that fluid coming out of the three holes.

The idle circuit has a strong influence up to about mid throttle and a bad idle circuit won't let the engine make enough power to pull the hat off yer head.

It's good that you could fill a bowl with gas in a minute. That indicates that the petcock is fine.

By the by, do you have Vaseline, Chapstick, a Thermarest patch kit or any similar sorts of things? Those can be useful to limp a bad diaphragm home. Vaseline or Chapstick can help seal the edge of the diaphragm and hold it in place while the cover is put back. Applied to both sides of the edge that could help if the cap is warped and also ensure that the edge doesn't get pinched.

Tom [email protected]

“I lit a cigarette and dragged a smoking stand beside the chair. The minutes went by on tiptoe, with their fingers to their lips.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.

Last edited by Tom Schmitz; 06-18-2019 at 03:37 PM.
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post #9 of 20 Old 06-18-2019, 04:12 PM Thread Starter
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Tom and Paul, I hope you guys get a tax credit or something for the time you put in here. The pipe gasket is new as of a few months ago, but international shipping confusion means I have three extras on hand. Will swap one in to be sure. As for jets, I must have learned how to clean them from a prior Tom post, because the wire trick is exactly how I do it. Same with pathways through the carb. Both fine.

Never heard of the Vaseline trick for diaphragms. I'll try that next, although I reckon it's worth buying a new one anyways.

Thanks again. I'll let you know how it goes.
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post #10 of 20 Old 06-18-2019, 06:12 PM
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Originally Posted by Eric Swoyer View Post
Never heard of the Vaseline trick for diaphragms. I'll try that next, although I reckon it's worth buying a new one anyways.
The Vaseline or grease merely holds the diaphragm in its slot around the mixing chamber while the plastic cap is cinched down by tightening machine screws. Purpose? Insure air-tight seal around diaphragm, with its lip securely bottomed in its circular slot.

"Buying a new one (diaphragm)" may be a larger enterprise than one might think; could be in an assembly including slide; kinda pricey (pricey when purchased from Kawasaki; an equivalent Harley CV40 part may save some money).

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre
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