Vacuum leak? ??? any ideas - Kawasaki KLR 650 Forum
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post #1 of 25 Old 12-08-2010, 07:56 PM Thread Starter
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Vacuum leak? ??? any ideas

My bike will start and idle perfect….. and will stay running for hours and not stall. But the second I give any gas at all, the bike stalls…. The part that makes me think that there is a vacuum problem is when I shut the bike off there is a hissing noise coming from the gas cap….. Any ideas
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post #2 of 25 Old 12-08-2010, 08:05 PM
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Quote:
Originally Posted by Crazy Jake View Post
My bike will start and idle perfect….. and will stay running for hours and not stall. But the second I give any gas at all, the bike stalls…. The part that makes me think that there is a vacuum problem is when I shut the bike off there is a hissing noise coming from the gas cap….. Any ideas
If you open the gas cap will the bike rev up ok? Perhaps you have a blocked vent. The hissing could be the vacumn generated as the bike is running. Give it a shot with the cap open and see if it still stalls when you rev it up.

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post #3 of 25 Old 12-08-2010, 08:08 PM
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Quote:
Originally Posted by Crazy Jake View Post
My bike will start and idle perfect….. and will stay running for hours and not stall. But the second I give any gas at all, the bike stalls…. The part that makes me think that there is a vacuum problem is when I shut the bike off there is a hissing noise coming from the gas cap….. Any ideas

Open up the gas cap while it's running and see if you can give it gas. There are vent lines on the tank. There's also a vacuum line on the back of the petcock. Vent lines on the carb too.

This is the bike that sat for a long time yes? Take it apart and go through it or you're going to be chasing stuff all the time.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
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post #4 of 25 Old 12-08-2010, 08:15 PM
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The hissing may be a tank vent issue. Remove the seat and look at the lower rear of the tank where it bolts to the frame. Above that bolt flange you'll see a hose barb coming from the tank. It should have a hose attached, running down towards the ground. Check for pinching or kinks, especially if you have an after market seat. Then leave the tank lid open and start the bike and see if you find joy. I suspect you will find no change. Tank vent issues usually result in an engine that won't run at all until some pressure is let off or it bleeds down on its own. There are air vents in the fuel filler cap. They may hiss when venting.

What have you done to get the cob webs out of the circuits in that carburetor?

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post #5 of 25 Old 12-08-2010, 08:29 PM Thread Starter
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I ran the sea foam with the mustard bottle…(I cant believe I never thought of that mustard bottle trick before) I let the bike run at idle for about 15 min. I will let the bike sit over night. After work tomorrow I will start and see if the Magic sea foam has made any fix… if not I will tear down the Carb … hell I may tear it down anyway, we will see what mood I am in when I get home. The part that concerned me was the hissing at the gas cap… I will try running the bike with the gas cap open and see what I get….. This bike dose have a corbon seat on it so I will look at the tank vent lines also.
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post #6 of 25 Old 12-09-2010, 07:48 AM
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Did the SeaFoam treatment do any good??

If not, I'd follow spec's suggestion and just tear it apart. Chances are the pilot jet's plugged with crap and it just needs a good cleaning.
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post #7 of 25 Old 12-09-2010, 09:01 PM Thread Starter
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The Sea Foam did not make any different effect at all. So I tore the carb down tonight. I hosed it all out with gum out and I am letting it sit I will do it again tomorrow. Is there any thing I should check or do with the carb out and apart. (this is not my first carb job so I know the deals but is there any thing special with the klr carb I should look at?)
The way the vent hose ran under the seat from the tank looked like it could have been pinched so I re-routed the vent hose. Thanks for the pointer on that, I would have never checked that.

The one thing that seams strange to me is that for some reason I think the float bowl is only filling half way. It just seems to me like there should be more gas in the bowl than there is??? Any in put on that?
Jake
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post #8 of 25 Old 12-10-2010, 09:16 AM
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Quote:
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The Sea Foam did not make any different effect at all. So I tore the carb down tonight. I hosed it all out with gum out and I am letting it sit I will do it again tomorrow. Is there any thing I should check or do with the carb out and apart. (this is not my first carb job so I know the deals but is there any thing special with the klr carb I should look at?)
The way the vent hose ran under the seat from the tank looked like it could have been pinched so I re-routed the vent hose. Thanks for the pointer on that, I would have never checked that.

The one thing that seams strange to me is that for some reason I think the float bowl is only filling half way. It just seems to me like there should be more gas in the bowl than there is??? Any in put on that?
Jake

Be sure to take out all the jets and blow them and the passages out. Look at the float valve, it should come to a nice smooth point not worn looking at all. Blow out the vent lines also. Inspect the slide's rubber bladder thang (technical term!) for nicks and tears, be careful it's seated right when you put it back in.

The float bowel should not be full of fuel it would drain out the overflow if it was. Just needs enough to keep the main and pilot jets submerged.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9

Last edited by Spec; 12-10-2010 at 09:24 AM.
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post #9 of 25 Old 12-10-2010, 05:32 PM
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You might want to do the 22 cent mod and remove the air adj. cap on the bottom of the carb. and adj the it out to about 1 3/4 turns.

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post #10 of 25 Old 12-10-2010, 08:29 PM Thread Starter
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So I tore the carb down cleaned the thing and the bike seems to be the same… Ideals perfect… as soon as I touch the gas ..the shuts off…….. I must be missing something
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