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Discussion Starter · #1 ·
I have an old sled that I can't seem to straighten out the flooding problem with it. It is a 1981 Yamaha SRV 540 with a Keihin carb.It runs "ok" but floods while shut down. I put an in-line fuel shut off on it, if I shut off the fuel and let it run dry it will start again but it is a pain in the ass to start again. I took the carb apart & cleaned it(there was a little debris in the bowl),put a new needle valve in,cleaned the seat lightly with very fine steel wool and it looks ok with a magnifying glass,the float looks ok. With the carb off I can't blow any air through fuel fill tube when needle is seated, it should be ok! right? I also drained the gas tank, put a new filter in, changed all fuel lines and added an extra in-line filter just in case I was getting ocassonal debris. I'm starting to go nuts over this problem!! I'm going to change the o-ring on the enriching valve next, at idle if I just lift the choke lever a hair it will stall the motor. I don't think the oil injector is over enriching even though there seems to be excessive smoke. Any advise would be appreciated! I would like to change the entire carb because the seat is incorporated into the carb body but yamaha has discontinued them and no one has replied to my requests for a used one. Is there an after market carb or any other carb I could replace this with? THANKS if you have any suggestions, I'm starting to think that the only way to solve this problem is to buy a new sled!

This is my first visit to this site and I think its great! I hope someone can help me out. We have tons of snow here in PA this year & not many sledders to get advice from.
 

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Welcome to the site. I think your on the right track with the needle valve, but it could also be your pump. Check the pulse line to see if there is any gas in it. It's the line that runs from the block to the pump. It should be completly dry. If that is not the problem, try lowering the float height. Do this by slightly bending the float clip up. Hope this helps.
 

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Also, did you completely clean both carbs? Pull ALL the jets and clean out ALL the passage ways? If not, I'd do that first. Be sure your float levels are adjusted to spec as well, if they're not, this would allow too much fuel in even if the needle n seats were sealing.

Also check your choke cables, make sure neither are stuck. Be sure they're adjusted to spec.
 

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Discussion Starter · #4 ·
Thanks for the help guys, I'll check that pulse line this morning, I figured it should be dry but didn't check it,pump seems to be ok though. I did clean carb by soaking it overnite with OMC engine tune, it came out sparkling, however I was having trouble removing stationary main jet and didn't want to chance ruining carb body because I cant find 1 anywhere. I did have some varnish in carb before cleaning,sled sat idle for 5 years with stable in gas tank I was told, I know thats way to long to sit. I'm sure thats where the problem is??? maybe. Sled is 22 yrs. old with only 560 miles on it. Maybe their is a habitual problem with carb body and that is why I can't find one?? I was going to lower the float height but was afraid to make to many changs at once, I checked the height and it was within specs and factory specs said it is a none adjustable float,I was afriad to snap off thang. Choke cables seem ok,there is a noteable change in idle when I operate them. Adjusted it to specs then added more travel to lower oil feed in case oil was fouling up, didn't make a difference either way, still seems to be excessive smoke in exhaust. I'm going to order a new rubber seat and spring for the choke enriching valve today, takes about 2 weeks to get here,BUMMER, and I don't have much faith that it will help. Still pulling my hair out! I hope I'm not bald before I get this straightened out, just got 26" of snow, great weather but afriad to go on a nice trip with this sled. I guess I'll pick-up a dozen plugs today, I'll think I'll be going through them!

I'll try all advice, if anyone has any other suggestions, HELP PLEASE

Have a great day out in the snow.
Jay
 

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Jay, why not just pull that carb off there and go with a tried-n-true Mikuni? There's nothing more frustrating than problems like that, and for a couple hundred bucks at most you can get more riding and less wrenching in.
 

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Discussion Starter · #6 ·
Thanks NightTrain, Best advice yet, I'm going to look for one today. I guess I just hate to be defeated by a machince, logically the only thing it can be is the needle & seat even if float isn't adjusted perfectly it should close when the bowl fills with fuel, since I can't change the seat because it is part of the carb body, I'll empty my pockets and spring for a brand new carb. I just wasn't so sure that you could easily change over brands with different linkage set-ups.I suppose I'll figure it out though. Then that will be the end of my frustrations!

Thanks, Happy Sledding
Jay
 
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