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post #1 of 15 (permalink) Old 12-11-2010, 02:24 AM Thread Starter
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yamaha sno scoot carberator problem

I just bought 2 one-owner 1988 electric start sno-scoots for my grandchildren. Both are like new. I took them to my mechanic to clean the carbs because they had been sitting. He cleaned them and they run great.

The problem. The day after cleaning the carbs, neither will start without spraying carb cleaner in the intake. Then they'll run for the day and the same thing happens the next day...they won't start without spraying carb cleaner in the intake.

The mechanic says to buy new carbs and fuel pumps for both. That's spendy...$800. He cleaned the carbs on both twice. Funny that both have the identical problem.

Any ideas? Any part to replace on old carbs rather than buy the whole carb?

Thanks
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post #2 of 15 (permalink) Old 12-11-2010, 08:13 AM
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Here's a micro fiche breakdown of your carb. If it's not starting well, you need to look at the parts numbered 16, 17, 18 19, & 32. Specifically the o-rings 19 & 32.


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post #3 of 15 (permalink) Old 12-11-2010, 03:27 PM Thread Starter
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Thanks Old Man. I'll order the parts today and give it a try.
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post #4 of 15 (permalink) Old 12-11-2010, 08:16 PM
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But that blow up does not show the welch plug ( the extra cirle nothing in it). Pop it out with a sharp ice pick!
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post #5 of 15 (permalink) Old 01-28-2011, 11:56 AM
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Quote:
Originally Posted by byrd View Post
I just bought 2 one-owner 1988 electric start sno-scoots for my grandchildren. Both are like new. I took them to my mechanic to clean the carbs because they had been sitting. He cleaned them and they run great.

The problem. The day after cleaning the carbs, neither will start without spraying carb cleaner in the intake. Then they'll run for the day and the same thing happens the next day...they won't start without spraying carb cleaner in the intake.

The mechanic says to buy new carbs and fuel pumps for both. That's spendy...$800. He cleaned the carbs on both twice. Funny that both have the identical problem.

Any ideas? Any part to replace on old carbs rather than buy the whole carb?

Thanks
what finally fixed your problem? I have one with the same problem. My problem isn't anything to do with the enrichment valve O ring. But I did plug the little black vent tube that comes off the top of the carb and that made it run alot better. It's wierd that that little black tube isn't shown on any pictures of that carb on any parts diagram.
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post #6 of 15 (permalink) Old 01-29-2011, 03:00 AM Thread Starter
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I just received the parts Old Man suggested (#s 19 and 32) in the mail and will install them this weekend or next. I will tell you when I'm finished if it works.

I have a friend who's mechanic had him block the tube too, and his ran better he said. I will try it both ways and report back.
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post #7 of 15 (permalink) Old 01-29-2011, 07:23 AM
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Once you get that welch plug out and EVERYTHING else off it soak it over night in carb cleaner.
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post #8 of 15 (permalink) Old 03-01-2011, 08:48 AM
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Hey I had the same problem and I found the source. There is a tiny tiny hole in the enrichment valve fuel pick up. The hole was plugged. The scoot that I am working on starts perfect when it's cold every time (3 kicks) I also removed the brass plug and cleaned the enrichment valve passage.
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post #9 of 15 (permalink) Old 03-01-2011, 09:03 AM
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I don't know if I was clear enough because I don't know the correct name for the carb parts. But what I called the "enrichment valve fuel pick up" is the part of the main body of the carb that is submerged in the fuel that is in the bowl. With the bowl off you will see 3 passages molded into one. 1 passage will have a rubber plug, the center one will have the main nozzle in it (#5 on diagram) and the third will have a brass plug in it. The passage with the brass plug has the tiny hole in the side of it. LOOK CLOSE. No wonder it's plugged it is so small. This is probably why people put primers on these snowmobiles.

Last edited by Yamagirl; 03-01-2011 at 09:04 AM. Reason: spelling
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post #10 of 15 (permalink) Old 03-01-2011, 10:08 PM
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#10 or 31?
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post #11 of 15 (permalink) Old 03-02-2011, 08:11 AM
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not # 10 and not #31 either. The brass plug that I am referring to is not in the picture. #10 is the main jet. it is brass but it has a hole ,it also goes in horizontaly. #31 is a rubber plug that (if you are holing the carb right side up like it is in the snowmobile) goes in vertically. The brass plug I am referring to goes in the same way as the rubber plug only on the other side of the center.
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post #12 of 15 (permalink) Old 03-02-2011, 08:28 AM
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Also if you want to remove that plug and clean the enrichment valve passage, what I did was drill a small hole though the plug and inserted a screw into the hole, put the screw in a vice and pulled the carb off of the plug. The plug is about 3/8 of an inch deep so if you are really careful you may not have to drill all the way though to get a screw to grab. I didn't know the plug was so deep and I did drill all the way though. What I did to fix the hole was take some gas tank repair putty, kneaded it untill it was one colour and rolled it thin so I could insert it into the hole in the plug. then I packed it in tight, waited for it to set up and put it back in the carb. One more trick I learned was to try to drill it upside down so the brass shavings don't get into your carb. otherwise be really really carefull to get them all out.
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post #13 of 15 (permalink) Old 03-02-2011, 05:20 PM
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OK I think I did the same thing you are talking about doing, by removing the Welch plug on the top! And then soaking the whole thing!
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post #14 of 15 (permalink) Old 03-02-2011, 07:27 PM
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what do you see under that welch plug? That's the only thing I didn't do. Can you see into the enrichment passage?? I don't know why I didn't pop that welch plug out . The scoot that I am working on starts great, runs great but doesn't idle worth a bean. It revs up by itself then idles down by itself and sometimes stalls. I was hoping that what ever I missed under that welch plug, on top, was my problem and all I had to do was clean under there.
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post #15 of 15 (permalink) Old 03-03-2011, 08:04 PM
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Yep and had the same prob with a 2 barrel on a Ovation!
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