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Discussion Starter #1
Hello,

I have read through quite a few posts on here and still have not fixed my problem I am having with my sled. When I first pulled it out of storage I pulled and pulled and pulled on the handle and it would not turn over. I pulled the plugs and checked for spark and fouling and everything seemed fine. I put the plugs back in and pulled again and again and no fire up. I then removed the carbs and cleaned them out according to the carb cleaning tips I read on this site. After replacing the carbs and everything else I tried starting again and it would not start. I was told to pump air into the gas tank to get fuel to the carbs and after I did that WALLA it fired up and ran kinda funny for the first few minutes. I stored the sled with about 1/4 tank of gas and added stable to it. When it finally was running again I added sea foam and added about 5 gallons of 93 octane fuel. I took the sled out ice fishing about two weeks ago and everything worked fine until I shut it off. I let the sled sit for about 20-30 minutes and when I went to fire it up again it would not start. I pulled about 8-12 times and finally held the throttle down to get it to start and it did. When I got home the next day I tried starting it and it would not start and since then I have not got the thing to start. I noticed fuel dripping from the exhaust "Y" coming off the motor and when I pulled the plugs and gave it a few yanks on the cord gas was spraying out the heads.

My question is could the floats be stuck on the carbs and be flooding my engine??? what other problems could I have? Is there an actual fuel pump on these 94 Vmax's? any help is greatly appreciated!
 

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excess fuel all the way to the pipe would indeed point to stuck floats, float level improperly adjusted or needle and seat and possibly an air leak. save that theory for last since you said it did run fine for awhile.

yes there is a fuel pump. its vaccum actuated by the engine. its located under and to the right of the airbox. it wont work unless your pulling the cord or the engine is running.
i would say you need to take a closer look at the carbs, including the choke plungers. now that the old fuel should be out of the system and fresh fuel is in, go back inside the carbs thoroughly.
 

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Discussion Starter #3
I think when I reassembled the carbs and put the choke plungers back on I might have misaligned or mis seated them. What doesn't make sense is that the sled ran fine after I cleaned the carbs until I let it sit for roughly 24 hours. I plan on taking the carbs apart again but would like to make sure I find the problem so I can spend more time riding and less time tinkering. Could you recommend a proper method for cleaning the carbs since these style are different from what I have watched videos about and the like? Are the jets or needles supposed to be screwed all the way down and tight?

I am new to snowmobile motors and would like to fix my own stuff without having to send it to a shop.
 

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i have nothing to offer as to why it worked one day and not the next. could be several reasons.

as for the jets, they are simply a screw in until snug. being that they are brass, they will strip out or break if set too tight. the needle jet is adjusted by an e clip and washer. the needle that goes into the seat hangs by a wire off the float. your carbs are mikuni flatslides and are fairly simple in design. even though your carbs appear different physically, the same cleaning principals apply. all carbs will have floats, needles, seats, main jets, pilot jets, choke plungers, and fuel or air screws, etc. the object is to not only clean the jets' orifices but to make sure all the circuitry in the carb bodies are free from obstruction.

while your in there, note the main and pilot sizes and dont forget to adjust or reset the air screw to its original or specified setting.
 

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Discussion Starter #5
Thanks for the info,

Do you know what the specs are for the air screw? I could turn it all the way in while counting turns and figure out what it was set at but after cleaning them I wonder if it needs a new setting. I just bought this sled last year from a guy who had it stored for quite some time. All I did when I bought it was change plugs, check and lube everything that needed lube and top off with gas and oil.
 

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Discussion Starter #7
Thanks a lot!

I took apart the carbs and this time I found that the float needle was stuck on one of them. I disassembled the float and found that the needle was all gummed up and the screen on the needle assembly had chunks of gummed up gas. I also replaced the fuel lines coming from the pump to carbs and plan on installing a fuel shut-off valve at the end of the season from the main going into the pump.


I was wondering what type of plugs I should run in this sled. I am currently using BR9ES NGK's and was wondering what you think about using iridium plugs on a 94 VMAX 600.
 

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that all i have ever ran in all my yamahas, the good old br9es.

you try the fancy ones and let us know if you notice a performance difference. i would be curious.

i was given some others to try a few years back like ev's or something. they had the smaller electrode and were supposed to be better but i honestly dont remember if they were or not.

glad you found what should be the root of your running problems. be sure and clean the air screw(or fuel screw) circuit as well as the choke circuit.
 

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Discussion Starter #10
another question, what kind of gas should I run in this? I was told to use the 93 octane but I was also told that higher octane gas does not burn as fast as 87 octane for example. I might try the NGK iridium plugs after I make sure I am not fouling plugs but then again a change in plug might make changes in ignition.

thanks again!:D
 

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i run premium in all my sleds, always have. the way fuel quality is these days i dont trust it. to me the premium is cheap insurance. some brands have issues with using higher octane, i have never had any issues using it with the yamahas.
find non ethanol premium if you can. ours runs 91. used to be 92 until the ethanol invasion.
 

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Discussion Starter #12
Thanks for all the input! Things are going great so far with the sled and I only been using it for ice fishing. I would like to hit the trails soon and I think this coming weekend might be a good time to do that since we are finally getting consistent snow around here.

Might try the iridium pretty soon in the future and let you know if there are any differences.
 

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Just one more question(s). I am not too familiar with the fuel system on this sled and was wondering how the fuel pump works? I understand that the vacuum or compression from the motor helps feed fuel to the carbs but what are the internal parts of this pump doing? If I were to install a fuel shut-off before the pump and run the sled with the fuel shut off to clear the lines would this create a problem?

Any help is greatly appreciated
 
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