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Discussion Starter #1
Will cracked carb boots on engine side keep it from firing ? Has spark at plugs. Tried staring fluid still no fire.
thank!
 

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Cracks on the boots can create a lean condition and that could definitely cause issues. I would check compression. If the cracks have been there a while, the engine may have sustained damage, which caused the low compression. Check it to rule it out.
 

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Discussion Starter #5
What should the compression be about? I read they should only be a pound or two different is that correct?
 

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Compression should be over 120, with a good engine maybe even as high as 140-150. Compression difference between cylinders should be less than 10%. An engine may not run well at all and may not even start with less than 100 psi compression.

I can't see the plugs well enough in the pic (it does not expand) but your plug color should be a cardboard brown. Black would indicate too rich, white too lean. Grey may indicate a transfer of aluminum from the piston onto the porcelain of the plug electrode, especially if it shows spots of metal.
 

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Are the cracks all the way through? If so, replace them. And yes, it will make it hard to start. Once warmed up it will seem like it is running great, but lean condition will cause issues.
 

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Discussion Starter #14
Compression check was with new boots. I’ll clean the carbs and see if it changes. Thanks again everyone!
 

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Discussion Starter #15
So I cleaned the carbs and now with starting fluid it somewhat tried to start only with throttle wide open but won’t actually fire all the way.
 

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Don't use starting fluid, pour a little bit of gas down each cylinder most use gas with 2 stroke oil in it say for a chainsaw or weed trimmer. Starting fluid was made for diesel engines not 2 strokes. Did you clean every single jet with a small piece of wire? After that try cleaning or replacing the fuel pump. Look into the gas tank and make sure the fuel line hasn't rotted off either. Hopefully BearAK can pop in as he is the go to guy for Ski-Doos, good luck.
 

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Sounds to me like you still have issues in the starting circuit in the carbs... try cleaning again, paying particular attention to the pilot jet (the one up the tube) and the air and fuel passages that lead to it. You may have to shove a small soft wire into the passages to dislodge any crud that has grown in there over time. I use a strand of Cat-5 cable with the insulation on to do that. The pilot jet can become so varnished that it becomes smaller than designed, so poking a wire through there may help "floss" the jet to clean out the varnish. I've had to go through carbs as many as three times before they were clean enough to run properly, especially if gas with alcohol was used. That stuff is horrible on carbs that sit a lot.
 

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See if you can go aftermarket, is it a mikuni? If so you can buy those all over the place...well most of them as there is different styles of course. Post a picture of it if you have one.
 

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NVM I found a picture of it. Seems that no one sells one even aftermarket. It does 31 liters as that is all I can find. I did find a rebuild kit though on eBay for it.

Also it seems Yamaha used the same pump, and the pumps are made by Mikuni. Yamaha part # is


picture of it



Personally at that price I would rebuild it for 12 bucks first before spending 90 dollars. Also what Yamaha does on some of their sleds with that pump is us two of them bolted together.
 
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