Problems with 1978 Yamaha Enticer 250

Well, Taking all my experience so far. I have some knowledge. I am sure the rest of the guys will correct me if I am wrong.

You will need to try a few things to make sure its just your carb.

Take a spark plug out and lay it on the top near where you took it out, make sure the end has a spot to touch or near touch a piece of metal on the engine. Do you see a bluish spark. This means you have spark.

Next: Take out a spark plug and Try putting about 2 tablespoons of gas (REmember to use some mixed gas because your putting directly into the engine). Put the spark plug back on and do the same for the other spark plug (s) depending on how many you have but I suspect on your engine you wont have more than 2.

Once the plugs are back on, give her a pull. She should start up, and heres where you find out if its your engine or possibly your carb. If it starts up and then runs for a bit and stops, and you cant start her back up again and keep her running, then its a good chance you have gummed up needles in your carb.

If you check thru some of the previous posts, some guys have posted steps to cleaning a carb, and I have posted a bunch of links to the various sites offering help to carb cleaning.

Clean your carb real good, taking note to where your lines and stuff all go. DON'T lose any parts and then try again.

Hopefully this information helps you. Again Im not an expert but I am quickly gaining knowledge. He guys, how was my steps to check out his machine. Did I explain everything correctly and stuff. Feedback on how I did would be greatly appreciated so I know if im learning something from this forum.

Cheers

Giger

Excellent summary Giger!!

If you find the sled runs momentarily then dies, you may also want to check the float level and condition in the bowls of the carb (assuming Mikuni not Tillotson) and also if the fuel pump is delivering any fuel from the tank.

You can check your pump by taking the line off the carb and pulling a few times (easier with the plugs out) and see if you are getting any fuel through that line. If not you may have a bad pump diaphram and/or a bad engine vacuum pulse.

Or it could just be a blockage in the tank. Sled that year could have picked up loads of crap in the tank over the years. Just a few other things to try anyway.

If you have a Tillotson carb, you're on your own!! (from experience)

Let us know how it goes!

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I think.... therefore I sled
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Two '94 Indy XLT SKS

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote> Finally, after some work, too much gas ran through the carb, the snowmobile started, then died--it would not take any throttle.[/quote]
If you are getting gas now and your plugs keep getting wet, I would check out your points. My repair manual list a '78 as the last year for pionts on that engine,
Point gap: .012 - .016

If that don't work, some times when these older engines don't like to be throttled the crankshaft seals are cracked or worn out. They suck air through the seals and only run well at high RPM's. (when they start!)




Edited by - firepinto on January 11 2002 6:01:45 PM

If his carburator is stock, it would be a Keihin CDX32. Which looks to be a Diaphragm type. Might want to check that your vacume pulse line isn't leaking or plugged. One way to check to see if your engine will even throttle up is to fill up an old spray bottle with gas/oil mix and spray it into the carb (as fast as you can) as you open the throttle. If it does then you can narrow it down to the carb.