need help with a 2 stroke

[ghost civic]

I tried getting help in some snowmobile forums, but got nothing.

I got a mid 80's Yamaha excel 340. It isn't in bad shape and the guy sold it for just $40!!!

So no the problem. The sled will start FIRST pull...but after you rev it a bit the amount of smoke increases...the idle will slowly drop and then stall. You can keep it running with some throttle...but to much throttle and it bogs really bad.
Try to restart it, and you will have to give it some throttle to start and it wont idle.
Plugs look like they are being oil fouled.
Give it some time to dry out, and it will start first pull again and repeat what it did before.

The sled is oil injected. I wanted to check the linkage to the oil pump, but 1 screw stripped on me. That said, if I move the throttle back and forth I think I can feel the rotary slide in the oil pump move through the case.

But, thinking maybe the linkage was busted and the oil pump was wide open...I removed the lines from the pump to the intake runners and then ran 1 line between both runners (to close them off) and then I put mixed gas in the tank.

But alas...the same thing happened. This time the plugs don't look as bad, but the motor is doing the same thing. Starts first pull, rev it up and get more smoke and then it wont idle. If you start it and just let it idle then it will idle for a fair bit of time without any problems(if it hasn't been run in a while)

Any ideas? Could there be some seal that has gone bad and is allowing extra oil/fuel to get into the cylinder? I got 110psi on both cylinders.

I am at a loss as to what I should try next.

 

[rushking19]

Did you clean or check the carburetor?

 

[ghost civic]

Did you clean or check the carburetor?

not yet. I might have done that first, but according to the previous owner the sled was running good until one day last winter when it fouled the plugs. He put it in the shed and didn't touch it after that. To me, that sounds like "some thing" happened rather than just a dirty carb.

That said, I may go through the carb tomorrow or the day after if I have the time.

 

[rushking19]

It definitely is carbs if it boggs like that my snowmobile used to do it till I tuned the carburetor correctly it had a intake leak and I fixed it, it's running a little better now

 

[Desertduler]

Check the enrichment plunger in the carburetor and make sure that it is not stuck open and make sure that the cable that operates the plunger has slack in it when the choke lever is off, you can remove the plunger from the carburetor, follow the choke lever cable and you will find the plunger location on the carburetor, remove the drive belt so you can hold the throttle wide open so you can rev the engine up and "clean it out".

 

[ghost civic]

Check the enrichment plunger in the carburetor and make sure that it is not stuck open and make sure that the cable that operates the plunger has slack in it when the choke lever is off, you can remove the plunger from the carburetor, follow the choke lever cable and you will find the plunger location on the carburetor, remove the drive belt so you can hold the throttle wide open so you can rev the engine up and "clean it out".

the choke I believe operates...it will change how the engine runs when I move the lever.

Hoping to remove and inspect the carb today. I was looking in other places because of what the previous owner said and thinking that it was a worse issue. But then, this guy acted like the sled was "really old" and that was why he only asked $40 for it. to me, really old means 70's and stuff that looks really beat to heck.

 

[Desertduler]

That is a steal for 40 dollars, there is a snowmobile in my location in the local ads for free with a 440 Rotax engine in it.
http://www.ksl.com/?nid=218&ad=36994209&cat=146&lpid=&search=&ad_cid=3

 

[rushking19]

Wow you got it for a steal I got my rotax 399cc snowmobile engine for 65 that was just for the engine, and free snowmobile that's crazy

 

[ghost civic]

Wow you got it for a steal I got my rotax 399cc snowmobile engine for 65 that was just for the engine, and free snowmobile that's crazy

Desertduler...better jump on that one!

I don't see why the guy sold it for $40. You would think if he just didn't care and wanted it gone he would have asked $50...nice even number, not $40.

I could get $40 for the carb on ebay.

I just let it idle for about 5 minutes. It only needs a tiny bit of throttle to stay running (1/8 diameter stick holding the throttle lever open a touch) I think I will get new plugs tomorrow and let it run for 10 minutes. If it doesn't clear up then Ill pull the carb and give it a cleaning.

I should mention that the guy I bought it from did drain the tank and pull the fuel line before he stored it. If he hadn't, it probably wouldn't have run at all. It is nice when people take the time to drain the fuel so it doesn't gum up the carb.

 

[rushking19]

It's still good to check

 

[Desertduler]

I have so many engines right now that I am kind of selective as to what engines I want even for free, I don't know why more people don't use these inexpensive power plants for karts as in their stock configuration they would murder any modified utility engine powered kart and they are super reliable if they are taken care of correctly.

 

[rushking19]

I have so many engines right now that I am kind of selective as to what engines I want even for free, I don't know why more people don't use these inexpensive power plants for karts as in their stock configuration they would murder any modified utility engine powered kart and they are super reliable if they are taken care of correctly.

Exactly what I was thinking everyone is going predator swap it's like the ls motor swap for go karts now

 

[ghost civic]

I put new plugs in it today and ran it a bit.
I was able to drive back and forth on the lawn several times and it would still idle after each pass. There is still a lot of smoke but that might be more to do with the near 50:1 mix in the tank.

Here is a pic of 1 of the plugs after 5-6 minutes of running plus a few 20' passes. still a bit of oil, but a heck of a lot better looking than the old plugs.

I might drain the tank, put the oil injection lines back on and try it again.

 

[ML-TOYS]

Did you happen to replace the oil itself

 

[ghost civic]

Did you happen to replace the oil itself

not what was in the reservoir. But when I put mixed gas in the tank I used what I had on hand.

I ran the sled some more and the new plugs did end up fowling...it just took longer than with the old plugs.

I think I am going to pull the carb and check the float to see if it is sticking. I will also drain the tank, put fresh gas and hook the oil injection back up since it doesn't seem that it was the problem.

 

[ghost civic]

took the carb off.
was surprised to find the inside of the bowl was covered in rust.
Jets looked good though.
It seemed like the float needed to go up too high to close...so I adjusted it.
But there was no change in how the sled ran.
Not sure what Im going to try next.