This 2 stroke 400 I picked up recently has been running on pre-mixed fuel. The oil pump cable had problems before I guess. Today I removed the cable from the oil pump and plugged the hoses. I lubed the cable for the throttle and put everything together. The spring for the slide looked like it was stretched or something.(it came out this way). The slide will not return all the way down as it should. I have adjusted it every which way. Is it possible the spring has just lost its tension? Did stretching it hurt it or help it? I need a stronger spring it feels like. Can I buy one with more tension? When I would work the thumb throttle I could hear the spring crunching in the body of the carb. I do have the idle adjustment screw backed all the way out. --Dave

 

It does look to me like that spring is bent out of whack. I was having issues with my 400 not quite returning to idle, along with lubing the cable I pulled the spring and stretched it a tad....probably "added" 2" in length. My throttle now returns much quicker and my high idle is gone. So for me it helped to stretch it.

If you pull the cap and spring, does the slide move freely and return all the way? It should, then your issue is with the cable or spring...your cable may be pretty gumed up, kinked or frayed. Check that to make sure it operates smooth. If that's good then it goes back to the spring being worn, bent. The spring shouldn't be "crunching". It's all possible the coils are doubling over each other, binding up and causing it not to return. A new spring is $12.

This might be off but I'll throw it out there. I'm not even sure it's possible to put the slide in the wrong direction but there is a notch out of the bottom of it that goes around, I believe the throttle screw?? If the slide is in backwards it'll hit the throttle screw. I know you said you had it backed out but...just a thought that may be keeping the slide from returning?

For sure I'd replace that spring, it looks pretty bent out of whack.

 

Thanks for the response. I'm going to try and locate a new spring today.

 

Slide in backwards or

The cable came out of position at some point. (where it adjusts, at the carb, at throttle or in the slide)

You should be able to have slack in your cable to make sure it is not holding your slide open.

Thats a normal look for a spring.