Jump to content
Sign in to follow this  

Erratic idle, hard starting, possible runaway.

Recommended Posts

My 2011 250 XC has been causing me a bit of grief the last few weeks and I need some help. 

 

Its been running great until the last ride which was about 3 weeks ago. I noticed that the idle would jump up a few hundred RPM every once in a while at a stand still and if I just fanned the clutch out to creep the bike forward it would go back down when I pull the clutch back in. 

 

Anyways I washed it, put it away and let it sit for a few weeks. I pulled it out last weekend and it was a bitch to start. It must have taken a good 50 kicks and the electric start wasnt having it either. Once it had warmed up a bit the idle started going nuts so I adjusted it and it seemed to work ok. 

 

I wanted to go riding on Sat so I stopped at the shop today to make sure she will be good and went to kick her over.. again.. at least 50 kicks, and this time when the bike warmed up it tried to take off on me when I was putting around on it. I pulled in the clutch and killed it. 

 

Curious, I fired it up again and it seemed to run normal for a minute, then it went damn close to WOT to the red line so I killed it and started taking it apart for inspection. 

 

First was the compression test: 179 PSI COLD. 

I pulled the carb and cleaned it out, put it all back together and its sitting on my bench.

 

Before I go any further I would like some opinions. What else should I be checking?? I dont have plugs to do a leak down test, and I'm at the point where I'm kind of lost. When these bikes start acting this way is it usually an air leak? crank seals?

 

Any input would be appreciated. It is easy to restart after the initial startup, but previously this bike was a one kick machine when cold.  

Edited by sixOHfour

Share this post


Link to post
Share on other sites

I'd check your throttle cable to see if it's hanging up. If the throttle is open a little it'll be hard cold starting, then could rev out.

Share this post


Link to post
Share on other sites

Sounds like an air leak to me. I've never in my life seen reeds cause this, reeds usually cause an extreme rich condition with hard starting and flooding. I would start with a new base gasket and crank seals and go from there

Share this post


Link to post
Share on other sites

Quick update:

 

You can't really do a leak down test on modern KTM two strokes, due to venting issues. The air just comes out of the vent hose. 

 

Some people still find the test helpful for finding leaks, but the rule of 1 psi per minute does not apply. 

 

On my bike, air just pours out of right power-valve vent cover. I'm not sure if this is normal, or if I've found my leak. 

 

The leak down just caused confusion.

 

But I did make a leak down test kit for $20 out of plumbing supplies. And didn't pay $250 for a kit. So, I felt cool for that. 

 

Would have really sucked if I'd paid $250 for a Motion Pro Leak Down Tester, only to find it didn't work with my bike. 

Edited by portlandtwostroke

Share this post


Link to post
Share on other sites

Sounds like an air leak to me. I've never in my life seen reeds cause this, reeds usually cause an extreme rich condition with hard starting and flooding. I would start with a new base gasket and crank seals and go from there

I think you're right, but . . . 

 

This is a LOT of work. And it may not even provide the solution. 

 

I think it is an air leak, but rather than just tearing everything apart and replacing all the gaskets, seems like it would be better to find the leak first. 

 

I can picture a scenario where I replace all the gaskets only to put it back together and still have the same problem. 

 

In which case, I would punt the bike off a freeway bridge. 

Edited by portlandtwostroke

Share this post


Link to post
Share on other sites

I think you're right, but . . .

This is a LOT of work. And it may not even provide the solution.

I think it is an air leak, but rather than just tearing everything apart and replacing all the gaskets, seems like it would be better to find the leak first.

I can picture a scenario where I replace all the gaskets only to put it back together and still have the same problem.

In which case, I would punt the bike off a freeway bridge.

I definitely see your angle here but it's 20 dollars in parts and 2.5 hours of your time, not much else can leak air after that. With that being said I know the feeling of wanting to discard a bike off the side of a bridge

  • Like 1

Share this post


Link to post
Share on other sites

I definitely see your angle here but it's 20 dollars in parts and 2.5 hours of your time, not much else can leak air after that. With that being said I know the feeling of wanting to discard a bike off the side of a bridge

I've chased my tail more than once on bike problems. ....

I don't think it's at all common on modern motors but cases have been found to have pores in the past, doubt that's the case but thought it a worth noting.

One way to treat for air leaks is by spraying carb cleaner or electric parts cleaner where you're looming for leaks and see if there's any change to the idle.

Share this post


Link to post
Share on other sites

It is with shame and humility that I post:

 

I found the problem on my bike, if not the one of the original OP. I found the problem. And it was a stupid one. 

 

I had just put on Task Elephant Ears for the winter. What was happening was that every time I cinched the strap on the ears, my throttle cable would get pulled and cause the bike to rev, or not start, depending on the situation.

 

But I couldn't see it because each time I checked the slider, the straps had loosened and everything was working fine. 

 

I've shamed myself and the good name of Husqvarna. For that I must do at least 50 laps. 

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...