Ms170 hard to start. Choke doesn't fully close

[etbrown4]

Have a nearly new ms170 and yes I know you pull it until it pops then slide to half choke.

Problem is that at full choke it sometimes wont pop, no matter how many pulls. And you have to assume that continued pulling likely creates flooding.

Yes I have a new plug, good blue spark, clean filter, new gas, a clean carb and plenty of compression..

I mounted up a new carb and see that if used, it also doesn't fully close at full choke.

Anyone studied this enough to find a way to fully close the choke, and see if that helps starting

 

[Lightning Performance]

Asked an answered in your title.
If you can't figure it out find someone who can.
Likely has the butterfly off center or the linkages needs replaced or bent a touch. Control levers do go bad over time.
This is a common problem on 034 because of the design.

 

[ZeroJunk]

Make sure your control lever is snapped all the way in.
I have seen carburetors where the choke would not close all the way, but replacing the carb cured that.
If it does it with two different carbs then the little linkage piece may be off a little.
If there is much of a gap there at all it really isn't choked.

 

[coffeebrk]

Make sure you squeeze the throttle when setting the choke.
Here's pictures of my MS180 for comparison

 

[etbrown4]

Thanks Coffeebrk for the pics. Mine looks exactly like yours.

The choke linkage looks likes its factory formed at about 45 degrees. Id have to bend it a lot to close the choke fully.

Can you believe the first reply to my post said, "If you can't figure it out find someone who can." Gee whiz isn't that why this very forum exists in the first place?

 

[coffeebrk]

Post some pics when you get a chance
Also be careful when you snap the control lever into its home. The notched plastic is part of the chassis.

 

[etbrown4]

The horizontl control lever is snapped down hard into the open clip thats part of the chassis.

I don't believe my linkage is bent or worn. Im pretty sure it came this way from the factory.

Although only used a few times, it's past warranty.

 

[coffeebrk]

Iffn it's me I'd remove the choke linkage and manually put the choke on full and try to start it

 

[etbrown4]

I think we know the answer to your suggestion. That will work.

My dilemma is how I am going to bend the factory linkage enough to close the choke, as right now it misses fully closing by 1/4" or so.

Said another way, it seems hard to believe that unused factory parts could be that far off!

Correcting a factory design flaw seems like almost too big of a plan, because operator error is more common!

 

[buzz sawyer]

Any chance you added a gasket between the carb and air filter housing? Had the same problem until I realized no gasket is used there - it was keeping the choke from closing.

 

[etbrown4]

There's the factory gasket between the carb and the cylinder. That's all I see.

 

[cscltd]

Just have to bend the choke rod lever a little more, come across the odd one that needs a little more angle on it.-no biggie, just as mention like 034 series
Put it in vise and hammer or bend it a little and test fit till choke closes.

 

[etbrown4]

Are we really saying that Stihl quality is off that much and this problem is often seen?

 

[coffeebrk]

Unless you religiously move the lever to choke each time the top cover is installed and removed i could see over time, the linkage could bend

 

[Keith Lee]

Are we really saying that Stihl quality is off that much and this problem is often seen?

I've been seeing a decline in Stihl quality the last little bit. It's possible the that linkage wasn't bent properly from the factory. I have an MS 171 at work that has the exact same problem. It doesn't engage the notch on the cam for the choke or rather it doesn't stay locked in place.
I got it to start by taping the choke lever down in the full choke position. But, that's not a solution. It also floods VERY easily. 2 - 3 pulls and it's flooded. I wish I had taken pictures of it. It's in pieces ATM.

It does need a carb rebuild or replacement. But, I don't think that's the primary issue. I think it's just a bad design. Once I get it started, pull the tape off, it runs fine. I think the linkage is too long. Bear in mind that this is just theory. I'll throw it back together enough to take some pics or a video to show you what I think the problem is on Monday. (I'm not supposed to take pics or post to social media. But, screw it.)

 

[ZeroJunk]

I think on the MS171 it is a linkage issue on the carb itself where the two barrels are locked closed by a slot in the wahtumaycallit on the end of the shaft.
Sometimes they won't stay locked and the carb has to be replaced.

 

[Sloughfoot]

The filter cover on my 180 doesn't go back on easily. When it's not on right it messes with the linkage and won't start or run well.

 

[HarleyT]

There's the factory gasket between the carb and the cylinder. That's all I see.

There is no factory gasket between the carb and the manifold, just the rubber boot/manifold. Put up some pics.

 

[stihltech]

Can you close the choke without the linkage? Any wear in the Master Control shaft? Does it have a fast idle?
As for bending the linkage, been there, done that. Just make sure nothing else is binding first.
Always do the cheap diagnosis first.

 

[ZeroJunk]

There is no factory gasket between the carb and the manifold, just the rubber boot/manifold. Put up some pics.

There is a little white plastic insert with the impulse hole to the side, may be what he is talking about.