Ms170 Runs Great, Very Hard to Start

[Snowchaser]

I bought a wt215 knock off. One of the very few china carbs that has worked great. This is the same carb that is on a ms250 i think. All you have to do is remove or drill out a little plug on the carb and plug the impulse hole. Essentially changing the location of the impulse hole on the carb. There is a thread on here that explains it better. There are no permanent alterations to your saw except for a little hole drilled in the plastics to access the high/low.

 

[user 122190]

Thanks for clarifying that. If you are sure the choke is closing completely and there are no air leaks, then I'd go for another carb.

Did you check the choke by covering the air intake with your hand? Pretty simple to do, and was suggested as a simple test 3 days ago. No need to spend money until you know what the problem is. But what do I know. I'm no expert...

 

[Oletrapper]

She'll start on ether only. Runs really smooth.

What to try?

Remove the muffler and check for piston scoring. If there is any, it will eventually not start on the ether. Piston scoring is caused in several ways if the engine overheats. Straight gassed, dull chain, chain too tight. If your bar shows heat marks along the grove it got hot. So did the engine. :-( OT

 

[AxFan20]

The only way to see if choke is 100% closed is to remove air filter base To visually inspect it. The metal choke rod may need a little more bend in it to close choke more.
a lot of 170 have the control lever pop up over the spring tab and thus not fully engage choke Also.

She'll start on ether only. Runs really smooth.

What to try?

I agree with cscltd. Remove the air filter. Engage the choke. Make sure that the choke plate is closed tight. You might have to bend the "bend" on the choke lever to close the plate completely. This is a common problem in 170/180

 

[user 122190]

I agree with cscltd. Remove the air filter. Engage the choke. Make sure that the choke plate is closed tight. You might have to bend the "bend" on the choke lever to close the plate completely. This is a common problem in 170/180

That's to hard for the OP. Better to just buy a new carburetor, then return here and complain that it doesn't work, what to do, then buy a new saw.

 

[stihltech]

There is one more thing to check- does it have a fast idle?

 

[etbrown4]

This will sound a little hard to believe... But it's for real.

Now I have no spark on this otherwise like new saw. Yes I replaced the plug with a new one, and still no spark.

I tested it in full choke and in run mode.

 

[cookies]

pull it like it owes you money, needs to hit 200ish rpm for the coil to really discharge spark. You may have a coil with a weak pickup.

 

[user 122190]

This will sound a little hard to believe... But it's for real.

Now I have no spark on this otherwise like new saw. Yes I replaced the plug with a new one, and still no spark.

I tested it in full choke and in run mode.

The spark is hard to see. How did you test for the spark? The best way to test for spark is with your hands. Grab the plug firmly and crank the engine. You will be pissing yourself, but you will know definitively. Was this discover after the new carburetor?

 

[etbrown4]

I used a plug tester. It connects instead of the plug and has been reliable in the past.

Assuming I have no spark, I guess something could be grounded out, or perhaps a problem with the mag

 

[cscltd]

I think you have an issue with control lever and is grounding out stop wire.
did u disconnect the ground wire from module when testing spark. If not try that before.

 

[user 122190]

There is not many wires to check. Get a can of electrical spray cleaner and blast away. A small file to roughen up the surface can make a big difference.

 

[buzz sawyer]

FWIW, I just put a 180 together and had the same problem - choke not closing fully. I found that the choke plate was catching on the gasket between the carb and AF housing - see photo. I made the gasket opening bigger and all is well. Update - Already learned that no gasket is used there. I removed it. Thanks cscltd.

 

[cscltd]

They don’t use a gasket between air box and carb-it doesn’t hurt unless it may not let compensator seal and allow dirt to come in? (but more goes through filter not sealing well anyways)

 

[buzz sawyer]

They don’t use a gasket between air box and carb-it doesn’t hurt unless it may not let compensator seal and allow dirt to come in? (but more goes through filter not sealing well anyways)

Ooops, my bad! Looked like one should be there. I'll remove it. Thanks!