MS 180 Issues after Complete rebuild

[BrokenSVT]

Most would contend that the best strategy is to "get it in wood" ASAP. Treat the saw as it will be treated. Getting it into wood and properly tuning the carb will hasten break-in and maximize compression and power later down the road.

 

[Aggie 2012]

Okay thanks. I'll do that.




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[a. palmer jr.]

Most of my break-ins just consist of not doing a full throttle no load.

 

[rupedoggy]

What do you think you have in it at this point? Maybe $200 in a saw that sells new for $179? Well I know the experience you are gaining is valuable, but some guys like to make money when they work. Mike

 

[Aggie 2012]

Mornin Rupe,

Yes sir this is a matter of pride at this point. I don't care if I have to spend another $100 at this point. It WILL run one way or another.

I am pretty good at pulling this thing apart and putting it back together.

I wonder if it would be worth finding one of the used Foredom rotary tools for cylinder cleanup in the future?

I got a couple more saws that were given to me that have been straight gasd I'd like to salvage for no reason other than enjoyment.

What other uses do these tools have other than cylinder porting and cleanup?


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[David Guptill Jr]

Does your commission gauge have a Schrader valve at the very tip where it screws into the cylinder? Have you used in on another known healthy saw?

Air leak aside, it sounds to me like your not getting fuel.

I agree with the air leak causing a lack of fuel..

 

[rupedoggy]

Aggie been there done that. LOL Mike

 

[Aggie 2012]

Here's the latest issues.

As you can see nothing has changed. ####!!!!

Compression is 125 which is not great. Power is lacking some in the cut but the biggest issue I'm having is the throttle response.

Cylinder is NWP and the rings/piston came from Hyway.



Do y'all think comp will build some during break in after 10 tanks or so of normal cutting?

Maybe I should get a new carb. I've rebuilt the original and tried an aftermarket carb with the same issues persisting.

I know it sounds lean on the high side. (Tach reads 12.5 to 13k)
Could this be carb related.

Holds pressure and vacuum great at 7psi and 7 bar.

Should I just run the #### out of it for a while and see what.

As mentioned before, I don't care that I have spent a bunch of money on this saw. I do this for enjoyment and get pleasure from thought of running a saw that I built/fixed myself.

Thanks
Travis


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[Aggie 2012]

Also worth mentioning that I originally bought the NWP piston/cylinder combo. Ran great for 1 tank then scored piston again due to air leak on the intake boot.

Only hit the exhaust side and wasn't that bad. I didn't hardly any streaking in the cylinder, just the bottom of the piston skirt.

I scotch brited the inside of this cylinder then washed with soap and water

Could it be that I've got some transfer in that cylinder that might be causing this 125 psi?

Or maybe the 2 different aftermarket brands of piston/jug don't mesh?

I did replace the intake boot that screwed me up after the first rebuild so that lean seizure shouldn't happen again. Crank seals are also new and sealed wit yamabond#4


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[Thommo]

It still sounds way too lean. I wouldn't run it like that

 

[dswensen]

It still sounds way too lean. I wouldn't run it like that

I agree, especially the high side, but it also sounds fuel starved when you hit the throttle.

 

[HarleyT]

Take off the top cover and partially block the air intake with your thumb to see if it performs any better, just to see
if richening it that way, can let you know that it is an air/fuel related problem.

 

[HarleyT]

The rod isn't bent, is it?

 

[Aggie 2012]

Thanks for your ideas here gentlemen.

I will try this as soon as I get home and report back.

How would I be able to tell if the rod was bent?
I didn't think about that being an issue but I guess with the drag created from the previous burn up it could have put that much more force on it?


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[HarleyT]

No, the rod can be "bent" by taking off the clutch or flywheel nut incorrectly.

 

[HarleyT]

It may explain your low compression reading.

 

[Aggie 2012]

Evnin Harley

I can halfway hold my thumb over the carb intake baffle and it loads up a lot more on the high side and sounds more like it should.
It still lags when I hammer down on the throttle.

I agree with y'all that it is certainly screaming at full rpm but where could I be getting air in at?

There is neither a gasket on the front or the back of the carb but maybe I could be sucking in air somewhere around the carb maybe?

Crank seals are aftermarket but as mentioned the saw has passed vac and pressure test multiple times.

I did bang on the crank with a hammer to knock off the fly wheel.
I guess I could pull apart the cylinder again and check to make sure the rod isn't bent if you think that's worth me looking at?

Thanks for all your input


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[HarleyT]

Nah, sounds like it is likely carb/fuel related.

 

[rupedoggy]

I think you have a little tunnel vision going on here. Screaming at top end and failure to accelerate can be lack of fuel as well as extra air. These little saws were made EPA compliant and that means LEAN. The carbs are not easy to adjust (and get more fuel) because they are set internally. I have worked on a lot of 017/018/170/180 and they are frustrating as all get out. There are at least four different type carburetors. There was an old version that was fully adjustable and those could make a saw into a wonderful running machine. Newer ones not so much. Bottom line....these are cheap homeowner units with short run time expectancy. I know some one is going to come on here and say "I have one that has been cutting for 10 years without problems" but I stand by my comments.
On the compression, the aftermarket have extra squish to accomidate all manner of original tollerence. They don't want a cylinder that might have a piston hit the top of it. Now buy a piston that is a different manufacturer than the cylinder and you can see that a large squish can result. That equals low compression. That is why many aftermarket "big blocks" don't run as well as a stock set up. Bent rod? I don't think so. Mike

 

[Aggie 2012]

Harley.... I have an idea. I found a thread from a guy that had similar issues last year around this time one an ms 170. He used an aftermarket carb just like me. (You had actually weighed in on the conversation with some suggestions)

The topic was "Stihl MS 170 bogging down, no power"

I believe his issues were found in the Welch plug.

I might go pick up a new oem carb tomorrow and see if that fixes my problem.

I am also guilty of using the thin after market chitty filter (I've cleaned out the plastic elbow of the intake more than once due to fine saw dust)

Guess I'll buy one of those while I'm at it since I've gone this far.

I'll slap it on there and let you know how she runs.

Can't thank you enough for all your time spent here on me.

-Travis



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