worth fixing an MS180?

[Climbingmagnus]

Hi All,

 

A mate of mine has an MS180 that he says has just blown the spark plug out of the cylinder head. Is this worth bothering to fix given that a new MS181 is around £200?

 

Presumably it will have to be stripped down into bits before the head can be drilled out and helicoiled? or is it possible to do it with the saw mostly assembled and blow the swarf out of the cylinder with an air line?

 

Do you think it was running lean to have caused this and will it have damaged other things like the piston and bearings?

 

Cheers.

[TGB]

If you're going to retread it, it would be best to strip it. You'd only need a small piece of debris to screw the pot 'n' piston, (if they're not already done). Plus it would be good to know why it blew in the first place.

[spudulike]

Hi All,

 

A mate of mine has an MS180 that he says has just blown the spark plug out of the cylinder head. Is this worth bothering to fix given that a new MS181 is around £200?

 

Presumably it will have to be stripped down into bits before the head can be drilled out and helicoiled? or is it possible to do it with the saw mostly assembled and blow the swarf out of the cylinder with an air line?

 

Do you think it was running lean to have caused this and will it have damaged other things like the piston and bearings?

 

Cheers.

 

Personally on a saw with this value and construction, I would take the piston down to BTDC, stuff protective cloth over the piston, retap the plug hole, fit the insert/helicoil and then carefully remove the cloth/swarf. Use a compressor to blow it out and then fire it up.

 

The danger is that aluminium will get down the side of the piston but hopefully not too much.

 

I wouldn't normally do it this way but on a £100 saw.....

 

Running lean will not cause this. A plug coming loose and being blown out or being cross threaded is most likely the culprit!

 

Do not use a £6 ebay special to do the job, nothing beats decent quality machining taps and reamers for this job. V-coil make some good kit and would be my choice!

[Macpherson]

Hi, it`s not much work to strip it at which time you can check for other problems, I wouldn`t imagine that the stripped thread is a symptom of anything else, more than likely careless workmanship and although I have repaired many in situ, mostly 4 strokes it`s prob not worth the risk, imo, cheers:001_smile:

[spudulike]

I just hate working on clamshell saws and you have the added complication of having to seal the lower clam to upper clam as well on rebuilding the saw. For the average home owner without a scoobie on saw construction, the job may be a little complicated.

 

You could put plenty of grease around the piston to catch any swarf that may get past the cloth. Perhaps use a piece of rolled up paper the shape of the bore to open when in the bore and direct the swarf out of the exhaust port.

 

You could do the whole job with the saw upside down - perhaps that isn't as silly as it sounds and any swarf could be blown straight out the plug hole!

 

V-tech do a nice pilot nose tap - expensive but does the job very well!

[Macpherson]

Hi again, I have done it successfully the way that Spud suggests except I would also fix a piece of 1/2" plastic pipe onto a hoover with some tape and put it in the cylinder through the exhaust and get as much of the cuttings out that way before they have a chance to land. Alloy cuttings are one thing, the tang off the helicoil is another and is better removed from the top with long nose pliers rather than snapping it off with the insertion tool, you need to know where it`s gone!!!

all the best.

[Stubby]

Hi again, I have done it successfully the way that Spud suggests except I would also fix a piece of 1/2" plastic pipe onto a hoover with some tape and put it in the cylinder through the exhaust and get as much of the cuttings out that way before they have a chance to land. Alloy cuttings are one thing, the tang off the helicoil is another and is better removed from the top with long nose pliers rather than snapping it off with the insertion tool, you need to know where it`s gone!!!

all the best.

 

I was going to mention the tang of the helicoil . Well done on that . I helicoiled the sparkplug hole on a VW air cooled engine once and was advised by a German that the Magnesium alloy swarf would burn up on the first ignition of fuel !

[onyx landscaping/fencing]

personaly I would bang it on ebay with an accurate description as spares or repairs I done this with a ms170 and got nearly the price of a new saw! people pay stupid money for broken saws on there and I cant see why? then go and buy a new one

[Macpherson]

I just hate working on clamshell saws

 

Yep,me too, forgot about that, but upside down, a spark plug turns into a sump plug, done loads of them.

[Climbingmagnus]

Thanks everyone. Lots of genuinely useful info there. I'll see what he wants to do. I'd lean towards having a crack at doing it in-situ with a hoover and a load of grease then blue roll on the piston. Quite interested in the flogging it on ebay and buying a new one plan though!