Ms180 over sized piston.

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Ms180 is the biggest saw in that series. You could remove the lower piston ring & polish the piston skirt on the intake side... removing the ring will lower your compression a little bit, but reduce your drag and heat build up, to the point that you can lean it out a couple hundred rpms. Skirting the intake side will allow the engine take a longer, deeper breath of fuel mixture... But remember you're still messing around with a entry-level saw- the av system and general design just good enough for the joe blow homeowner or weekend warrior. A perfumed pig is still a pig. If you really want to step up to the plate and get a saw you don't have to mod, consider a ms201c rear handle or a ms241c.

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Brad,
Just read your write up on a mod 361 https://www.arboristsite.com/community/threads/porting-the-361-big-bore.85488/ and it’s a great read. Is any of that applicable to the 180 eg squish and playing with the port timing? Have you played with that sort of thing on one of these small saw? Is it also worth playing with the ignition timing once everything else is done or do you just wait and see if it needs it?

Cheers
Mat
 
Hi all,
3 questions:
1. What’s the best way to lower the squish in this saw? Do you take a bit off the jug? If you do, are you then required to also move the bearing holder up as well?
2. Can you machine these cylinders out to 40mm so 1mm of wall shaved off and throw an ms 200 piston in?
3. Is there a thread on here how to advance the saw. I’ve picked up you need to remove the key and rotate the flywheel, just chasing a bit more info.

Cheers
Mat
 
Hi all,
3 questions:
1. What’s the best way to lower the squish in this saw? Do you take a bit off the jug? If you do, are you then required to also move the bearing holder up as well?
2. Can you machine these cylinders out to 40mm so 1mm of wall shaved off and throw an ms 200 piston in?
3. Is there a thread on here how to advance the saw. I’ve picked up you need to remove the key and rotate the flywheel, just chasing a bit more info.

Cheers
Mat
Any progress on this project?
 
No one makes a kit that I know of. It could be done but you would need to nikasil your cylinder and that’s a lot of mucking around. Making the piston would be the easy part.
I have been looking at lowing the jug but you need to take the same amount of material out of the bearing and seal journals. I bought a couple of these for the job but as yet have not had a chance to use them. F0F192A1-7909-403A-82E5-F22779807333.jpeg
 
No one makes a kit that I know of. It could be done but you would need to nikasil your cylinder and that’s a lot of mucking around. Making the piston would be the easy part.
I have been looking at lowing the jug but you need to take the same amount of material out of the bearing and seal journals. I bought a couple of these for the job but as yet have not had a chance to use them. View attachment 916928
I was just looking at HLSupply and they have got an aftermarket ms180 cylinder and piston for 12 bucks. May be worth getting a couple for experimental purpose.

I don't know that I would try using that cutter to recut the bearing seats. If it's me, I'd set it up in a Bridgeport type mill, but even that would be tricky because of the seal seats.

What is it you are trying to achieve? If all you're trying to do is reduce the squish, I would think it's a fair bit easier to weld up the piston and machine it back or maybe weld up the squish area in the cylinder and all the port timing wold stay the same.

Theoretically, I think it should work.

Interesting to think about....
 
Have you poked your head inside a 180 cylinder? I can’t weld in there.

There not enough room. Maybe someone super skilled could put the jug in a jig, fix the hand piece in position and turn the jug by hand as the welding was taking place.

Seemed pretty straight forward to using a cutter for the bearing and seals. Find same diameter, file a smidge off the cutter and away you go. You can buy them in a stack so you can cut the bearing and seal grooves at the same time for precision. I don’t have the skill to do it any other way at the moment.
 
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