Diagnosis & Teardown of Dolmar PS540 Chainsaw 

Dony, Great video!!! You're right you would never suspect anything was wrong by just looking at the piston and wall, by moving the piston side to side you can clearly see the problem. Thanks for the great tips!! Mike

Piston skirts collapse from heat over time, too. It isn't always from wear. The bottom on that engine looks great. Aftermarket piston and cylinder kits are the way to go with these older saws. They aren't quite as good as OEM, but they aren't bad either.

Two weeks ago I completely tore down 2 Dolmar weedeaters and rebuilt them. The carb gasket kits for both weedeaters were 160.00. We have a Dolmar parts supplier about 30 miles west from me. Very expensive toys!

Forget the wobbly piston. Either the nicasil bore is worn or its not. Take off the ring and spec it against a new ring. Check end gap on the ring in the bore, it should be somewhere between 0.3 and 0.7mm. If it's bigger then try a new ring and see if it's nearer the correct measurement. If the new ring seems better maybe treat it to a new piston. The arrow points to the exhaust. New cylinder and piston cost would potentially make it unrepairable

dolmar is usually good, I hardly see any 4 cycle blowers here though

i have a stihl 021 thats like this the piston moves in it as well but it runs and cuts great

You can buy a new piston, seals, and carb kit and have a good saw for a $100.00 it would well worth it. The cylinder looks fine, just clean it and hone it.

Thanks for letting me know, I was thinking about getting the Dolmar or an Echo PB255 blower. I may go with the Echo though because there's a lot more service dealers for Echo than there is Dolmar

a rare breed here

@Smallgasengine1 if a ring fails, there is most likely a bigger problem that caused the ring to fail.

Hey Dony would you recommend Dolmar? I'm looking at a Dolmar PB-251.4 leaf blower on eBay, it will only be used around my house nothing commercial at all. It's $189 and it's a 4 cycle engine, it's also sold under the Makita name.

I had to fit a new cylinder kit onto a Stihl hedge trimmer because the compression was down to 75 PSI with the old rings & even with new rings,I was unsure if it would even run as the compression was at 97 PSI. Motors such as that are really temperamental because I've heard of some engines that don't run at below 100 PSI whereas some will run poorly,I will not service a motor which has under 100 PSI of compression unless I fix that up. The original cylinder may not have had that much piston slap in it but it may have been oval in shape & the rings may not have sealed off fully,it had 105 PSI before being run in then 124 PSI afterwards. As far as Dolmar lawn equipment goes,in Australia, they service their own in house rather than outsource the warranty repairs to a service agent, they are a division of Makita !!!! We'd only repair their power tools but we'd repair Ryobis lawn equipment as well as their power tools !!!!

Just worked on a Dolmar today!

after a seizure I have done the repairs on my sach 120, it has a lot of compression, plenty of spark and is getting fuel but won't fire. when it seized could the timing have changed?

Just put a ms290 piston in it with one ring. Wider skirts. Mark it out and port it.

you can get a new piston and cylinder on ebay for about 200 dollars right now with shipping, or a whole running dolmar ps540 for 240 dollars

@th19940305 how much do u want to give me for it

@Smallgasengine1 bad carburator tuning (running to lean) of no, or bad oil in the fuel

That's wear and tear alright ! lol that's pretty bad. But everything will get that way at one point or a nother. Thumbs up !

Were do you get parts for these older dolmars

I Remember About Dolmer PS540 Chainsaw Went Offline. There Is Any Damage Inside The Engine Parts. If It Is. It Needs Replace It. The Chainsaw Problems To Open The Cover Take Look The Engine Parts. If You All Don't See Any Damage The Engine. That Is Fine. When You All Saw The Engine Parts Was Damaged. It Needs To Replace It. The Chainsaw Will Be Back Online. Good To Go.

Where is there a good source for Sachs parts? I have a 114 that need work.

i fix some stihls and they seem pretty simple looked like you knew what you was doing so it looked easy to you but not me lol

Whats the easiest saw to work on?

Are the Stihl also T27 torx? I broke my beta T25 today on a engine bolt on a BR-600. Maybe becouse it is too small? Thanx.

@Smallgasengine1 90% of all chainsaws run with one ring, even the top of the line Stihl and Husqvarna models. Nothing wrong with one ring.

hard to say

its this CS the Dolmar sachs 111? looks the same. I have one of those and it has been imposible to remove the clutch. I locked the piston with a piece of rope and hit the clutch clockwise with a hammer and screwdriver but still impossible to remove. I dont want to damage it going too crazy with the hammer and screwD, any ideas??

Tenho um motosserra Dolmar PS-34 e a pessoa que tem os parafusos adonde aperta a lâmina e a corrente estragada oe ditos parafusos já não apertam a lâmina. gostaria que enformacem honde posso conseguir esta pessa que é de plástico. Obrigado

I,m trying to find handle for PS 540. Do you have one and would the price be

Looks like the older model 110.

@th19940305 yes for free

Dolmar is cheaper version of Stihl...not bad but overall for one German made Saw , they didn't care too much, what is not common for them