Dolmar 5105 scored piston

[OBX Koastie]

Dolmar stepped up to the plate

Dolmar is sending me a new PS-5105 and they are having a local dealer set it slightly rich for the first several tankfuls and after that I'll take it to a local Stihl friend who will tune it with a tach for me.

I really appreciate all that I learned and will be running this right on the rich side of 50:1 but probably not 40:1 as it is going to be set using 50:1.

I learned a lot and appreciate all the input. I hope I didn't PO to many.

 

[SawTroll]

I too have trouble hearing. Buy a tachometer. Tune to 13,500 and you should be safe with good power. Max rpm's on 5100 is 13,800 down from 14,500 which is in the score your piston zone. Not trying to start an oil war but believe it or not more is better to a point. I run mine @ 32:1 full synthetic 93 octane non-E gas in my stock and ported saws. An additional benefit esp in ported saws crank bearings live longer.
Shep

The 5100 and the early 5105s were speced at 14,500 - and my 5100 still is fine, after mostly being set at 14,400. It would be pig rich at 13,800 - but each to their own....

 

[SawTroll]

Did you not read what I wrote?
32 or 40 is fine...... If your saw is tuned for it

I'm done

Yes, if it is tuned for it.

 

[Andyshine77]

This is the last time I'm going to say this!!! I've tested this theory with a tac, switching fuel mix from 50:1 to 32:1 and the saws all run a little fat when ran on 32:1 mix. Oil has energy, things are not as linear or as simple as many make it out to be. If you want your saw to run better and longer run 40:1 or 32:1. What do I know I've only seen the inside of saws ran on different mix ratios, and to me that's conclusive evidence.

Glad you're getting a new saw, the 5105 is a great saw and will last you a long time if taken care of. Happy cutting.

 

[ncfarmboy]

Dolmar went to the plate again. It all depends on who youu call. Very happy you are getting a new 5105. Here is some reading for you:
http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf
The R/C Aircraft Proving Grounds - 2 Cycle Oil Test Summary
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power
This is what I do and have since 1966 or so. Ed Heard (saw builder) states crank bearings last longer with more oil. Just read that this AM on another site.
Shep

 

[exSW]

Dolmar went to the plate again. It all depends on who youu call. Very happy you are getting a new 5105. Here is some reading for you:
http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf
The R/C Aircraft Proving Grounds - 2 Cycle Oil Test Summary
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power
This is what I do and have since 1966 or so. Ed Heard (saw builder) states crank bearings last longer with more oil. Just read that this AM on another site.
Shep

Yep,run it like you stole it.

 

[Andyshine77]

Dolmar went to the plate again. It all depends on who youu call. Very happy you are getting a new 5105. Here is some reading for you:

http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf

The R/C Aircraft Proving Grounds - 2 Cycle Oil Test Summary

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

This is what I do and have since 1966 or so. Ed Heard (saw builder) states crank bearings last longer with more oil. Just read that this AM on another site.

Shep

oil doesn't just lubricate, it also acts like a cushion.

 

[OBX Koastie]

I thought some might be interested in what the person who purchased my saw found. No matter how he adjusted the carb after cleaning up the piston and cylinder he could not get the saw to run properly. (There was no damage to the bearings as the dealer had told Dolmar!) The problem he found was there was a crack in the carb casting allowing too much air and the saw ran lean. He tried four other carbs off similarly failed Dolmar 5105s. Could not get one to make the saw run properly; each one had a crack in the carb. So he bought a new carb from Dolmar, adjusted it and sold the saw for more than I got for my brand new, never been used saw with three spare Stihl chains. (I actually did OK because between what I got for the old saw plus the new saw that I paid nothing for except the three chains and the $40 the dealer charged me to take it apart and then tell Dolmar something that wasn't true) I came out ahead. With no Dolmar dealer within two hours each way driving time I put my "profit" plus $200 and got a good deal on a new MS261 before they went to the "C" version.

 

[psuiewalsh]

Where was the crack located on the carb?

 

[OBX Koastie]

He never told me. He only told me that there was no way the carb could be adjusted so the saw would not run lean and produce the required max RPMs without being lean. Check his request for information on the Dolmar 5105 piston window.

 

[treelove]

I am new to this site but not to cutting wood. My first saw was a Craftsman Pro Saw made by Poulan, moved up to a Homelite 360, to a Stihl 029, to a Stihl 036, to a Stihl MS441, then a Stihl MS362, newer 441 after my boys liked my old one too much and now I have a MS441, MS362, Echo CS-360 and a Dolmar 5105 in the shop with a scored cylinder and piston with metal transfer

I bought the saw new off Ebay but when received it was four years and three months old. Should have sent it back but Dolmar told me they would stand behind the warranty. First time out I used about 2-1/2 tanks of fuel, and the saw did not run right. My son who was with me and a tree climber said' "Dad, this thing isn't right. Take it back." Kept cutting off after making a cut. Took it back to a local Dolmar dealer and they had it for about 1/2 an hour and gave it back. I had it out last weekend cutting wood for our church and after about 2-1/2 tanks, it quit. Thought it was out of gas, checked and it was still 1/3rd full so I refilled it. Tried to start it, NADA. No compression. Took it back to the dealer and they called me today to say that Dolmar will not cover the damaged cylinder and piston due to insufficient oil in the fuel. But they will fix it for $380 plus tax!

Here is where it gets interesting. I use only Shell 93 octane non-ethanol. I use only Stihl Ultra full synthetic mixed approximately 40:1 (3 ounces of Ultra to one gallon of gas.) I drain my tank after every use and let the saw idle to run the carb dry making sure not to rev it when low on gas and running lean. I have had my fair share of saws and have never had a problem like this. I was using the 362 and the Echo 360 with the same mix. It is the same mix I use in my Stihl blower, Dolmar edger, Echo Shred-N-Vac and all my saws. Prior to the Stihl Ultra I ran only Amsoil synthetic and believe I know how to mix gas and oil having done it without incident for almost 45 years.

Any ideas or insights. I bought the saw thinking I was getting a great pro 50cc saw. Now I am not so sure!

Kim

Hey, I was tickled to find your post. I bought a brand new 5105H last year and thought I'd be buying real quality. From the start, just as you report, the saw would cut out after making a cut - and in the month or two that I was able to use it, that habit didn't change. And then it became more difficult to start and abruptly died. No compression. Took it back to the dealer who flatly asserted without any other evidence that I must have omitted oil from the gas. Just as you say, piston scored and dealer said that the piston wasn't covered by the warranty whether or not it was user fault. I am totally anal about mixing fuel and have used saws for decades so I am not inclined to believe their analysis.
I'm now trying to repair it with cylinder kit and wondering which way the A + arrow is supposed to point. I'm guessing it's 'ausgang' for outlet but unfortunately the manual does not mention which way (and the curious thing is it's very difficult to discern a difference in the two sides of the piston).

 

[Adirondackstihl]

Arrow towards the exhaust.

Your dealer is an ass BTW

 

[OBX Koastie]

Hey, I was tickled to find your post. I bought a brand new 5105H last year and thought I'd be buying real quality. From the start, just as you report, the saw would cut out after making a cut - and in the month or two that I was able to use it, that habit didn't change. And then it became more difficult to start and abruptly died. No compression. Took it back to the dealer who flatly asserted without any other evidence that I must have omitted oil from the gas. Just as you say, piston scored and dealer said that the piston wasn't covered by the warranty whether or not it was user fault. I am totally anal about mixing fuel and have used saws for decades so I am not inclined to believe their analysis.
I'm now trying to repair it with cylinder kit and wondering which way the A + arrow is supposed to point. I'm guessing it's 'ausgang' for outlet but unfortunately the manual does not mention which way (and the curious thing is it's very difficult to discern a difference in the two sides of the piston).

I would find out the distributor for Dolmar in your area and go back to them. If the dealer is not helping you, as mine didn't, the only alternative is the manufacturer. Dolmar distributors are more inclined to do something to keep their reputation intact versus dealers like yours and mine that don't seem to care. You can point the distributor to this link if you think it would help. Or send the saw, at Dolmar's expense, back to the distributor and let them test the carburetor. If you are building a new saw, I'd strongly encourage replacing the carburetor with a new one. That is what the individual who purchased my saw had to do as four used carbs off saws that had failed similar to mine that he bought inexpensively had cracks in them which prohibited proper adjustment to keep them from running lean.

I am sure you read the entire post and the issues regarding mixing of oil. I never knew some of the points brought up and had never seen these comments/observations anywhere else. But apparently 40:1 is not as good for a saw set up for 50:1 and unless you want to void the warranty and tune the carb outside the original limits, I'd stick to the 50:1. BTW, I also got a good deal on an Echo CS-500P , put an 18" narrow kerf bar and chain on it and it now my go-to saw over the MS261 with 16" bar and chain; lighter and appears to cut as fast if not faster.