Dolmar Factory Upgrade

[JimmyT]

I have a friend that has worked for Dolmar/Makita for 38 years at the Hamburg Germany Plant. Several years ago he told me that the pistons and cylinders on the 7900RS saws that were built in 2003 had been modified at the plant and they did use the standard 13,500 rpm coil. So I'm guessing that they did a factory port and polish at the plant. My question is what did they do to the pistons to increase performance. Did they use a Kolben piston with 2 rings to increase compression or did they trim the piston skirts. He never said if they used pop up pistons so I'm guessing they just modified the OEM pistons.

 

[Sagebrush33]

Interesting info you are presenting.
This question may be better posted in the brand specific forum.

 

[huskihl]

I have a friend that has worked for Dolmar/Makita for 38 years at the Hamburg Germany Plant. Several years ago he told me that the pistons and cylinders on the 300 7900RS saws that were built in 2003 had been modified at the plant and they did use the standard 13,500 rpm coil. So I'm guessing that they did a factory port and polish at the plant. My question is what did they do to the pistons to increase performance. Did they use a Kolben piston with 2 rings to increase compression or did they trim the piston skirts. He never said if they used pop up pistons so I'm guessing they just modified the OEM pistons.

2 rings doesn’t help compression, it helps transfer heat from the piston to the cylinder better than 1 ring.
I don’t do anything to a 7900 piston when I port them

 

[Basher]

Sachs Dolmar actually did in house hop up of certain saws that were supposed to only be used for demonstrations but not sold to the general public. My dad and I ended up with one back around 1985.

 

[JimmyT]

Maybe I can pin him down on their performance secrets before the plant closes on March 31st 2022 but that nice impending pension may cause lockjaw.

 

[JimmyT]

2 rings doesn’t help compression, it helps transfer heat from the piston to the cylinder better than 1 ring.
I don’t do anything to a 7900 piston when I port them

2 rings doesn’t help compression, it helps transfer heat from the piston to the cylinder better than 1 ring.
I don’t do anything to a 7900 piston when I port them

Kevin, don't most of the Stihl saws have double rings. I always thought that you would lose about 5 lbs. psi due to blow by with a single ring set up because the ring gap has a minute space between the ring ends against the pinned ring groove on the piston.

 

[JimmyT]

Sachs Dolmar actually did in house hop up of certain saws that were supposed to only be used for demonstrations but not sold to the general public. My dad and I ended up with one back around 1985.

Howdy Basher, I have a neighbor that is a retired timber cutter.He bought a big Jonsered back around 1985 from a Jonsered Rep at a county fair. The saw must have been factory ported because it would cut so fast that it would be all the way thru the tree before the tree would begin to fall.

 

[Hinerman]

@Wilhelm
@FATBOY2017
@166
@Lee H
@mdavlee
@Black Dog Chainsaw

 

[huskihl]

Kevin, don't most of the Stihl saws have double rings. I always thought that you would lose about 5 psi due to blow by with a single ring set up because the ring gap has a minute space between the ring ends against the pinned ring groove on the piston.

Yes, they do. I just don’t see it making a difference in compression by the time the air fills the void between the rings

 

[FergusonTO35]

Maybe I can pin him down on their performance secrets before the plant closes on March 31st 2022 but that nice impending pension may cause lockjaw.

Fer f___'s sake Makita, couldn't you try to sell Dolmar instead of burying it alive? You really don't need their help to build an all electric lineup.

 

[Basher]

Howdy Basher, I have a neighbor that is a retired timber cutter.He bought a big Jonsered back around 1985 from a Jonsered Rep at a county fair. The saw must have been factory ported because it would cut so fast that it would be all the way thru the tree before the tree would begin to fall.

My thoughts on that subject was that Sachs Dolmar wanted to jack up everyones expectations with these demonstration saws at country fair`s but keep them for this purpose only. We bought two saws at the demonstration just as everything was being packed up, I got the dog but my dad got the thoroughbred but it took about two months before we found out what had happened.

 

[Woodpecker]

Fer f___'s sake Makita, couldn't you try to sell Dolmar instead of burying it alive? You really don't need their help to build an all electric lineup.

I second this emotion! The 7910 is one of my favorites.

 

[Wilhelm]

I second this emotion! The 7910 is one of my favorites.

Hands down, best saw ever made - in its class!

PS-7900 is fine stock, even better with a MM.
The PS-7910 needs a MM to get back to stock PS-7900 performance.

 

[Wilhelm]

@Wilhelm
@FATBOY2017
@166
@Lee H
@mdavlee
@Black Dog Chainsaw

Sorry, I have no info on the "RS" saws!

 

[mdavlee]

I’d probably own a RS 7900 if I ever run into one

 

[Wilhelm]

There is/was one on German eBay, asking price was 1500€ IIRC.
Same seller had another one listed and sold prior to that one.

 

[Piston Skirt]

Fer f___'s sake Makita, couldn't you try to sell Dolmar instead of burying it alive? You really don't need their help to build an all electric lineup.

That's not how it works. They've tried to make it work since '91 but the upcoming emmission limits makes everyone fully refresh their engine lineup. That is not what the smaller maker can afford hence Makita decided to cut the OPE engine branch altogether.
The rest is just a nice and polite PR word-wrap.

 

[Wilhelm]

I’d probably own a RS 7900 if I ever run into one

Go nuts!

https://m.ebay-kleinanzeigen.de/s-a...-von-300-motorsaege-stihl/1784940777-84-19835

 

[FergusonTO35]

That's not how it works. They've tried to make it work since '91 but the upcoming emmission limits makes everyone fully refresh their engine lineup. That is not what the smaller maker can afford hence Makita decided to cut the OPE engine branch altogether.
The rest is just a nice and polite PR word-wrap.

I understand that, however they are making zilch and not helping anyone by just burying Dolmar like they never existed. Even selling the name, intellectual property, and unneeded real estate/machinery/parts etc. for a song to *gasp* Husqvarna Outdoor Products or Stihl would be better for all involved. I mean, Jonsered has been totally eviscerated but they are still going to have a much larger presence than Dolmar (and maybe even Makita OPE in general) come next year.

 

[huskihl]

I understand that, however they are making zilch and not helping anyone by just burying Dolmar like they never existed. Even selling the name, intellectual property, and unneeded real estate/machinery/parts etc. for a song to *gasp* Husqvarna Outdoor Products or Stihl would be better for all involved. I mean, Jonsered has been totally eviscerated but they are still going to have a much larger presence than Dolmar (and maybe even Makita OPE in general) come next year.

Stihl or Husqvarna aren’t going to buy it if Makita is going to stop production for free anyway.

But yeah, it’s a shame no one else picked the name up