New Dolmar 7900 piston

[Edge & Engine]

New "lightweight" piston for the 7900 for "better motor operation". Weighs 1/2 oz less than the original piston.

 

[FATGUY]

who makes it?

 

[WoodChuck'r]

Hmm....

Curious about this "better motor operation" Kyle.


What did they consider to be "bad motor operation"? What was going on in the cylinder that needed to be addressed?

 

[Edge & Engine]

who makes it?

It's still Mahle.

Hmm....

Curious about this "better motor operation" Kyle.


What did they consider to be "bad motor operation"? What was going on in the cylinder that needed to be addressed?

No clue.

 

[WoodChuck'r]

Well that answers that!

Thanks for the reply though buddy.

 

[Edge & Engine]

According to the bulletin, "The light weight piston is required for a better motor operation."

 

[WoodChuck'r]

Would be interesting to see why they needed to make it "better".

 

[ancy]

Does it now come with the kit to upgrade a 6401?

 

[nmurph]

Dang, them Germans must have a real inferiority complex if they think the 7900's motor needs improvment!!!! The only thing I would ask of Dolmar is to make a factory 85-88cc set-up and trim about 10oz off the saw (maybe a better stock filter for those few that need it). Otherwise, it's just about perfect.

 

[Edge & Engine]

Does it now come with the kit to upgrade a 6401?

That depends. Most dealers (including us) probably still have stock in the 038130031 piston/cylinder kit. The new kit is #038130070, but you won't see it until the old inventory is cleared out.

 

[AUSSIE1]

Lighter? Don't they read AS? A wider skirt would have been No 1 on the list!

 

[ancy]

That depends. Most dealers (including us) probably still have stock in the 038130031 piston/cylinder kit. The new kit is #038130070, but you won't see it until the old inventory is cleared out.

So the old one should be on close out and if so how much? Would order a HD filter kit too!

 

[Edge & Engine]

So the old one should be on close out and if so how much? Would order a HD filter kit too!

No such luck I guess we're out of the old ones, but we got 2 new ones in today. That'll be it for a while as they've gone on backorder once again.
Dolmar Genuine Parts [DOL 038130070] Cylinder & Piston, PS-7900 - $189.95

 

[watsonr]

Are you carrying just the new piston?

 

[WoodChuck'r]

Are you carrying just the new piston?

Yes. Dolmar requests that customers mold a cylinder around the new piston using Play-Doh and have a competitive build off to see which one has the best performance.

E&E will start carrying the cylinders when the winning one gets picked.

 

[Edge & Engine]

Are you carrying just the new piston?

Can't get them as of right now. Our distributor has about a dozen in stock that will need to go before we can even order the new piston.

 

[tdi-rick]

Thanks Kyle.

Dolmar and Mahle obviously don't think little end lubrication and crown cooling is an issue ? (as that's why I assumed they had windows in the current style piston)

I just wonder if this ones cheaper to make ?

 

[Rudolf73]

It looks like an old school style 2-stroke piston.

To the saw builders out there, how would this design improve performance...?

 

[tdi-rick]

Dang, them Germans must have a real inferiority complex if they think the 7900's motor needs improvment!!!! The only thing I would ask of Dolmar is to make a factory 85-88cc set-up and trim about 10oz off the saw (maybe a better stock filter for those few that need it). Otherwise, it's just about perfect.

Naa, a 95-100cc lightweight monster with great AV and balance that makes the 660 and 390/395 look ordinary

 

[tdi-rick]

Rudy, lighter's always nicer to have in terms of reciprocating mass and acceleration.

Here's the old piston, you can see how thick the webs are in comparison, as they probably need to be with windows.

1/2 Oz = 14g, 'spose it all adds up.....