New Project Saw. Dolmar PS-7900!

[Adirondackstihl]

If you're running a paper base gasket, be careful running anything over a 20" bar.
Just ask 166

 

[nnero]

You mean the cylinder gasket? It looked felt like plastic

 

[jar944]

I run a 32" bar on mine but it doesn't quite oil enough with that for me to be happy. I have the 20" and under category covered so I only grab 7900 for the big stuff. I like the look of the Carlton bars but honestly the total bars are just a couple bucks more. I say go with a 24-28" total bar

I like no shorter than a 24" as I am tall. I'm running 2 ' on most of mine...plenty of power to pull them. The oiler seems to be the weak link as a 32" is about max. There is a thread that was done to modify the oiler to oil better...which it did!!! Gotta try it when I get time to tinker....don't have a lathe or the skills to use one as the poster did. He did AWESOME work!!

Really it will be your choice. What size wood you will be cutting and what your comfortable with.

The 32" on the unmodified oiler is marginal at best. Modified, it will oil anything you bolt on (that it can pull).

 

[Adirondackstihl]

You mean the cylinder gasket? It looked felt like plastic

It's plastic/rubber coated steel.
You're fine in that case.
The older saws had paper gaskets

 

[Adirondackstihl]

The 32" on the unmodified oiler is marginal at best. Modified, it will oil anything you bolt on (that it can pull).

Got any tutorials on the oiler mod?

 

[jar944]

Got any tutorials on the oiler mod?

Yep
http://www.arboristsite.com/community/threads/dolmar-makita-oil-pump-upgrade-modification.264696/

 

[cgraham1]

I disagree

Good
For
You

 

[cgraham1]

The 32" on the unmodified oiler is marginal at best. Modified, it will oil anything you bolt on (that it can pull).

I burned my 32" Sugi after just a couple cuts!

I really need this for my saw, but I don't have a lathe, or the skills to accomplish the mod.

 

[jar944]

I burned my 32" Sugi after just a couple cuts!

I really need this for my saw, but I don't have a lathe, or the skills to accomplish the mod.

That sucks about the bar.

I think you could do it without a new adjuster screw. If you drill out the nub on the adjuster and insert a steel wire (like a section of tig rod or even a coat hanger) it might work. The pump rotor could be done on a grinder if you are really careful.

 

[jar944]

Yep...that's what I've done. Opened up intake and exhaust and cleaned up and matched lower transfers. Been taking baby steps to try to figure out what the top dogs here do to make them run. Still a mystery too me. I can get good gains from every other saw out there but the 7900's I'm clueless. My carb mods make a big difference but it really helps feed a good ported saw and helps the bottom end of the stockers.

Good rings are a given. Pretty much use OEM or Caber's

I've been working on my 2nd 7900 ( am cylinder) I even picked up a cheap spare am carb to try some mods after looking @ what you are doing in the carb mod thread.

I really want to cut the head off and make a bolt on head with proper chamber, but I'm not sure how well that will work on a work saw.

 

[nnero]

I think i may go with a 20" bar for now. Then we can use the same chain as the 6100. That will be sufficient for most everything we do anyways.

 

[Poleman]

Hey Jar, question for you .... Do you think changing the angle and possibly grinding the nub off the nylon adjuster and redrilling a hole closer to the edge and epoxying a slightly taller adjusting nub would work. I and others dont have the equipment nor the skills to do what you did....pretty amazing!!!

Rich

 

[RedneckChainsawRepair]

I run a 32" bar on mine but it doesn't quite oil enough with that for me to be happy. I have the 20" and under category covered so I only grab 7900 for the big stuff. I like the look of the Carlton bars but honestly the total bars are just a couple bucks more. I say go with a 24-28" total bar

I wonder if something changed later on. I ran a 32" windsor speed tip on a ported makita 6401/7901 and it oiled like a gusher with 32" and ripping cuts. Never noticed anything close to showing any lack of bar oil.

 

[jar944]

Hey Jar, question for you .... Do you think changing the angle and possibly grinding the nub off the nylon adjuster and redrilling a hole closer to the edge and epoxying a slightly taller adjusting nub would work. I and others dont have the equipment nor the skills to do what you did....pretty amazing!!!

Rich

I think so. The adjuster would be cheap to test even it didn't work. The only thing that might cause a problem is the steeper angle on the rotor causes more side loading on the pin. The plastic might not be able to take it.

If it didnt work it could be possible to cut/grind a helix rather than a flat angle into the rotor doing that would reduce the side load on the pin and keep the same stroke.

 

[Poleman]

I was wondering that also but still thought it would be with a try.

I have four of these saws and they all oil different....the Mak I got from Clint is the best oiler and the newest one is the worst....go figure.

 

[fordf150]

muffler split and body tools ready.

 

[fordf150]

new deflector pressed out and ready to be trimmed to shape and the body work finished.

 

[fordf150]

finished with a spark screen installed.

 

[nnero]

Looking good! This is worse tham Christmas lol

 

[Poleman]

Nice work!!!! I especially like your body tools!!! Really did good getting the dents out!!

Nate do you heat the muffler rim when you open it and reseal it??