New Project Saw. Dolmar PS-7900!

[fordf150]

Got the cylinder off. The piston is trashed but the cylinder looks like it can be saved. Theres still some light scoring around the exhaust port after cleaning it up but doesnt look too bad. Will def need flywheel, piston, rings, oil pump, chain brake handle, impulse line, 1 av mount, choke lever, kill switch and top covers to start. will update more tomorrow

I will hook you up with a black air filter cover. I have a couple new take offs or a used red top. AV mounts just replace them all. They are $8 each or $14 for a set. With those prices it's a no brainer and if it doesn't have the limiter on the AV that's up on the cylinder be sure to add it

 

[cgraham1]

fordf150 can hook you up with parts!

I've bought a few of these saws, and they're usually missing the spacer for the top muffler bolt, the heat shield for the muffler, and the little cover for the AV spring on the handlebar. Not sure why.

 

[fordf150]

The 7900 Didn't come with that limiter. Not sure when it was introduced. May have been late in the 7900 production or with the 7910. I remember reading about it but can't remember the date. 7900 coil or flywheel is NLA can't remember which at the moment but if you need whichever piece is NLA you get a coil/flywheel set that is expensive.

 

[nnero]

Yeah the flywheel and coil have me worried. I had just assumed they were the same for 7900 and 7910. I take it that usnt the case? Also the decomp is on the left side of the cylinder. So i need to make sure the cylinder cover is correct too. Are there both red ans black ones that will fit?

 

[fordf150]

its the black coil that you have to buy as a set of flywheel and coil. $180.

limiter was introduced =
Into serial production from:
November 2006

and here is the info on ignition system changes.

 

[nnero]

Ok. So I can't get a used flywheel and use the coil I have now? Is the set available? Sorry for sounding dumb lol

 

[fordf150]

you just have to match the flywheel to the coil.

 

[nnero]

Ah ok. So worst case scenario is the $180. Thanks I appreciate all the help

 

[nnero]

Thanks for the pdf, it was helpful and cleared things up. Even with the cylinder being good I can still convert to 6400 cheaper. Hmmmm lol. Gonna check a couple dealers for parts saws for coil and flywheel today.

 

[nnero]

Ok, now for some opinions please. I dont really want to spend $95 on an OEM piston in a less than perfect jug with no idea how the saw will run/unforeseen circumstances. Especially with the flywheel/coil still being needed. This a budget build for me with the main purpose being reliability. Meteor does not make an AM piston for this saw. I can get a cheap golf or hutzl piston for around $30 and add a Caber ring and reuse OEM wrist pin and clips. Im not gonna pretend thats as good as OEM. I would still have to get top covers. Or I can get a new OEM 6400 piston and cylinder with top covers (Package deal) for a little bit more. This is my dilemma. I even dreamed about it last night and didn't come up with a solution there either lol. I would welcome any insight people have. Thanks

 

[jar944]

You could also blow the budget and spend $200 on the OEM 7900 cylinder.....

 

[nnero]

As much as I would like to I cant lol. It just seems like the 6400 stuff gets me the best quality for the money. And I still have the 7900 cylinder for tinkering later on. IDK haha

 

[jar944]

I'd run the cheap 52mm piston as the first option.

Baring that and not wanting to get the oem piston id pick a cheap 52/54mm kit.

 

[nnero]

I was lucky enough to have a member contact about a oem 7900 piston and ring they had. It made my decision much easier. How come there isnt a separate flywheel key like on other saws? Then I would only need a $2 part instead of an entire flywheel. Also on the newer saws there is a bracket that looks like it attaches to the muffler and the case. Whats the benefit/purpose?

 

[fordf150]

that bracket is just a support for the heavier muffler that comes on the newer saws. SLR or Cat depending on the model. The old 7900 without the bracket is just a hollow can with a cage in it.

 

[jar944]

I was lucky enough to have a member contact about a oem 7900 piston and ring they had. It made my decision much easier. How come there isnt a separate flywheel key like on other saws? Then I would only need a $2 part instead of an entire flywheel. Also on the newer saws there is a bracket that looks like it attaches to the muffler and the case. Whats the benefit/purpose?

If you were friends with a machinist, you might be able to broach a key way into the FW

 

[nnero]

Makes sense, I was browsing through the parts list, saw it and was curious.

That is a possibility, I just wish they didn't do it that way. Its so easy and cheap to replace a key.

 

[mdavlee]

You don't need the key for the flywheel. Just mark it and put it on the crank lined up and take a socket or something and lightly tap it to seat it on the taper. Put the nut on and tighten and enjoy.

 

[nnero]

Thanks for the tip. I never really thought about it before but its the nut and taper that keep the flywheel in place, not the key.

 

[fordf150]

the key is just an alignment guide.