Dolmar 5105 Snellerized Style

[blsnelling]

Well, I went and bought my first new Dolmar. I was so impressed with that 5100 that I did a few weeks ago for @computeruser that I thought I'd try my hand at the 5105.

Here she is on her 1st tank of fuel, sporting a 18" 3/8 bar and running the factory tune. Initial RPM checked showed 12,800. However, she was just barely hitting the rev limiter at 13,500 after a few cuts. The tune was spot on. It would 4-stroke with very light load and clean up immediately. Throttle response and idle were perfect. The chain that came with the saw has the curved over raker gauges. It certainly is not an aggressive chain. It will be coming off and be replaced with a proper chisel chain.



These saws have a cat muffler, so that was the first order of business. Why is Dolmar so cruel to us, putting cats and crazy cages inside mufflers that must be uncrimped and pried apart?!!! This alone makes these saws sooo much more work to mod.

Here's the back half after uncramping it and splitting the halves.

The cat!

Here's the same piece with the spot welds ground out and the cat removed.

This heavy flange is sandwiched in place.

Back on the saw with the heat shield over it.

The deflector needed work as well. Dolmar even spot welded the spark arrestor screen in place. I failed to get a pic of that before removal. I've opened up the deflector quite a lot.

I'm not sure if or how I'll go about getting more area. I might just leave it like this. It sounds plenty open and throaty as is.

You can see the wide mesh stainless screen I added.

 

[CoreyB]

Dolmar definitely knows how to make an easy start and great AV!

 

[Termite]

A muffler on a 6421 is just as bad.

Is the "easy start" an option? Does it add weight?

 

[Chris-PA]

What's interesting is that the cat is already bypssed from the factory. There is another port right next to the cat that feeds into the spiraling output tube. I'm not sure you'll gain all that much beyond opening the output as the combined area of the cat and the bypass was pretty large.

 

[blsnelling]

I had to venture out into a light rain to get some videos this afternoon. The first is after re-tuning the carb, with the same chain. The next is with a new Stihl RS33 chain.

 

[blsnelling]

What's interesting is that the cat is already bypssed from the factory. There is another port right next to the cat that feeds into the spiraling output tube. I'm not sure you'll gain all that much beyond opening the output as the combined area of the cat and the bypass was pretty large.

Yes, it does have a bypass. However, it's certainly not what you would call a good flowing muffler. Modding this muffler was good for a 20% gain. That's huge.

Better than that, replacing the crap chain was good for an additional 26%, making the saw 41% faster than stock.

 

[CR888]

46% gain and no cylinder porting....has this build thread ended with chain replacement and a muffler modd? Dolmar is struggling to deal with the U.S emission regs selling old tech. How long they can do this I don't know, maybe they are waiting for strato patents to expire. But its not to bad for someone who is happy to de-epa them. Our government is talking about adopting emission regs to match the U.S........I dearly hope they do not!

 

[computeruser]

Nice to see the Dolmars getting some attention again!!

 

[a. palmer jr.]

Does the 5100S have the cat muffler also? If so, I may have to mod mine..

 

[blsnelling]

Does the 5100S have the cat muffler also? If so, I may have to mod mine..

It does not.

 

[Andyshine77]

Does the 5100S have the cat muffler also? If so, I may have to mod mine..

Not that I know of.

 

[a. palmer jr.]

It does not.

Great! I think I'll just run it as is, runs pretty good for it's size.

 

[wde_1978]

I never feared a bad tune of my Dolmar PS-6400 until this site made me weary about it.

My PS-6400 has been bought new in 2006. and I joined AS in 2014. , the saw never missed a beat, 4-stroked w/o load and cleaned up under load.
Once I bought a tach and checked the tune she was just shy of the rev limiter - spot on factory tune after 8 years of work.

Brad stating that the factory tune on his Dolmar PS-5105 was spot on too is reassuring that Dolmar knows how to tune the saws they send out of their factory.

I purchased my Dolmar PS-6400 in a tool & electronic store, it did not get any check up before I happily walked out the door with her!

I agree with Brad, that factory chain on his PS-5105 might be "safe" and "smooth", but it is cutting too slow.
Even stock the PS-5105 sounds like she could handle significantly more load.

I am eager to see this builds progress.

 

[Chainsaw Jim]

Maybe it's that they let them warm up a little more before they tune them at the factory.

 

[SOS Ridgerider]

After reading this , I might have to open the muffler on my new 5105 again. I did a muffler mod just days before this thread got started. I cut out the cat and opened everything up a little, but not as much as the pics show here. This being only my second MM, I was perhaps a little too careful with how much I removed in there, knowing that it needs some resistance to work well.

 

[Chris-PA]

Yes, it does have a bypass. However, it's certainly not what you would call a good flowing muffler. Modding this muffler was good for a 20% gain. That's huge.

Better than that, replacing the crap chain was good for an additional 26%, making the saw 41% faster than stock.

It would be interesting to see one done with the cat removed but leaving the baffle and the output tube in place, plus some opening of the output & screen as you did.

 

[blsnelling]

It would be interesting to see one done with the cat removed but leaving the baffle and the output tube in place, plus some opening of the output & screen as you did.

That would be worth while. The cat could be removed without splitting the muffler.

 

[stihlaficionado]

Any other mods coming?

 

[blsnelling]

Absolutely! Hopefully this next week. I had to pull off this project till do a customers saw.

 

[birddogtg]

Anymore work on the 5105.