Dolmar 6100 - Am I hitting rev limiter?

[Jere39]

I've been sawing firewood with a Dolmar PS-510 with an 18" bar for about 5 years. It has performed flawlessly, even when I push it through more hardwood than I should. Recently I started looking for a 60cc class saw to run a longer bar, and was lucky enough to find a local Dolmar dealer retiring and selling all his stock at "his cost". I picked up a new Dolmar PS-6100 with a 20" bar. I am still running my first tank of fuel. I added a 24" bar and let it cut off a couple 14" cookies with it's own weight.



A couple times when I was repositioning myself, the engine tone seems to stutter. It's not easy to hear on that first video. So, I walked across the lawn to a big ugly cross-grained crotch that swallowed the 24" bar. This time you can hear it more easily. I'm not sure if this is just an early life (still first tank of TruFuel), or if I am hitting the rev limiter. Maybe someone can hear what I am describing and tell me what it is.

And, I know, this is a long video, I captured three cuts through this block. It is mostly noodling, but with all the cross-grain it is never a total noodling cut.



Thanks for any diagnosis

 

[blsnelling]

Your saw is WAY too rich. Lean it out 1/8 turn at a time until it runs clean. Don't go to far. It'll take less than you think.

 

[rdtreewalker]

Sounds to me like its tuned a little ritch, which is not necessarily a bad thing on a new saw. Just push it a little bit harder and it'll clean up. Mine don't seem to care how much you push it. They are great saws, I wish I would have got one a lot sooner then I did.

 

[Duane(Pa)]

Jere, It sounds tuned slightly rich, which is just where you want it for break in. Good call on the purchase!

 

[blsnelling]

Constant 4-stroking in the cut is not doing your saw a favor at all, not even for break-in. You need heat and load on those rings for proper break-in.

 

[Duane(Pa)]

The tone stutter is called four stroking. You always want to have some at the top rpm. If you tune to eliminate any four stroking it will be too lean, and run very hot. Seizure will be the next bad thing. I agree with Brad, it needs leaned out some. Just be super careful going about that..... A rev limiter hit is going to sound like a machine gun staccato sound. Sort of like a dead miss, and it would be at pretty high rpm

 

[Duane(Pa)]

Constant 4-stroking in the cut is not doing your saw a favor at all, not even for break-in. You need heat and load on those rings for proper break-in.

Did you watch both vids? It will clean up buried with some dawging. Like from the seven minute mark through eight minute mark in second vid.

 

[blsnelling]

Did you watch both vids? It will clean up buried with some dawging. Like from the seven minute mark through eight minute mark in second vid.

Admittedly, I did not. I couldn't only stand to hear so much, lol. You're right though. It's much closer than I thought. Give it an 1/8 turn and try it again.

 

[Duane(Pa)]

By the way Jere, this leaning we are talking about is accomplished by turning the "H" screw clockwise. This lets less fuel through the jet, as the needle is getting closer to the seat. Again, be careful not to close it down too much. Just go slow. Better a little rich than a little lean.

 

[Jere39]

Ok, Thanks for the words of wisdom. I didn't notice this when I was running the 20" bar. But, I really haven't run the saw much at all yet. Noodling that big piece was the most cutting I've done on it.

And, Brad - no worries, who would watch a full 9 minutes of a guy letting a new saw work it's way through a big old oak crown piece.

So far I am pretty impressed. And, my experience with my 5 year old 510 has been all positive.

 

[Perry pioneer]

Damn nice saw Jere I want one , how much was at cost? Lean it just a tad.

 

[Jere39]

The retiring dealer had one 5100, one 7300, one 7900, and this 6100. No 6400, another candidate on my short list. He still had his prices on the tags for each saw, and he had this one listed at $569, but he told me he could do better. Not sure why the mystery, maybe he was not supposed to be selling them at the price he was willing to let it go for, or didn't want a distributor rep to see what he was doing, or was using some mystical power to determine what I might pay. But, ultimately, with only me and him in the shop, he offered it to me at $469. I had already considered a new Echo CS-590, and a couple used saws, including a few here on the Trading Post, but my experience with the Dolmar 510 led this saw and price to the top of my list. Based on my very limited saw time so far, I am very happy with the saw, the ergonomics, the starting (easiest pull and start of any saw I've ever started), the clean lines. A bonus I wasn't actually aware of was bar interchangeability with my 510. With my included screw driver, and some confidence here, I'll adjust the H screw and be even happier.

Indulge me a couple pictures:



Oh, yea, and he threw in a hat too:




And, finally, with the 24" bar I used in the videos:



Thanks again for quick diagnosis. I had heard the term 4-stroking, and watched some videos where guys described it, showed it, and tuned it out, but I am a slow learner, and needed a hands on experience to let it sink in.

 

[Duane(Pa)]

Hey Jere, That is a sweet deal on a great saw to add to your arsenal. Lots of upside. If you get into wood beyond the scope of that one, you can look for a 7900.....(I had to say that, this is Arborist Site) Looks very efficient under the hood. There may be limiter caps on the carb adjusting screws. However, they want to limit how rich you can make it. That helps them meet emission standards. Altitude, temperature and fuel differences all affect the tune. So if you cut in extremely different temps, or switch to pump gas, expect to tweak the H screw. Nice Dolly!

 

[blsnelling]

Nice air filter. Big improvement there!

 

[nnero]

These are great saws and should treat you well. I was lucky enough to stumble upon a 7900 that needed some TLC and now I have two Dolmars as well. Have an 18" bar which for the 6100 which will be going on soon. Enjoy!

 

[Jere39]

Your saw is WAY too rich. Lean it out 1/8 turn at a time until it runs clean. Don't go to far. It'll take less than you think.

I followed the link in your sig and watched all your videos. Thanks. The second one in that thread seemed most directly what I was experiencing, and showed how you leaned it out for a clean cut. I appreciate your comments and your video.

 

[CTYank]

Screwdriver won't get it done for H mixture adjustment. You'll need a "Double-D" tool. I've got one for my 6100, and have used it to bring the high-speed mixture into line on my saw. (Well-meaning dlr set it way rich, to bring max unloaded rpm to factory spec 13.8K. Brad and others will tell how that procedure just doesn't work.) Mine's still a tad rich at about a year old and maybe 15 tankfuls. That'll change.

Running a saw too rich will build up chamber deposits, which then can flake off and act as micro cutting tools on bore and piston skirt.

Another thing in the vids, the chain looks dull- barely self-feeding, and generating too much dust vice chips. At least that's how it looks from such a distance. The 6100 is so powerful that it can easily direct lots of power into wearing down bar & chain.

The tank capacities (30 oz mix) let you do a lot of cutting on a tankful. A big plus, IMO.

 

[Jere39]

I finally got back to address the recommendations, and found, as CTYank indicated, it needs a special tool. But, I believe it needs to have the caps on the H screw removed to even apply the tool. I am hesitant to do this while the saw is still under warranty. So, I am now stuck debating with myself which is the greater good: voiding the warranty, and removing caps and adjusting the High a little leaner, or taking it easy for a while.

BTW, CTYank, the chain wasn't too bad, at least I didn't think so. The wood was a very tough old oak crown that had grain in all directions. No cut could either be cross grain, or noodle, they were all combinations. So, it was pulling nice long noodles for a while, than throwing up end-grain dust, then back to noodles. Probably not a good piece of wood for the purpose.

Here it is back on the cooking cutting of an old but straight grained log left in the woods behind my house for just this purpose. And, it now is into the second tank of mix, but, I think it is still 4-stroking.



I'm headed to the PA GTG Saturday and I'll try to get some first hand advice from additional folks who know a lot more than me.

Thanks again for all the comments and the teaching. Obviously I need it.

 

[Macky Anthony]

I'm still learning how to tune it by sound, actually tuning a saw Video above sounded better when the saw warmed up right? Initial cuts sounded the same as the initial video to me. Of course, I don't know what I'm talking about haha.