Jonsered 930 Power Issue

[Johnwell]

I have a question about the Jonsered 930 and other large saws: should the power of this thing really ‘wow’ me? Or is something wrong with mine?

I have a few other saws, including a 550xp and a slightly modded CS590. I picked up the 930 to do some hardwood milling; and while it is a torquey brute that milled 20” cherry and walnut quite well, albeit slowly; it doesn’t seem to have the oomph I would expect over my CS590 considering it’s ~50% larger.

I don’t have a compression tester but it starts and runs well. It’s honestly hard to pull over. I have it tuned by ear to get four stroking at the higher RPM’s.

It cuts through wood faster than other saws listed; maybe my expectations were just too high? I have a 7 tooth sprocket now, should I go to more teeth to get higher chain speed? I guess I expected this to be like when I went from a husky 445 to a 550xp, but it was more like going from the 550xp to the cs590.

 

[NSEric]

I doubt there's anything wrong with the 930.
The bigger saws are only noticeably faster in big wood, if you bury a 28 or 32 inch bar on the 930 and the 590, the 930 will be a lot faster, in 12 inch wood they're likely the same speed.

 

[Bob Hedgecutter]

What size timber is being cut in order to wow you?
If you are using the old 930 to cut timber the 550 could easily handle- then yes, the 550 will do so better and more comfortably.
However, if you were to fit a say 28 inch bar to both and run them with the bars buried- then the 930 wins.
Horses for courses.

 

[Johnwell]

What size timber is being cut in order to wow you?
If you are using the old 930 to cut timber the 550 could easily handle- then yes, the 550 will do so better and more comfortably.
However, if you were to fit a say 28 inch bar to both and run them with the bars buried- then the 930 wins.
Horses for courses.

I do have a 28” bar on the Jonsered (couldn’t imagine running anything over 20” on a 550); the logs were probably 18-20” in diameter (which is about average for me). I was just expecting it to really rip through; but I guess that makes sense. I just always hear the arguments for larger saws even in smaller wood and assumed there would be a more noticeable difference.

 

[Bob Hedgecutter]

You are also comparing a couple of generations of design difference- 2186 will cut faster than a 930 same for same.
Compare your 930 to a Husqvarna 50 Rancher rather than the 550 and see what you think?

 

[Johnwell]

You are also comparing a couple of generations of design difference- 2186 will cut faster than a 930 same for same.
Compare your 930 to a Husqvarna 50 Rancher rather than the 550 and see what you think?

Absolutely fair enough; I know the 930 is a bit long in the tooth. But it usually gets compared to the husqvarna 288xp so I assumed it would be close to the modern 80-90cc saws, perhaps just a bit heavier and worse on emissions/fuel consumption.

 

[cbfarmall]

Always possible someone stuck a 920 or 820 or 830 topend on it. It would be less of a saw that way. Have to compare to another good 930 to be sure. Mine would get some looks from the uninitiated. I always liked that saw.

 

[Johnwell]

Always possible someone stuck a 920 or 820 or 830 topend on it. It would be less of a saw that way. Have to compare to another good 930 to be sure. Mine would get some looks from the uninitiated. I always liked that saw.

I suppose it’s possible, but I kinda doubt it. They guy I bought it off of had this saw since new, as well as a 920 that I probably should’ve bought for parts.

He said (and I know, don’t trust previous owners) that he never had to replace anything on it other than the bar and chain. It was pretty beat up, but it looks all original. Maybe I should pull the jug and check though.

 

[Johnwell]

Well I tore it apart last night, it is a 54mm bore and it is open ports on the bottom; so it does appear to be a 930 jug.

There was, however, significant carbon buildup on the exhaust side of the piston/cylinder and some scoring on the piston. I think the cylinder bore will clean up with some elbow grease though.

Looking around, the oem pistons are long gone. All I can find are the little red barn ones, which I know don’t have a great reputation around here.

I’ve also seen it mentioned that a 066 stihl piston can be used if the piston is slightly modified. I have a lathe; would it make sense to go with a meteor piston for the 066 and modify it? Or just stick with the LRB? Or just scrape the carbon off the OEM piston and say it’s good enough?

 

[Bill G]

As mentioned a large saw (stock) with a short bar in small wood will not be overly impressive. Put a 16 inch on a 3120 and you will think it is a dog. I have done it.

 

[cbfarmall]

Haven't ever tried to put a piston in my 930 but I imagine just about anyone will tell you a Meteor piston is way better quality than LRB.

How scored is your piston? Maybe you can knock down high spots and use a new set of 54mm rings. Your cylinder condition will be critical. I've been using a scotchbrite green pad threaded through an eyebolt chucked in a drill.

 

[Johnwell]

…How scored is your piston? Maybe you can knock down high spots and use a new set of 54mm rings. Your cylinder condition will be critical. I've been using a scotchbrite green pad threaded through an eyebolt chucked in a drill.

It’s rough enough you can feel it with your finger. Both cylinder and piston. I’ll try to get pictures tonight. It seems like the cylinder is mostly carbon and aluminum smearing, but I haven’t tried to remove it yet. There is some damage to the piston that won’t clean up with scotchbrite. Some damage around the rings—the rings themselves look great; could be the previous owner already replaced those and reused the piston.

It was a running saw when I took it apart, so presumably it isn’t that bad.

 

[cbfarmall]

Unless plating is gone, the cylinder can generally be saved. People have used muriatic acid delicately applied with a swab to the aluminum smear although I've never had much luck. Whatever you try, take your time. Once the plating is damaged, the cylinder's days are numbered. Below the ports, you can get away with more.

 

[cbfarmall]

Pictures will tell a lot.

 

[Johnwell]

Pictures will tell a lot.

 

[cbfarmall]

Seeing a lot of carbon scoring/scratches. I'd scotchbrite pad the piston, clean the grooves, new rings. The cylinder definitely needs to be cleaned as well with scotchbrite as well. I like my aforementioned pad through an eyebolt hole. I have had to stuff a second pad in the cylinder and spin with the eyebolt. Clean real well when done.

Other ideas.

https://www.arboristsite.com/threads/cylinder-clean-up.331017/

 

[cbfarmall]

Presumably, the pictures show all the damage and nothing is being withheld.