Jonsered 490 Advice

[Chainsaw Mark]

Hi - I just joined today. I have been hanging around reading off and on over the years and have learned avlot. Finally took the plunge and joined today. I must confess I'm hopelessly addicted to chainsaws!!!! I cut firewood for myself and have a Stihl 029 Super, Jonsered 490, Olympyk 950, John Deere 80EV and a McCulloch 3216 aka my dual purpose saw (door stop/boat anchor).

I was given the Jonsered 490 from my brother that barely ran and was running very lean. I got the carb issue fixed, but when cutting with it quickly got hot and started to loose power. I took the muffler off and I can see scoring on the piston through the exhaust port. It has decent compression, starts great (it just sat for 6 months and it started in 6 pulls this winter) and once it starts it stays running and idles great.

Looking for some advice, do you think it is worth trying to clean up the cylinder and piston? Sounds like it is not easy to get a new piston for the Jonsered 490's anymore. Can I lightly hone the cylinder?

I have done some searching and some say that you could also put a piston / cylinder combination on it from a Husqvarna 51 or 55 rancher? Anyone ever had any experience with that?

Any advice appreciated. I have been tempted to sell it being I don't use it, but it seems like a well built saw and I would like to use it and is in good condition otherwise.

Mark

 

[almondgt]

Welcome.....Jonsered 490 piston, yes, difficult to find. Can you clean up the cylinder and install a new piston ring to the original piston? Check your crankshaft seals for leakage. Pictures here help diagnosis alot if you have a mind to provide same.:msp_smile:

 

[mtfallsmikey]

Welcome, looks like you already have a good start on your collection, CAD must be setting in, glad you found us....
Newbie rep for ye.

:newbie:

 

[Chainsaw Mark]

Thanks for the advice and welcome. I need to pull the cylinder off and get a better look at the cylinder and piston and go from there. When I get it pulled off (may be a while as my son is badgering me to get his snowmobile fixed first) I can get some pictures and post and get some advice from there.

Welcome.....Jonsered 490 piston, yes, difficult to find. Can you clean up the cylinder and install a new piston ring to the original piston? Check your crankshaft seals for leakage. Pictures here help diagnosis alot if you have a mind to provide same.:msp_smile:

 

[Chainsaw Mark]

Hi mtfallsmikey, Thanks for the welcome! CAD has definitely set in! I'm at the point where there is always room for another! I've come along ways since my low point when I bought the McCulloch 3516 from Home Depot back in the early 90's! I've learned a lot since that day and hope to learn a lot more from you guys on the forum.

Welcome, looks like you already have a good start on your collection, CAD must be setting in, glad you found us....
Newbie rep for ye.

:newbie:

 

[mama]

Yes you can use a husky 55 top end it, I put a closed port 5000 top end on my husky 55. I do believe that the 490 is the same as the partner 5000, never owned a 490 so not positive though.

 

[nmurph]

I think the 490 uses a 46mm cylinder while the 5000 uses a 45mm. Yes, a closed port 55 P/C is the same (I believe), but they are very, very hard to find.

 

[SawTroll]

I think the 490 uses a 46mm cylinder while the 5000 uses a 45mm. Yes, a closed port 55 P/C is the same (I believe), but they are very, very hard to find.

Afaik, the P5000 and 490 use 44mm, and the 590 and 2051 45mm - the closed port 55s also used 45mm, and some more. 46mm was used on the P5500, 2054, open port 55s, P540, P543 and 2055.

There were more models involved as well, but that is enough exemples for now.....

 

[nmurph]

Afaik, the P5000 and 490 use 44mm, and the 590 and 2051 45mm - the closed port 55s also used 45mm, and some more. 46mm was used on the P5500, 2054, open port 55s, P540, P543 and 2055.

There were more models involved as well, but that is enough exemples for now.....

OK, I was a mm off, but I thought the 325 and 490 both used the 45mm and the 5000 used the 44mm. There is some serious confusion on the specs of these models.

 

[Chainsaw Mark]

I happen to have the book for the 490 here and so here are the specs from the book. It is a 44 mm bore. Will pull it apart in a week or two and post pictures. Hopefully the piston / cylinder can be salvaged given how hard they are to find.


Mark

OK, I was a mm off, but I thought the 325 and 490 both used the 45mm and the 5000 used the 44mm. There is some serious confusion on the specs of these models.

 

[nmurph]

I happen to have the book for the 490 here and so here are the specs from the book. It is a 44 mm bore. Will pull it apart in a week or two and post pictures. Hopefully the piston / cylinder can be salvaged given how hard they are to find.


Mark

Please do. I am interested in concrete info on the permutations of these saws (490, 5000, 5000+, 325, 55CP).

 

[Modifiedmark]

OK, I was a mm off, but I thought the 325 and 490 both used the 45mm and the 5000 used the 44mm. There is some serious confusion on the specs of these models.

Neal, Niko has them all correct but didnt add the PP325 to the 46mm list. Just remember that the PP325 is the same saw as the Partner 5500.

 

[nmurph]

Thanks...there shore is a lot to lurn!

 

[pioneerguy600]

Neal, Niko has them all correct but didnt add the PP325 to the 46mm list. Just remember that the PP325 is the same saw as the Partner 5500.

Very good to know that ,Mark as I was just gifted with two of them 325`s, they seem to have a lot of compression for a small saw. I have been messing with the 590, 500, 5000and 5000+ saws for a couple months now and garnered some serious respect for them all.

 

[Modifiedmark]

Very good to know that ,Mark as I was just gifted with two of them 325`s, they seem to have a lot of compression for a small saw. I have been messing with the 590, 500, 5000and 5000+ saws for a couple months now and garnered some serious respect for them all.

Jerry, I still have not been deep in these yet myself but have a couple of projects on the shelf just waiting a turn on the bench.

What was that top end change you were trying with the 590 to 5000? Did it work out?

I know the 325/5500 were the top of that heap, I have one of each and there hot rods. They will run with the present day 50cc hot rods like the 5100/346. Heck the 490 is really the same as a 5100. I know, I checked em. :hmm3grin2orange:

Someday I'm going to run the 5500 back to back with the 540 just to show how much or how little difference there is between the closed and open ports. I have not run it much but the 56mm open port 540 seems to run pretty good.

 

[pioneerguy600]

Jerry, I still have not been deep in these yet myself but have a couple of projects on the shelf just waiting a turn on the bench.

What was that top end change you were trying with the 590 to 5000? Did it work out?

I know the 325/5500 were the top of that heap, I have one of each and there hot rods. They will run with the present day 50cc hot rods like the 5100/346. Heck the 490 is really the same as a 5100. I know, I checked em. :hmm3grin2orange:

Someday I'm going to run the 5500 back to back with the 540 just to show how much or how little difference there is between the closed and open ports. I have not run it much but the 56mm open port 540 seems to run pretty good.

I did not change/swap that one yet but everything looks easy enough, only the clearance in the cases may need to be enlarged a little to acccept the 590 cylinder sleeve that projects down into the case, it has been claimed, not by me yet, that the 590 is a little wider diameter wise at that point.

 

[SawTroll]

Neal, Niko has them all correct but didnt add the PP325 to the 46mm list. Just remember that the PP325 is the same saw as the Partner 5500.

Didn't remember the model number! :hmm3grin2orange::hmm3grin2orange:

 

[Modifiedmark]

Well Niko, looks like you need a reminder. :msp_tongue:

She's a pretty shade of yellow if you ask me.

 

[Captain Crunch]

. I need to pull the cylinder off and get a better look at the cylinder and piston and go from there.

Might be a good idea to find the cause of the scoring before you year it down. Pressure and vac test are always good starts. Like Sherlock Holmes getting to examine the crime scene Before Lestread tramples the ground up.

 

[Chainsaw Mark]

Good advice, but I think I found the cause of the scoring. When I got it from my brother it was running very lean. I cleaned the carb and it ran 100% better immediately. It idles, accelerates and runs full throttle great now when you first start it up, but will over heat if you cut with it due to the scoring. I'm thinking I should probably put new seals on the crankshaft too just for good measure?? It is a relatively low hour home owner saw. My brother was the original owner and he cut only a few cords of fire wood each year with it. It has the original bar on it yet.

Might be a good idea to find the cause of the scoring before you year it down. Pressure and vac test are always good starts. Like Sherlock Holmes getting to examine the crime scene Before Lestread tramples the ground up.