Jonsered 920 piston and cylinder ID

[beavis331]

This is my uncles 920 jonsered. The fuel tank was all messed up. I was going to go through and clean the tank and put all new seals bearings piston and rings. My uncle has had this saw to every saw shop in the country and I don't think even he knows exactly what all has been done to it. Is this the right piston and cylinder and the new piston is wrong or is the new piston right and the old piston and cylinder wrong. Everything measures 54mm.

Thanks
Tom

 

[Foragefarmer]

That is a 930 cylinder. The piston may be from a 910 but I am not sure on that.

Yup, It has the 910 decomp. on the cylinder.

 

[shawn022]

Your uncles 920 appears to be a 910, at least the p/c is. Is the rear handle of the saw metal or plastic? There has been some discussion of 910- 920 p/c swaps but I don't think anyone has gotten around to trying it.

 

[shawn022]

I don't think its a 930 cylinder. See the small hole above the transfer? Thats for the decomp that only the 910 has.

 

[shawn022]

I will say that the 910's I have seen, the intake clamp is a plastic zip tie. That one has the metal wire clamp found on the 920's. Some one may have upgraded it or there was a change in the 910 clamp and I have not seen one yet.

 

[Foragefarmer]

I don't think its a 930 cylinder. See the small hole above the transfer? Thats for the decomp that only the 910 has.

Yeah, I missed the decomp. hole on first glance.

 

[Cantdog]

The one in the saw looks more like a 90 piston to me......though it may just be the angle of the pic....the 910 piston has some crown but the 90 has about twice as much....they both are machined from the same piston blank and carry the same casting numbers on the inside of the piston and measure about 0.618"from the top of the wristpin to the edge of the crown.....a 90 piston will up the compression a good amount in a 910 cyl.....definitely a 910 cyl......

 

[beavis331]

Here is the thread from back when i first acquired it.
http://www.arboristsite.com/community/threads/help-with-jonsered-id.127540/
At that time we figured that it was either a 820 or 920.

The story my uncle told me was that he burned up a cylinder on it and the dealer did not have a new one on hand. And he was not willing to wait so the dealer put a different cylinder on it. I always just assumed that it was a 920 that the dealer put an 820 p&c on to. So they must have put a 910 p&c on it. It also has a 910 ignition system with the coil on top of the sparkplug. Cripes maybe it is a 910 with 920 air cleaner and top cover. It is at the shop now so I won't be able to look at it until tomorrow.

Thanks Guys. Your expertise is much appreciated.

 

[beavis331]

just looked at some google pics. It definately has the 920 rear handle.

 

[beavis331]

@shawn022 , you are right. It is a 910 with enough 920 parts added to make identification tricky.

This pic is of the saw in question on the left and a 920 case half I bought for another saw on the right.


This is a close up of the saw in question.


This is a picture of a 910 that google images pulled off an old ebay auction.


Looking at the mounts for the top handle definitely seals the deal. Definitely a 910 that is know sporting 920 front and rear handles.

Does anyone know if the bearings and seals are the same between a 910 and 920? My current plan is to go ahead and replace the bearings and seals and install new rings and run it as it is. Since the piston and cylinder are in good shape it should run forever with the amount of use it will get with me.

 

[beavis331]

Looks like my case gasket isn't gonna seal the fuel tank. You can see my fuel tank issues real good in this pic. My plan is to clean the fuel tank really well and then line with a quality fuel tank liner. The liner will work to seal the gap in the gasket as well.

 

[Fishnuts2]

I will say that the 910's I have seen, the intake clamp is a plastic zip tie. That one has the metal wire clamp found on the 920's. Some one may have upgraded it or there was a change in the 910 clamp and I have not seen one yet.

I'm redoing my 910 and am wondering where to find that clamp. Or just a zip tie?

I bought a 920 chassis for handle parts and it appears that with some minor mods the 920 handles can fit on a 910.

 

[beavis331]

I'm redoing my 910 and am wondering where to find that clamp. Or just a zip tie?

I bought a 920 chassis for handle parts and it appears that with some minor mods the 920 handles can fit on a 910.

According to @shawn022 the 910 originally had a zip tie and the 920 had a wire. There is nothing special about the wire. Looks like a piece of baling wire. I think I would go that route if I were doing it.

 

[Jacob J.]

It was pretty common as dealers ran out of 920/930 parts to rebuild saws with 910 top end parts. The shop I worked at back in 2000-2006 was a Jonsered dealer from 1971 to 2002 and they had put some 910 pistons in a couple 920s. I got the saws back in from customers during that time and I was able to source them 920/930 parts off ebay to get the saws going again.

 

[beavis331]

It was pretty common as dealers ran out of 920/930 parts to rebuild saws with 910 top end parts. The shop I worked at back in 2000-2006 was a Jonsered dealer from 1971 to 2002 and they had put some 910 pistons in a couple 920s. I got the saws back in from customers during that time and I was able to source them 920/930 parts off ebay to get the saws going again.

That is very interesting. It looks like this saw was the opposite. It is a 910 with plenty of 920 parts added to keep it going.

 

[beavis331]

The case halves are all cleaned up. I am going to brush some gas tank liner to coat the inside of the tank area. Everything will be sealed and no more fuel issues.

 

[beavis331]

This is as far as I am going to get today. Might be a week or two or three before I get back to it.