Jonsered Chainsaws

[edju1958]

I think I found a pic ...is this what it looks like ?
View attachment 1110603

Here's what I got Ernie.

 

[ErnieG]

Well these are the ones in my kit with some other smaller ones and it doesn't look like I have that one...

Ernie

 

[numnutz6383]

I'm back to my Jonsered project(s), this time to my 910, as I started working on it as the 451 cylinder was being welded.

I tore down the 910 yesterday. The connecting rod doesn't have any excessive slop in it, the crankcase looked clean, and the bearings spun without grinding or noise, so I'm happy about that. As you can see, the piston was quite damaged, the top ring was seized up in the grooves, and major scoring is present on the exhaust aide. But I think the cylinder may be salvageable using the Mastermind method, I didn't feel any major raised areas with my finger nail.

Intake side:

Exhaust side:

Cylinder, exhaust side:

Cylinder, intake side:
l

In the process if disassembly unfortunately I found that that muffler CAP* is in pretty poor condition. Bottom right (bottom left in the image) attachment point has rusted off, as well as a spacer on the back side of the front cover of the muffler (top left in the image).
Interestingly, there was no muffler gasket in place, and I'll need to make one since they're NLA.

I haven't had any luck finding a replacement on fleabay as of yet. Longshot, I know, but if someone has an extra laying around, PM me.
*Is this cap a necessary component of the muffler? It isn't even listed in the IPL that I can see.

Out of curiosity, what is this black tube underneath the muffler? Oil line?

The fuel tank vent valve tip is also pretty rusty, also hard to find. Any substitutes from other models?

Is the Fel-Ramic gasket material something I should invest in or just cut it from Karropak stuff I have fine?

 

[Real1shepherd]

I'm back to my Jonsered project(s), this time to my 910, as I started working on it as the 451 cylinder was being welded.

I tore down the 910 yesterday. The connecting rod doesn't have any excessive slop in it, the crankcase looked clean, and the bearings spun without grinding or noise, so I'm happy about that. As you can see, the piston was quite damaged, the top ring was seized up in the grooves, and major scoring is present on the exhaust aide. But I think the cylinder may be salvageable using the Mastermind method, I didn't feel any major raised areas with my finger nail.

Intake side:
View attachment 1113364
Exhaust side:
View attachment 1113367
Cylinder, exhaust side:
View attachment 1113369
Cylinder, intake side:
View attachment 1113370l

In the process if disassembly unfortunately I found that that muffler CAP* is in pretty poor condition. Bottom right (bottom left in the image) attachment point has rusted off, as well as a spacer on the back side of the front cover of the muffler (top left in the image).
Interestingly, there was no muffler gasket in place, and I'll need to make one since they're NLA.
View attachment 1113373
I haven't had any luck finding a replacement on fleabay as of yet. Longshot, I know, but if someone has an extra laying around, PM me.
*Is this cap a necessary component of the muffler? It isn't even listed in the IPL that I can see.

Out of curiosity, what is this black tube underneath the muffler? Oil line?
View attachment 1113371
The fuel tank vent valve tip is also pretty rusty, also hard to find. Any substitutes from other models?
View attachment 1113385
Is the Fel-Ramic gasket material something I should invest in or just cut it from Karropak stuff I have fine?

Not familiar with Fel-Ramic.....these aren't intricate devices and so I just use Karropak and similar. Oil line, yes,

On the exhaust gasket, I use that metal impregnated stuff that resembles the OE. Hard to cut, but worth the effort. Piston looks pretty bad. You can clean it up and drop it in your cylinder with the cylinder turned upside down. If it floats down, it will probably work.

Cylinder will most likely clean up if you can't run your fingernail across anything bad. You've got nothing to lose, so give 'er a shot!

Kevin

 

[numnutz6383]

Not familiar with Fel-Ramic.....these aren't intricate devices and so I just use Karropak and similar. Oil line, yes,

On the exhaust gasket, I use that metal impregnated stuff that resembles the OE. Hard to cut, but worth the effort. Piston looks pretty bad. You can clean it up and drop it in your cylinder with the cylinder turned upside down. If it floats down, it will probably work.

Cylinder will most likely clean up if you can't run your fingernail across anything bad. You've got nothing to lose, so give 'er a shot!

Kevin

Well I have that P+C I got from @Cantdog, I'm just thinking ahead in case I need another one in the future.

Could you share which metal impregnated stuff you use for exhaust gaskets?

 

[numnutz6383]

On my 910, what is the purpose of this muffler cap, and issue running the saw without it?

 

[Cantdog]

No problem running without it. It's purpose is to protect the muffler from being dented and beat up in use from the saw being pullled into the work. A good thing to have but not a necessity. It also provides an insulated barrier to keep the hot muffler away from flamable materials

 

[Real1shepherd]

Well I have that P+C I got from @Cantdog, I'm just thinking ahead in case I need another one in the future.

Could you share which metal impregnated stuff you use for exhaust gaskets?

I'm working down in SoCal until Oct 4th, so am a long way from home. I would have to look at the gasket sheet for a brand name when I get back. Had it forever....

Kevin

 

[numnutz6383]

No problem running without it. It's purpose is to protect the muffler from being dented and beat up in use from the saw being pullled into the work. A good thing to have but not a necessity. It also provides an insulated barrier to keep the hot muffler away from flamable materials

Kinda figured, thanks!

I found this bar on fleabay and was curious if you guys can decipher the numbers to tell whether this is a d024 mount. I asked the seller but they seem to be poor communicators and my Google-fu seems to be weak



Also, if anyone is looking for a top end for a 910, I found this searching around for parts.
Considering what parts are going for, I thought it was a decent price, given all the parts included, and looks to be in good condition Jonsered 910 top end.

 

[numnutz6383]

I realize that there is a lot about best practices for rebuilding small engines that I know I don't know, I've gleaned much information from many posters on the forum, particularly on this thread, howevers there's probably even more that I don't know that I don't know.

What are some of the biggest mistakes you guys find newbies/DIYers/non-pros make with respect to rebuilding chainsaws and small engines that you wish they knew?

 

[Cantdog]

I realize that there is a lot about best practices for rebuilding small engines that I know I don't know, I've gleaned much information from many posters on the forum, particularly on this thread, howevers there's probably even more that I don't know that I don't know.

What are some of the biggest mistakes you guys find newbies/DIYers/non-pros make with respect to rebuilding chainsaws and small engines that you wish they knew?

Biggest mistake is rebuilding a blown up saw top end without finding the reason it failed in the first place….. and curing that before the new top end goes the way of the first…..

 

[numnutz6383]

Biggest mistake is rebuilding a blown up saw top end without finding the reason it failed in the first place….. and curing that before the new top end goes the way of the first…..

I've seen you make this comment numerous times on the forum. It's been well cemented in my head, but I feel I may have already made the mistake not pressure/vacuum testing before disassembly.

When I eventually do get this 910 assembled I will make sure it passes before even attempting to start it.

 

[Cantdog]

I've seen you make this comment numerous times on the forum. It's been well cemented in my head, but I feel I may have already made the mistake not pressure/vacuum testing before disassembly.

When I eventually do get this 910 assembled I will make sure it passes before even attempting to start it.

Yep I generally replace the crank seals just as part of the rebuild…. Cheap insurance and unless I know they have been changed recently they get replaced. Most saws I work on are 30-40+ years old and even if they hold vac and pressure when tested you never know how long before they don’t !!!! Rubber only lasts so long!!

 

[numnutz6383]

Yep I generally replace the crank seals just as part of the rebuild…. Cheap insurance and unless I know they have been changed recently they get replaced. Most saws I work on are 30-40+ years old and even if they hold vac and pressure when tested you never know how long before they don’t !!!! Rubber only lasts so long!!

Good thing I purchased 2 sets of seals (Dichtomatik and SKF, just to see how they compare) as was expecting to hear this from you and @Real1shepherd. The seal debacle with my 451 left me scarred and I didn't want to accept reality at first.

 

[numnutz6383]

Nice looking for sale 910 in CT. Guy says he has a 920 as well.

 

[Cantdog]

Good thing I purchased 2 sets of seals (Dichtomatik and SKF, just to see how they compare) as was expecting to hear this from you and @Real1shepherd. The seal debacle with my 451 left me scarred and I didn't want to accept reality at first.

Another couple things to be certain of on the 910 is the intake boot and impulse line. Both rubber….. any cracks or unusual soft spots in the boot or line and it/they will want to be replaced. Also make certain the joint between the boot and cyl is tight with no leaks

 

[numnutz6383]

Another couple things to be certain of on the 910 is the intake boot and impulse line. Both rubber….. any cracks or unusual soft spots in the boot or line and it/they will want to be replaced. Also make certain the joint between the boot and cyl is tight with no leaks

I was able to find a NOS boot, figured I'll just replace it. I saw either you or @Real1shepherd calling the zip-tie holding the boot to cylinder silly, so I figured I may as well replace it with the clip or clamp from the 920/930. So those were purchased as well.

 

[Cantdog]

I was able to find a NOS boot, figured I'll just replace it. I saw either you or @Real1shepherd calling the zip-tie holding the boot to cylinder silly, so I figured I may as well replace it with the clip or clamp from the 920/930. So those were purchased as well.

Nice!!! But still check it once installed for leaks with light pressure and soapy water

 

[Real1shepherd]

Biggest mistake is rebuilding a blown up saw top end without finding the reason it failed in the first place….. and curing that before the new top end goes the way of the first…..

I would go even further......if you don't understand how the damage happened, can't see it etc., you shouldn't be repairing it without an Elmer of some kind. I find often the people who are self-taught are the same ones fueling misconceptions across the Net. The exception being people in the mechanical/engine trades can easily adapt to chainsaws.

No shame in learning from someone experienced. Good shop practices are taught; you're not born with 'em.

In answer to the original question.....it's the shop practices that make a good repair......that and using decent parts.

BIGGEST mistake? Assuming that the crank seals in a 30+ yr old saw are 'OK'. Even passing the vac/pressure test, you have time working against you. I know of people that bought uber rare saws with virtually no support, ran a couple of tankful's through them only to destroy the top end from leaking seals. Expensive, rare saws.......just dumb, especially when crank seals are relatively inexpensive.

Kevin

 

[Cantdog]

Now that's one worn out 80 !!!!!!...LOL!!

https://www.ebay.com/itm/4045270152...Iauxwy4MEd7XaULGLODxRVvQ==|tkp:Bk9SR76CgdzdYg