Jonsered Chainsaws

[SawTroll]

A question that has turned up a couple of times lately is about alternative topend for the rather obscure Jonsered 525. All I can think of is possibly a 520 or a 535 top end, but I don't really know if they fit.

I'm also thinking of the 2051/2054/2055 top ends, as those also have vertically split mag cases, but really have no idea if they fit.

Does anyone have any input regarding those, or something else?

 

[67L36Driver]

Initial L & H jet settings for a 670?

My Clymer book calls for 1 1/4 turn on each but, it has been wrong before. R&R'ed the freakin carb. about six times now and I am millimeters away from just buying a new one. Yikes!

Yes, I cleaned it with Gumout spray and swapped metering levers setting 'em low and high. Full kit and tried different metering diaphrams (Stens and Tillotson) etc. but no love. I can nurse it along with the choke almost shut so I think something is hopelessly clogged up. Pump side is feeding fuel just fine.

The only thing I have not done is pull the welsch plug.

 

[SawTroll]

Initial L & H jet settings for a 670?

My Clymer book calls for 1 1/4 turn on each but, it has been wrong before. R&R'ed the freakin carb. about six times now and I am millimeters away from just buying a new one. Yikes!

Yes, I cleaned it with Gumout spray and swapped metering levers setting 'em low and high. Full kit and tried different metering diaphrams (Stens and Tillotson) etc. but no love. I can nurse it along with the choke almost shut so I think something is hopelessly clogged up. Pump side is feeding fuel just fine.

The only thing I have not done is pull the welsch plug.

The Jonsered specs are 1.0 turn out on both screws.

 

[67L36Driver]

The Jonsered specs are 1.0 turn out on both screws.

That being the case something is deff. clogged up.

If if find crud under the welsch plug it will be a first.

It is a Tilly HS but not the same body style as what I have laying around or I would just swap throttle and choke shafts and pump side cover.

 

[Real1shepherd]

This is why I always start by stripping out the carb and soaking it in specific carb cleaner stuff with the built in tray. I've never had a problem that way and they look like new. Sometimes just spraying carb cleaner around is not enough. Every HS carb I ran was 1 1/4-1 1/2 for low speed and 3/4-1 turn out for high speed. If it can't run in that range, stock, something is rotten in Denmark.....

Kevin

 

[67L36Driver]

Could this be part of the problem?



Someone has pried open the muffler outlet and discarded whatever deflector had been there. The exit area is way large and maybe cause contamination of the A/F mixture.

Sometime back I attempted to start a rebuit Homelite (reed valve saw) without any muffler without success. Only after I installed the muffler from another saw, was I able to get it to run.

 

[cambl]

The missing deflector and screen won't matter- it will just bark louder.

 

[Real1shepherd]

I agree with that....after all, in muffler modding they often make two opposed outlets with deflectors or 'hoodies'.

Kevin

 

[Cantdog]

Could this be part of the problem?

View attachment 340635

Someone has pried open the muffler outlet and discarded whatever deflector had been there. The exit area is way large and maybe cause contamination of the A/F mixture.

Sometime back I attempted to start a rebuit Homelite (reed valve saw) without any muffler without success. Only after I installed the muffler from another saw, was I able to get it to run.

Hell....you gergot ta put the piston back in it!!!...LOL!!

As already said the muffler won't cause this kind of problem.....

Sounds like an impulse problem to me.....with either with the carb/pump or the line/corridor. Check and make sure your impulse line has no splits or leaks and internal corridor is clear.....should be able to blow or suck air (both) easily into the crankcase through the impulse line. I assume you already have checked the fuel line and filter....also make certain the final fuel filter under the top cover in the carb is clear...or maybe you replaced that with the rest of the kit........if you think it may be crud under the welsh plugs...take out both H & L needles and using the red straw inserted all the way into holes where the needles go, and spray WD40 in each whilst holding the throttle plate and choke open and watching.....WD should come out two orifices when sprayed in the L......one on either side of where the throttle plate is when closed (idle). WD should squirt freely out of the single orifice in the center of the bore when sprayed in the H...if not then you gotta pull the offending welsh plug.....it's rare but I have had clogged H orifices before....hope this is of some help....

 

[67L36Driver]

Pulled the welsch plugs and found nothing. Shined penlight and you can see the tiny holes are clear. So, we raised the metering lever half a thickness above the chamber floor in the carb. and now we are flooding again.

Going to pull the carb. for the seventh time and put the lever back to level.

B.T.W. This thing pumps only 125 with new piston/ring and cleaned up cylinder. No pits scores or scratches. I was looking for 140-150.

 

[67L36Driver]

This reminded me of a Husky 340 I had. Pup would flood at the slightest excuse. Never did get the A/F mix just right.

Traded it for a Homie XL-925.

 

[WoodDean]

Sorry for the time between posts......down in Costa Rica and few places to get on line. I sent Dean a NOS carb gasket along with the NOs cyl base gasket and though it has two holes it is still possible to get it flipped the wrong way I believe......that's why I said to be certain that the hole in the gasket lines up properly with the hole in the carb body..........don't worry about how it goes against the manifold as long as it lines up with the carb.....be back stasteside in a few days......looks like more snow on the Rockbound Coast of Maine today.....haven't seen any of that down here!!!

Hey Guys, finally got a chance to look at this. See attached pics;

The carb gasket before it's slid into place. If you flip it, you get the same fit.

 

[WoodDean]

Sorry for the time between posts......down in Costa Rica and few places to get on line. I sent Dean a NOS carb gasket along with the NOs cyl base gasket and though it has two holes it is still possible to get it flipped the wrong way I believe......that's why I said to be certain that the hole in the gasket lines up properly with the hole in the carb body..........don't worry about how it goes against the manifold as long as it lines up with the carb.....be back stasteside in a few days......looks like more snow on the Rockbound Coast of Maine today.....haven't seen any of that down here!!!

The same carb gasket on the carb. If you flip it, it looks to me like you get the same fit.

 

[67L36Driver]

Cannot find the 'happy place' on this 670. Dropped the metering lever back down to level with the chamber floor and at first it would only run with the choke 2/3 closed. Then it proceeded to flood out.

On a positive note; I can clear a flooded saw by running both mixture screws all the way in and pull untill it runs and runs out of fuel.

 

[Real1shepherd]

The same carb gasket on the carb. If you flip it, it looks to me like you get the same fit.

View attachment 341240

Dean,
Did you do a vacuum and pressure test on the carb itself? The gasket looks fine....eventually, that saw needs to just live here....when you get tired of fighting it, of course.

Kevin

 

[WoodDean]

Dean,
Did you do a vacuum and pressure test on the carb itself? The gasket looks fine....eventually, that saw needs to just live here....when you get tired of fighting it, of course.

Kevin

Not yet, but I think you're right and that should be my next move. Everything else seems to be checking out ok.
I have a little bit of fight left in me yet . . . . . . plus, I have all these new parts now!!!

NOS cylinder is currently in my possession. I won't be long now . . . .I can feel it.

 

[Real1shepherd]

Not yet, but I think you're right and that should be my next move. Everything else seems to be checking out ok.
I have a little bit of fight left in me yet . . . . . . plus, I have all these new parts now!!!

NOS cylinder is currently in my possession. I won't be long now . . . .I can feel it.

Lol...the parts will sell again for at least what you paid.

Kevin

 

[Real1shepherd]

Decent looking 801 on the bay right now....seems to be complete. Two days to go, no bids...starting@$250.00USD. If you've been waiting for a complete 801 for a long time, this may be the saw for you....no 'deal' though. Love me the old saws with no chain brakes...
http://www.ebay.com/itm/Jonsered-801-Runs-Good-Nice-Shape-

 

[67L36Driver]

Where can I get a new carb. for the 670 at resonable price? Tilly HS230C or HS237A

Tired of messing with the darn thing. It either starves for fuel or floods out.

 

[Real1shepherd]

I see used HS carbs for J'reds all over the Net, but mostly on the bay. I got tired of buying them and had to put the brakes on future acquisitions...I won't live long enough to use them all.....lol

They're not the size you are looking for, sorry.

Kevin