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Switch from spur to rim on a 61

Started by DHansen, May 01, 2022, 09:10:49 PM

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DHansen

I removed a excessively worn out and neglected 7 tooth spur drive sprocket from a Husqvarna model 61.   I see an Oregon part number replacement 26831 rim style with 7 tooth rim.  But I also found a Husqvarna # 501 831 503 rim style.  However, the Husqvarna comes with an 8 tooth drove sprocket.  I have an extra 7 tooth also.  I plan on running an 18" bar.  So I think I should just run the 8 tooth sprocket.  Looking for advise on pros vs cons on the 7 vs 8 tooth drive sprocket.  Looks like the 61 was available new with either a spur or rim.

 

sawguy21

You will be fine with the 8 tooth, the saw has the torque to handle the additional chain speed. For more than occasional consumer use the rim is preferable.
old age and treachery will always overcome youth and enthusiasm

DHansen

Thank you Saw Guy.  Appreciate the information.  Will the 8 tooth rim spin the chain faster than the 7 tooth?  With eng rpm the same.

Real1shepherd

Yes it will. You need some torque to pull it off, but you'll be fine for the bar size you're using and that saw. 

Kevin

ladylake

 

 Most likely a 8 pin will cut slower in big wood but you sure can try it.   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

Spike60

I think, (not sure). that the multiplier is around 15%. So, 15% increase in chain speed and a corresponding loss of torque. 8 pins were almost universal on saws like the Jonsered 70E, as it had gobs of torque but only spun at 11,000 rpm.  On something like the 61 it is definitely not for users who like to push on the saw. But like the other guys are saying, you should be OK with an 18 on it. It's a bit of a technique thing; pushing vs letting the chain speed do it's thing.

Since you have them both how 'bout you compare them and then share your impressions? :)
Husqvarna-Jonsered
Ashokan Turf and Timber
845-657-6395

DHansen

I will try the 8 tooth first.  Then switch to the 7.  Will see how it goes. My take on this is performance will be based on if the engine doesn't get lugged down. Like pulling up a hill in second gear when I should have been in first.

Real1shepherd

Like Bob said, torque is everything when you step up the tooth count. But given the bar you want to use and a sharp chain, it's doable. However, you'll definitely notice the difference in available torque. Whether or not you can compensate for it, or even like using the 8 tooth rim remains to be seen.

I tried it in back in the day on large cc Huskies. I don't like anything messing with my torque....so I wasn't a fan, but some swore by it. Different strokes for different folk, literally!.

Kevin

Sprinter

In the power transmission world, drive sprockets are normally odd numbered while driven sprockets are even. 
This is to even out wear to sprocket and chain by allowing the teeth to encounter a different link on every turn.
Some folks use a 7 tooth driver as standard and change driven to make speed adjustments.
May not matter here, just a thought.

DHansen

So, while doing this upgrade from a spur sprocket to a rim sprocket, I found the 61 used a fine thread or a course thread for the clutch to crank threads.  Also two or three shoe clutch.  This 61 is fine thread, and three shoe.  I decided to test run the 8 tooth rim first.

 

DHansen

So one solid day of cutting with the 8 tooth rim sprocket.  No complaints of the performance of torque in the cut.  Ash and Oak.  New bar and new chain. Using Oregon 72EXL chain and Sandvic bar.  Will cut one more day with it, switch to 7 tooth and put a new chain.  This way it will be as close as apples to apples that I can do.  

DHansen

There were some new parts used with the rim setup vs the spur setup.  Photo shows a steel plate that protects the oil drive gear and a plastic white shield that sets into a groove in the oil pump housing.  This seems superior over the spur that only has a metal plate that is attached to the hub.  Spur style seems to allow more debris in the oil pump drive gear area.

 

DHansen


DHansen

Well the broken fins on the starter cover were bothering me.  Just cosmetic, but might as well make the old 61 look respectable.

In the photo upper left corner you can see the damaged fins.  Well easy enough.  Bought a opened package new OEM starter cover and went to switching it over.

 

DHansen

Thought it would be just untie knot, remove starter handle, thread rope through cover and two Philips screws holding the recoil assembly to the starter cover.

When all else fails, read the instructions, right!

Well the spring comes out and reminded me of my youth and having to rewind the springs on the old Brigess and Stratton go cart motors.

A few patient minutes later and three attempts, the cat was back in the box. Reassembled and happy with the final product.

 

 

 

DHansen


DHansen

Information for someone who is putting the recoil spring back into position here was what worked for me.  With starter cover on the bench, start with the outer most coil of the spring.  It has a hooked end that fits snug into the tab on the starter cover.  Start rolling the coils one loop at a time into the cover.  Use your fingers to hold the coils down and in position.  Three points equally spaced around the spring works well.  Put center spool in with rope already spooled.  There is a slot on the spool to retain the end of the rope.  Rotate the spool about 1/2 to 3/4 of a turn clockwise.  Thread rope end through the hole in the cover and put handle on.  Tie off end with a good knot.   This gave me good recoil tension and pulled handle back to a secure rest into the cover.

DHansen

 

 

A double loop knot on handle end.

    a tuck under the first wrap on the recoil end.   Melted both ends to prevent fraying.

petefrom bearswamp

Regarding Husky 61 saws, anyone here have a problem with the muffler working loose and the attaching screws stripping the holes?
If so is there a good fix?
I bought the saw in 93 and gave it to my son about 12 years ago When I upgraded to an Echo cs600p.
He has retired it due to the muffler problem
Kubota 8540 tractor, FEL bucket and forks, Farmi winch
Kubota 900 RTV
Polaris 570 Sportsman ATV
3 Huskies 1 gas Echo 1 cordless Echo vintage Homelite super xl12
57 acres of woodland

DHansen

I have always torqued, test run for 10-15 minutes then retorque again while still warm.

However, once the threads are damaged and no longer able to be torqued to spec, I have drilled and installed a time-sert brand insert.  You could also go up a size and modify the holes through the muffler.   

I would also wait for a reply from Spike who would have some great advise.

DHansen

Had storm damage Monday evening.  Had to get to work on it so power lines could be repaired.  So just ran the 61 with the 8 toothed drive sprocket.  Full day of cutting.  4 Gallons of fuel through the saw.  Cut up some pine, oak and ash.  No problems at all with this 8 tooth sprocket.  Neighbor noted how well the saw was cutting.  He put his saw down and run my 61 for two tanks.  Now he wants one just like it.


Al_Smith

Four gallons in a day on that sized saw is a lot of run time and a long day .Most saws no matter who made them is about 40 minutes of run time per tank full on a stock saw .More of course if it's modified .I myself would not use that much fuel in a month .

DHansen

I had a mess to clean up.  

 

 

DHansen

I did fill neighbors Jonsered saw once, and my echo twlce.  All the rest went into the 61.  Started my day at 4:30, started the saw at 6:00. I know I cut for a good 12 hours.   Had a lift truck come out to pull the trunk out of my pole barn.  That crew made four large cuts and hauled away the pine trunks.  One pine was 85 feet.

Al_Smith

Those straight line winds can do some damage .Usually around here they come from the west and going over Indiana they pick up speed .As far as I know the only thing I lost was a black cherry from a big blow about 3 weeks ago .Too skinny to save for lumber but growing in competition about 90 feet tall .Broke it off like a match stick .There were trees down every where in this location like big hickories .Business for the tree trimmers and next years firewood for some I suppose .

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