Got my Closed Port Husqvarna 50 running

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dsell

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I've been collecting parts to put together some 50's for about 3 years. I took this one completely down, new bearings, seals, 246 Golf piston, Partner 5000 Plus closed port cylinder, 51 carb set up, and 55 top cover. Had to file a rib on the top cover that was hitting the cylinder. I eliminated the base gasket and the squish was still .045, I was surprised and a bit worried it wouldn't pump enough compression. Got it running tonight and I am pleasantly surprised, it's already starting to wake up. Warm compression is 150. Tried the zip tie trick on the piston ring and I was ticked. Don't use premium quality zip ties, get the cheap ones with a smooth back and then it works slick.
 

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Nice job, David, but you're probably 40lbs light on compression.

A 5000 Plus would probably be the last stock saw I would sell.

I agree. Is the large squish common on this set up?
 
Nice build. Would you consider a different piston for possibly more performance? I'm leary of golf Pistons.
 
Nice build. Would you consider a different piston for possibly more performance? I'm leary of golf Pistons.

Yes, what else is there? I assume the OEM is rare. The Golf retainer clip broke as I put it in, first time that's happened to me. So, I threw those away and found some Husky clips. They were loose in the grooves, so I had to expand them a bit. I was also concerned that the wrist pin doesn't go from clip to clip.
 
There is a aftermarket piston, factory replacement, but I don't know of any reports on usage. You can use a 44 mm husky open port cylinder piston(50 or 51), will need to do some cylinder work. If you continue to run the golf piston I would keep a close eye on, the circlip story scares me. Let me search for some pictures.
 
I just checked the squish on my nicest 5K+. It was greater than .036" as that is the diameter of the solder. Compression is about 190psi. I have never considered a base gasket delete, but after checking, it has my wheels turning. I may not do it with this saw, but it good to know there's a good bit of gain to be had by eliminating the gasket. I had always assumed the squish would be pretty tight given the high compression number.

The 51 piston will need to have windows cut as the OEM piston is windowed and the 51 is not. I know you can run a non-windowed piston in a window set up, I don't know the implications of doing so in this particular application.

There is a pretty nice AM 5K+ piston on the market. I bought one a year or so ago. Here's a thread I did last year...I still haven't used the piston (and I would do as Dan suggest and use a Caber ring and 346 clips).

http://www.arboristsite.com/community/threads/partner-5000-plus-aftermarket-piston.250381/page-2
 
I need to test my compression gauge. The 51 I rebuilt last week has so much compression that I broke the starter. It reads 150psi and the rope pulls much harder than this saw, squish is .025. If my gauge read 190, I don't think the starter would hold up. I'll have to check with our pneumatics department at work and see if they have an accurate gauge to compare. How do you guys test your gauges?
 
I just checked the squish on my nicest 5K+. It was greater than .036" as that is the diameter of the solder. Compression is about 190psi. I have never considered a base gasket delete, but after checking, it has my wheels turning. I may not do it with this saw, but it good to know there's a good bit of gain to be had by eliminating the gasket. I had always assumed the squish would be pretty tight given the high compression number.

The 51 piston will need to have windows cut as the OEM piston is windowed and the 51 is not. I know you can run a non-windowed piston in a window set up, I don't know the implications of doing so in this particular application.

There is a pretty nice AM 5K+ piston on the market. I bought one a year or so ago. Here's a thread I did last year...I still haven't used the piston (and I would do as Dan suggest and use a Caber ring and 346 clips).

http://www.arboristsite.com/community/threads/partner-5000-plus-aftermarket-piston.250381/page-2

Nice to know about this piston. Did you happen to check to see if it was round and how much taper? How much clearance did you have at the bottom of the cylinder and skirt?
 
Had the pneumatic department test my compression gauge. They said it varies 10 psi, 150 to 160 at 160 test pressure. If the needle comes all the way down, it's accurate, but it doesn't always completely return. So, I orderd an OTC 5606 from Sears for $35. Had 11k shopper points and 10k surprise points, besides it's on sale.
 
Checked the cold compression twice with the OTC and it's 185. Ran a few tanks through it this weekend and it absolutely screams. When I took the cover off I noticed the air filter was off the base. I'm sure it sucked in some dust, but happy I caught it. I changed the base the filter snaps into and it seems to hold the filter better. I see why the later models have a screw to hold them on.
 
:guitar: When you let those R's come up, she was cuttin' great!

On a side note, I need a new comp tester. Any chance you double checked the accuracy on the OTC?
 
Yes, last weekend when I was cutting smaller branches it was going nuts.

The OTC is showing 35psi more than my old tester at 185. The old tester was 10 lbs off at 150 tested against an air compressor with a good gauge. The way I'm going through 50 series starters, I don't doubt the reading.:)
 

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