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Pro Mac 650 bar/chain questions

Started by McLovin, March 10, 2012, 04:49:43 PM

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McLovin

Hi guys - great forum you all have here, so I hope I can get a little knowledge on my saw if someone can assist.

Trying to find out a couple of bits of info about my chainsaw for buying parts for it as it needs a spruce for work I need to do (new chain mostly for now).

It's a McCulloch Pro Mac 650 which is quite an old beastie of a saw and weighs a ton compared to a modern one, but it runs superbly as it's been out of action most of its years, before it was given to me.  I was told it didn't work, but it had good compression so I stripped it down completely and it was soon apparent that it just wouldn't run as every conceivable nook & cranny were rammed solid with oily wood mulch.  Cleaned it all up and reassembled and it runs easy and strong now.

Need a new chain and I know I can just take it to the garden centre bloke and say "I'd like one of these please", but I ought to know what's what really.
The bar is fairly short on it considering the bulk/weight of the saw, but the measuring techniques described online seem a bit vague.

Removed from the saw, the full length of the bar is 18.5 inches, and I gather the 'actual' (stated) length usually measures the length of the bar that protrudes from the saw body.

Seems daft given that when you adjust chain tension the bar moves in & out.  Is there another exact way to measure (without seeing a webpage that states the part number and what it is)?

Anyway, the bar has 3/8 on it, which I gather is the chain pitch.  So far so good.
It's an Oregon bar and most of the paint has gone from it, but it has the following stamped into it:
7717 VT
160---H102

These numbers aren't telling me a lot so far from Googling or the Oregon website but will keep trying, as the info is nearly always out there somewhere!

The chain itself is marked with '72' on the drive part of the teeth, and '25' on another part of them.

At first I assumed 72 would be the number of teeth/links on this chain for easy reference, but on the Oregon site the chains listed for a Pro Mac saw with varying length of bar seem to have way fewer teeth than this.

Not sure what the 25 refers to though.

Appreciate any input on this thanks.  Hoping to go and get a chain for it tomorrow if I can as I have work to do.
Which leads me to another question - I'm guessing for any given size chain it's possible to get ones that suit certain specific materials?

I've got to cut plywood if there is a style of chain that suits this in particular (excavating wet plywood from my boat's transom).

Many thanks anyway!
Jim

McLovin


Cut4fun

Oregon 72 = 3/8 050 chain. 25 is the factory raker height.

Al_Smith

A 650 is a later version of a PM 610 .Somewhere in the neighborhood of around 4 HP .They're heavy for 60 cc but they can hang right in there with about any 60 made today and although they won't have the speed they do have the McCulloch torque .

18.5 inchs would probabley be a 16" usable bar length .As such it takes 60 drivers of 3/8" chain .As matter of fact the same driver count as a Stihl 16" .

Because of the design they are terrible about packing full of chips under the cylinder .As such if that happens they will overheat and usually cause the solid state ignition modual to fail .Usually after it cools off which might take an hour they start up again .

Pay attention to the muffler screen .Because this saw uses an impulse driven oil pump they can leak and suck bar oil into the crankcase which given enough time will clog the screen and pyralite around the exhaust port which will cut the piston .

Just a few tid bits of info from using a 610 for years .If you keep the crude blown out of the cylinder fins they are usually pretty dependable .

beenthere

Welcome to the Forum.

One of our good sponsors is Bailey's for bar and chain. Don't know if they have what fits, but suspect they do. See left column and tied with Lucas.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

McLovin

Thanks for all the replies guys - really useful info thankyou!

I just counted the driver teeth and there are indeed 60 of them, so thanks to you guys I have the info I need to buy the right chain.  I believe the three main chain types are chipper, chisel, and semi chisel?  Is there a particular one of these that would be especially suited or avoided for cutting end on into plywood?

If I had to guess, I'd imagine that the glues within ply might blunt a chain fairly quickly, but I need to get this old wood excavated and this is the only viable option at present, and the accepted way of doing so.

Al - where you mention the oil pump, is there any way to easily test its operation or identify a failed part of it?
The reason I ask is I was actually under the impression that to lube the bar/chain on this machine I had to manually do it with the pump on the back of the saw body, since otherwise it seems to run dry, so I think maybe it's not oiling itself as it maybe should be doing.

The only other thing with this saw that I'm usure of is the correct positioning of a rotary spring near the brake mech.  The brake works fine I should add, but this spring doesn't appear to be particularly useful for any purpose no matter how I rotate/position it, and it doesn't seem that anything fails to work correctly due to it not being properly hooked up.  That probably sounds like gibberish the way I've described it sorry!

But anyway, this thing was free, and whilst it's a bit scruffy the engine seems very good so I'm pleased to have it.

Al_Smith

The oil pump sets under the cover .It has a screw adjustment which basically limits the stroke on the pump piston .More stroke more oil .Counter clockwise would be more oil .

The easiest thing to do would be run some kerosine through the system which fixes most of them .I've never had any luck trying to repair a diaphragm pump which is what this thing is .They sell new pumps on flea bay for varied prices .

As for the spring ,I have a picture of the assembley some place on one of my computers which I'll try to find and post .It can be a kind of a challange to figure out .

If you're going to cut plywood semi chisel would be the best .Chipper would be better but I have no idea where you would find any .I have some new loops someplace but it's part of my antique stuff and I really don't want to part with it . Flea bay maybe ????

lumberjack48

Carlton Chipper chain, the number is A1S for 3/8, 50 gauge, Semi chisel  guard link, A1EP-GL 3/8, 50 gauge. I think the guard link chain will cut plywood pretty smooth.

A 18" premium Carlton bar, 3/8, 50 gauge, replaceable nose, for a 650 MuCulloch,  bar #18-41-AI64-PS, 64 Driver count.
Third generation logger, owner operator, 30 yrs felling experience with pole skidder. I got my neck broke back in 89, left me a quad. The wife kept the job going up to 96.

McLovin

Thanks for all the info again chaps.

I'm going to have to strip the saw down again I think after using it today.  Managed to get a new chain and a set of files.  Was surprised though as the new chain, whilst fitting the numbers and fitting the saw, was a lot lighter and smaller overall (from the bottom tip of the drive link to the top of the teeth).

Seems to work fine, but presume it won't be as robust.

Anyway, after using it briefly it seemed to be the case that the blade wasn't being oiled.  I used the pump at the rear a few times but couldn't really see anything happening from doing so.

After I left the saw earlier though, I just went and picked it up, to find a big pool of sticky oil under it.
So I guess there's a leak somewhere, and possibly this is causes the oil not to reach the blade if this is a diaphragm system or suchlike.  Any likely parts that would cause what I'm describing?

Re' the spring I was describing, it's shown here (part 9):


It's positioned as marked in this diagram but doesn't really seem to serve a purpose, having rotated it around in various spots and tried to position the ends against things.  I'm puzzled, but obviously missing something staring me in the face!

Another part I don't quite 'get' is part number 11.  It pivots around its pin but again, doesn't seem to serve any purpose.  When the brake is back, this latch moves over the peg (part 5), but in no way holds it or adds any tension or anything.  i just can't see what it's for since it doesn't seem to have any influence over any other part, yet must be there for a good reason.

Probably dumb questions I'm afraid.

The saw itself works really well, ie the engine is fine, the blade/bar/clutch/brake etc are all good, and the oiler is the only issue at present really, so given everything else seems fine, these parts are a bit of a mystery!

McLovin

As an afterthought, what sort of size bar would be the recommended sensible limit for this kind of saw? 
I could do with a bit more reach down into the transom of my boat to excavate the plywood, so a longer bar would be desirable really, but wouldn't want to fit anything bigger than will work well with it.

Is there a certain 'kind' of bar that I need to get to make sure it fits this particular saw?

Again - I hope you'll excuse my ignorance.  Just in the last day I've learned a fair bit thanks to the replies here, and already know the parts that make it up since I've already had it stripped right down, but am not familiar with all the options and varieties of chainsaw stuff in general.

Cheers
Jim

McLovin

This is the oil pump assembly by the way.  If there's a part on here that's a common cause of these sort of problems it'd be handy to have a pointer:

lumberjack48

Check the filter in the oil tank, if you haven't
Third generation logger, owner operator, 30 yrs felling experience with pole skidder. I got my neck broke back in 89, left me a quad. The wife kept the job going up to 96.

McLovin

Thanks. I guess if it was blocked then it wouldn't feed through but there's also the issue of loads of oil pooling under the saw of course too.

Al_Smith

All Mac automatic  oilers regardless of the saw model work on impulse except I believe the few that were made in Italy under the Titan name .

That said as long as the engine is running the oiler will be pumping oil .So if it sits in one place running it will dump oil on the ground .You outta see how much oil a 125 can pump on the ground .Looks like the wreck of the Exxon Valdez

If it's oiling via the manual pump it's obviously getting oil to the pump assembley .It could possibley be the automatic portion  perhaps the pump piston is stuck .That would be part number 13 .I think part number 12 is a check valve .

You could take it apart and see .As I said though I had no luck at all .I did however find a guy that had 900 pumps on flea bay for 10 bucks a piece .They normally want 25-30 for a new one .

Take the bar off that thing and fire it up .If it's getting oil out the discharge you probabley have the oil hole plugged on the bar or maybe even the wrong bar .

Usually if a pump goes bad like the diaphragm it will suck oil into the crankcase and smoke like it's burning pine knots 

Al_Smith

Bar size .They came with either a 16 or a 20 .They'll run a 24 but they don't like it .I guess they used them with 24's on the left coast in soft woods .It makes em grunt in the hardwoods .

Al_Smith

While I'm babbling I'll tell a little story .When these things or rather the PM 610 came on the market they were sold for around 225 bucks .A stihl 042 was around 400 .After a while on sale they sold for 169.95 with a 16" bar and they sold thousands  of them .K-Mart, Wall -Mart .Sears and Monkey Wards sold them too for a higher price of course .

The one drawback is the things are heavey as a 100 cc saw .Then again remember the time period .These things followed the Mac 250's and Homelite C5's so they didn't seem heavy .--trivia 101 .

Al_Smith

More .The chain brake spring holds the catch in place over the pin until you release it with the brake handle .At that time full spring pressure is applied to the brake band .

I can't find the picture I had so the best I can do is take another when I get time .With a picture it's pretty easy to figure out .

McLovin

Brilliant info on all counts, thankyou!

That all helps a lot.  I ordered a 20" bar for it (Oregon 200SLHD276) so I can get more reach down into my boat transom - need to get a chain to match.  Local place only has 72 drive ones in the right fitment and I think this needs a 70 link one.

When you mentioned removing the bar and starting without the chain/bar to observe the oil, I might try that tonight (although possibly will need to wait til the weekend to avoid upset/woken up kids!).
Could you possibly point me to the exact point where the chain oil 'should' emerge, to pass into the bar?  I can at least then check hopefully if the manual pump works, even if I can't try running it up tonight.

Will be nice to get this thing working really nicely.  I don't mind the weight etc, and it's built to take a beating! :)


Al_Smith

Right near the top of the bar studs there's a cavity with a hole in it .Squirt the manual oiler and watch where it comes out .

Say now if I can remember how to do it I did find the pics .It took going through 3 computers to find them .

   .

Al_Smith

Here's a couple more .The saw it came from one of the most pristene unrestored PM 610's I 've ever seen in my life which I snagged off flea bay with a bad coil for little of nothing .My son has it .

  

  

McLovin

That's brilliant - appreciate the effort you've gone to finding the pics, thanks.

Saw looks great as well.  I'm afraid mine is nowhere near that nice to look at!!
I wonder if I can get similar paint to put on where it's flaked off...
I guess if I was going to try that I'd need to get the parts blasted and then powder coat them or something?  Not many places locally that can do that, and when I had my bike frame done recently it was a rubbish job. >:(

First things first, I'll try to get the pump side of this sorted out.  If it needs a new one, then so be it, but hopefully not.  Got a new air filter coming too as the one on it is pretty destroyed, yet it still runs very well despite this.


Next thing I need to sort out is a chain for the new bar I've ordered.  I'm slightly unsure about the number of links I need though.  One advert for this 20" bar mentioned needing a 71 link chain, but elsewhere I've seen other numbers stated.  Is there any way I can find out for certain what length loop I need to match the bar and saw combo?

Al_Smith

It's 70 links standard on a 20" loop .It takes 71 if you run an 8 tooth rim which won't apply on that saw .

They don't run any better if you paint them .If you prefer to though  the color is OSHA safety yellow .

If you go to chainsaw collectors corner and look up a McCulloch SP 105 ,that's my saw .The only parts of  that saw which were repainted were the muffler guard and the recoil starter .The rest is 30 some year old paint .Pretty good match considering

McLovin

You're right of course, I just thought since I'm spending money on it I might as well give it a spruce up, but I suppose it doesn't matter.  That one of yours looks good by the way. :)

Well, I can order a chain for the new bar if that's the case, although I've kinda found disaster tonight which might stop me in my tracks.

Decided to strip the saw to clean it all out again and to inspect the oil tank/pump etc.
Now I can confirm the manual pump works fine, so that's good.

What is very very far from good is the reason the oil is pooling under the saw.
The tank is broken!!!

Observe the huge split in the oil tank casing:


Pretty horrific and I'm not sure that can be repaired anyway really.  Looks like cast metal so I'm assuming it can't really be welded, but then I only know about welding steel, and not any other metals.

I can't see myself finding another one of these easily or quickly alas, so it might have to be some sort of bodge where I carve out a good size channel in this crack with the dremel, and then use some sort of metal/resin product.  I can't imagine it'd be especially good, but I think it might be the only option at the moment. :(

Have to guess that due to the design of the casing and the bar bolts that they've been overtightened, causing the bolt heads to rotate and split the casing as a result.

So I don't yet know if the auto pump does work and is just causing oil to pump out through this crack instead of pressurising it into the bar, or whether that's dodgy on top of this.



McLovin

Actually, a quick look shows I can get a new tank on ebay for about $50 delivered.  It's a nuisance having to spend even more but since I've already spent money I may as well get it all sorted out I suppose.

Al_Smith

You gotta watch flea bay .I didn't pay that much for that saw I had pictured .Let me check see what Scott  has .

< chainsawr

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