MCCULLOCH The official McCulloch thread

[Squareground3691]

Did the old bar a paint makeover

 

[edju1958]

The 660 bidding ended today after noon & I forgot about it.Just as well as the saw ended up going for $270 - a bit out of my price range.

 

[Bigmac]

Now I have to decide, used 76" hard nose bar, used 50" sprocket nose, new 40" sprocket nose, or new 54" sprocket nose bar. What length would best suit a CP125 in NorCal? .404 is a given, fyi.

50” 7 pin

 

[Bigmac]

What makes a 797/CP125 block mo' betta? Aren't they all the same displacement?

According to the mapping the Jacob and I have done, the sp125 has the lowest port timing and highest compression, and the sp125c has the heighest port timing. the cp and 797 have the biggest squish and lowest compression.

 

[Bigmac]

I'm certainly no expert but have heard the 797 block was closer to the 101 kart engine than any other like a 125 .Mention was made by the California crowd the round mufflers are a better choice than the later used on the 125 . In the glory days of two cycle go-karts about a zillion companies made parts .Where they all went heaven only knows but it has been upwards of 40 years ago or more . The proverbial needle in the hay stack .

The 797 standard has nearly identical cylinder to the mc101, minus the removable head. But the mc101 is also the only 101 motor that way, the 101a, 101aa, 101b and 101d all are ported more aggressively and allmost ported the same as each other, with the 101a being a little bit of a transition motor, that may have had a hand port to the exhaust in early cylinders.
The only advantage to the mc101 is the removable head, it takes a lot of porting to get them to run with the later cylinders. But also could make an excellent long bar saw motor

 

[Al Smith]

Actually I only have two old Macs with removable heads . One is a super 44 A which for it's age is quite impressive .The original air vane governor has been removed so it runs full open now .
The other is a super 44 that Dan Henry sent me and it's frozen up .It's kind of a back burner project to first toss it in a bucket full of kerosene for a month then get it apart .Then soup it up and put the engine into the shrouding of a 250 with a pipe to change it to a vintage hotty . I don't have any delusions of grandeur on how it might do just thought it would be an oddity ,something you don't see every day but it might surprise me if I get around to it .
Dan also sent along a couple of 5 gallon buckets full of old Mac parts and one part is a brand new unused flywheel that might work to change it to left hand start . I used to talk with Dan a couple times a year and have no idea what has became of him lately .

 

[heimannm]

 

[Bigmac]

Actually I only have two old Macs with removable heads . One is a super 44 A which for it's age is quite impressive .The original air vane governor has been removed so it runs full open now .
The other is a super 44 that Dan Henry sent me and it's frozen up .It's kind of a back burner project to first toss it in a bucket full of kerosene for a month then get it apart .Then soup it up and put the engine into the shrouding of a 250 with a pipe to change it to a vintage hotty . I don't have any delusions of grandeur on how it might do just thought it would be an oddity ,something you don't see every day but it might surprise me if I get around to it .
Dan also sent along a couple of 5 gallon buckets full of old Mac parts and one part is a brand new unused flywheel that might work to change it to left hand start . I used to talk with Dan a couple times a year and have no idea what has became of him lately .

With some work any of the removable head Mac’s have potential….

 

[Vinnywv]

Ok, ive got a 82cc mac question. Last week i sat down after work and started a random search on ebay and just listed as a buy it now for $140.00 was a "mcculloch sp80 engine". I looked the pictures very briefly and hit the button! I got it today. Checked it over and thought hmm, looks pretty good. Decided it best to take it apart to see all the spots inside the cylinder and found a pretty darn nice cylinder!! Very nice actually. Great chrome, no scratches scores or peeling anywhere. FANTASTIC. So i looked at the piston and it had a lot of carbon on it. A lot. Cleaned it all up and found the 87791 number on top which i was looking for. Sp80 piston..check. bearings are good, seals are actually tight, the crankshaft has key ways on both ends which i found differdnt for the 82cc saws. No big deal. Oil tank is clean and i basically need to get it back together and make a decision on this one. But ive got a question to the more knowledgeable, this cylinder is set up for a points system only, no visible letter, correct piston for a sp80 however it has the bridged transfers?? Did the sp80 ever have that? I know the early sp81 had the open transfer and sp80 had that feature also, but ive not read of a sp80 having the later sp81 bridge in the transfer??? Makes me wonder about this one a bit. I think i have a sp81 cylinder but would like more thoughts. Also did a sp80 have a keyed clutch? I think thats a little peculiar. Any thoughts are welcome on this. Thanks vinny

 

[Bigmac]

Ok, ive got a 82cc mac question. Last week i sat down after work and started a random search on ebay and just listed as a buy it now for $140.00 was a "mcculloch sp80 engine". I looked the pictures very briefly and hit the button! I got it today. Checked it over and thought hmm, looks pretty good. Decided it best to take it apart to see all the spots inside the cylinder and found a pretty darn nice cylinder!! Very nice actually. Great chrome, no scratches scores or peeling anywhere. FANTASTIC. So i looked at the piston and it had a lot of carbon on it. A lot. Cleaned it all up and found the 87791 number on top which i was looking for. Sp80 piston..check. bearings are good, seals are actually tight, the crankshaft has key ways on both ends which i found differdnt for the 82cc saws. No big deal. Oil tank is clean and i basically need to get it back together and make a decision on this one. But ive got a question to the more knowledgeable, this cylinder is set up for a points system only, no visible letter, correct piston for a sp80 however it has the bridged transfers?? Did the sp80 ever have that? I know the early sp81 had the open transfer and sp80 had that feature also, but ive not read of a sp80 having the later sp81 bridge in the transfer??? Makes me wonder about this one a bit. I think i have a sp81 cylinder but would like more thoughts. Also did a sp80 have a keyed clutch? I think thats a little peculiar. Any thoughts are welcome on this. Thanks vinny

Is the cylinder painted? Unpainted cylinders are usually replacements

 

[Vinnywv]

The cylinder is unpainted. The oil tank does look rather "new". I felt the same that this is a replacement block. I still lean that way. Another thing i checked before i went to sleep is the clutch. A 3 shoe clutch does not fit the taper of the crankshaft. I took one off a 125 and it goes on yes but doesnt fit right. The more typical 2 shoe clutch fits it just right. So it was listed as a sp80 and at one point may very well have been. Right now the only sp80 part is the piston that i can tell for certain. Not complaining at all cause its a great engine.

 

[Al Smith]

Again I'm far from an expert .That said I did read I think in the service bulletins on micro fitch the mention of non keyed clutch side crank shafts on the 125 c . It may contain something about the SP 80 .In one of my parts boxes I have a crank shaft of an 805 but I've forgotten how it is .However if it post dates the SP 80 it should be non keyed .I'll see if I can find it .This I do know .The SP 81 did have points and I really do not know if a solid state coil would work or not .If so they should not be that hard to find .

 

[Vinnywv]

If it will mount to the cylinder the coil will work. The replacement pm850/sp81 cylinders have coil mount ability for both types of coils. The keyed clutch though...kinda new for me. Lol. Leave it up to mcculloch.

 

[Al Smith]

Evidently McCulloch experienced failures with the clutch side getting destroyed .According to reading about the 125 using just the taper and no key which solved the problem . Fact I've got three cranks from early 10-10's and one 6-10 with damage but those are right hand start .I've also got one of the last 10-10's ever made and have no idea how that model is made because I've never been into it .One of the very few I've never had to turn a wrench on .

 

[heimannm]

I think the keyed clutches on the large frame and 10 Series saws got started with the RH starters. You needed something that would hold when the saw was driving the clutch, but you also needed it to hold when the starter was turning the engine over. The later solution of a left hand thread on the clutch side may not have been enough to hold tight when starting the saw through the clutch. There were a few intermediate models like the SP80 and early 7-10 that utilized the keyed clutch on a LH start saw. I expect they had some inventory of crankshafts that needed to be used up.

Quite a few crankshafts were damaged when the clutch nuts were not properly tightened or came loose in operation. Turns out JB Weld does not make a good repair.





Mark

 

[Al Smith]

This pic is an 805 crankshaft with an 850 cylinder .I used this cylinder as a replacement for the original and cooked the piston by mistaking a prime bottle that was straight gasoline with no oil .The crank has not keyway .The 805 now has a complete early 850 engine under the covers

 

[Al Smith]

Now this pic shows an 805 cylinder left hand side and an 850 right .The 805 clearly shows a relief port in addition to a decomp . The 805 had the chrome delaminate as I think McCulloch had some problem about that period of time and for all intents chrome auto bumpers just about disappeared .For political reasons hard chrome was nearly impossible to find during that time period .What eventually replaced it they now call nikasil ,Hard nickle, silicon and a form of carbide .

 

[heimannm]

I received a big box of 600 Series parts from Knightmax a couple of weeks ago, finally got around to getting the out of the box and cleaned up. My grandson "volunteered" to help...



For 14 years old he was very diligent about getting the parts clean.

Mark

 

[edju1958]

I received a big box of 600 Series parts from Knightmax a couple of weeks ago, finally got around to getting the out of the box and cleaned up. My grandson "volunteered" to help...

View attachment 343826

For 14 years old he was very diligent about getting the parts clean.

Mark

Gotta get 'em when they're young Mark.otherwise it's a lost cause,Lol.

 

[edju1958]

I picked up a M<ac 1-10 with a f\bullfrog carb in it a couple of months ago.I didn't rerally have much time to fiddle with it till today.I dug it out & had to give it a prime to get it running somewhat.I put a baffle & muffler cap on it first that I got from Mark.The primer button is missing & I tried using a screwdriver to get it primed,but I guess it's not working.Anyway,I had it running for a very short time & when I'd flutter the throttle it'd die.Each successive time I fired it up it ran for a shorter period each time.This leads me to believe that the condenser is breraking down,so tomorrow I'll put a known good condenser in it & try to tune the bullfrog carb.