McCulloch Chain Saws

[Eccentric]

The Tilly HL103 was used on the early Super 797's before they went
to the Walbro SDC carb.

I did buy the one on ebay "Sorry Eccentric" But i'm not sure if the 103
was used as it was advertised on a 1-70 series.

Lee

No worries Lee. That was a clean looking HL103, but went for more than I wanted to spend. I thought it was funny that he got it off of a 1-70 as well. He listed an earlier saw that he parted out as a "72M". Don't think he knows much about Macs. He does have a good attention to detail though. Cleans parts well, and describes them accurately. I recently got a nice EZ6 shortblock/drivecase assembly from him. Saved me the trouble and expense of finding a useable P/C for my EZ. He took the time to thread all the fasteners back into the drivecase after removing the other parts that he sold separately.

Thank you Lee!

On my next trip out to imbibe, I'll take down some more numbers.

It had crossed my mind to put a 48890 on the 790, it won't bother me to hand prime it. That leaves one for the MC20.

That saw's gonna be a beast with that carb. P/C and rings are really fresh. Didja pull an oil tank to swap onto it? Better do that during one of your 'trips out to imbibe'. That reminds me........time to grab a Sam Adams and some JD Single Barrel on the rocks...

 

[RandyMac]

Monday and Tuesday are going to be wet and windy, lots of shop time. I have plenty of supplies to be happy with. I also have three DoNs to polish.

 

[cpr]

I din't use the BDC carb, There too big.
I used the 48890 carb which has a .940 bore.
Bolts right in the saw with no problems.
There are other .940 bore kart carb's with
different numbers but i'm not familiar with them.


Lee

Excellent. I actually have 2 saws to try this on. The junkyard special 797 I picked up Friday, and the "project", which will be the more exciting of the 2. It'll be of the Frankensaw variety... Gonna buff up a 1-76 and let it receive a much hotter transplant.

EDIT: Dumb question, I don't see 48890 in the Mac Carb book. What is it? Anything like the Tilly HL 360?

EDIT 2: 48890 seems to correspond with a MAC 9: same as the "faultback" in my Super 250... expletives deleted! Appears to be an a and b version, one has choke, one doesn't.

EDIT 3: My MAC 9 has .940 choke bore, .810 throttle bore. Didn't feel like yankin' plates and shafts to cram a snap gauge in the venturi...


HHHMMMM....

 

[leeha]

Chris, I just measured 2 48890 carb's and the
choke and throttle bores are at .940



Lee

 

[cpr]

Good to know. From the videos you had before, I thought they were different than the flatback. I found on mcbob's kart site Steve O'Hara corresponding a 48890 with a MAC 9 which is what my Super 250 says...

Glad it's something else.

 

[leeha]

Chris, Here's the skinny on these kart carb's.
First, the 2 i measured this morning are 48890B.
Here is what the 48890 carb's were used on in the kart world.

48890 MC7, MC20, MC30
48890A MC8, MC40, MC70
48890B MC9, MC45, MC75, MC100

Every 48890 carb i have messed with had a .940 throttle bore.
But i can't remember if they were A's, B's or just a plain 48890



Lee

 

[cpr]

Thanks Lee, saw that list on mcbob's place.

Details later on tonight about what I'm doing with these...

 

[54stude]

I am definitely interested in seeing what it would take to put these carbs on a 790/795/797 saw! Pictures and details please!

 

[cpr]

Bolt in affair. Search Lee's postings for a 797 he restored and you'll see video of it.

 

[54stude]

So these 48890 carbs are still flatbacks with expensive carb kits, but the advantage is a larger venturi?

 

[leeha]

So these 48890 carbs are still flatbacks with expensive carb kits, but the advantage is a larger venturi?

Thats correct.



Lee

 

[Brian13]

Might be a dumb question, but do the carbs all interchange as far as fitment at the airbox? An extream example, taking a 101 carb or out of a 797 and putting it in a 1-43?

 

[cpr]

Might be a dumb question, but do the carbs all interchange as far as fitment at the airbox? An extream example, taking a 101 carb or out of a 797 and putting it in a 1-43?

I'm no expert, Brian. What I have learned is that it will fit, but the 1-43 is so much smaller than the 123cc engines that it can't suck hard enough on that bigger venturi to get proper fuel metering. I read somewhere that even on a 101, the straight bore carbs give crappy metering.

 

[Brian13]

Ok, thats what I was thinking. I was thinking down the road maybe a BDC carb to try out on the 797, and at some point a Super 250 Kart saw well down the road.

 

[a. palmer jr.]

Ok, thats what I was thinking. I was thinking down the road maybe a BDC carb to try out on the 797, and at some point a Super 250 Kart saw well down the road.

They'll react somewhat like a car with a too big carburetor...good at extremely high rpm and sluggish down low. If it's way too big it probably wouldn't run well at any rpm, maybe not at all.

 

[donthraen]

Ipl s

I just got some IPL'S thought I would give you mac people first crack at them just pm me to sea if I got the one you want theirs 18 models to choose

 

[promac850]

Here's a link to my "new" Pro Mac 850 build thread. Figured it would be easier to find, now that the name of the thread is Pro Mac 850 project.

http://www.arboristsite.com/showthread.php?t=164658

 

[HeRoze]

How to pull the 640 clutch. Here's a pic from the Old School thread since I didn't take one.

The nut on top of the clutch just spins the shaft while the flywheel, drum, and everything else stays put. So, I can't find anything to lock to bust the nut loose. When I read the service manual it speaks of a hole and inserting a locking pin. I can't find a hole (yea, that too). Do I just take a box end wrench and try to whack the crap out of it to spin the nut off (which I've done on other saws) or where is the hole to lock the shaft? Thx. Vic

 

[a. palmer jr.]

How to pull the 640 clutch. Here's a pic from the Old School thread since I didn't take one.

The nut on top of the clutch just spins the shaft while the flywheel, drum, and everything else stays put. So, I can't find anything to lock to bust the nut loose. When I read the service manual it speaks of a hole and inserting a locking pin. I can't find a hole (yea, that too). Do I just take a box end wrench and try to whack the crap out of it to spin the nut off (which I've done on other saws) or where is the hole to lock the shaft? Thx. Vic

I always got by with a small square wire brush handle stuck in the exhaust port with the piston down. The nut may not be too tight. I've tried the impact wrench with good and bad results.

 

[cpr]

You mean the nut that goes in the center of that photo, right? That's on the crankshaft. My reccomendation is to set the piston above the exhaust port then cram a peice of rope through the plug hole to serve as a piston stop. The pin-hole thing is more for setting the points. There should be a hole on the bottom of the saw that lets a pin go through the flywheel back cover and into a hole on the flywheel. Wouldn't trust that to hold things to get a nut off. Use PB blaster, a few hammer taps and constant mounting pressure, don't use a breaker bar type removal method. Some guys like impact guns (the cordless ones, not air), but I think they can do damage if you're not careful.