Northern Piped saw

[Al Smith]

That long shaft Ford starter is what they used back in the day to get them lit off . They used a cart with the starter and a 12 volt battery .That one there looks like it wouldn't be real handy .
It might be such a thing you could tap in on the side of the cylinder and install a big compression release from a Harley Davidson .Other wise with no comp release you'd never pull it over .

 

[Willard]

The brothers 101 had the factory Mac 125 rewind starter with a hole cut in the grille to see the flywheel.
They had a timing mark on the flywheel to be able to turn it over a bit past TDC, then it was ready for the one pull cold start of the race.

 

[Al Smith]

Back in the day they had these things at about diesel compression range .On a kart so much so the average running time was maybe a couple of hours of race running time before they needed a rebuild if they didn't grenade before then .Some of them that ran direct drive which I'd never seen with a 101 but have with a MC 6-7-9-10 there was a trick on a short dirt track ,rather than brake going into the turn they let the high compression slow then down which would load the crankcase full of fuel .When they juiced it about half way through the turn it gave them a mighty burst of speed but every so often they would blow the cylinder heads right off .Not good on a hot saw .

 

[Yukon Stihl]

So with the tip to use a 6 point 6mm socket i was able to convince everything to come apart.Tomorrow i will take it to work and clean as much as i can off of stuff.
So is this a normal 101 Kart piston?
If the rod needs to be changed,whats involved?sending it to a shop?
All bearings should be changed,including wristpin.
So if anyone has a good crank,rod with a piston or rod... i am in the market.
Oh yea carb and reed block would be awesome too.

 

[jacob j.]

That's pretty normal for a motor that's been run on high-oil content methanol. The rod may be salvageable. The trick there is look over the mating surfaces
closely. That looks like a 1/2" wrist pin set-up.

The first step is is to measure the piston - before sourcing a replacement you'll need to know the diameter and whether your block needs bored (I'm
guessing it does).

In order to get the wrist pin out, it's best to use a wrist pin puller. If you wanted to heat the whole assembly and then gently tap the pin out, that would work too if you make a cradle for the piston out of wood with a hole in it for the pin to slip through.

 

[Yukon Stihl]

Need a puller for this one,only one side has the hole for the wrist pin.First time i have seen that.Not that i have seen as much as most of you.
I was hoping to clean everything up yesterday...
I have a seven speed spicer transmission to change in my rollback truck now as a priority.There goes 6 grand that i wasn't going to spend on that truck,and a few days.

 

[jacob j.]

Yep - you'll need a blind wrist pin puller. Those are pretty easy to come by. Once you you find out what piston you need, I may be able to set you up.

I bought a whole box of pistons and rods from a retired Mac dealer out of Reno in 2003.

 

[Billy Currie]

This may help you with needle bearing:

https://www.123bearing.com/section-general.php?advanced_search_ref=LOOSE+NEEDLE

 

[Yukon Stihl]

This may help you with needle bearing:

https://www.123bearing.com/section-general.php?advanced_search_ref=LOOSE+NEEDLE

Cool that may help for a few others as well.
Thanks

 

[Yukon Stihl]

Yep - you'll need a blind wrist pin puller. Those are pretty easy to come by. Once you you find out what piston you need, I may be able to set you up.

I bought a whole box of pistons and rods from a retired Mac dealer out of Reno in 2003.

Hi Jacob
I found what i needed to pull the pin...
I am sure the rod is bad,the bearing surface for the big end is pitted,same as the crank.
The piston has torrington bearings in it.Can they be replaced,or do you just replace the piston?
The crank is hooped as well.The block would probably be ok with the pitting as an occasional use saw,not a lot of racing up here.
But just out of curiosity,if i find any info on the piston.What does it cost to have the block bored to match a piston.
Thanks Thomas

 

[jacob j.]

Getting an open block with a steel-sleeve (removeable head) bored and sized to a bigger piston isn't that much. Vince Hughes charged me $40 for the last one he did for me.

Terry Ives would be the man to contact about getting that bored over, if he's still in the game. Terry has been doing the kart motor thing for about 50 years. I don't think
anyone apart from original McCulloch engineers knows more about Mac engines than Terry.

http://www.vintagekartclubofamerica.com/images/2014/Santa Maria 2014/terry_ives.htm

https://vkakarting.com/for-sale-wanted/kart-parts-contact-info/

I can see if Vince is still working over motors - he's one of the top guys in the Mac game as well. Dave Bonbright does some Mac stuff but I've been told he's mostly
a West Bend guy.

Dave Bonbright -
ENGINE MASTERS
P.O. BOX 14
VINEBURG CA. 95487
707-938-8122

 

[Lee H]

Terry is still in the game and has lots of parts including 101 pistons made by Burris
on sizes of .004 oversize up to .068 in every .004 increments. Your piston may
clean up but it looks like the rings might be stuck which may not come out. If
the bore is questionable I would bore it and see where it cleans up then get a
piston from Terry. Terry may also have all the parts you need.

 

[Al Smith]

Don't give up the ship,that thing might clean up .I'm out of town right now being held hostage by a very convincing woman but I'll escape in a day or two .When I get back home I'll look up the kart engine specs but if memory serves they can be surprisingly off regarding taper and ovality and skirt clearance and still be within tolerable specs .
It isn't like you're going to fall timber with a 40 year old kart engine saw with a tuned pipe . It's a toy so to speak you just run it for fun on occasion .It doesn't have to be factory fresh perfect .

 

[Al Smith]

Now then regarding the semi slider type piston used on the 125 saws and 101 kart engines they were made from the factory up to 30 thou over but Horstman and a few others made them up to 100 thou over .The only place I've ever seen the larger ones was on e-bay and very rarely .The blocks rarely too but you are buying a pig in a poke so to speak .
However for that matter a block can be sleeved and salvaged .I'm probably the only one who has shown the process on the internet but it can be done .

 

[Yukon Stihl]

Hi All i appreciate all the info.
Yes this will be more of a novelty saw than anything else.Maybe one year i will load up the MCI and try and make a GTG or two and bring some of the unusual stuff along.This would be one to take.
Also i knew the original owner and would like to get it going in his memory,instead of it rotting in a scrap heap.
I have the piston in the ultrasonic to see how it looks.So far i havn't seen any numbers or marks on it. The crank and rod are shot,and i think the bearings in the piston are rusted as well.The wrist pin was clean and rust free.
There has been some work done on the block.
Thanks
Thomas

 

[Lee H]

If you can measure your piston I may have a good used one you can have.

 

[Al Smith]

I made the great escape,back on the ranch .Took me a while to find the data but here it is right off a McCulloch micro fiche .Cylinder taper and ovality not to exceed 5 thou .Chainsaw piston fit to cylinder 2.5 to 5 thou not to exceed 5 thou over .Kart engine fit 5 to 7 thou not to exceed 7 thou over .Ring end gap ,steel rings .051 to .097 .
When I sleeved the 125 with cast iron the cylinder finished out at less than 1 thou taper or ovality .Took me forever using a Lisle precision hone .I just guessed and set the fit at 4.5 thou.
In looking at the IPL's of the 101 series it looks like the early model had a keyed crankshaft and the later models had just a taper like the 125 with no key way . I don't know for certain but somebody does but assume a 125 crankshaft might interchange .I never checked the bearing or seal numbers but also have the same assumption .Which doesn't help much because finding a bare crank for either won't be an easy task .Every so often some parts or a donor pops up on e-bay . Best I can do ,I don't own nor have I ever worked on a Mac kart engine .I do have a Westbend 580 though buried in my shed some place .

 

[jacob j.]

McBob always said that the SP-125 cranks were better in the 101 engines - less vibration and the welded on crank weights minimized potential problems (karters have had issues on the cranks with the bolt-on weights coming off and destroying the engine).

 

[Al Smith]

From the picture which could be deceiving the rod doesn't look that bad ..The crankshaft might not be that bad either unless the journal got pitted from rust .
I've got a Mac super 44 I wish was a Super 44A but it's not .Dan Henry sent it to me .Stuck tight as a bulls butt in fly time .I'm just going to toss the whole thing in a bucket of kerosene and let it marinate for a month .
My idea should I ever get on it is for an 80 cc vintage hotty .Might happen might not .Might be fun but I don't have any delusions of grandeur it will out run any thing .Then again just how many people have a 60 plus year old hot saw .

 

[Lee H]

McBob always said that the SP-125 cranks were better in the 101 engines - less vibration and the welded on crank weights minimized potential problems (karters have had issues on the cranks with the bolt-on weights coming off and destroying the engine).

I've seen the weld on weights come off. Happened last spring at
the NY GTG.