Mac hotsaw in progress

[ozflea]

Keep what you have Jared as the BDC carby is ideal for what you want to do the twin carb setup is an old idea long gone, my new setup will be with duel BDC'c that will give the old 101 a bit more grunt.

I'll have more to say about this when Steve O'hara helps guide me through the finer points of this conversion.

Can't even think that them there Stihl and Huskie boys might be even getting close.

Power what power "Mc Power"

Mc Bob.

 

[Marky Mark]

The dual carbs give you better air flow when running alcohol.They can be used in the unlimeted class. That setup with the V12 went for $180.00. This Mac was unstoppable for many years. It just got a face lift this past winter and will be up and running again. There is a dual carbed Westbend that it will be running against.Stay tuned.

 

[ozflea]

Yes duel carbs where the hot setup before the BDC was developed and sorted and suited those with the older and earlier Kart engines the only reason guys dropped the BDC was because of replacement parts were getting hard to get but new carb kits are available along with the Duckbill valve thats needed for the BDC.
So BDC's are back mixing fuel for Mac's and are worth the effort.

 

[GOBRDGO]

carbs

Are the BDCs adaptable to alcohol? I heard my saw run tonite, dumped some gas in the carb. BEAUTIFUL!!!

 

[ozflea]

Certainly

 

[NWCS]

whats the best carb setup for a hotsaw SP125 using the stock block/piston?
pipe will probly be an old kart pipe modded to fit a saw better, possibly a fresh built tuned pipe, head ported and tuned up, and eventualy a 5degree kart flywheel. right now im just collecting info for the future, not doing anything yet. would love to get a 101 block but that looks like slim to no chance.

 

[Al Smith]

Well,there is no removable head on a 125,it's part of the block.It might be possible to use a Wiseco hi comp piston from a 101,but you would probabely have to change to a 101 or cp 125 rod assembly.The higher comp piston would change the the port timing ,so this would have to be accounted for,depending on the rpms you are shooting for.The same applies with the advance flywheel .You could probabely get creative and use a larger bore Tilley Hl,but I would think the intake would have to be enlarged to justify this.I think it would be possible to somehow adapt a 6 pedal reed set up,similar to a Homey 2100/2000.All this and still get the cover for the air cleaner back on?I'm somewhat of a day dreamer,pay no attention,this may be the ramblings of a mad man

 

[NWCS]

the stock tank/intake would not be used.. i would probly use an old briggs & stratton gas tank and gravity feed the carb. just fabricate a frame up to hold everything together. guess i could call it a "semi-hotsaw" as it will be kept fairly low budget.

 

[klickitatsacket]

Hey Al, you like one of these?

 

[Al Smith]

Yahvo,that's the one.I thought you sold it.I don't know if it would work well or not,just speculation on my part.

 

[klickitatsacket]

I just got this one in yesterday. Some guy walked in and asked if I wanted to "dispose of this old beat up thing" The saw looked as though it sat in the dirt. Piston and cylinder look awsome. Perty muych everything was nice except the pull start housing was gone and the plate behind the clutch was broke.

 

[ozflea]

Well Al i would imagine the SP125 would perform quite well using the Kart intake manifold and reed assy along with the BDC carby but the fuel tank assy for the SP125 would have to go then you would have to fabricate a new fuel tank and handle assy.

The BDC would certainly improve the breathing capacity of the engine but the SP125 doesn't have the same porting as the 101 therefore would not deliver the same performance.

The 3 of my hotsaws run BDC's but as a minimum are Kart engines utilizing the 91b/1, the 101, 92. At this stage my 91b/1 has delivered the goods and even knocked off the 101's.

Anyway Jared it's your choice what you run as far as carb's are required i suppose it depends on just how fast you wish you want to be.

Mc Bob.

 

[Al Smith]

I'm with you,Bob.If I ever build a Mac powered hotsaw,I would use a Kart engine instead of trying to rework a saw engine.Take it from one who knows,It's a black hearted beech to try and cut a set of ports in a blind ended cylinder.My 2 125's are good ole heavy timber cutters and do real well,in general "who's saw is the fastest" local playing around.They would not stand a snowballs chance in the neither world against competition saws.

 

[ozflea]

Here's one for you Al, i have fitted and run a low profile Auto Sharp L/P 3/8" chain on a SP125 it cut and cut exceptionally quick but that was a piece of brand new chain of cause straight off the roll, but after about 3 cuts it broke as it failed when it came to chain strengthand was horribly stretched as well to much power on such a light chain.

Thats what you call trial and error.

Mc Bob.

 

[Al Smith]

Here's one for you Al, i have fitted and run a low profile Auto Sharp L/P 3/8" chain on a SP125 it cut and cut exceptionally quick but that was a piece of brand new chain of cause straight off the roll, but after about 3 cuts it broke as it failed when it came to chain strengthand was horribly stretched as well to much power on such a light chain.

Thats what you call trial and error.

Mc Bob.

The trial and error part I got down pat.I had a huge Del'orto carb on a souped up Harley,years ago.When it ran,it ran good,when it didn't, it didn't.I took it off and put the good old Tilley model Hd back on it.As they say,nothing ventured,nothing gained.

 

[NWCS]

i wont even be adding ports, just having the current config polished and maby opened up a bit. going to be a VERY basic hotsaw with mostly just bolt on parts.. kart intake and such.. unless somebody wants to trade something for a 91 or 101 block thats still borable/usable.

 

[ozflea]

Hey Dedcow you "treehugger" worry about them there lite saws, us ground dwellers will carry the heavy ones.

Mc Bob.

 

[GOBRDGO]

Is the magnesium shroud polishable like aluminum is? I need to order a BDC carb rebuild kit, can anyone suggest a dealer?

 

[ozflea]

Maybe i'm not sure but i painted mine to protct them against corrosion.

I have emailed you details on obtaining carb kits Jared.

If you need Duckbill valves as no doubt your's will be Mc rooted contact me.

Mc Bob.

 

[GOBRDGO]

I think I will incorporate a large snowmobile style pull start handle. I tore up a couple fingers today as the old pull starter handle gave way in my hand. OUCH. No wonder why they used the electric starter whatchamacallits.