mac chain saw
Posted: Thu Jan 31, 2008 3:48 pm
I seen a couple of old mac chainsaws at yard sales. I was wondering is it more trouble to convert these for kart use verses buying the mac kart motor?
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Re: mac chain saw
Posted: Thu Jan 31, 2008 4:02 pm
If they are cheap you can use the inner and outer shroud. Some guys even use blocks. Sometimes some small parts but not worth much as far as that goes. But they do make one hell of a chain saw....right Mcbob..
Re: mac chain saw
Posted: Thu Jan 31, 2008 5:31 pm
Your certainly right on that one ol mate .......... i think the biggest hassle is the stepped crank and fixed head on a lot of them.
Do you fellas run the stepped cranks on karts ?
If not why not ?
Mc Bob.
Do you fellas run the stepped cranks on karts ?
If not why not ?
Mc Bob.
Re: mac chain saw
Posted: Thu Jan 31, 2008 5:41 pm
No clutches for stepped cranks.... 
Re: mac chain saw
Posted: Fri Feb 01, 2008 7:16 am
However, those old Mac's are a great way to get the old Benders fired up!
Re: mac chain saw
Posted: Sun Feb 03, 2008 5:02 pm
Hi Paul,
Those old yard sale finds can be fun, I use those saw engines for my kart because they're relatively cheap and adapt well using regular kart engine bits.
The stepped crank ends can be a small hurdle, but there have been work arounds to use them with a regular, 5/8 size clutch.
pm me or email me for any help here......they're all I run nowadays
be good,
Ray
Those old yard sale finds can be fun, I use those saw engines for my kart because they're relatively cheap and adapt well using regular kart engine bits.
The stepped crank ends can be a small hurdle, but there have been work arounds to use them with a regular, 5/8 size clutch.
pm me or email me for any help here......they're all I run nowadays
be good,
Ray
Re: mac chain saw
Posted: Mon Feb 04, 2008 1:52 am
Rob
Yep, there are no clutches for those stepped cranks. There is a way to use a stepped crank with a clutch. It takes some work but it can be done. Look around in my website, there is an artical about it someplace in the site. Bob Blackburn came up with this ideal of a machined extension shaft that looks like it should work good plus it will use a easy to find 3/4" bore clutch. Also you can chop off the teeth on a chainsaw clutch and weld on a sprocket that you can get at an industrial supplier. This approach you actually could use the clutch that fits the stepped crank.
Yep, there are no clutches for those stepped cranks. There is a way to use a stepped crank with a clutch. It takes some work but it can be done. Look around in my website, there is an artical about it someplace in the site. Bob Blackburn came up with this ideal of a machined extension shaft that looks like it should work good plus it will use a easy to find 3/4" bore clutch. Also you can chop off the teeth on a chainsaw clutch and weld on a sprocket that you can get at an industrial supplier. This approach you actually could use the clutch that fits the stepped crank.
Re: mac chain saw
Posted: Fri Feb 08, 2008 2:23 pm
The MC-I series(not MC-1) and MC-200/250/250A saw engines are very similar to a MC-9, but they are only 80cc. John T's mod is an easy one to do if you have a lathe, just make up an adapter nut and bolt on a 3/4" Max-Torq 12 tooth.
The saw engines above have no booster ports, but can be 9 ported. Some versions only have two of the three holes drilled for the exhaust and transfer ports, inviting you to do some home brew drilling to open the additional ports, or not.
The other issue is they have thick rings, for durability and lower RPMs than a racing version, just gear for more low end torque.
Saw engines seem to be popular with the mini-bike guys as alot of them are on a budget. I saw one(pun intended) on a mini-bike last year at our annual 2-Stroke Extravaganza at Woodley Park in Van Nuys. he had twin MC-250 engines on a Taco!
The saw engines above have no booster ports, but can be 9 ported. Some versions only have two of the three holes drilled for the exhaust and transfer ports, inviting you to do some home brew drilling to open the additional ports, or not.
The other issue is they have thick rings, for durability and lower RPMs than a racing version, just gear for more low end torque.
Saw engines seem to be popular with the mini-bike guys as alot of them are on a budget. I saw one(pun intended) on a mini-bike last year at our annual 2-Stroke Extravaganza at Woodley Park in Van Nuys. he had twin MC-250 engines on a Taco!
Re: mac chain saw
Posted: Sat Feb 09, 2008 3:18 am
Jay et al-
The 250 is all the ports are drilled is a Mc49 with a saw crank and thick ring piston. The 49 crank and thin ring piston are a direct drop in with no problems. I've built two MC250 saw motors this way and they work great.
Dean
The 250 is all the ports are drilled is a Mc49 with a saw crank and thick ring piston. The 49 crank and thin ring piston are a direct drop in with no problems. I've built two MC250 saw motors this way and they work great.
Dean