whats the better mac

[kevin sirois]

what mac is better 92-93-101 witch one is easyer to find parts for what were the hp ratings on them in stock trim and what can of power can they make in mod trim with atuner pipe

[Bill Hermsted]

Kevin- In my opinion the MC 92's and 93's were the best Macs of all time.
I think they were the only ones with true finger boost ports and a bridge between the exhaust ports, making the cylinder stronger in structure, as well as reducing ring wear to those areas of the cylinder.
Both mains were ball bearings like the super series used. This was not only a benefit of Mac's constant design progress, but also eliminated the issue of the pto journal running in needle bearings like is the case of other standard series. It's no secret what long storage does to a journal in needles ( personal experience from a MC 91 rescue ), not to mention simple wear and tear on a crankshaft that has become extinct.
And the L.H. thread pto, so important on any R.H. rotating engine.
bill

[kevin sirois]

thanks for the info any one know the hp stock and mod

[Terry Bentley]

McCulloch wasnt known for publishing any HP numbers. In the early years they were all based on a percentage of the output from a Mc 10. Modified numbers.....I would love to hear claims on what some peoples dyno results are. From a couple of Mac builders back then, I got a big kick from what they told me the motors produced. I would love to bolt them up to a dyno and actually see that much power being produced. But that opens a whole other can of worms for some of the hardcore guys that used to race.

Now from just a few years back at one of those big shifter kart races in Las Vegas, a friend of mine that was racing 125 Moto, was asked how much HP his motor was producing. He said on our dyno it was about 41 hp. A well known racer at that time was suprised to hear that. He quickly responded without thinking, telling my buddy to bring the motor over to his shop. He should be able to get at least 43 hp on his dyno. My buddy set fast time and won the race with that ill low hp motor. It was funny after that guy offered his dyno, he got a slighty embarassed look on his face and shut up for a few minutes.

Now considering a Mc 101 is 25% larger in displacement, it should produce a lot more power, comparing stock to stock with a Mc 91-93 model.

[Butch Kavanagh]

kevin, many will say the 100cc 91b1 is the best mac ever made and for 'pure' racing, back in it's day probaly was. as for my vintage outlook, cost of replacement parts, maintainance etc, i like mc92. recessed block for copper 'o-ring' head gasket (reusable). it's is easy to blow a head gasket on oth mac engines, especially if the block-head is warped or the head bolts are too long(bottom-out). the 92-93 cranks, not only left hand threaded(self-tightening) but there is no keyway. there are so many 91 cranks out there with chipped keyways that are junk. i personally like the double ball bearing 92-93 cranks vs the 91 series. with vintage events, demo race or just parking lots, i'm not trying to obtain the most horsepower like in the old days. parts can be rare and cost, i just try to assemble a good running engine that i can use next weekend. been involved since 1962, wish i had my 1st go-kart