McCulloch Mc49 - Horsepower Rating

[Scott Kneisel]

Does anyone know what the approximate horsepower rating is for an Mc49?

I am just curious.
I remember the old factory stock standard 100cc engines like Mc7-9 were about 10 horse, about 1HP/lb. But I have never seen anything on the 80cc Mc49. I have one to restore and want to set it up for my grandson but don't want it to be too powerful.

If anyone has an idea, I would appreciate it.
Thanks and have a happy Thanksgiving,
Scott

[Dean Seavers]

Right around 5 HP with the stock carb and a box muffler. Supposedly some kind of expansion chamber wakes them right up- at least that's what the late 60's Mac ads claim.

My 10 year old has a Mc49 on his kart and it's a great motor for him. To be honest, they aren't even a bad motor for adults-they don't have the same kind of kick that a 91 or 101 does, but they wind up pretty good and scoot you right a long. Great motor for late 50's/early 60's karts if you don't have access to the Mc10-Mc6 era motors. Slots in nicely with the vintage performance of the era.

[Butch Kavanagh]

an idea...my son was lucky to be involved racing, his hey day was the rookie class when macs were the only legal engine. the mc49, no question, with any type maintainence, was very dependable. wka with their insight, 1978 and after allowed the mc93 with a restrictor plate and .032 head gasket. this was a gas and oil only, class( ??? ) his last ride as a rookie was b-ville 1981 with a restricted mc93. the idea-any mc 100cc engine can be used. .032 head gaskets are out there, just finding a restrictor plate in someone's tool box. using the thicker head gasket obviously reduces compression and just a suggestion, keep the timing stock. you should have no problem starting the beast. it has similiar characteristics as the 49, the 49 engine was starting to become scarce. at the local track, we even allowed the 91-a-b blocks just to keep people racing. good luck with your 49. keep that clutch tight so you don't chip the pto keyway......butch

[Jeff Campbell]

Scott,
Dean is right, those MC49's can be a lot of fun for Adults too. I set one up last year for my kids, right now the kids have about 10 laps on it, and I have about 200. I do most of my vintage racing these days high performance dual engine karts, but I still find that Mc49 darn fun! At TBO this year, I spent about 20 laps learning how to get around the whole track without lifting off the gas and without using the brake, tossing it sideways into a few of the turns to get around, it was a real hoot! There still are a lot of these motors, parts, and pistons out there, and many of the chainsaw powerheads are nearly or somewhat identical (cheap parts).

my Fox with the MC49 on it at TBO this year:
http://www.rearenginekarts.com/TBO2008/ ... 066031.jpg
http://www.rearenginekarts.com/TBO2008/ ... 066041.jpg

Note in the photos, that I used a tilly gas carb with a stock mac manifold, to give the motor a more vintage look. The later model 49's came with those little walbro carbs, twisted at a funny angle, IMO those just don't look like early vintage. The manifold I used are easy to come by, as they were used on a lot of chainsaws, just be careful with the reed plate though, as there are basically 2 different types, one for the block with a long manifold opening and one for the more standard chainsaw block short manifold opening. If you put a short reed plate on a long opening block, you will have a huge opening (massive air leak), no, I never made that mistake, LOL!!

Jeff

[George Sellon]

Scott, The 49 will run pretty well with a lighter driver. If you want to keep the power down for your grandson look for a smaller bore (saw?) carb or make a restrictor plate for it then when he gets to where he has good driving skills you can go to a standard size carb.

I know some guys that run the 49's in sportsman at "racing" events and just have a ball with them. They are not as fast as 90 and up but they really don't care about winning they are just having fun running with each other.

Hey Jeff, I noticed the throttle arms on your Fox looked "aftermarket". The arms Dick Teal had made up are really nice and give that "correct" look to the kart. I have a set and would definitely recommend them. They are stainless and polish up very nicely.

George

[Scott Kneisel]

Wow,
There is a whole Mc49 culture out there.
Thank you all for your input. I do have a smaller Mac Flatback chainsaw carb the I can put on there for my grandson. I have a lot of Mac chainsaw power heads that I have picked up. I particularly like the Mac450's since they have BB PTO and tapered cranks. I have converted a pair of them to put on my R1. These are about 90cc. I opened up the intake area to full size since they had the added sealing flange, removed most of the ribs, raised and squared the exhaust ports a bit and added VanTech Manifolds with regular kart carbs. I think they will be just about right for this old man, not too powerful and should give a vintage dual feel. See Photos. I hope to have them ready for spring and also hope to get to TBO next year.

Thanks again,
Scott

[Dick Teal]

Scott,

We used to have a dual 49 class at Brodhead in the late 60's and early 70's. One of my sons had a Blackhawk that had two 49's on it and he had a lot of fun running it then and I'm sure you will have a great time.

Your kart looks great and I'll see you at TBO next summer.

Dick Teal