need sprocket help

[Ed terco]

building a gk1200, have an original stock mc7 with stock clutch (9 tooth), i am wondering if anyone can give me size(number of teeth ) for a low range ,mid range,and high range sprocket. not sure which way i want to set up yet, that's why asking for all 3. any help would be great and everyone have a good and safe day.

[David Luciani]

ed, 
that question is a little confusing could you please clarify.
i'm not really sure what you mean when you ask for low, mid, high  range.
 L

[ted johnson]

Ed, nobody can even give a good ballpark without info on the track, your weight, Etc. I was a Go Kart dealer in '61/'62, and sold more than one 1200/Mc7 setup. Our track was short and tight, and we usually set them up geared about 10-78. which translates to about 9-70 or 9-72. We always discouraged using a 9T top gear, due to excessive chain wrap and chain wear. I ran open motors, so I used about 10-76 on my kart. I weighed 125 at that time. Heavier means you need more axle teeth for decent acceleration.
Remember, if you plan to race, a good percentage of the early Macs around the country have been nine ported, and you'd be at a serious disadvantage against a boost port engine.
At least you run a GK 1200, which, for me, is the best REAR engine kart ever made. It needs Go Power magnesium wheels and an aluminum axle to lighten it up. We ran the 1200 as an A Super, a B Super, and with triple Macs as a C Super. It handled superbly no matter how we ran it. Ted

[Terry Bentley]

A blind answer to a blind question, 9/68, 9/72, 9/76.

[Ed terco]

A blind answer to a blind question, 9/68, 9/72, 9/76.

weight is 180lbs. , kart will be run on track with numerous turns and a couple of long distant straight aways. already have original magnesium rims and aluminum axle. any help is greatly appreciated. would like to get out of the turns quick, but also would like a little peed on straight away. thats why i am considering mid way gearing

[David Luciani]

ed, 
forgive me for asking but have you ever raced a kart before?
if you haven't i recommend reading up a little on the subject of gearing then returning with questions.
right now you've given us only the most general of answers. 
all tracks have "numerous turns and a couple of long distant straight aways".

the length of the straights is important. the types of turns is it changing elevations.
 theres alot we'd need to know. 
as far as rims gk's came with steel rims or azusa rims mostly. 
what type of rim do you have in magnesium
. a few pix of your kart would be nice.
 L

[John Wolkiewicz]

I have raced all of the VKA tracks here in the northeast, most tracks I am running 9-68 and a 66 on the longer tracks.

[Terry Bentley]

Why do you have an aluminum axle on a GK 1200?

[ted johnson]

How about because a lighter kart accelerates faster? Why are Go Power magnesium wheels faster than Azusa aluminum/steel wheels? You do not run an aluminum axle on a dual, nor on a fast foreign engine sidewinder. Too much flex equals wheel hop in hard turns. They work fine on a single reed engine, even an open reed. Steve Welte and I have been discussing this issue. The old Reed Engineering tubular 4130 axles were the good compromise. You could easily use them on even a triple Mac kart. I wish somebody would reintroduce the tube axle. It must have been a chore for them to figure out how to install the 1/4" square keys, but they did, and they worked well. I had a 7075 axle in the n1ke. It was fine with the swing mount, but wore the keyways with the Dyna Drive/open West Bend center mounted. The extra bearings and less weight with the swing mount worked O.K. Ted

[Terry Bentley]

I never had any luck getting the aluminum axles working. I got to play around with a lot of the old obsolete karts from the early sixties in the mid seventies. I had better luck adding a 5 lb chunk of lead on the front end to help the kart handle. Following most older karts with aluminum axles i was surprised to see how much the did flex.

My first kart to actually race was one of those dead axle Fox karts sold in the early sixties. My dad swapped it over to a live aluminum axle(hum this sounds very familiar for some reason) before we took it to the local track. After a few attempts of getting it to handle, I changed it over to a steel axle and problem solved.

One of my Cates karts had one. It worked decent using the original hard as a rock Tex-cons. But again with fresh tires, the axle was changed over to steel for it to handle decently.

During my early years of road racing I had used one inch tubular axles, but not with the success I was expecting. On the long road courses, not so much of a difference. But the shorter tighter tracks like Oak Hill and Hallet, solid steel worked better.

My later years of road racing, I even tried a 1-1/14 axle of titanium. It seemed to work well on the long tracks that didnt have very tight or sharp turns. But still were slower on the shorter road courses.

At Daytona, I can see where they could be beneficial. But by then I had already worked out a solid setup without the extra weight reduction of an aluminum axle. I also had a few mishaps of axle breakage on the aluminum and titanium. I realized it didnt matter how fast I was if I could not finish the race.