Burco Clutch Set Up

[steveohara]

Scott,

You can machine them out until there is almost nothing left to the drum and they will still engage. The amount of slip won't change much on the type of internals that have the long arms with a pivot but with the Rev Grip internals the larger ID will cause the shoes to have to stretch the spring more so the engagement speed will increase as the ID gets bigger. We used to grind the shoes down to simulate worn out shoes to increase the engagement speeds and machining out the drum would produce the same effect. If they are machined too thin they will not get rid of heat as well as the original configuration but we don't beat on them in vintage karting quite the way we did when the racing was more serious so it should not be a problem to take the ID out as much as would leave at least .050" wall thickness at the thinnest sections.
Back in the mid and late 70s Bill Adkins used to have the Burco drums metal sprayed with hard chrome and then grind them back to a nice finish. It made the drums last a long time but I never liked the way they hooked up with the chrome.... they would cycle in, out, in, out of engagement in the hard pull sections.
I didn't run any of the modified stuff in those days and I think the setup Bill produced was pretty good for the open Komets and 135s but I didn't like the way it worked on the Macs.
Regards,
Steve

[Rob Voska]

Mac's (low RPM engagement engines) were mainly run without the extra ring. Mac without a ring takes less weight. Also you can run them as 3 shoe clutches also. All a Burco does is play the balance of weight vs. piviot point. Farther the weight is from the piviot the "heavier" it acts. I used to make fine adjustments with flex. I think I had my Burco's work like magic about 3 times!!!! Running unlimited all you did was come in & take the engine off & flip it on it's side so you could work on the clutch. I used to make my throttle cables & fuel lines so it did not have to strech them to turn engine on side.

Anyone remember the stock Yamaha karts with Burco or Burco style clutches & the pipes out the front? When it got the least bit cold there were 4x4's everywhere in the pits so they could jack up the back end, start the engine, rev the heck out of it & step on the brakes to get the oil thinned out.

[steveohara]

Rob,

Out here in So Cal we used to call the used Burco oil "black mayo". When they were working right the oil would become more like a black light weight litheum grease and you could take the cover off without the oil running out.
I could never make a Burco work consistently on a Mac until Bob developed the ring setup. I ran 8 long plates per shoe with the extended part of the weights mounted away from the pivot and a single 1/8th wide ring. Engagement speed was low to mid 7s and they would run an hour enduro and never vary. Next race, new shoes and ring for the start of the race. I would practice with parts from the previous event and then rebuild the clutch for the standing starts and the results were impressive. At the 1979 enduro Nationals at Ontario Motor Speeway I started in the #1 position as defending champion and had a 7 second lead at the completion of the first lap!
With a new ring and shoes and fresh oil the Burco behaved like a conventional clutch that you revved up the motor and then slid off the clutch pedal on the standing start. The key was to start the motor with just a few seconds before the green and not rev it up until they waved the flag... the thing would take off like a rocket!
BTW... if anyone out there has or sees a Burco clutch drum set up for the removable belt drive pulleys I would like to get my hands on one. I ran a 23 tooth front pulley on the 101s... that was the only size that fit over the seal boss on the PTO side of the motor.
Steve O'Hara

[Scott Kneisel]

Like this Steve?
Not sure if I want to let it go though, send me an email.
Scott

Burco Pulley Drum 001.jpg

(292.89 KiB) Not downloaded yet

Burco Pulley Drum 002.jpg

(230.32 KiB) Not downloaded yet

Burco Pulley Drum 004.jpg

(321.7 KiB) Not downloaded yet

[Rob Voska]

Anyone wanting to make their own I have a BUNCH of Burco stuff. Lots of new 14-18T drums maybe bigger that you can machine if you wanted. Mac & foreign hubs.... very light on new shoes but have a bunch of used ones.

We used X15. Never had to use a banana weight on Mac's. 1-2 small plates at the most. They were sensitive enough that a washer under the head would change them.

If you saved all your old oil & put it in a can..... the heavy metal particales would fall out & the top oil would be have that green hue to it but I never reused it.

[Rob Voska]

In all fairness Steve is talking enduro setup & I'm talking about sprint.

Diz used to run X80 & lots of it but never change it in his HIGH PORTED open 78's.

I still remember reading the directions over and over....... "if it feel good add weight"!

[steveohara]

Rob,

if you have any of the long weights you can spare I am interersted. I need a bunch of them.
Steve O'Hara