Pocket Size Terror – Building a CRG ICC Shifter Kart
If you are a long term reader of MotoIQ you have probably seen some of our stories on karting. We think that karting provides excellent low cost training for racing cars and for some of us it's actually harder than driving a car.
So we have several karts in our palatial shop, everything ranging from 100cc air cooled HPV karts to 125cc senior Tag karts. These karts are all pretty good and the 125's are really fast. So of course we had to do something even more extreme by building a shifter kart. Not just any shifter kart but an open class ICC kart.
An ICC kart is the fastest sprint kart class. It is not to popular in the USA as it is a pretty expensive class to run in and most local organizations just lump these karts into a general open shifter class. An ICC shifter is not to be confused with the popular 125cc Moto class where adapted dirt bike, usually Honda CR 125cc spec engines are used. Moto karts produce around 35 hp and are pretty damn fast but an ICC kart puts out over 45 hp from a 125cc engine making it the fastest most powerful sprint kart available.
If you take a look on YouTube you can find videos of identical karts to ours running low 11's in the 1/4 mile and beating Ferraris in drag races. These are pretty wicked machines so of course we had to build one!
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It all started when a friend sold us a kart he had sitting at his shop. A customer had brought the kart to his shop for him to store it for a week and never came back. After a few years he pushed it out back and let it rot. Not knowing what it was he sold it to us for a few hundred bucks, we didn't really know what it was either but we sold the chassis for a few hundred bucks to cover our costs then took the engine. We wanted a new chassis and we found that Acceleration Kart Racing in Las Vegas had a 2013 CRG Road Rebel chassis that they wanted to clear out of inventory which they sold to us for cheap. There are hardly any changes between a 2013 and 2015 CRG so this was a great deal. The Road Rebel is a CRG chassis designed for America's lower grip, rougher tracks and heavier American drivers with a 32mm 3 rail chassis. We also liked the Road Rebel's high degree of adjustability.
The front spindle is adjustable for camber and caster with this pretty cool upper spindle plate. Most karts are adjustable with “pills” and usually only adjustable in camber. The CRG's spindle adjusts faster with greater flexibility.
The front spindle is also adjustable for steering geometry with the Ackerman angle being adjustable at the spindle. Adjusting the Ackerman here affects the curve toward the end of lock. On a kart Ackerman really affects the rear wheel lift which is critical to minimize scrub on a spool axle chassis. More Ackerman can make the chassis looser mid turn this way.
The Ackerman is also adjustable at the steering shaft. Adjusting it here controls the Ackerman more in the initial part of steering wheel movement. Karts run a lot of Ackerman compared to cars due to the short wheelbase and the rear wheel lift tuning effect.