What makes a 4Cycle Chassis a 4Cycle Chassis?

Steve Pribyl

That is pretty much the question. This might be specific to the B&S 206 forms but technical details would be appreciated. I see some makers refer to 4 cycle chassis and 2 cycle chassis and I am looking for the difference.

Thanks

Craig Drabik · Posted: Thu Apr 05, 2012 9:25 am Post subject:

Clearance for the chain and clutch on the drivers left side of the motor. Many 2cycle frames have cross members that get in the way of the chain.

Rob Kozakowski · Posted: Mon Apr 09, 2012 8:35 am Post subject:

Craig's covered half of it - some chassis are not made to "fit" a 4-cycle - rear cross-member angle and placement, design and location of engine-side seat strut, and whether the axle has an "internal" keyway for the axle sprocket hub are the 3 most common mounting issues to consider.

The other thing to consider is that most 4-cycle engines have lower hp than the 2-cycles.

As a result, while a lot of "2-cycle chassis" will allow a 4-cycle to be mounted without trouble, the chassis may not work as well with the lower hp of the 4-cycle.

Many of the Euro chassis offer 4-cycle models, generally with 28mm tubing, rather than the normal 30mm or 32mm used on the 2-cycle chassis. The 4-cycle frames will generally come with a 40mm (or smaller) axle, whereas most 2-cycles have 50mm axles. Some of the 4-cycle chassis may feature only 2 bearing hangers, whereas 2-cycle chassis will have 3. These differences generally allow the lower hp karts to run more "free".

Depending on the design of the cross-members, and the engine side seat strut, some of these frames may have similar frame designs to the 2-cycle chassis or may be very different.

Some 2-cycle chassis will work fine in 4-cycle, others not so much.

Jeff Stamper · Posted: Fri Apr 20, 2012 5:17 am Post subject:

Please keep in mind the angle and attachment point of the rear cross member to the engine side of the chassis. There are some karts out there that will not allow a sprocket hub and gear inboard due to lack of sufficient clearance. There are at least 2 at Norway that I know of. One is being modified this week and the other only has enough clearance to allow rear gears up to aprox 60 teeth. Come out on a Race day Steve and have a look at the variety of the chassis in the 206 class. We are qualifying this sat at Norway. Come on out buddy