Click on picture for larger image.
The Comer C-50 Kid Kart engine as it is supplied by the factory is a mass produced product. The engine was a good choice for kid karts since it is very reliable, readily available, fairly easy to tune, and relatively inexpensive. One of the cost saving measures taken by the factory is to use the cylinder as close to an "as cast" condition as possible. Each machine operation adds to the cost of production so the engineers at the Comer factory decided that it was not necessary to machine the bottom surface of the cylinder where it mates to the crankcase. While this operation may not be needed to produce an engine that in most cases runs satisfactorily, truing the bottom of the cylinder is very important if the full power potential of the engine is to be realized. This operation insures that the cylinder bore is as perpendicular to the centerline of the crankshaft as possible.
The effect of truing the bottom of the cylinder is enhanced when double row self-aligning main bearings are used in conjunction with truing of the crankcase.
The picture shown above shows a C-50 cylinder mounted on our custom cylinder truing mandrel mounted between centers on a lathe. The picture was taken right after a light cut was made to the cylinder. The picture clearly illustrates how uneven the bottom surface of the cast cylinder is. The lighter grey area on the left has been cut but the area on the right remains uncut. Every Comer cylinder that I have checked so far has been found to be uneven prior to the truing operation.
Here are the benefits of truing the bottom of the Comer C-50 Cylinder;
1. Since the cylinder sits flatter and is virtually perpendicular to the centerline of the crankshaft the engine can rev quicker and higher since binding of essential components has been eliminated.
2. Removing material from the bottom of the cylinder allows compression to be increased by moving the top of the cylinder closer to the top of the piston when the piston is at top dead center. By using multiple gaskets between the cylinder and crankcase the engine tuner can adjust the combustion chamber as close to the 7.5cc minimum as possible for "stock" engines and less than that for outlaw engines.
3. Since the piston moves parallel to the cylinder bore the piston to cylinder clearance is more consistent and the seal between the piston rings and cylinder is as good as it can be.
Crankcase truing is one of the most important parts of our C-50 Kid Kart engine blueprinting or outlaw preparation. If you are a do-it-your-selfer we can also true your cylinder. The price for this service is $30 plus UPS shipping. Keep in mind, you will also need several cylinder gaskets as well.
For more information contact
Bergfelt Racing Engerprises, LLC
4412 W. 6th Ave.
Beaver Falls, PA 15010
(724) 847-3677
Fax (724) 847-1566
info@bergfeltracing.com
This page was updated November 23, 2006