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Steel Bearing Liners – The original Husaberg crank main bearings are really undersize even for the “650” engine. They have proved problematical in every application that the Husaberg engine has been put to be it the high revs of Supermoto or the high loads of Sidecar.

JBS Racing was the first tuning company to use 20mm wide bearings in place of the 16mm wide OEM bearings. Initially we ran a 20mm wide roller on the drive-side and a 16mm wide roller on the magneto-side, this was easy without a counter-balancer as there was room for the 20mm bearing to sit in the original housing.

As mentioned in a previous post we decided that to achieve the smoothest engine that we could we would re-install the counter-balancer. This means that the original bearing bore in the case must be machined 4mm deeper to allow the 20mm wide bearing in without impinging on the space that the counter-balancer swings in.

As we had decided that we would set the cases up on a machine and bore the drive-side it seemed just as well to do both sides of the engine and run the 20mm wide bearing in both sides. The only problem with making the bores deeper is that the seals msut then be move out by the same amount that the bores have been deepened, 4mm. To do this we welded aluminium rings to the cases and machined a very small amount off of the back of the magneto rotor. This system works very well, but the bearing is only retained by a press-fit into the cases. Our ultimate goal on the crank main bearings was to fully retain the bearings in the cases and fully retain the crank in the bearing thus eliminating any movement and sources of damaging vibration and hammering. Many Japanese bikes have fully retained bearing and crank systems by design.

Eventually JBS Racing had enough time to design and machine steel bearing liners. The cases are bolted together line-bored, with ensures that the bearings in both sides are in perfect alignment, then the steel liner and pressed in and screwed to the cases. This system has 4 major benefits 1) The bearing bores are permanently lined with heat-treated steel so re-builds do not ware the cases 2) The bearings and crank are fully mechanically retained, not relaying on a press fit 3) The bearings are in perfect alignment 4) They are not compressed by the OEM over-tight press-fit which reduces the “C” clearance in the bearing by about 2 numbers in our experience.

This entry was posted on Wednesday, April 30th, 2008 at 10:19 pm and is filed under Engine Develoment. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.