Development: Comstock Engineering
Description: We are very excited about offering the most efficient breather modification for Commandos on the market. This kit is developed and designed for maximum performance. We have operated this through a variety of circumstances and rpm ranges and how found it to actually pull a vacuum in the crankcases up to about 4000 rpm. From there to red line it’s virtually running at 0 pressure. The benefits are many and the idea of reducing the excessive pressure in the crankcases that, due to the parallel twin design, will free up the engine and actually create some horse power. It will also virtually eliminate any and all leaks associated with the pressure in the cases. You will notice this where there is a gasket, seal or a material joint. Because of additional modifications that we do in the timing side case to further increase the performance of the breather we are also lowering the operating temperature of the engine oil.
In order to install this kit the engine needs to be completely stripped down as we mill a mounting surface on the lower backside of the drive side case half. We also modify the timing case half.
The above mentioned results are of course directly related to how the engine is built as piston clearance, cylinder bore, piston ring quality, head work, gasket quality and much more will all play a part in how well the engine breather will operate and what kind of results you will experience.
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- Experience an increase in engine performance
- Eliminate persistent leaks at gaskets, seals, tach drives, head, crank case joints and more
- Lower the operating temperature of the engine oil
- The valve can operate consistently during a far higher rpm range than the Commando engine can ever reach
- The valve is not affected by oil contamination and can perform even if submerged
- The valve will actually aid in returning the crankcase oil back to the oil tank in case the engine has wet sumped
- The valve housing is CNC machined out of high quality billet aluminum
- The valve has an indefinite service life and will not have to be replaced
- Turnaround on this service is 7 days
Price $ 265.00
- Milling the drive side case half
- Modifying the timing side case half
- Breather components
- All parts necessary to install the breather valve
Special order – Please contact us for information (not available through online ordering)
Note: If you have a 1972 engine case, you do not need the machining done. You can install our bolt up version of the valve available for puschase in the parts catalog in the Engine category