Improved Crankcase Venting

Hi guys, looking for ideas on how to change crankcase venting on my KZ650, which is now an 810 with GPZ750 cams.  I noticed a lot of oil mist getting pushed into the intake tract and possibly causing some of the carbon build up on the piston and exhaust valves.  The pistons are fresh so it's not poor seal blowby, just high rpm pumping pushing oil mist where I don't want it.  What have people done to change venting?  Straight pipe into the atmosphere?  Catch can then back to airbox?  Has anyone installed a PCV valve?  Is the vent in the case too small?  How about adding a second vent on the valve cover?  

diamondnik wrote:

Hi guys, looking for ideas on how to change crankcase venting on my KZ650, which is now an 810 with GPZ750 cams.  I noticed a lot of oil mist getting pushed into the intake tract and possibly causing some of the carbon build up on the piston and exhaust valves.  The pistons are fresh so it's not poor seal blowby, just high rpm pumping pushing oil mist where I don't want it.  What have people done to change venting?  Straight pipe into the atmosphere?  Catch can then back to airbox?  Has anyone installed a PCV valve?  Is the vent in the case too small?  How about adding a second vent on the valve cover?  

Catch can would reduce the oil in the airbox and additional venting would likely reduce pressure

You can start by simply adding a breather to the oil filler cap and go from there.
Earls used to make them for the 650 and 1000's etc if you don't want to modify your existing or make your own..
You should run the hose to either a catch tank or position the open end to a point higher than the top of the engine..

I have always run extra vents on my enlarged engines, no pcv just straight to atmosphre thru a small K&N type filter. 

On my 831cc 650 engine I run a -6AN fitting on the cam cover in addition to the air box vent. You can enlarge the stock vent fitting outlet slightly. The cam cover vent runs a hose up under the top frame tube and terminates with a filter hidden next to the frame neck gussets.

 

 

 

I don't have great pics of the install. That engine was pulled and a 1197cc Z1 replaced it with a different vent system that has two lines terminating into a ABS pipe.

 

 

 

The Z1 is vented from a fitting bolted to the modified top breather cover and a fitting on the cam cover. Both vent lines terminate next to the steering tube behind the frame neck gussets. 

I see your engine has a Zephyr top end and a air box. When using the stock air box the cam cover is the only other option unless you want to drill and tap the stock cover for another fitting then have it run to a small breather.

Just leave the air box setup as is and put a -6AN bulkhead fitting on the top of the cam cover like I did with my Z1 build. You don't need to build a ABS catch can like I did, just install a tiny filter on the end of the vent hose.




 

Hey Injected, I notice in one of your pics you have the carb manifold vacuum fittings tied in pairs.  Is that a carb balance thing?

I've seen a member here post using this reed valve PCV. I don't know how much a performance difference it would make but it probably helps remove water vapor and other blowby gasses from the crank case. 

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sf4t7 wrote:

Hey Injected, I notice in one of your pics you have the carb manifold vacuum fittings tied in pairs.  Is that a carb balance thing?
 

I did not have any proper rubber caps at that time, so sorted it out later. It was a quick fix that works, but I don't like how it looks.
 

Did it seem to have any effect on the sync of the carbs?