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. 

japan.webike.net/products/20285416.html

japan.webike.net/products/24146665.html

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?

sf4t7 wrote:

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

No and I did not notice any difference in the way it ran with those ports joined.

DoctoRot wrote:

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. 

japan.webike.net/products/20285416.html

japan.webike.net/products/24146665.html

I have found this solution intriguing. The reed valves are opened by negative pressure waves in the exhaust ports that ought to help draw blowby from the crankcase, also burning any oil mist.

TexasKZ post=921599 userid=14419

DoctoRot post=921594 userid=21108I'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. 

japan.webike.net/products/20285416.html

japan.webike.net/products/24146665.html

I have found this solution intriguing. The reed valves are opened by negative pressure waves in the exhaust ports that ought to help draw blowby from the crankcase, also burning any oil mist.

 

I wanted more info on this and found this review : 

www.fitfreak.net/forums/2nd-generation-g...t-rev-system-do.html

(partially copied from the link above)

On the surface, sounds like a great and simple way to improve the performance of your engine right? Well, everything comes with their disadvantages as well. This is where the bulk of my search came from, as there are little-to-no reviews I could find at all, mostly only sites that essentially say "it just works," and provide ZERO information on the potential drawbacks. That is until I found this Japanese YouTuber  who explained some of the system's advantages and disadvantages. Keep in mind, there are no English captions for the video, so I had to use a FireFox extension which creates captions (albeit terribly translated) YouTube videos. between this and translating the comment section, I was able to get some more insight into the disadvantages:





1. Reduced Engine-Braking: This depends on what type of build you are going for. For Daily Driver Builds, this is a disadvantage as your ability to drive economically through slowing your vehicle down by engine braking will be diminished. For Track or Performance Builds, it can be argued as an advantage as lessening the effects of engine braking can increase downshift speed, and improve cornering stability.

2. Added Maintenance: This is not a 'set it, and forget it' kind of upgrade. The system requires regular maintenance and cleaning. The filter must be cleaned or replaced, and the system itself must be completely dismantled and cleaned at least every month.

3. Limited Manufacturers (High-Priced!): This was one of the break-its for me as the GE T-Rev System from J's Racing is priced over $620! Furthermore, they seem to be one of the only manufactures who designed one for GEs. According to what I have seen on J's Racing's website, each T-Rev is made to perform for their respective vehicle engine's positive crankcase pressure. Therefore, a T-Rev made for one engine is not necessarily interchangeable with one another as each valve system is designed to decrease crankcase pressure by a respective amount (it is a matter of first determining the amount of positive pressure in the crankcase, then determining the amount a specific T-rev depressurizes). From what I have heard on different threads, there does exist Chinese-made T-Revs on places like Ebay, but the quality of those are understandably questionable, and I have not looked into this myself.

4. Lower Engine Oil Temperature (Reduced Engine Oil Life): Not 100% sure on the science behind all of this, but this is perhaps one of the most significant drawbacks behind using the T-Rev. Since the system also introduces outside air into the crankcase, it can have a cooling effect on the oil temperature, impeding the ability to maintain regular, desired running temperatures depending on outside temperature (this is effect will be greatly exacerbated in colder climates). Furthermore, depressurizing the crankcase also introduces the issue of oil emulsification , which is when water moisture enters into crankcase and condensates when cold, and evaporates when the engine heats up to running temperature, creating a white and foamy deposit. This will greatly reduce the oil's ability to keep the everything lubricated, decrease performance and the life of the engine oil.

Overall, the performance boost you will see from installing one of these on your car is questionable at best. Although it has seen moderate popularity for application in motorcycles, it seems like the advantages you gain from using one in anything larger than a 4-cylinder engine is diminished, almost to the point where it is unnoticeable, while all of the drawbacks are heightened. After looking into what limited research I could find on this, I would say this is definitely not an upgrade I can see myself getting. If anyone has more information or experience using one, or if I simply got something wrong, please share! 

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The non anodized version is the cheapest and with the shipping to the USA its $217 without any customs or tariffs included. That price does also not include any other fittings or hose that may be required for a proper installation.

 

The current BOTM Zephyr is running one of these devices so would be interesting to get his feedback (I believe it has been fitted for a little while) but for sure if the oil temp is below it's "self cleaning" point (where contaminants are burnt off) it's not going to be great (unless you like changing oil)