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Discussion Starter · #1 ·
For those who are running 2V BBK kit I think this would be a good add on to release crank case pressure and in combination with the added Takegawa oil catch can it will help you out with internal pressure and heat. I got almost the same setup on my Takegawa 181-4v setup with the intake cover a 4 bolt mounting instead of the OEM 2 bolt mounting.

2V tapped valve cover which normally mounts on the intake valve cover of the head.
https://japan.webike.net/products/21983443.html
 

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this might be OK for a drain back from an oil / air separator.... that stated, the tappet cover is a HORRIBLE spot to release crank pressure without proper baffling. The main head oil squirter is right there and shoots oil right onto the intake rocker arm essentially exploding the oil into oil mist.

There is a reason i plugged back up my tappet cover vent after i made it because oil just loved to puke out of that spot.
 

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Discussion Starter · #3 ·
this might be OK for a drain back from an oil / air separator.... that stated, the tappet cover is a HORRIBLE spot to release crank pressure without proper baffling. The main head oil squirter is right there and shoots oil right onto the intake rocker arm essentially exploding the oil into oil mist.

There is a reason i plugged back up my tappet cover vent after i made it because oil just loved to puke out of that spot.
If I remember correctly the cover can be turned 180 so the hole can be position on the other side, just a little observation.
 

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Ok guys.

What is the preferred method of getting rid of excess crank case / head pressures?

I have seen talk of catch cans, but that is just the can. To clear head pressures where does one tap into? I am assuming the crankcase breather is not enough, eh?

I am going to build a Big motor and I want to do it right the first time.

Thanks for any guidance.
 

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Grom Fatherz vented cam cover. When you compare the price and bling to other options out there, it makes sense. You may have to shave a bit of casting off your head for it to fit, but its easy to do with a Dremel.
 

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Discussion Starter · #9 ·
Grom Fatherz vented cam cover. When you compare the price and bling to other options out there, it makes sense. You may have to shave a bit of casting off your head for it to fit, but its easy to do with a Dremel.
I seen results of the vented cam cover, and speaking from pass testing and results I would rather have a see thru cam cover with the vented intake valve cover with the added oil spout hole vented hose going to a Takegawa oil catch can with the Crank Case vent going out either a DIY front OEM airbox or a small filter hanging out the back swing arm of the grom. That is only my own opinion.
 

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Grom Fatherz vented cam cover. When you compare the price and bling to other options out there, it makes sense. You may have to shave a bit of casting off your head for it to fit, but its easy to do with a Dremel.
I have messaged the dude twice. He is crossed off my list to purchase from. YMMV

I have not seen a pic of a vented valve cover. Sounds like an easy peasy item to make. Drill & tap and bam, vented valve train area. Thanks for the idea!
 

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Discussion Starter · #11 ·
I have messaged the dude twice. He is crossed off my list to purchase from. YMMV

I have not seen a pic of a vented valve cover. Sounds like an easy peasy item to make. Drill & tap and bam, vented valve train area. Thanks for the idea!
If I was you I'd buy the valve cover from Takegawa, I've done various versions of valve cover, welding a spout, tap and screwing a spout in place " not enough room to worry about rocker/tappets hitting it, oil leaks etc. Save your time and frustration and buy the cover "my 2cents"
 

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Grom Fatherz vented cam cover. When you compare the price and bling to other options out there, it makes sense. You may have to shave a bit of casting off your head for it to fit, but its easy to do with a Dremel.
x2. i've been running it for a few months now with no problems. I initially ran my breather filter near the port to see how well the baffles collect the oil mist and I've found it works very well. No oil build-up on the filter. I might just leave it as-is

gf-vented-cam-cover.jpg

besides being a functional breather, due to the amount of material and fins, it also helps cool the head.
 

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btw, before i got the gf vented cam cover, an alternative to the a breather at the head that i did was a breather port on the kitaco case. not prettiest, but it has been very functional and i still have it on.

location of the port. it's an aluminum barb that was welded on.
001.jpg

side pic
002.jpg

rear pic
003.jpg

i vent to atmosphere with an inline baffle (stainless wool in a fuel filter casing). zero issues with large amounts of oil going past the baffle. oil mist that is collected drains back into the case.
004.jpg

btw, i don't ride the grom in the rain, dirt, mud or in conditions where the breather would be compromised.
 

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From all the talk about "proper" venting I see on this form, I am assuming, that with the addition of a BBK to these motors, a negative is the excessive pressure build up in all areas of this motor, due to the fact that heat = air expansion.

All the air inside the engine is connected together. Or is it not? It just seems to me that keeping inside temps down, and with the stock breather location that SHOULD be enough to purge excess pressure from the engine.

Is the stock breather not of sufficient diameter to purge the air fast enough? Is the air not connected by various passage ways? Are the rings supplying additional pressure due to the bigger bore & more blow by?

Help me out here. I seem to be missing a key issue somewhere.

Thanks for the schooling gents!
 

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From all the talk about "proper" venting I see on this form, I am assuming, that with the addition of a BBK to these motors, a negative is the excessive pressure build up in all areas of this motor, due to the fact that heat = air expansion.

All the air inside the engine is connected together. Or is it not? It just seems to me that keeping inside temps down, and with the stock breather location that SHOULD be enough to purge excess pressure from the engine.

Is the stock breather not of sufficient diameter to purge the air fast enough? Is the air not connected by various passage ways? Are the rings supplying additional pressure due to the bigger bore & more blow by?

Help me out here. I seem to be missing a key issue somewhere.

Thanks for the schooling gents!
The entire case is connected and breathes for the most part- The oil drains from the head back into the case by way of the cam chain passage.

The stock crank vent is sufficient for the smaller bores, probably up to about 150'ish cc, but after that you really should consider additional ventilation to avoid windage pushing oil out the case. Engines are nothing more than an air pump, so you have to imagine the bigger the plug(piston) that's pumping, the more air it's moving both in front and behind. Add in heat and additional blow by and you've got yourself an oil saturated bike!

I'm running a high compression stock bore but I still put crank vent measures in place just to aid the bike in any way to free up ponies.

 

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The entire case is connected and breathes for the most part- The oil drains from the head back into the case by way of the cam chain passage.

The stock crank vent is sufficient for the smaller bores, probably up to about 150'ish cc, but after that you really should consider additional ventilation to avoid windage pushing oil out the case. Engines are nothing more than an air pump, so you have to imagine the bigger the plug(piston) that's pumping, the more air it's moving both in front and behind. Add in heat and additional blow by and you've got yourself an oil saturated bike!

I'm running a high compression stock bore but I still put crank vent measures in place just to aid the bike in any way to free up ponies.



Sounds reasonable. And your breather install looks clean and well thought out!
 

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......I'm running a high compression stock bore but I still put crank vent measures in place just to aid the bike in any way to free up ponies.
I do not wish to over-think this issue (and I am only running a stock bore engine), but is there any PEFORMANCE advantage to be gained by enhancing the crankcase breathing?
 

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I do not wish to over-think this issue (and I am only running a stock bore engine), but is there any PEFORMANCE advantage to be gained by enhancing the crankcase breathing?
Like Kenny said, it all adds up in the end. The benefit in most cases will be such a small fraction of a horsepower, but after doing a lot of work here and there, those fractions can add up. It could be placebo but I noticed an immediate difference in my throttle stabs and the bike seemed to idle a bit "easier". Reducing crank case pressure is a benefit because it lessens the effort for the piston moving down into the case.

I would definitely recommend picking up one of Kenny's cam covers. I did this as an experiment on my own during the cold months of winter lol.
 
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