Crankcase Ventilation and Blow-by

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desertrefugee
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Crankcase Ventilation and Blow-by

Post by desertrefugee »

Well, hoping to avoid any major expenditures on this custom wakeup, so far I've been successful in doing only "expected" things (carbs, swingarm, brakes, alternator, cosmetics).

But...as this machine has K&N pods installed, of course it sports a K&N filter for the crankcase vent. I've run them on other bikes with varying amounts of oil haze emanating from the vent. This Z had a pretty sizeable buildup of oil in those nether regions when I got it and I faithfully detailed the area while the carbs were out. Now doing the alternator job, I notice that there are the beginnings of more oil haze. And that's with just under 200 miles. Sheesh.

How much is normal on the CBX and at which point do I begin to concern myself with excessive blow-by and start considering a top end refresh? I'd really prefer not to go there just yet. I'll do another compression test soon - I haven't done one since the baseline. Baseline was done before I ever fired the motor.
'86 VMax, ‘83 ZN1300-6, ‘78 GL1000, '75 750K

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daves79x
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Re: Crankcase Ventilation and Blow-by

Post by daves79x »

Every pod set-up I've seen with the K&N vent filter does that to some degree. Best to route it so it can 'drain' back down into itself and the hose as much as possible.

Dave

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desertrefugee
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Re: Crankcase Ventilation and Blow-by

Post by desertrefugee »

Thanks Dave. I'll see if I can get creative.
'86 VMax, ‘83 ZN1300-6, ‘78 GL1000, '75 750K

"The older I get, the more I understand. Don't let the fear of what could happen make nothing happen." - Anonymous

EMS
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Re: Crankcase Ventilation and Blow-by

Post by EMS »

desertrefugee wrote:
How much is normal on the CBX and at which point do I begin to concern myself with excessive blow-by and start considering a top end refresh? I'd really prefer not to go there just yet. I'll do another compression test soon - I haven't done one since the baseline. Baseline was done before I ever fired the motor.
Every motor has a certain amount of crankcase pressure. It is caused by the pistons moving down, not necessarily by excessive blow-by. A leak-down test should give yo an indication of the condition of your rings.

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cross
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Re: Crankcase Ventilation and Blow-by

Post by cross »

What i did on my prolink is i routed clear hose from the crank case vent, under the airbox and up below the seat with breather filter at the end.
This way P trap is created at the bottom and all the liquid from condensation and some oil gets trapped there. ENd with filter on it is to high for any liquid o some up there. I should make some kind of drain at the bottom but there never is much fluid there

Sasha
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'82 Honda CBX
'99 Triumph TBS
'01 Honda Valkyrie

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