Author Topic: K100RS Cyclonic separator / PCV mod  (Read 7405 times)

Offline vintagevalves

  • Curious
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K100RS Cyclonic separator / PCV mod
« on: August 10, 2014, 06:19:15 PM »
My new to me K100RS4V runs great, starts easy etc.    It has 30,000 indicated miles.  Who know if that's accurate?   I tend to believe it due to the overall condition of the bike .    I've put around 500 miles on it so far.        I'm working through replacing ALL the rubber hoses on the bike (Fuel, brake, and breather) due to them all being in poor condition due to age.  While riding with a friend, it was noted that I occasionally had puffs of oil smoke out the tailpipe.

While replacing the somewhat cracked breather hoses to and from the cyclonic separator, I noticed that the drain tube had a fairly high loop in it.   I suspect that this would make it impossible for the separator to drain properly causing the oil to be drawn back into the intake.   I attempted to open the separator to clean it out, but I think that it must have been assembled prior to the airbox tops being glued together.   Did I miss something here or is there a way to get the separator opened up without ungluing the airbox top?   

I read on a post on the K11og about bypassing the cylclonic separator with a PCV type system routed to the vacuum sync test ports.   Anyone here done this and care to comment on that? 

Offline wmax351

  • ^ Quintessential Motobricker
  • Posts: 1237
Re: K100RS Cyclonic separator / PCV mod
« Reply #1 on: August 10, 2014, 07:50:12 PM »
I have thought about doing this. It would make a lot of sense. That hose is a weak spot on these bikes, but not as bad on a 4valve. On the 2 valve, the hose breaking allows unmetered air into the engine, causing poor running.
  • Albuquerque, NM
  • 91 BMW K75 Standard, 98 Moto Guzzi California EV
Bikes:
Current:1991 BMW K75 Standard, 1998 Moto Guzzi California EV11
Past: '83 BMW R65LS, '75 Honda CB550F, '69 Honda CB175, 1999 Royal Enfield Bullet 500, 1973 Triumph Tiger TR7V, 1971 BMW R75/5 in Toaster outfit, 1979 Harley Davidson XLS-1000 Sportster Roadster

Offline vintagevalves

  • Curious
  • Posts: 7
Re: K100RS Cyclonic separator / PCV mod
« Reply #2 on: August 10, 2014, 08:12:54 PM »
My bike is a 4V and the crankcase breather hose had certainly seen better days.  Rather than a $40+ (with shipping) replacement, I cobbled together a perfect replacement from my FLAPS for around $15.   

Here's the post on the other forum with regards to the PCV modification.    What I don't like about it is that it requires a vacuum header be created for the vacuum sync ports.  I'd think that this could add another point of failure.  Intriguing idea anyhow:

http://www.k11og.org/forum/viewtopic.php?p=89011&sid=251c876afa3be5e398687cf7b3b7ac3a

Offline frodef

  • ^ Proficient Motobricker
  • Posts: 181
  • 1986 K75C
Re: K100RS Cyclonic separator / PCV mod
« Reply #3 on: August 11, 2014, 12:01:47 PM »
I'm just curious what this "separator" is and what it separates exactly, if you could indulge an ignoramus?  :dunno

Offline Inge K.

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Re: K100RS Cyclonic separator / PCV mod
« Reply #4 on: August 11, 2014, 04:00:42 PM »
I'm just curious what this "separator" is and what it separates exactly, if you could indulge an ignoramus?  :dunno

Input to the cyclonic separator is the crankcase breather...oil and the fumes/gas being separated...
the oil goes back to the sump, the fumes/gas to the TB's....via separate hoses.
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Offline vintagevalves

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  • Posts: 7
Re: K100RS Cyclonic separator / PCV mod
« Reply #5 on: August 12, 2014, 10:52:25 AM »
That's how it's supposed to work.   I hear that there's a sponge of some sort in there that breaks down and causes separation problems.    Oil ends up getting sucked down the TB's, or worse the crankcase breather just gets blocked up. 

I just found this post with a teardown of one of the separators, and also a couple pictures of the PCV mod.

http://www.k11og.org/forum/viewtopic.php?t=7197&highlight=breather

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