tonytee
Parking Attendant
Posts: 20
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posted August 09, 2010 12:20 AM
fast by gast vacume pump
anybody every tryed one of these.i just found out about this i never heard of anything like this.i guess u hook it 2 your crankcase vent so it pulls air from your motor.i wonder if i can rig something up on my compressor 4 my airshifter so the compressor pulls the air from the engine instead of just outside air.i think that would be cool as hell if that would work.
  
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Stuart Racing
Zone Head
N.H.R.A . Dragracing.
Posts: 999
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posted August 09, 2010 05:43 AM
You must turn all your seals around or the pump will suck them into your motor....
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blueshark
Novice Class
Posts: 99
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posted August 09, 2010 06:33 AM
The ones I've seen on dragbikes are bulking, would be hard to fit on a street bike. All the prostock bikes run them, but they are trying to get every last horsepower out of them.
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entropy
Moderator
Posts: 8671
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posted August 09, 2010 08:18 AM
I ran a FBG vac pump at 1/4 mile. it added 4-5 hp, but didn't like the way it made my oil light flicker.
BTW: i did not turn any seals around
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Stuart Racing
Zone Head
N.H.R.A . Dragracing.
Posts: 999
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posted August 09, 2010 10:36 AM
quote:
I ran a FBG vac pump at 1/4 mile. it added 4-5 hp, but didn't like the way it made my oil light flicker.
BTW: i did not turn any seals around
You got lucky.....Should have said it might suck in the seals......
It`s not really meant for a streetbike, mostly for getting that last few HP out of the motor.....
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Life in the Fast Lane..........
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Shane661
Needs a life
Posts: 11494
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posted August 09, 2010 10:38 AM
 Edited By: Shane661 on 9 Aug 2010 18:38
I believe these pumps are more suited for bikes with dry sump oiling systems?
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rtbain
Expert Class
old, fat and slow
Posts: 244
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posted August 09, 2010 12:51 PM
Whatever happened to using two stroke reed valves on the crankcase breather to pump down the crankcase?
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Randy
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2000redrocket
Pro
Posts: 1662
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posted August 09, 2010 02:29 PM
i did that. can not say it gave me anything i can see power wise.
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rtbain
Expert Class
old, fat and slow
Posts: 244
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posted August 09, 2010 02:55 PM
good to know. we used to do it before the days of accesible dynos. tried lots of things that were impossible to quantify.
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Randy
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Shane661
Needs a life
Posts: 11494
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posted August 09, 2010 03:04 PM
Edited By: Shane661 on 9 Aug 2010 23:05
So, there would be a flapper valve that opens under positive pressure, but closes under vacuum, thus inducing suction (negative pressure) within the crankcase?
I know I may be off base, aka wrong, but I had never thought of such a thing. It seems like it would work best under roadracing conditions, with the constant engine braking?
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rtbain
Expert Class
old, fat and slow
Posts: 244
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posted August 09, 2010 04:57 PM
The thinking was it works best under high rpm steady state conditions.
Here is the theory as I understand it.
As the pistons approaches BDC crank case pressure increases. As the pressure increase the reed valve opens and lets the pressure escape.
As the piston goes to TDC the reed valve closes as the crankcase pressure drops.
This pressure differential helps the rings to seal better as its pressure differential that forces the rings against the cylinder wall.
As sustained high rpm run would pump down the crankcase giving stronger ring seal.
There was a BMW twin WAY BACK when that had a row of TZ750 (gawd I am old) reed valves on the crank case. They swore it gave more power. But then he did not have dyno charts.
I wonder if an inline four would even pump down. As two cylinders go down the other two go up, so is there a change in crankcase volume? I dunno. On a boxer motor there is a large change on cranks case volume. Maybe that’s why they are going to a pump.
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Randy
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NOX
Needs a job
PMRA / TMRC Super Street 4022
Posts: 3745
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posted August 10, 2010 05:33 AM
This is the theory behind the kleen air mod......, most guys have proven 1 to 2 hp on the dyno.......
I have it done on my bike........
I have a friend with an old gsxr1100 that is a 1371, and he has a small fbg pump on his bike......, he has no issues.........
what seals would you have to flip around???
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Stuart Racing
Zone Head
N.H.R.A . Dragracing.
Posts: 999
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posted August 10, 2010 05:55 AM
The 2 crank seals....
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entropy
Moderator
Posts: 8671
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posted August 10, 2010 10:46 AM
quote:
The 2 crank seals....
what crank seals (on the 12)?
you mean the output shaft seal?
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Ken 12r
Novice Class
Posts: 86
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posted August 14, 2010 08:49 AM
I had the Kleen air mod on my big motor 12 and it tends to suck a little bit of oil out at sustained high revs and make the motor smoke a little,it soon clears but it worried me that I might miss something more destructive thinking it was just the Kleen air mod so its coming off this week and a conventional breather is going on with normal block off plates.
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