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1Back to top Go down    Vacuum line location on Wed May 13, 2015 9:42 pm

Puccini


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Where is the vacuum line to the Fuel Pressure Regulator located on a 85 K110RT?

Anyone have a picture?

    

2Back to top Go down    Re: Vacuum line location on Wed May 13, 2015 11:44 pm

Holister

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Don't have a pic but if you look at the throttle bodies, each of the intakes has a small vacuum takeoff spigot. 1, 2 & 3 will be blanked off with a rubber cap. No.4 has a vacuum line attached (probably encased in a protective wire spring) which goes around the end of the TBs (where your TPS is) and connects to your FPR located behind the TBs
EDIT: found this pic on another thread. The vacuum line is the one in the wire spring.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

3Back to top Go down    Re: Vacuum line location on Thu May 14, 2015 4:42 pm

sidecar paul

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An '85 probably won't have the wire spring, but the hose will be as in Captain's picture.

Paul.


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'84 K100RS (0014643) (owned since '85), 86 K100RS (0018891) with Martello sidecar (built as an outfit in '88),
'51 Vincent (since '67),'72 Montesa Cota (from new), '87 Honda RS125R NF4 (bought 2015)
....No CARS never ever!
    

4Back to top Go down    Re: Vacuum line location on Thu May 14, 2015 10:24 pm

brickrider

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Why is there a spring around that line in post-85 m/c? It seems to be a protective measure, but protection from what? My 1985 bike does not have it, and I've never seen the need for a spring there. What am I missing?

    

5Back to top Go down    Re: Vacuum line location on Fri May 15, 2015 12:21 am

Holister

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The short answer is it stops the vacuum tube collapsing on itself when the negative pressure inside increases. The spring casing holds the tube in it's round shape which is a very strong compared to being oval. When a rubber tube bends around a corner it tends to flatten out and can kink.

The long answer... Injectors rely on a constant pressure to deliver the correct amount of fuel. When the vacuum increases in the intake manifold under accelleration the flow of fuel will increases due to a change in the pressure differential between the fuel rail and the injector nozzle. The vacuum tube relays this change in pressure to the FPR so it can regulate the fuel pressure to maintai the correct flow thru the injectors. If the tube collapses/kinks, the FPR won't be able to adjust the fuel pressure and the mix will become very rich when accellerating.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

6Back to top Go down    Re: Vacuum line location on Fri May 15, 2015 7:59 pm

brickrider

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Early machines do not have this spring. Later ones do. I suppose it's a worthwhile retrofit then, even if my 1985 K100RS apparently never has experienced any problem that could be put down to a lack of spring on this vacuum line.

    

7Back to top Go down    Re: Vacuum line location on Sat May 16, 2015 6:02 am

Holister

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I'm not sure, but you may not even notice if there was a problem. Dirty emmissions, slightly poorer acceleration, increased fuel consumption especially if your heavy on the throttle. Certainly wouldn't be very common.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

8Back to top Go down    Re: Vacuum line location on Sun May 17, 2015 5:53 am

K75cster

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It's my understanding that the spring is there to keep the tube in the round (so no kinks) for optimal vacuum operation.


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

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