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K100-forum.com » Technical, repair and troubleshooting » Electrical » Pressure Relief Valve Testing

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1Back to top Go down   Pressure Relief Valve Testing Empty Pressure Relief Valve Testing Mon Feb 15, 2021 10:32 pm

AUBIEBMW

AUBIEBMW
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Is there a way to bench test the pressure relief valve that resides on the back side of the throttle body assembly and has a hose that runs to the #1 throttle body?
Thank you.
Pressure Relief Valve Testing Pressu10

    

2Back to top Go down   Pressure Relief Valve Testing Empty Re: Pressure Relief Valve Testing Mon Feb 15, 2021 11:54 pm

Laitch

Laitch
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That vacuum switch was deleted after 1985. It didn't fulfill its purpose. Plugging the vacuum connection and leaving the switch disconnected won't make your moto's engine run worse than it does now. It's vestigial.



Last edited by Laitch on Wed Feb 17, 2021 1:14 am; edited 1 time in total (Reason for editing : Exercising the opportunity to write "vestigial.")


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1995 K75 90,000 miles
    

3Back to top Go down   Pressure Relief Valve Testing Empty Re: Pressure Relief Valve Testing Tue Feb 16, 2021 1:29 am

92KK 84WW Olaf

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I have 2 Ks that have that, 83 RS and 84 RT. 

As said, just use the regular vacuum cap on the No 1.

But, but, but, I did try it on the RS and it does seem to make a difference. Mechanically these 2 engines are the same but the 83 is different if its on or off. I think the disappearance had more to do with the move to unleaded petrol as I am told it advanced the ignition timing.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

4Back to top Go down   Pressure Relief Valve Testing Empty Re: Pressure Relief Valve Testing Tue Feb 16, 2021 11:31 pm

AUBIEBMW

AUBIEBMW
active member
active member
Thanks, I am still trying to determine how to test it.  I would like to keep it on the bike, even understanding that it may not really have an effect.
Thanks,
Jim

    

5Back to top Go down   Pressure Relief Valve Testing Empty Re: Pressure Relief Valve Testing Wed Feb 17, 2021 12:58 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Are you thinking fuel pressure regulator? This is a manifold vacuum switch that has no connection to the fuel pressure.


__________________________________________________
Present: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

6Back to top Go down   Pressure Relief Valve Testing Empty Re: Pressure Relief Valve Testing Wed Feb 17, 2021 2:23 am

92KK 84WW Olaf

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AUBIEBMW wrote:Thanks, I am still trying to determine how to test it.  I would like to keep it on the bike, even understanding that it may not really have an effect.
Thanks,
Jim
Its a vacuum sensor, so I expect that at a certain vacuum level it provides an earth as there is only a single electrical connection. I don't know what the level of vacuum should be. I do have a couple of them lying about but never tested them.

If my memory is good then I think someone said it gives a 6 degree advance in the ignition timing. That makes sense because it seemingly disappeared after the engines became listed for unleaded petrol.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

7Back to top Go down   Pressure Relief Valve Testing Empty Vacuum switch. Wed Feb 17, 2021 10:17 am

daveyson

daveyson
Life time member
Life time member
From Bert's guide it's purpose is to change the timing curve at middle throttle.

With a computer safe test light clip on battery positive, and probe to the brown wire the light should glow.

With the probe on the violet/grey wire, the light did glow on mine when the RPM's exceeded about 2,000, and went out below that. DO NOT use a normal test light.


__________________________________________________
11/1985 BMW K100RT (late model)  Vin. 0090567
 ~120,000 km
    

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