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1Back to top Go down    Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 8:02 am

shintaro

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Hi, I have a '85 R100rs. Lately there has been an issue with the idle being lumpy and faltering particularly when cold. I noticed there was a vacuum cap missing just behind the back of the fairing. Putting my finger over it smoothed out the idle. This seems to work better when the engine is warm. So i got some caps from Auto-One and went for a ride (120km) bike went well, as i got close to home it started to surge and feel like it was missing. When i got off the bike the cap was missing and the idle was "lumpy". Putting my finger over it smooths it out again. Today I ride the bike after putting another cap on. As I accelerate I feel something hit the inside of my knee, the bike starts to surge again. I pull over and the vacuum cap was again missing, Im pretty sure thats what hit my knee. What would cause the vacuum cap to be blown off.? The others remain in place. Thanks.

    

2Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 8:35 am

Laitch

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@shintaro wrote: What would cause the vacuum cap to be blown off.?
A fit that is too loose would contribute to that.


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1995 K75T 68,000 miles
    

3Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 12:26 pm

BobT

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Using the wrong sort of glue?

    

4Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 12:54 pm

brickrider2

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"Using the wrong sort of glue?"

    

5Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 3:48 pm

BobT

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Here in France we would tend not to use those little black plastic things that fit over the holes, but after 2,000 years of wine production we would probably develop some very small wine corks that fit nice and tight inside the tubes.

    

6Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 7:20 pm

blaKey

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I have seen caps made from different materials...some are a vinyl type material and others are rubber-like. The rubber type material would hold on better than the vinyl type.

The fit should be fairly tight...but this is something that you now already know!


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Neil
K100RS 1986 RED!
K100RT 1987 (now nekkid with red bits)

Remember Rule No. 6
    

7Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 8:16 pm

Inge K.

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@brickrider2 wrote:"Using the wrong sort of glue?"


Only vacuum glue can be used.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

8Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Sun Apr 23, 2017 8:30 pm

RicK G

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@Inge K. wrote:
@brickrider2 wrote:"Using the wrong sort of glue?"


Only vacuum glue can be used.
I suppose that any sucker will know where to get some.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

9Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Mon Apr 24, 2017 9:49 am

shintaro

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Yes, I tried both Rubber and a Plastic type one also. 4mm size as mentioned in a thread here. My thought was to put a drop of silicone on and leave overnight to make it stay. I thought maybe there was something else at play here as Ive had the bike for nearly 2 yrs and this has not happened before. Thanks.

    

10Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Mon Apr 24, 2017 10:27 am

RicK G

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About the only thing that would make them come off is a backfire but you would hear that. I would say that they probably were a marginal fit in the first place. maybe silicone as suggested or rubber caps which will grip better as against plastic which would tend to slip off.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

11Back to top Go down    Re: Vacum Caps, Surging and Rough Idle on Mon Apr 24, 2017 1:19 pm

Dai

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Once they start to rot, then they'll come off really easily. Fall off, in fact. I made a set from 3mm id silicon tube with the ends blocked off.






Okay, if you really want to know, I used 8mm long no.10 stainless steel self-tappers to block the ends off. Go on - you can laugh now


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

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