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#1000976 - 11/15/17 05:40 PM Loss of power and tick sound  
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Dave Labrecque Offline
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Dave Labrecque  Offline
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Tucson, Arizona, USA
Any wisdom welcome.

I was riding my '88 K75s last week, and suddenly there was much less power available. There was also a soft tick or click sound (which could also be felt throughout the bike) every second or two. This tick/click did not correspond to engine or bike speed; it was fairly regular and consistent.

A friend who thought my bike is carbureted says it sounds like internal backfiring due to a clogged air filter. I've never changed the air filter in nine years.

Any other thoughts?

Many thanks,

Last edited by Dave Labrecque; 11/15/17 05:41 PM.

Dave Labrecque
Becket, Massachusetts

1988 K75S
#1000979 - 11/15/17 06:06 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Dennis Andress Offline
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Dennis Andress  Offline
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Port Orchard, Washington
Sounds like the fuel pump. The pump runs for 1 or 2 seconds when you first turn the bike on (before pressing the starter). Do you hear the sound then?

#1000984 - 11/15/17 07:20 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Dave Labrecque Offline
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Dave Labrecque  Offline
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Tucson, Arizona, USA
Thanks, Dennis.

Just tried it. When the key is turned on, I hear single click (coming from somewhere under the tank), but the pump doesn't run at all. Is there a fuse I could check for the fuel pump?

If it's the fuel pump, what would explain that click/tick that I get every second or two when the engine is running? Is there a relay that calls for the pump to run as needed?


Dave Labrecque
Becket, Massachusetts

1988 K75S
#1000998 - 11/16/17 03:01 AM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Dennis Andress Offline
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Port Orchard, Washington
There should be a relay under the tank. You could tank your tank off and try again. I suspect the fuel pump though. The relays are too small to make a loud enough noise to be heard, and the pumps fail with age.

Last edited by Dennis Andress; 11/16/17 03:02 AM.
#1001032 - 11/16/17 05:19 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Dave Labrecque Offline
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Dave Labrecque  Offline
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Tucson, Arizona, USA
I guess I need to check the fuel pump or whatever allows power to get to it, since it's not running like it should. Thanks.

Last edited by Dave Labrecque; 11/16/17 05:20 PM.

Dave Labrecque
Becket, Massachusetts

1988 K75S
#1001044 - 11/17/17 01:28 AM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Tri750 Offline
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Tri750  Offline
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Has the been sitting for an extended time ?


Classic Cycle Connection
Current:
1971 R75/5 roadracer
1973 Kawasaki Z1 roadracer
1976 BMW R75/6
1999 BMW R1100RT
2007 Kymco People 200S

#1001052 - 11/17/17 03:25 AM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Dave Labrecque Offline
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Dave Labrecque  Offline
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Tucson, Arizona, USA
Not sure how extended you mean. For the last five years it sits in the garage all winter, and I run it for ten or fifteen minutes every couple of weeks. During the summer I take it out a few times. Not as much riding as I'd like, unfortunately. But it does get run and/or ridden.

Last edited by Dave Labrecque; 11/17/17 03:26 AM.

Dave Labrecque
Becket, Massachusetts

1988 K75S
#1001098 - 11/17/17 07:29 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
Joined: Apr 2009
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Dave Labrecque Offline
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Dave Labrecque  Offline
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Tucson, Arizona, USA
See (hear) what you think. Video linked below.

I'm starting to think that the tick/click sound is backfiring at the intake. Would a dead fuel pump cause this in and of itself? Dirty air filter? Dirty fuel filter? I'll replace the filters, but I'm still interested in everyone's thoughts.

Sorry I don't know what's what with the intake parts; please forgive my use of the layman's term "little hole." laugh

https://www.dropbox.com/s/lugwfwql6s6vg0g/K75S%20loss%20of%20power%20and%20rough%20idle.mov?dl=0 to stream it. (click "no thanks" near bottom of prompt if you're asked to sign into or up for Dropbox)

https://www.dropbox.com/s/lugwfwql6s6vg0g/K75S%20loss%20of%20power%20and%20rough%20idle.mov?dl=1 to download it.

Last edited by Dave Labrecque; 11/17/17 07:31 PM.

Dave Labrecque
Becket, Massachusetts

1988 K75S
#1001106 - 11/17/17 11:02 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
Joined: Sep 2004
Posts: 1,041
Tri750 Offline
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Tri750  Offline
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CA
that’s a short tube used to synch the fuel injection butterflies .
put your finger over it while the bike is running and i’ll bet you a buck the bike runs fine .
look at the same area #1 cylinder (forward cylinder) there is rubber cap over the tube on that one but it’s cracked. it’s ready to fall off as well.
oh, had your fuel pump died, you would be pushing . there is no gravity feed . it needs the pump to run.
be back .

Last edited by Tri750; 11/17/17 11:17 PM.

Classic Cycle Connection
Current:
1971 R75/5 roadracer
1973 Kawasaki Z1 roadracer
1976 BMW R75/6
1999 BMW R1100RT
2007 Kymco People 200S

#1001107 - 11/17/17 11:13 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
Joined: Sep 2004
Posts: 1,041
Tri750 Offline
Member
Tri750  Offline
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Joined: Sep 2004
Posts: 1,041
CA
ok
PN 1354 7694 924
you can use an automotive vacuum cap as well.
an experienced K bike guy keeps several of these in his tool kit along with the crankcase breather hose .
here’s a link to the picture from a K100, same thing . same cap as used even today .’
http://www.realoem.com/bmw/enUS/showparts?id=0533-USA-12-1991-89V1-BMW-K_100_RS_0523,0533_&diagId=13_1389


Classic Cycle Connection
Current:
1971 R75/5 roadracer
1973 Kawasaki Z1 roadracer
1976 BMW R75/6
1999 BMW R1100RT
2007 Kymco People 200S

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