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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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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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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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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]  
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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]  
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Tri750 Offline
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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]  
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Tri750 Offline
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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

#1001117 - 11/18/17 04:38 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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Oh, item # 18


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

#1001186 - 11/19/17 01:21 AM Re: Loss of power and tick sound [Re: Tri750]  
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Dave Labrecque Offline
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Dave Labrecque  Offline
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Tucson, Arizona, USA
Thanks, Tri! Lemme try that and report back!


Dave Labrecque
Becket, Massachusetts

1988 K75S
#1001475 - 11/24/17 04:03 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
Thanks, gents. I have the caps on order (as well as the air and fuel filters). I did put my finger over the one open vacuum port, and it didn't seem to make any difference, FWIW. The intake backfiring continued. Still little power on revving.

BTW -- I listened real close to the tank the last time I ran it. I do hear the fuel pump running. So that's good.

Is it telling that the loss of power happened all at once during my last ride, about five or ten minutes in?

I've heard that my winter habit of running the bike for ten minutes every two weeks is NOT GOOD for the bike. frown

I'm not crazy about draining the tank (though I could do that). Would simply adding fuel stabilizer and putting a tender on the battery be good for five or six months? Not running it at all during that period? (We typically get a lot of snow, and there's no way to ride it from December through March or April.)

Thanks, again.


Dave Labrecque
Becket, Massachusetts

1988 K75S
#1001478 - 11/24/17 04:24 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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If you have ethanol as I guess you probably do, it will start eating the pickup screen ,the black rubber vibration damper and the float wiring in the tank.
You can remove the gas cap, siphon out the gas, carefully lift the pump up a bit and reach in to feel the black vibration damper . If it "smears" or obviously if there are shards of it in the bottom of the tank, your pump may have begun to ingest this stuff.
If so, the pumps days are numbered an it and all the attached parts need to be replaced as well.

Beemer Boneyard or Euro Motoelectric have aftermarket replacement kits for this as sadly, it's all too common.

Your symptoms are more vacuum leak in nature to me unless of course your airbox is full of mouse nest or dog food.
You can test by spraying a fine mist of water from a spray bottle around the fuel rail while the engine is running. If the engine races or stalls, you found the cracked hose(s)

For storage, the true "best way" in my opinion is by buying a couple gallons of unleaded race fuel after you sort the bike out.
Any octane is fine, 98, 105, etc.
run the bike a few miles to make sure the race fuel is thru the system and park it.
Race fuel will evaporate a bit but keeps its gas properties without turning to gunk for up to two years.
VP or Sunoco are two easy to find brands. Try a Karting shop or race supply place to buy bulk or you'll have to buy a 5 gallon can.
If you have a couple bikes, then use on both.

Last edited by Tri750; 11/24/17 04:26 AM.

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

#1001909 - 12/04/17 03:07 AM 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
Thanks for the pointers, Tri. smile


Dave Labrecque
Becket, Massachusetts

1988 K75S
#1001934 - 12/04/17 04:05 PM Re: Loss of power and tick sound [Re: Dave Labrecque]  
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Tri750 Offline
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SO IS THE BIKE FIXED ?


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

#1001936 - 12/04/17 04:37 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
Fraid not. Finally got some parts in (vacuum port caps, fuel and air filters). It's supposed to be "warm" (low 50s) tomorrow. Hope to get out in the garage, then. Too much stuff to do!


Dave Labrecque
Becket, Massachusetts

1988 K75S
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