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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: K75riderilm on August 17, 2017, 02:29:39 PM
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I have a 93 K75 that I bought about 6 months ago. It has been well maintained by the PO. The trouble I am having is the motor starts misfiring after about 80-100 highway miles. Upon doing a bunch of research I decided to replace the Hall effect sensor. This didn't fix the problem. During the last ride I noticed a fuel smell prior to it acting up. My instinct told me to open the fuel filler in case it was vapor locked. It was not. I have since throughly cleaned the tank and changed the fuel filter as I did find some water in the fuel. My throttle response improved after doing this and was hopeful the problem was fixed. After an 80 mile ride it happened again. Another symptom is backfiring through the exhaust on decel. When the bike is cold it runs flawlessly. I have a running parts K75 I can scavenge parts from. Any ideas are greatly appreciated.
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greetings...
did you use a fairing gig on that heap...
have you cleaned your jetronic connector...
did you replace the fuel filter with oem...
how much you want for the good hes...
did you clean the 4pin...
whats that z hose look like...
how much techron have you run through there...
what did your throttle body sync show...
did you remove the tennis balls from the velocity stacks...
what greese did you use on the splines....
you gotts chinese hid lights on there...
you running no corn ethyl...
did backfior blow apart your new air filter...
is this thing still stock or is it queered out...
are tior rotation arrows pointing right way...
what plugs and wiors you got on there...
does it pull to the left...
did you use denatured water in the radiator...
you gotts bimmer or beemer roundels on there...
are your tragkorbs and ignition keyed to your gas cap...
are you a filmcamera disciple...
post up some photos...
j o
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I replaced the fuel filter with a Napa in anticipation of doing it again soon. Make me an offer on the HES, I did not clean the 4 pin but it appeared good. One bottle of Techron and a sync was done just prior to me getting the bike. I have no reason to suspect it is off.
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I use Honda M-77 on my splines. This one won't get done until tire replacement
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greetings...
trust nothing the previous owner says as being absolute truth... you know that...
needs a 4pin warshing and a jetronic connector warshing and lotts of techron and no corn ethyl over a few hundert tached up miles...
getts bottles of techron in that iconic 22 tankorb and commence motobricking...
j o
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I bought this bike from a friend who owns a BMW shop and has all the records of the maintenance he has performed for several years. Otherwise, I wouldn't give what the PO says any consideration.
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greetings...
will your friend give motobrick.con members 20% discount and free shipping on internet parts orders over $200...
j o
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greetings...
will your friend give motobrick.con members 20% discount and free shipping on internet parts orders over $200...
j o
Asking the real questions here.
Sent from my iPhone using Tapatalk
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I have a 93 K75 that I bought about 6 months ago. It has been well maintained by the PO. as I did find some water in the fuel. My throttle response improved after doing this and was hopeful the problem was fixed. Another symptom is backfiring through the exhaust on decel.
When decelerating close the throttle completely; a partially-open throttle often causes backfiring. The throttle position switch might need adjustment.
If water was in the fuel, the drain system might be clogged. When the fuel cap is open a hole will be visible in the left side of the cap assembly flange. That hole is designed to drain water accumulating around the cap's perimeter by diverting it through a pipe that goes though the tank then exits as one of the two ports beneath the rear of the tank. It either deposits water into a cup hanging from the frame or a hose is attached to it and the hose should exit behind the right footpeg plate. Check the pathway to be certain it's open.
The crankcase breather hose should be checked for cracks and replaced if it has any.
Clean your bike's 4-pin under-tank connector and verify that it is a tight connection; don't just look at it. The same goes for the ignition switch connector under there. DeoxIt is usually recommended here.
This bike might need a tuneup consisting of spark plug replacement, air filter cleaning or replacement, throttle body balance and throttle switch adjustment. When were those performed last? Have you looked at the air filter?
You'll sort out this problem. Plenty of information can be found in the Repair Guidance Master List section.
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Thanks for your reply, the plugs and breather hose are new as of 100 miles ago. I did verify the drain tube was clear when I cleaned the tank. I have not cleaned the 4 pin connector yet. TPS clicks as it should but could be out of adjustment. Throttle bodies have not been balanced recently though it idles and has perfect throttle response until "it" happens after about 80 miles.
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Take it out and ride the piss out of it for 40-50 miles(not enough to make it act up) and take a plug reading. Take some good photos and post them.
Then take it out and ride the piss out of it until it starts to run crappy. Pull the plugs and see what they look like. Take some photos and post them.
While the plugs are out, you might want to check the numbers. It's a long shot, but you may have a colder plug than specified and it is fouling on an over rich mixture when the engine gets hot.
Johnny is right about Techron and no corn. You may have sticky injectors that are not closing completely and causing a rich mixture. One or two tanks of Techron may not be enough to get them working properly. It can sometimes take a thousand miles of flogging to really get things loosened up.
Ethanol is not kind to engines that are not used regularly. Always store a bike with no corn fuel.
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Has no one mentioned the spark plug wires/leads yet? That sounds like something I had decade or so ago. Seems when the block and wires got warm the spark was more prone to arcing over and I lost fire in that cylinder. Since fuel was still being injected into that cylinder, everything got all gassy and in particular that plug was wet with fuel.
You might want to take off the spark plug cover, toss a blanket over the headlight and see if you can see anything arcing in there at night. Or pull each plug and see which one is wet. If your bike still has the original wires with the brass heads, they are probably well on their way out.
I didn't read this post with a fine toothed comb and am running out the door, so if if the OP already did this then please don't jump all over my sh...for not reading at tentatively enough.
MH