Turning but not starting-- 86 K75C - K-Bikes.com - Excellence in Motion
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post #1 of 10 (permalink) Old Nov 20th, 2010, 2:11 am Thread Starter
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Turning but not starting-- 86 K75C

So last week it happened to rain for 3 days straight, and for all three of those the K sat outside my garage under a motorcycle cover (I swear I could hear it crying). Well on the fourth day I was excited to finally get back on and take the ride to school in the way it was meant to be. Well I got all loaded up and went to start it up and all I got was some lousy, slow, painful engine cranks. Very low battery. So I cursed it up, unloaded and made the trip in the cage while the battery sat on the tender while I was away.

Got back that night and went to see how the battery was coming. Turned the key, flicked the killswitch, saw all the lights coming on as usual for startup, oil pressure, temperature, battery, speedo lights, clock, and the choke, but when I hit that start button all I got was more empty cranks-- albeit with more gusto from the freshly charged battery. Turned over a few more times and gave it up. I heard the fuel pump running and a few (and by few I mean 2 or 3 non consecutive) puffs from the engine but not enough to get her started.

I figure that since it had been sitting in the rain for a couple of days it had to be something electrical. For some reason the first thing I thought about was the starter brushes. Mostly because I have been noticing the engine cranking more and more slowly as time goes on, and at night I can see the battery light in the dash glowing a bit more than I would expect, especially when I hit the brakes. Bad ground? (and might explain slowing cranking?) So I popped out the started and went to open it up today... only to find the screws totally stuck in place (and borderline stripped). I've had the screws soaking in WD40 all day with no effect. So before I go any further with that...

Do you guys think it would be wise to check some other things while I'm at it? Not real excited for a whole teardown so soon after the last spline lube a few weeks ago, but if I have to then I have to.
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post #2 of 10 (permalink) Old Nov 20th, 2010, 8:37 am
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I'd get the starter clean, it can cause some strange problems when its not clean. You may want to pop out a plug if that doesn't do it and see if you're getting a nice spark. Fuel filter perhaps? You can check the gas flow pretty easy on the bar above the injectors. How many miles on it?

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post #3 of 10 (permalink) Old Nov 20th, 2010, 8:42 am
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I'd check the spark plugs. If it's not starting easily then it's not hard to flood it. How old are the plugs?

Agreed on the starter. Try something better than WD-40. Use a penetrating oil like Liquid Wrench or Kroil. Also, if you have a torch of some sort, try heating up the screws.
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post #4 of 10 (permalink) Old Nov 20th, 2010, 10:29 am
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WD-40 really sucks as a penetrating fluid. 50/50 mix of Acetone and Automatic transmission fluid is pretty good. In a pinch and because you do not need much.....get the GF nail polish remover and pull the tranny dipstick out of your car and squeeze the fluid off it. Mix the two and apply....! Don't try to unscrew the bolts all at once, slowly work them out back and forth to clear the threads.

But good call on the starter, the brush set at $25.00 is a lot cheaper than a new unit. But make sure you mark the case/ends well so you can re-assemble the same way.

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post #5 of 10 (permalink) Old Nov 20th, 2010, 3:08 pm Thread Starter
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66,000 miles. Spark plugs replaced at, I believe, 40,000 miles. I checked for spark and got sparks from all three plugs. Created what H696669 calls penetrating oil and applied some to the screws. Going to wait a bit and hope for success.

But if it comes down to it, what do you think the best way to check for fuel flow is?
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post #6 of 10 (permalink) Old Nov 20th, 2010, 4:09 pm
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The BMW recommended service interval for spark plugs is every 12,000 miles as part of a Level II service but that's most likely too often. Try some Autolite 4163 plugs. I used to run those and change them every 10,000 miles or so just because it didn't cost much and it meant I didn't have to worry about them,
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post #7 of 10 (permalink) Old Nov 22nd, 2010, 11:23 am
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It could still be the battery. Sometimes a battery failure occurs under load. In which case you will have all your electronics working fine, but the moment you need to get the amps out to fire up the starter, it just doesn't have them. Try jump starting the bike.
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post #8 of 10 (permalink) Old Nov 22nd, 2010, 3:32 pm
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If you suspect it's the battery then take it to an auto parts store. Most will load test batteries for free.
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post #9 of 10 (permalink) Old Nov 22nd, 2010, 11:52 pm Thread Starter
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I hooked it up to my car and hit the ignition and got the same empty cranks as before. Tried again and got one puff out of the muffler. Tried again and got a couple more. Then just cranked the throttle and it kinda, coughed to life. Idled on the verge of stalling for a while but finally stayed up. Took it for a spin around the block and everything felt fine.

It may just be me but I think I have a lazy bike, seems to work great for a while, then something will happen and put it out of service for a week or two. Then when I finally get running again it feels like a new machine. That tapping sound I had coming from the transmission? Gone. Notchy shifting I've been noticing? Smooth as glass.

Will run the battery by a shop sometime and see what's up, but for now I'll just enjoy not having to drain that entire tank of fuel I just bought

Thanks again guys for the help. Trying to learn this stuff on my own would probably have made me sell this thing way before now, you guys are worth a million.

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post #10 of 10 (permalink) Old Dec 25th, 2010, 8:40 am
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maybe suffocation

The ancient rule of thumb is air + fuel + spark = run, so as others have already pointed out plugs and fuel filter, I would have to ask; have you checked your air box and exhaust system for mouse nests lately? Rodent damage is a very significant problem in my experience and the boosted startup as you most recently described would be very typical of an air intake restriction or plugged exhaust.
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