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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: strodeb on April 21, 2014, 11:12:09 AM
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A week ago i did a basic service on my K75c hack.
Changed oil, air cleaner element & re-greased the shaft (plugs will be done when I get chance as they don't need the fairing off)
Since then It wont tick over at all when cold & almost not at all when hot. Choke helps a little when cold, but not much. Above 3000rpm it pulls like a train.
I have had no time to pull it all back down due to work commitments.
The airbox seems to be clamped down (from what i can see through the after market Sprint fairing)
The choke light has decided to stay on even when the mechanics look to be off at the throttle body (but this is since yesterday & until now the choke was never used, so new unrelated fault?)
I am assuming it could be the air flow meter (from what I have already read on here today) is there any other obvious culprit that I haven't checked?
Is there an easy way to disable the air flow meter, to force the bike onto an alternative map, proving or disproving it's at fault?
The fairing is a bugger to remove, I know I have to do it, but if I can fault find before I need to that would be great.
This isn't my bike, but one Google found with the same fairing... http://farm2.static.flickr.com/1193/1330226585_a708e3ae62.jpg?v=0 (http://farm2.static.flickr.com/1193/1330226585_a708e3ae62.jpg?v=0)
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greetings strodeb...
welcome to motobrick.com...
what year is your moto... how was it running before you did all this work...
j o
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greetings strodeb...
welcome to motobrick.com...
what year is your moto... how was it running before you did all this work...
j o
its a UK C plate, so 1985. It was running ok, but not great, in that it ticked over without stalling, but would occasionally miss a beat then catch back up. Once it was off tickover it was fine & pulled well across the rev band.
Now it won’t tick over, if I try to hold it at say 2000rpm it will stall. If I give it a hand full of throttle it will very slowly pick up to about 3000rpm, then very suddenly revs will fly up, but as soon as the revs drop under about 3000rm it tries to die again. If it was carb’ed I would suspect the idle jet was partially/completely blocked.
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Check the crankcase breather z-hose. It's on the aft part of the plenum/airbox, visible from the left side. If broken, it can cause metering issues at idle/low flow conditions.
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sorry work has kept me busy (and therefore away from my computer) I will check it out today.
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Well I got very bogged down with work & had to take the car everywhere for a while!
But this morning I decided to check out the hose with it off the bike, its only 2 jubilee clips, should be 5 min job.
I quickly realised that the lower half of the air box stops the hose coming off unless I want to get rough with it (which I didn't as I don't have a replacement yet)
so 45 min later & with the bike stripped down to give me access I got the part off. I didn't get a photo, but it had a 1cm split by the lower jubilee clip (but at the back out of sight) & there are quite a few cracks in it (so it must be getting very old).
As I didn't have the part I figured I would clean it up & then wrap it with self amalgamating tape. I was careful to get a good overlap & did 2 layers over the whole pipe.
I refitted it with new (and slightly bigger) jubilee clips and rebuilt the bike.
Started it up & ran it up to temp, so far it sounds better than it has in a couple of years, tickover now works, but it is also much more consistent. no little misses every now & then.
If it starts to fail again I will replace the pipe, but if it doesn't play up it can stay wrapped up. the pipe is about £25 & the short length used off the roll of tape was probably about £1.
So thanks for the heads up wmax351... you were spot on.
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I'm too late to the party (per usual) but my breather hose also gave similar symptoms. Not as dramatic as yours but the bikes seem very sensitive to vacuum issues. It's not the old buick 455.
Your fairing (*the one in the pic) is outstanding. Good show :2thumbup: I'd love to find one. Not sure my bike will last long enough until the nickles are saved up.
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Well I figured I would give a quick update (should be working but needed a quick break)...
The bike is still going & still sounds much sweeter than it has in a long time.
Lets hope it keeps going for a long time yet :2thumbup: