MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Jeff Sichoe on June 24, 2013, 08:07:34 PM
-
:mbird
Hello!
First things first, thanks to all here for the very valuable information provided in these forums! I would be lost without ya! :)
Anyway, onto the problem at hand.
About 6 months ago I picked up a fairly clean 1986 K75s. I've had the 'usual' problems;
Dead Radiator fan (replaced)
Front Fork Seals shot (replaced)
Intermittent Speedo issues (ride faster than 80kph and it works fine ;))
etc etc
So far, nothing I've been unable to manage :)
HOWEVER - late last week, while riding to work 2-up, in the rain, the bike started... 'fluttering' at approx 3,4,5k rpm. When I say flutter, it's like the bike either dropped to 2 cylinders, or was having issues with gas flow. However, what was strange was I could rev it OVER 5k and things would come right again for about 30 seconds to 1 min, then it would begin fluttering again.
I was giving it quite a bit of herbs just at idle, when it stalled. All dash lights came on, I powered down the bike, restarted it and it kicked into life first go, only to stall again within a few seconds. I then started it up again, and made the decision to get it back home and catch the bus into work (how gay is that?)
That night I took it for a ride, and it was consistently fluttering at the same 3,4, 5k rpm, but would recover if I gave it heaps, and would pick up again about 6krpm.
I was thinking at this point that it was something to do with the fuel filter being too clogged, and under load, at that specific 'fun zone' of RPM (about 4k+) was bogging down. I shook the tank around and filled it up with some 98 octane, and basically gave it some shit, revving it out to redline and back in 2nd gear, riding up hills with as high a RPM as I could, and it seemed to come right.
A couple of days later, after running fine in the wet and dry, it did it again... fluttering about 4krpm, and stalling at the lights.
I'm at the point where I'm thinking it's one (or a combination) of 3 things, but want to confirm my thinking before I begin ordering bits.
Fuel Filter Clogged - would this introduce the 'fluttering' and stalling at idle?
Spark plugs / leads - could an fault with one of the spark plugs or leads cause issues at a specific rpm? I would have thought it would 'work' or 'not work' running on 2 cylinders from start up?
Electrical / wiring fault - I found a thread where someone had a very similar thing, and checked all the cables and connections, and after spraying contact cleaner on everything he could get his hands on, the problem was resolved? Could this be an ECU issue?
I'm going to order the fuel filter (no idea when last changed) and some new spark plugs, and see how that goes, but does anyone else have any ideas as to what could be causing this?
Cheers for any and all assistance guys!!
--
Thomas
-
Sounds like you are already on the right track with a Fuel filter and plugs.
You can use a Napa 3032 filter for a whole lot less than a BMW, and you can probably get it local as well.
-
Awesome, good to hear i'm on the right track!
I'll order the parts and update thread when installed, but if anyone else has any bright ideas please, let me know! :)
Keep on brickin'!
:mbird
-
the burd was stalling at idle a few weeks ago... installed a new napa 3032 fuel filter and its been yeeehaaaaa ever since...
cutting out at speed... the bug used to do the same thing... it was the 4 pin under tank fuel pump connector... was always f ing with that thing... ended up putting a 4 pin trailer connector on it and it never did it again...
j o
-
Interesting! I'll check the connector out tonight and see how it looks!
Sounds like i'm in the running for a new filter anyway, so i'll do that regardless...
Thanks!!
-
A couple things: check the fuel pump connector (as johnny mentioned) and also check for arcing at the coils. They can crack and allow shorts to occur. Just pull off the cover and look for sparks in the rain.
-
Alright, a quick update :)
Checked the under-tank connector to the fuel pump, it was a little ratty so gave it a good ole clean up.
Waiting for the fuel filter and spark plugs to arrive (I couldn't find any NAPA brand filters here in NZ :( )
Been riding the last couple of days, ZERO hiccups of any kind, so it's looking pretty flash!
It's raining pretty hard today, and ye olde bikey is out in it, so i'll see how it goes on the way home tonight :)
Thanks again for all your assistance!
-
wondering if this problem resolved. I have a similar issue with slightly different cirumstances.
new filter last season after stalling issue.
Yesterday, starts to stall and bog out at stops, got it started with choke, and managed to shift into 2nd and ride the last 3 blocks of a 20mi trip.
won't restart now, removed tank and started checking lines, couldn't start bike to depressurize lines, so I disconnectd, and then curiously, the bike started right up with the tank disconnected. Tank spits fuel from pump line, and fuel spits up from return line when disconnected. Then I connected the tank, and left pump unplugged, still got it to start up fine, as soon as i plug in the pump(to avoid stall) it bogs the bike out.
Any suggestions? I wouldn't think its injectors, ignition, air, filter or fuel pump. . . but i'm rechecking today
-
Woah! Sorry I didn't see that reply :(
yeah in the end i'm suspecting it was bad fuel, as after riding the HELL out of it and filling up with some higher octane fuel it came right...
-
Tom, over here on the big island, some of us use Ryco Z200 for the fuel filter. I've been using them for quite a while and they work a treat.
Forgot to add: Go to Jaycar Electronics and buy the DeoxIT Contact Cleaner and Rejuvenator Kit ($29.90NZ) and use the red stuff on every goddam electrical connector on the bike. Magic in a bottle.