K11 Owners Group

m1ks · Posted: Tue Jun 15, 2010 4:56 pm Post subject: Stuttering / hesitation / misfire

OK, quick synopsis of current events.

The K's been running great but fuel consumption getting a bit thirsty, replaced the air filter a couple of days ago, ridden to work and back the following day, (20 miles round trip, mainly national limit roads, 60mph ish) Smile

then replaced the spark plugs, it had Bosch twin electrode thigummys in, replaced with NGK D7EA, gap of 0.6mm.
Ridden to work today, all fine, on the last mile home started accelerating uphill and noticed a bit of stutter / hesitation.
Whipped the plugs out and checked them, replaced and made sure the caps were on snugly.
I then had to take a friend 50 miles up the road to catch a ferry home (she'd been visiting for a long weekend), so a bit of luggage and a skinny passenger and I noticed that the stuttering / misfire / hesitation was occurring when the throttle was opened rapidly as you would when overtaking for example this seemed to mainly be occuring between 4 - 5k revs seeming to pick up above 5.5k revs, if you accelerate very gently it seemed OK.
Brought it back sans passenger and her luggage, (just my general rucksack and bits in the top box), same story, very gentle acceleration OK but anything more rapid and stutter hesitate surge etc.
Got home, fished out the old Bosch plugs from the bin, cleaned and replaced, went for test ride and maybe very slightly better but prob still there, then it occurred i've just filled up at the filling station down the road rather than the one near work, this tank and the last one filled when I went to collect said friend from ferry on sat and i'd heard stories of bad fuel from a work colleague from this station.
I tried a cap and a bit of Methylated spirit, (denatured alcohol) in case there was water contamination and though I can't be sure I think it's a bit better.
Next plan is to run the bike for another 40 or so miles till the fuel light comes on then fill at the previous station and see if that makes a difference, if so then i'll retry the NGK plugs.

So all that said, does anyone have any NGK useage issues and other than the possible fuel prob any ideas on the cause of the problem here?

I'll add that the bike start, ticks over, runs evenly and revs cleanly at a standstill, no obvious signs of tracking across the HT system and no obvious damage to the leads.

Cheers,

Mike
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Scott_Anderson · Posted: Tue Jun 15, 2010 6:46 pm Post subject:

Moved this to Tech,

Anyway, yes run the fuel out and get some fresh from your regular source.
You may also try some Techron or other type of Injector cleaner and see if that helps any.
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Tim (Midland Section) · Posted: Tue Jun 15, 2010 6:55 pm Post subject:

Never had any troubles with NGK or Bosch, used both in 60K miles on 3 K11's.
Suggest a fuel filter change however. My bike does behave better on Shell V power, when I can afford it.
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m1ks · Posted: Tue Jun 15, 2010 7:06 pm Post subject:

OK, thanks.
Fuel filter was next on the list as it happens, was kicking myself just this morning when I realised I hadn't ordered one along with the air filter and plugs.
It figures that with the air filter and plugs being a bit tired looking the fuel filters likely not been changed in a few thousand miles either.

I assumed the NGK's would be OK, I've used them on all of my Jap bikes and never had bother with them but just wondered if there was a BMW preference for running on Bosch.
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Scott_Anderson · Posted: Tue Jun 15, 2010 10:37 pm Post subject:

Off the grid · Posted: Wed Jun 16, 2010 12:11 am Post subject:

Make sure your plugs are tight in the block.
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Glawseagle · Posted: Wed Jun 23, 2010 8:05 am Post subject:

It may be a dodgy earth somewhere.

I had similar problems and found it was the earth behind the battery holder.

Make sure its not loose/dirty.
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Technician · Posted: Wed Jun 23, 2010 2:12 pm Post subject:

NGK plugs are usually good i've always preferred them, had a bad experience with Bosch in a Guzzi some 20 years ago when it stripped the thread coming out.
Check your plug leads as well as i had some recent experience with my customers having leads breaking down and then have a look at your fuel pressure regulator if the consumption is still high.
All this is of course irrellevent if it's just a case of bad fuel which has already been said is the cheapest option along with a filter change.
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