K11 Owners Group

Rich_Brick · Posted: Fri Jul 10, 2009 3:00 am Post subject: Jerky fueling & backfire

Hi all,

New brick owner here!
I bought a 95 K1100LT a couple of weeks ago, to use for my upcoming trip around France, Spain & Portugal.

I picked the bike up from Yorkshire, around 250 miles away and rode it back with no problems, I have since racked up around 1500 miles on it in the past few weeks - the idea being to get used to the bike and discover any niggles it may have before the Mrs & I set off on our trip (at the end of this month).

Anyway, over the last few trips out it seems to have aquired what I understand to be a fueling problem, at low rev's the throttle response is jery and can 'kangaroo' unexpectantly, also on deceleration the bike is backfiring (loudly), im not certain but the bike also seems to be running a bit rougher - hard to describe but overall it doesnt feel as smooth as it did when I picked it up.

I have changed the plugs and cleaned the leads with contact cleaner but that is about where my mechanical abilities end! Im guessing its likely to be a problem with the injection system, i have also seen comments posted on here RE similar problems suggesting the throttle position sensor could be at fault, I have found the sensor but have no idea how I would tell if it was ok or not!

Help please!!..I have to have project K1100 complete for our departure on the 31st or she will kill me!
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Rich

Somerset, UK

tmoons · Flying Brick Rider Joined: 09 Oct 2008 Posts: 161

look up the TPS check procedure on this forum ( in the tech sticky section) and check if it is still in position.

While looking around in that section, also master the Motronic brain read out thing (not hard, find the right hole, short it to earth and watch a light... i think you will manage! Wink

)

otherwise PM me and i will try to assist you from here (holland).

Rich_Brick · Posted: Fri Jul 10, 2009 11:48 am Post subject:

Ta for that, got a few things going on this weekend then ill be on it.
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Rich

Somerset, UK

max · Posted: Sat Jul 11, 2009 5:04 am Post subject:

Also humbly suggest checking some other basics...

- correct octane & good quality petrol; it may have been tuned at idle with a different fuel blend than you've got in

- no water in the petrol or tank... it won't pass the filters well and may reduce the injector capacity. Injector cleaner usually helps here by including soaping agents (surfectants) to allow the water to mix with the fuel and so get burnt

- check battery condition & charge... lowest alternator o/p is at idle (near 0 if idle too low) so an iffy battery will show up then..

Anyway, some things that come to mind if it was "ok" before.

Max

Milton · Posted: Sat Jul 11, 2009 3:10 pm Post subject:

I second or third or forth the TPS as out of sync. Relative easy check and adjustment and will give immediate noticeable improvement.

Milton S.
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Jethro Tull: Thick as a Brick!

1992 K100RS 48K. Dead for now.
1998 Triumph Tiger 43K->56K. Doin it in the dirt.
1978 Honda CB400T 32.5K. For my boys.

Rich_Brick · Posted: Wed Jul 15, 2009 9:04 am Post subject:

I think its also the exhaust, just found a small hole, ordered a good used one and am getting a local BMW guy(not dealer) to fit it and check the bike over for me as im running out of time...2 weeks to go, very busy at work and still have to sort screen, radio + all of our kit etc etc so am being a little lazy im afraid.
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Rich

Somerset, UK

Milton · Posted: Wed Jul 15, 2009 9:25 am Post subject:

Don't think a hole in the exhaust will cause the problems you are describing with the poor running and loud backfire. But since you are having a mechanic look at the problems he should be able to sort it out, if he knows K-bikes.
_________________
Jethro Tull: Thick as a Brick!

1992 K100RS 48K. Dead for now.
1998 Triumph Tiger 43K->56K. Doin it in the dirt.
1978 Honda CB400T 32.5K. For my boys.

ulm210 · Posted: Thu Jul 16, 2009 9:19 am Post subject:

Backfiring is unburnt fuel detonating in the hot exhaust chamber. It is not due to a hole in the exhaust.

When taking the inconsistent throttle response into consideration you would be well served to have your mechanic concentrate on the TPS.

Rich_Brick · Posted: Wed Jul 22, 2009 2:56 pm Post subject:

Exhaust changed and no more backfiring or jerky fueling, mechanic checked TPS at my request and reports that all is fine. Not sure what has happened but bike seems to be running well now, wil keep you posted.
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Rich

Somerset, UK

Rich_Brick · Posted: Wed Jul 29, 2009 11:02 am Post subject:

Still running fine so am starting to feel happier about taking it 2500miles to southern spain and back in a couple of days!
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Rich

Somerset, UK

slyderx · Posted: Wed Jul 29, 2009 11:27 am Post subject:

well a hole in the exhaust will cause a backfire but not necessarily poor running. I would have opted for a plug working loose or an iffy plug lead.....
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slyderx

K1100LT (1992)
ZRX1200R ( yummy)

Rich_Brick · Posted: Wed Jul 29, 2009 12:50 pm Post subject:

Changed plugs before I changed exhaust and was still running iffy. Could have been leads I guess. Its got me puzzled but as I say it seems to be running sweet at the moment.
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Rich

Somerset, UK

Tim (Midland Section) · Posted: Thu Jul 30, 2009 5:27 pm Post subject: