K11 Owners Group

tibbe · Posted: Wed Aug 20, 2008 4:42 pm Post subject: Backfiring -94 K11LT ( non cat. )

Hi.

After syncronizinig the throttle and enriched the mixture the engine backfires after letting the gas and let the engine alt as breaking the bike.
Then give a bit gas, it backfires from the silencer.

Info:
Valves are within clearence.
Plugs are white with a bit yellow.
New airfilter, oil.
Normal milage at 60mph.

What to check and adjust?

Off the grid · Posted: Wed Aug 20, 2008 4:45 pm Post subject:

Some backfiring is normal, especially with an aftermarket pipe.
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Bane of your existence since July 2006
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johnpeter · Joined: 14 Aug 2008 Posts: 20 Location: Los Alamitos, SoCal

Air leaks between the head-pipes and the muffler/silencer will promote back firing on any 4 stroke motorcycle.
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Red '91 K75S w/WILBERS damper..daily rider. Wanna K11RS
'79 Guzzi..stalled project
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Milton · Posted: Thu Aug 21, 2008 1:07 am Post subject:

Make sure the throttle position sensor is adjusted properly. Improper adjustment of the tps can cause back firing.

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.

Moondog · Posted: Thu Aug 21, 2008 7:09 am Post subject:

chopper_harris · Posted: Thu Aug 21, 2008 10:10 am Post subject:

And that the fast-idle cable (Choke Wink

) has a couple of mm slack.

When I got my old girl, the PO had set it up too tight, and it was pulling the TPS slightly off base without raising the idle revs noticeably.

When I solved that, I am convinced that the fuel consumption went down by 4-5 mpg.
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C1 200 (2001)
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Kawasaki KLV1000 (2005)
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Jim · Posted: Thu Aug 21, 2008 6:07 pm Post subject:

Tibbe - if nothing else works, adjust the TPS to cut off just a tad earlier - that's what I had to do with the K75. The K75 would backfire like a big truck (scared the chit out of me more than once!) with the TPS set to spec - once it was set to cut off a tad earlier, the problem was resolved.
_________________
Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."

tibbe · Posted: Sun Sep 07, 2008 3:16 pm Post subject:

Hi.

Renewed rubber tubes between throttle houses and inlet, new sealings at injectors, new tubes for crankshaft ventilation,,,.

Next syncronise throttles and most of all set the TPS.

Any tips on how to set the TPS.

BTW: season are running out, some mornings arround freezing point.
Like to do a last trip for the season.

/Sven-Erik Tiberg
Lulea ( 65.35 degrees north, 22.09 east. )/ Sweden.

chopper_harris · Posted: Sun Sep 07, 2008 5:55 pm Post subject:

tibbe · Posted: Fri Oct 17, 2008 4:06 pm Post subject:

Thanks all for the tips and advises.

Did like this:
Closed the idlemixture ( brass adjuster ).
Synced ( underpressure ) the throttles at 2500 rpm.
Adjusted the idlescrew to 600 rpm.
Opended and synced ( underpressure ) the 4 brass idlemixture to 900rpm.
Checked the sync ( underpressure ) at 2500 rpm.
Was fairly equal.
Stopped the engine.
Connected wires to pin 1 and 4 at the TPS-connector and adjusted the TPS to 0.375V +-0.025V.
Out for a testride and the result = Very Happy

/Tibbe

Jim · Posted: Fri Oct 17, 2008 4:26 pm Post subject:

good to know you got it - I figured you would...
_________________
Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."

tibbe · Posted: Sat Oct 18, 2008 6:40 pm Post subject:

Well couln't resist the challange Smile

With the help if you all, it's a joy to wrench.

BTW. the riding season are almost ower, was ice on the tarmac as i rode home ( bicycle ) from a b-day party this evening.
Maybee a last ride ( beemer ) tomorrow before move it into the garage until april next year. Will use the bimmer until the tarmac are clear next spring.

All the best and ride safe.

/Sven-Erik Tiberg

Mystic Red · Posted: Sat Oct 18, 2008 11:27 pm Post subject:

Jim · Posted: Sat Oct 18, 2008 11:39 pm Post subject:

No backfiring from the K - with the aftermarket Remus.

The K75 used to backfire like a big truck - almost caused me to pee my pants more than once - I didn't think anything that small could make such a loud noise! Adjusting the tps to cut off a little sooner cured it.
_________________
Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."

Off the grid · Posted: Sat Oct 18, 2008 11:42 pm Post subject: