R1100RT 1 cylinder problem

[Dave Millings]

hope someone can help. Using my holidays trying to sort this,

1995 R1100RT.

New to me. No cat. Was running ok. Stripped down to clean and add new shockers and other cyle parts, service etc. Didnt touch electrics apart from unplugging and cleaning. New plugs. Put bike back together. L/H cylinder running ok. R/h cylinder runs for awhile and then back fires really badly and cuts out. Swapped plugs/leads still the same. Checked spark ok. Put old plugs back...same. Checked for airleaks none. Checked exhaust clamps ok.Took injector out seems to be spraying fuel alright. Im stuck now. Any help appreciated.

[T__]

Dave the usual place to start is to make DARN SURE the R/H throttle cable is seated in the TBI furrel.. It is REAL EASY to get he cable to sit on top of the cable furrel & that will make the R/H cylinder run like crap..

 

Twisty

 

[Dave Millings]

Ill go check that now....thanks.

[Dave Millings]

The cable is seated ok. Tried running it again. The r/h cylinder ifres up but as soon as you open the throttle it bangs and pops and dies.

[Killintime]

Sounds like a bad ignition coil.

[T__]

Dave, on your 95 the cable for the R/H side comes off the L/H TBI cam & there is another cable furrel on the L/H side,, maybe it is dislodged there.. Maybe verify that both TBI throttle cams open at the EXACT same time (lift off the stop screws at the same time) & hit the stop screws at the same time.. This is about the number one reason they run poorly after any service around the cables or fuel tank..

 

Otherwise make sure the R/H spark plug wire is not pulled loose at the ign coil & the plug wire is in good shape at plug attachment end..

 

Twisty

 

[Dave Millings]

Twisty, I have checked all the cables and they seem ok. If I pull the r/h lead off the l/h cylinder runs really nice. If I do the opposite I can start the r/h cylinder but it pops and splutters with blowback to the airbox and then dies. Im wondering whther to swap the injector nozzles over?? as i said before Ive tried different plugs and swapping the leads over. Can i swap over where the leads come out of the coil?? it wasnt running perfect before I wonder if the previous owner has messed with the mixing screw? maybe i should try that i have a feeling he was the type who would.

[T__]

Dave, the same coil sparks both sides at the same time.. If you can get the wire reach you can swap coil sides going to the spark plugs as it should fire the same.. All plugs fire together on that bike as it sparks at every piston top-of-stroke..

 

You really shouldn’t just pull a plug wire off & try to run it.. That coil secondary is a continuous loop so the spark plug on one side is the ground path for the plug on the other side.. If you want to run it on one side,, remove the plug wire from the other side spark plug then ground that removed wire.. By just pulling the plug wire off the plug you force the coil to arc internally to provide a ground for the running side..

 

Swapping injectors is a good move as it will eliminate a faulty injector..

 

You state you have checked the cables/ cable seats correct? Have you also physically verified that both sides OPEN & close at the exact time? You should be able to hear & feel them both open & close together..

The reason I say this is it is possible the previous owner did his TBI balance with a cable out of place & now with them back where they belong the TBI timing could be way out of whack.. The L/H side has the TPS sensor on it so even if it is out of whack it will fuel to the throttle plate opening correctly.. The R/H side needs to be precise in phase with the L/H side as it gets it’s fueling info from the L/H side position..

 

Usually when they pop back into the air box it means that side is either lean,, not sparking at the correct time,, or has a leaking intake valve.. Have you pressurized that bad side cylinder with compressed air with the valves closed to see if you have any valve leakage?

 

 

Twisty

 

[Ken H.]

What does the sync check like just above idle?

[Unhofliche_Gesundheit]

re; "Stripped down to clean and add new shockers and other cyle parts, service etc"

 

what do you mean by "service etc" ?

specifically what was the list of things you did?

[Dave Millings]

Swapped the injectors over. Still the same. I dont have any compressed air to check the valves. The spark appears the same on both sides. Ive ordered a coil and leads second hand with return option if required.Checked the cables again and even altered the adjuster on the r/h side but it makes no difference. Wiggled the throttle body and any cable or connector.....nothing.Thanks for your input Twisty.Ill let you know how i get on. good job i kept my trust K100RS!!!!

[T__]

Dave, when you open the throttles with the twist grip then close them can you feel the each throttle plate hitting the closed stop at the same time.. How about hitting fully open at the same time?

 

As Ken suggested check the throttle sync above idle (you can make up a simple U tube manometer using a long piece of clear hose or tubing).. If that is correct & the injectors make no difference then you are probably looking at spark or valves..

 

 

Twisty

 

[Dave Millings]

Twisty,The bike was ok before i started cleaning it etc....I didnt do anything to the cables....and they seem to be ok i can feel the plates hitting the stop together. Mind you just after I bought the bike it did go onto one pot a couple of times. If its the spark would a new coil fix it or is there anything else that I might need to look at? I got feeling this is going to take some time.

Thanks

[Dave Millings]

Ive ordered a tested 2nd hand coil with a return option plus leads.

thanks.

[Dave Millings]

Mainly just clean it. New fork seals and oil, front and rear shockers new, new plugs. Clutch and drive shaft spline lube, new final drive pivot bearings. new battery.GS intake tubes to airbox and new air filter. I havent been in the engine at all.

Thanks

[Dave Millings]

Ken, Im going to call it a day for today.I have a gauge and that was the last job i was going to do. Even when i "mess" with the adjuster on the r/h pot it makes no difference. As i said the l/h pot is running great but the r/h one is basically "dead" even though its getting fuel and as far as I can tell the same quality of spark as the l/h side.

cheers.

[philbytx]

I know I am taking a WAG here but could this be another HES weirdness...one of the sensors/leads acting up?

[outpost22]

I know I am taking a WAG here but could this be another HES weirdness...one of the sensors/leads acting up?

 

I initially thought this too, however it should affect more than one "pot".

[T__]

Phil, problem is the HES is the same one for both sides.. Both sides spark at the same time on the same HES signal & both sides inject at the same time on the same HES signal.. In fact the ign coil is the same common coil for both sides & the injector trigger wires are tied together & are triggered as one..

 

 

Twisty

 

[r77toy]

Did you remove the TB's when you installed GS tubes? Replace the O ring? Maybe an airleak.

[Dave Millings]

I didnt take the TBs off. I have ordered new O rings one was like an overstretched rubber band. I thought i had found the problem, made 100% sure there were no air leaks but the r/h pot still wont run without popping and banging. i am going to get a compression tester.It it ws a single cylinder bike you would say the timing is miles out!

[Davis]

Watching this thread closely. I've got a very similar problem with a 94 RS, except mine cut out abruptly not after any service. Went out for a ride and it was running fine, then all of a sudden it's only running on one cylinder. Have checked spark, got a nice spray out of the injector but switched injectors just to be sure. Dead cylinder has good compression. Fuel, compression, spark all seem good. Everything else I can think of would effect both cylinders. Checked all the cables. Mine's a little different from the OP in that mine's dead at idle also.

[big-t]

 

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