2002 R1150RT won't idle when hot.

[CanyonCarver]

2002 R1150RT with 42K on it. Several weeks ago I synchronized the TB's which really smoothed out the idle. However, during the process, I noticed that several of the fuel lines were leaking. I tightened the clamps and seemed to have stopped the leaks; I only checked for leaks up to where they go under the airbox.

 

On my first ride since completing the synch, the bike started up just great when cold. I rode about 60 miles on a rather warm day (mid 80s) and shut the bike down at a store. I attempted to start the bike but it just cranked over, side stand down, in neutral. After three short attempts, I cracked the throttle open and she started, but idled low (600s) and vibrated heavily. I slowly increased the throttle to 3000 RPMs then slowly returned the throttle to the idle position, the bike stumbled then died. This process was repeated several times until finally I just drove off for home. Enroute the bike seemed to respond normally. Upon arrival at home, I shut the bike down in the garage and attempted a restart. The bike promptly restarted and idled about 1000 RPMs. I then performed another TB synch, adjusting the cables per the book, etc. After completion, the bike won't even idle without throttle applied. When turning the ignition to RUN, the fuel pump makes a higher pitch noise than normal until normal system pressure is establised; then you can hear the pump load up and sound normally. Subsequently turning the ignition off then back to on results in a normal sounding fuel pump. Fast idle has no effect on idle speed in any position. I am thinking that there may be a fuel leak under the airbox allowing pressure to drop after shutdown. Any ideas why this bike won't idle?

[CanyonCarver]

UPDATE: In reviewing the archives here, I noticed that one fine owner recommended having almost no slack in the throttle cables. The book calls for 1mm at the throttle grip and 2mm at each thottle body. I have cut this slop down to just a hair and now see that the fast idle works through it's various settings. It is too late now to run the bike and resynch the TB's, so tomorrow am I will be back at it. Also, the heads will be cool enough in the am to pull the plugs and see what is going on in the cylinders.

[SAAB93driver]

Unless the cables are too tight - ie pulling up the TB butterflies effectively opening the throttle, they should have no affect on idle speed. Assuming fuel system is working correctly idle speed is then governed by the butterfly stops and the large brass screws. If indeed the cables are too tight, then your idle speed would be higher.

 

It's an off chance but you might want to check the quick disconnects on the fuel lines near the clamps you tightened. I had one come unseated interemittently (you couldn't easily tell by looking at it) and when it unseats it closes off the fuel line causing a sputtering stall, and the pump makes a much different whiing sound when this happens. Make sure the disconnects are pushed together completely.

[CanyonCarver]

UPDATE: I checked the valves this am, inlets loose by .001 and exhaust dead on. Readjusted as appropriate.

 

Pulled the plugs, cleaned them and measured the gap, they are old but not worn.

 

I took most of the slop out of the cables near the throttle bodies, set the airscrews back to 1.5 turns out FFS (wanted a baseline to work from), and reset the idle by adjusting the butterfly stops on both throttle bodies with the Carb Max. This gave me a balanced reference of 1200 RPM idle (engine hot). I then tuned the individual throttle bodies at 4000 RPM (held there just briefly), dead on. The idle was a small amount off (1/4 of one unit) and this was adjusted out with a small turn of one airscrew.

 

The bike now idles at 1200 RPM, 2200 RPM with fast idle on, and the throttle bodies are balanced from idle to 4000 RPMs.

 

The bike doesn't seem to run any differently than the other day, but it does idle now. I will let it sit now that I have run it to see if I have starting difficulties when the bikes soaks in the latent heat from the engine.