The long winter has caused me to dive into the LT to the extent that it is now perfect, waiting only to ride once the salt is washed off the roads. After resetting the valve clearances and changing out all the fluids, I replaced the brake lines with Spiegler braided stainless steel lines, and at last changed out the fuel quick disconnects using Jiffy-Tite couplers. Since the bike was sometimes idling a little erratically, I considered doing a TPS reset while all the covers were off. This turned out to be a pretty laborious task. Having done TPS adjustments and throttle body synchronizations on the R-series, the LT proved more tedious if only because of the access.
What prompted the TPS reset was the somewhat erratic idling, compounded by the GS911 indicating that the TPS was out of adjustment. With the fuel tank removed, the screws on the TPS are reachable with an L-type T20 wrench. The airbox does not need to be removed. It was initially however nearly impossible to get the GS911 to show a green bar indicating that the TPS is set correctly, although I did eventually manage to somehow get it to turn green. After spending much time fishing for the TPS mounting screws to tighten these and after replacing the fuel tank, the bike fired up but idled much worse than before, with an idle speed of up to 1,800rpm. Only then did I realize that I neglected to remove the TVA (idle actuator).
So the next day the fuel tank came off again, this time the TVA got removed (not unplugged), the throttle cables slackened, and the TPS setting procedure performed for about the fourth time. The instructions tell you to close the throttle against the idle stop, and I did that and set the TPS so the GS911 showed a green bar that turned into red as soon as the throttle is let go. This is not the correct way. I inadvertently also jumped to the next screen on the GS911, and never received confirmation that the TPS was correctly set. Contrary to my instinct but hoping all was well, the assembly process was completed. This time the bike didn't fire up at all. It would cough and then die, just as if it ran out of gas.
Off with the fuel tank again, remove the TVA, slacken the throttle cables and this time fabricate an extension for the T20 wrench – just a 6" length of smallbore brass tubing crimped over the end of the handle. This made finding the TPS screws much easier. And this time taking care to follow each screen on the GS911 diligently, the message that the TPS was set correctly eventually popped up. It appears the throttle should be rotated against the throttle stop, lightly and not forced, and then released. The end result was successful. The bike fires up right away, idles at 1050rpm and the idle speed is stable.
So herewith a few lessons learned for those that plan to do a TPS adjustment:
- Follow the prompts on the GS911 diligently and do not click PROCEED or OK unless you've completed the actions required.
- Slacken the closing throttle cable at least 3 turns. The opening cable can be left alone if it was adjusted correctly. By slackening the return cable the initial slack in the opening cable is returned.
- Loosen and remove the three T20 screws holding the TVA, but there is no need to remove the TVA. It should not be unplugged.
- Use a T20 L-type wrench and extend the handle at least 6". This will make it much simpler to reach the TPS screws. A small flashlight and a mirror will come in handy, although I managed without the latter.
- Do not force the throttle against the throttle stop. Twist it lightly against the stop and release it before adjusting the TPS.
- Nip the outside TPS screw and verify the setting by opening and closing the throttle before tightening the inside screw, just to save you the trouble of getting to the inside screw too often.
- If the screen prompts are followed and the setting is correct, the GS911 displays a message stating that the TPS is adjusted correctly.
When adjusting the throttle cables, the newer type has polymer adjusters and do not give a proper indication of free play. What worked for me is to remove the little cover on the throttle grip, giving access to the cable ends. The following may help someone to set the throttle cables:
- Slacken both adjusters at least three turns.
- Adjust the opening cable (the front one) to obtain free play of 4-5mm and lock the adjuster. The free play can be checked best at the flange on the end of the cable sleeve inside the throttle grip, hence the need to remove the cover.
- Pull on the closing cable sleeve to take up the slack in the opening cable and adjust the free play in the closing cable to 1-2mm. Lock the adjuster. If you aimed for the higher value on the opening cable, aim for the higher value on the closing cable. The difference in freeplay between the opening and closing cables seems to be best at 3mm.
- Check the cruise control cable adjustment – 9mm at the throttle body rail, 2mm at the cable adjuster in front of the left fan duct.
- Check the settings again with the engine at operating temperature.
Final word of warning: unless you have patience and access to a GS911, do not attempt to adjust the TPS. It can probably also be set with a digital voltmeter if you know the correct value, but I have only used that method on the R-series and have not tried it on the LT (yet).