Half-way through the calibration, all spring tension and action was lost from the throttle barrel on the handlebar?
Looking down at the throttle bodies confirmed what I feared the most. Both throttle sector plates had broken. Both sides had a bit of plastic hanging down from the throttle cables?
Broken Sector Plate: Hanging off the cable
Oh well. It's a good opportunity to give every part of the induction system a good clean.
And I have the correct tool to remove and refit those special hose clamps around the throttle bodies.
It's a pretty straight forward job too.
- Ensure that you photograph both throttle return springs to ensure correct refitment.
Photograph of Throttle Body: On the bench
- Do mark the butterfly valves so that they are re-inserted in the correct orientation. White paint pen will suffice.
- Remove the throttle shafts and replace with the new parts. Lubricate the shaft support roller bearings in the throttle body.
- Back off the idle stop screws so that the butterfly valves can close completely.
- Don't fit the return springs yet.
- Hold the throttle body up to the light and VERY GENTLY LIGHTLY TAP/BUMP the valve about until the absolute minimum light is seen around the throttle plate.
- Gently tighten the throttle plate screws checking the light as you go. Re-adjust as required.
- When accurately fitted, the throttle plates will stick in the throttle body.
- Turn in the Idle Stop Screw until that stickiness disappears. Only lightly tighten the Idle stop screw lock nuts. Set these properly during a throttle body balance.
- Fit the return springs.
Lastly I performed a Throttle Body Synchronization.
A short test ride confirmed a smooth idle with a good transition to power, smooth cruise and great WOT.
I will ride for a couple of days to confirm all is OK before refitting all the plastic.
After a good ride, I will again perform a throttle body synchronization.
The Bing Throttle Shafts with broken sector plates. Why? Time? Mileage? These have never been tampered with in my 15 years of ownership.
