If your XB has an Erratic idle or lean surging/coughing, READ ME

[DrMotorcycle]

Hey Folks,

Just wanted to share the solution to an issue that we FINALLY resolved on a customers XB12.

Customer reached out initially and said his XB needs a tune, it sometimes wouldn't start, and when it did, wouldn't idle consistently. He tried to ride it over, it died on him and wouldn't turn over again.

Anyway, we troubleshooted a few separate issues, got the bike running again, and did a TPS reset thinking that would solve it. I tuned the bike with my wideband, and even with the fueling spot on, it still had an intermittent miss both at idle and just off idle. A slight cough through the intake accompanied with a temporary low idle when pulling the clutch in, which would sometimes result in it stalling.

To be clear, no amount of TPS resetting or idle adjusting took care of the issue...trust me, I tried.



The problem is this;

Over time, the TPS (where it attaches to the throttle body) begins to develop an ever-so-slight amount of play between the TPS itself and the throttle shaft. In effect, this causes the TPS's reading to be unreliable when the throttle is closed, hence the surging idle and coughing.

I don't think there's any reference to this in the Service manual, so I'm just going to name this Procedure the "TPS Preload Adjustment".

1. Gain access to the TPS by removing the Tank Cover, Airbox, and velocity stack.
3. With a Scribe or a Knife, mark the original position of the TPS in relation to the TB to use for reference.
3. Remove the two bolts holding the TPS to the TB with a 7mm Combo Wrench
4. The sensor will have a slight amount of epoxy on it, LIGHTLY pull on the sensor body with your fingers, it will pop free.
5. With the sensor able to move freely now, rotate it clockwise until you feel resistance. Tighten the sensor down so that it has a very slight amount of pre-load; your TPS scribe mark will Likely be .010"-.020" to the right of the original setting.

Perform a TPS re-set following the procedure in the Service manual, and enjoy your smooth running, stable idling XB!

Cheers,

-Doc

[sprink]

Interesting and helpful tip!

[sportsterpaul]

Thank you for sharing that, it’s how we all benefit the family.