Rough Idle

[Spacecadet]

My valves are adjusted properly and my spark plugs are newly replaced. My idle is around 900 but seems to be on the rough/missing side at idle. Runs pretty good at speeds.When I come to a stop, I tend to have to give a throttle movement to make the engine stablize.

[Ken H.]

What bike are we talking about?

[Spacecadet]

1999 R1100RT with 32,200 miles

[Red]

Pull off the right side tuperware and check to see if a small rock has lodged itself in the throttle body pully. Quite common. Has happend three times on my 1100 in 70,000 mi.

[ninermatt]

900 rpms seems a bit low. I would bump up that idle a couple/few hundred more.

[T__]

My valves are adjusted properly and my spark plugs are newly replaced. My idle is around 900 but seems to be on the rough/missing side at idle. Runs pretty good at speeds.When I come to a stop, I tend to have to give a throttle movement to make the engine stablize.

 

 

Spacecadet, you could have about anything,, from poor gasoline, to an engine issue, to an ignition problem, to coked up throttle bodies, to compression problems, to a low idle with the TAC being inaccurate, to stretched, improperly seated, or worn throttle cables.. Could even worn TBI throttle shafts or bushings..

 

Probably the next thing you need to do is balance the TBI’s air flow side to side using a manometer or homemade U tube.. Unequal air flow between the cylinders could cause your idle problem & usually it is more noticeable at idle than cruising..

 

It probably wouldn’t hurt to pull the brass air screws out of the throttle bodies & clean the carbon off those & their seats in the throttle bodies (use carb cleaner but be careful to not get any on your paint).. I had an 1100 & cleaning those brass air screws & their respective seats made a tremendous difference in engine idle quality.. Make sure to mark the screw position before removal or you will definitely have to re-balance the sides when done..

 

Twisty

[Tominator]

Throttel body airscrews have to come out from time to time. They build up with Blow by engine oil and cause weird things to happen. I clean mine every season and syncronize the TB with my Twin Max.

 

Tomas

[glwestcott]

900 rpms seems a bit low. I would bump up that idle a couple/few hundred more.

 

I suggest the same thing. I had the same symptoms you describe and bumped up the idle speed to 1100 and have had no more difficulties. Mine is a 2001 RT with 77000 miles on it. If that doesn't do it, I agree with the others that suggest pulling the brass screws and cleaning them as a next step.

[Spacecadet]

I bumped up the idle and cleaned the brass screws. Works great. Why don't the maintenance manual or owners manual mention these brass screws? I guess the dealer wants our bussiness (money) to do what the average bear can do?