Rough running issue - Still not bloody sorted.....

From process of elimination its seems to be getting closer to a fueling / balance scenario

As Puk said if youve got wear on your throttle bodys that could give you the problem

what year is your bike

I'm sure i have a set of throttle bodys in the shed i bought as a backup, you can borrow those if you want to do a swap / comparison test

Edit - i never fitted them, so i dont know what condition theyre in btw
 
Today after a run.
2019-07-04-1.png
 
From process of elimination its seems to be getting closer to a fueling / balance scenario

As Puk said if youve got wear on your throttle bodys that could give you the problem

what year is your bike

I'm sure i have a set of throttle bodys in the shed i bought as a backup, you can borrow those if you want to do a swap / comparison test

Edit - i never fitted them, so i dont know what condition theyre in btw

2008... On one throttle body there was a little daylight that was around on one half of the butterfly valve, not much but could this really cause such a rough running issue? And why intermittent if the worn butterfly is there constantly?
 
2008... On one throttle body there was a little daylight that was around on one half of the butterfly valve, not much but could this really cause such a rough running issue? And why intermittent if the worn butterfly is there constantly?
Yes absolutely it would
 
Yes absolutely it would

Thanks fergus, can you explain why it is intermittent and if I can purchase the brass piece on its own to replace (also where to purchase)? I did unscrew it to remove/ clean then replace. I take it these are off the shelf or do they require to be specific items to fit individual throttle bodies in case of variances? Mine both had the number 5 on them??????
 
Chances are that when the throttle grip is closed, instead of air being accurately controlled via the idle air bypass circuit through the idle stepper motors, it is flowing uncontrollably around the butterfly plate into the engine. Any wear in the butterfly spindle bushes could exacerbate this as the plate can vary in position when closed.

I dont see why you can only see light around one half of a closed butterfly plate unless either the plate is not centrally fitted on its spindle, or the spindle bushes have worn oval allowing the shaft to drop. Is the light showing above or below the butterfly plate ?

After checking for bush wear/loose butterfly spindle I would be tempted to loosen/remove each screw in turn, apply loctite then refit the screws and try to adjust the butterfly plate to close fully with no light showing before fully nipping up the screws to lock the plate to the spindle centrally.
 
vacuum gauges....


lets pretend the vehicle is un molested...

you must set the balance between the two throttle bodies if you want it to run remotely properly at regular intervals (just like balancing carbs)....


1) do a service setting the tappets spot on,
2) clean the throttle butterflies and bodies of all crud and build up (particularly if its a high mile bike or just keen if less than 15k)
3) go for a quick ride and get the engine to normal operating temp
4) use a tool to calibrate the idle actuators (although pretty pointless if there a visible gap on one throttle body) it just runs the stepper motors full travel and sets at a base setting
5) use a diagnostic tool to lock the stepper motors out from messing you about
6) fit calibrated vac gauges to the two throttle body vac connectors (don't rev the nuts off the engine or the vac gauges will hate you)
7) at the throttle grip end remove the slack so you hold the engine revs above idle and pull the throttle butterflies open via their cables.... 2k rpm
8) using the small throttle cable adjusters near the throttle butterflies adjust to set a matching stable vac reading on the gauges
9) blip the throttle open and closed a few times and recheck changes at 2k
10) remove cable tension at throttle grip, snap throttle open and closed a few times and check reading at idle
11) if that's a long way out read this - seen posts from years back with BMW saying must fit new throttle bodies if anyone ever tampered with the base throttle stop screws - but sounds odd to me - if you took a brave pill set these up the same way. re enable the stepper motors and see how the world looks
12) when you think you got it right recheck holding the throttle open manually

you could have a play and redo steps 4 to 10 again….
the adjustment is rudimentary and a few blips may see the world move again, if you need more than 1/2 a turn, someone was messing about before you and messed it up

NOTE: its NOT idle you want to balance.... its as the butterflies lift off idle that gets the engine running well.... but if you want a good idle and a smooth running engine you want it right in both places

other techniques views / info welcome for debate (especially around the stepper motor lock out feature as I can imagine this is only if you play with the stop screws that you're not supposed to touch)
at 30k bodies should be good, at 90k I can imagine they should be replaced due to wear
 
Chances are that when the throttle grip is closed, instead of air being accurately controlled via the idle air bypass circuit through the idle stepper motors, it is flowing uncontrollably around the butterfly plate into the engine. Any wear in the butterfly spindle bushes could exacerbate this as the plate can vary in position when closed.

I dont see why you can only see light around one half of a closed butterfly plate unless either the plate is not centrally fitted on its spindle, or the spindle bushes have worn oval allowing the shaft to drop. Is the light showing above or below the butterfly plate ?

After checking for bush wear/loose butterfly spindle I would be tempted to loosen/remove each screw in turn, apply loctite then refit the screws and try to adjust the butterfly plate to close fully with no light showing before fully nipping up the screws to lock the plate to the spindle centrally.

The light was around the bottom half of the butterfly valve but not all the way around the bottom, it didn't figure as the top half was good so could not understand why the gap was there, wondered if it had worn in some way???
 
Sounds like the plate is eccentrically mounted on its shaft. It needs sorting.

Not much point in calibrating the idle steppers with a GS911 as it just fully shuts the stepper motors against their stops then counts the steps open to set a baseline position, this would not allow/compensate for your butterfly plate issue.
 
The butterflies don't fully close, they are held open a few degrees by the throttle stop screw, the ones you are not supposed to fiddle with. AFAIK they are set up on a flow meter and the screws then painted.
 
The butterflies don't fully close, they are held open a few degrees by the throttle stop screw, the ones you are not supposed to fiddle with. AFAIK they are set up on a flow meter and the screws then painted.

Unless somebody such as a previous owner had mistakenly adjusted idle on the baseline stop screws instead of adjusting the cable slack. Still doesn't answer how there is light showing around one half only.
 
I really think you should take it to Steptoe, the summer will be here and gone........just like your cash as time goes on. Not having a go, just want you to get it sorted once and for all rather than shots in the dark. :thumb
 
I really think you should take it to Steptoe, the summer will be here and gone........just like your cash as time goes on. Not having a go, just want you to get it sorted once and for all rather than shots in the dark. :thumb

Agreed wholeheartedly. :thumb2 (posts 122/123).
 


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