Rough idle

[evil_yoda]

Hi all.
Been lurking on here for a while now, and bought my 1st 1150gs a few weeks ago so thought I would say hi.
Now that I've put a few miles on it, I'm noticing that it seems to be really rough on idle, sounds like its missing a bit and it makes the screen/instruments and mirrors shake. I can also see the revs rising and falling a bit on the rev counter too.
Ive checked that the throttle cables are seated properly, but thats the limit of my mechanical ability!!

Basically just wondering how smooth/rough everyone elses runs.

Its got a remus and a y-piece by the way.

Cheers

 

[sproggy]

It should idle fairly smoothly, and certainly at a constant speed. Aside from obvious things like plugs and valve clearances (has it been serviced recently?) assuming these are OK it's most likely to be the throttles that need balancing. What speed does it idle at? If it's too slow (below about 1200rpm) then it'll never be smooth even if it's balanced properly.

 

[evil_yoda]

Its got a full BMW history, but is shortly due for its 24k service
The place I bought it from did a service but it was just a "fluids" change.
It idles at about 1000rpm and seems to bounce between there and 1100rpm.
Not bought a Haynes manual yet, but is it fairly easy for a mechanical numpty like me to raise the idle speed?

 

[Gecko]

Like the Sprogg man says - it sounds like throttle balancing to me . If you don't have a carbtune or twin max there isn't a heck of a lot you can do yourself.
To verify if it is the throttle balance you can try adjusting the big brass screw on your right throttle body. Turn it in a quarter turn inwards and see if that helps - important to remember where you started from !!!! Try tuning it back to the orginal position then stop - now try a quarter turn out and compare if things seems better.

If you don't dare to try this then you can take off the plastic cover that is above the right throttle body and lossen the lock nut on the cable. Now you can finger adjust the cable but it is very sensitive so I'd advise you trying the brass screw. It won't give you an exact balance but it will help you identify if the throttles are the cause of the uneven idle.

Once you have seen an improvemnt get into to someone who has a carbtune or twinmax and have the throttles properly balanced. Ideally you want to have the valves adjusted on a cold engine first then get the bike up to operating temperature and then do the throttle balance but there is no harm balancing your throttles at anytime between services.

I would guess you are feeling some buzzing vibration in the handle bars and/or footpegs too - this would also verify throttle balance and valve ajustment needs checking.

 

[evil_yoda]

Cheers guys, I think I will try adusting the brass screw tonight and see what happens. I do get some buzzing throught the footpegs, most noticably through the left footpeg at about 4000rpm while the right one is fine.

 

[Gecko]

Well.....how is it now then ?

 

[evil_yoda]

Had a bit of a tinker last night, didn't adjust it much but it definately seems to have made a bit of a difference. Nothing lifechanging but definately smoother at idle. I think maybe I should get the valve clearances checked and invest in a twinmax

Another thing I noticed whilst giving it a bit of a clean and polish, was that there seems to be a hole in the exhaust pipe. Just below the gear selector next to a collar around the pipe. It's quite small but its definately a hole as the pipe has black marks around it.

Is it supposed to be like this?

Matt

 

[fatnfast]

The pipe is stainless, so there should be no problem with rust, has the collar been fitted correctly? Loosen it and make sure it is in the correct place.With regards to the idle, mines the same. I have had the balance and valves checked during a service which made no difference. I rechecked them myself using the excellent 'dummy' guides (do a search for throttle balancing/valve adjustment) which was pretty easy, but made no difference. I would not fiddle to much with cables or air screws until you get hold of a twinmax/carbtune. I think sproggy has a point, if the idle is set to low it does make the fluctuations more noticeable. At the end of the day these bikes are pretty agricultural, so I accept it as character.

 

[evil_yoda]

Just had another look at the exhaust and the 'hole' seems to actually be a slot of some sort that is not quite covered by the collar. Just looks like the collar needs to be moved a couple of mm.

My previous bike was a VFR750 and this is my 1st twin, so its a bit different to what I was used to. Loving the bike so far though!

I don't mind that the engine is a bit rough and agricultural as long as I know that it's normal and there is nothing wrong it!

Matt

 

[fatnfast]

I think you will grow to love it, I 'traded up' from a Blade. Ref the exhaust, yes, it sounds like the clamp just needs undoing and resetting. Not sure why its moved, has a y-piece (replaces the cat exhaust section) been fitted? Anyway, enjoy the bike!