My K100 RS 16V idles normally at 950 rpm when starting out. However, after a longish ride, the idle speed increases to around 1100 rpm.

Is this normal or is there a known suspected cause and/or fix?

Reading 1100 accurately is not quite easy, so there could be a discussion over whether it really is 1050 = within spec., but there is a definite rise in idle speed when hot.

Temperature reading on the gauge is normal in the middle of the gauge. The radiator fan does not come on during riding, but does when stopped and engine running after a minute or so - this also seems normal from a logic standpoint. Outside temperature about 10-15°C.

that seema little high to me ager ...i seem to be able to idle after a ride for more than a minute or two ....running the bike always seems to me to be 2 stepps or so up from the blue bar but never seems to be more than the 4 th mark on the temp guage .......i guess its all dependant on if your in stop go traffic for longer times than me.

maybe a replacement of the fluid might help some ....in almost all cases there is green fluid added to the water t make what is called the coolant .....glycol is normally the active ingedient ....maybe yours is low on the glycol mixture ....the stuff helps prevent , or more importantly helps the transfer of heat out of the system and keeps the boiling temperatue higher than normal water .

other than that ...you could have a timing issue ....late firing always seem to result in higher running temps .



just a thought ...hopefully others will comment as well . but like you i do see a slight rise in idling speed when hot .

I would not be concerned about the idle speed however the fan comming on only after a short while would make me think there is a problem.

Is the coolant good as Charlie suggested and is the radiator clean, the outside. they can get an amazing amount of junk in the fins which stops air flow.

I have one here that is full of dirt because the fork seal was leaking and the oil gets in and collects dust and it is blocked in no time.

Could be that the bike has been adjusted whilst not on working temp. It should be adjusted for idle when warmed up. Then again an air leak could result in a different idle.

BMW manual says tickover should be 950 rpm + or- 50.
If the injectors are out of sync the tickover may be difficult to get right.
Remember, do the simple things first.
My fan would come on if I'm in traffic for a while.

Injectors are not synced, they all work at the same time.
Throttle valves have to be synced. A too high idle will have the fan come on faster than normal.

I would recommend a good adjustment/synchronisation, whilst the engine is warm.

Let me clarify what I meant for and our hair splitting friend above.
What you need to sync, are the air bleed screws on the fuel injector bodies. They need to be lined up with a device that measures vacuum in the manifold. I have used Carbtune and found it good. Others on the forum have tried different types and even made their own.
Never, ever be tempted to mess with the linkages between the injectors. It will end in tears and a visit to ebay.
They are factory set on a flow gauge.

http://www.r6messagenet.com/forums/r6-how-guides/136367-how-make-your-own-carb-sync-tool.html
another option

ungaas wrote:http://www.r6messagenet.com/forums/r6-how-guides/136367-how-make-your-own-carb-sync-tool.html
another option

A password is required for that.

I didn't think so, it was not from the download section.

K Freak wrote:

A password is required for that.

Just close the dialog box that asks for the password, and the page comes up anyway. Since win IE labels the box as "unsafe", it would be prudent NOT to enter any password.