What’s your 912iS idle rpm set to?

My Minimum idle is 1700 rpm. That is throttle fully pulled back.

Start up idle is 2500 rpm.

Numbers lower than these put unnecessary load and vibration into the gearbox.

I am pretty sure this is adjusted by the idle stop screw on the throttle body...

On the throttle body of the injected engines you should be aware that adjustment of the idle speed is done from the factory.  The idle screw is put in with LOCTITE and if you break if there is NO REPLACEMENT from Rotax.  Please leave it alone and use your throttle system if you wish to have a higher idle speed.  

This is fuel injected and the adjustment of the idle and setting of the throttle body potentiometer, TPS, is done by the supplier of the throttle body to the factory.  They do not carry spares for anything other than complete replacement. 

Cheers

Rotax Wizard, 

 Just curious. Is there a reason the idle screw can't  be heated to loosen the Loctite and adjust the idle up some? 

hi Roger...yes you can but I hate heating that area of the throttle body.  The temperature required to soften Loctite is about 400 F, it worries me at that level and where you have to heat.  For the past 10 years since the iS was introduced all the ones I have seen broken were on OEM adjusting the idle screw to meet what they believed was correct speed.  In the iS is is much less of an issue and given you must run the engine almost immediately to 2500 to switch on the A side of the computer it is much less of a problem.  The iS tends to idle much better since fuel is relatively lean compared to the carb version engines.  

The newest throttle bodys used, starting a few years ago, now have an additional screw to set idle independent of the one that was always there.

I need to be clear, Rotax has 2 versions of the throttle bodys used.  The original had only one screw.  This is fixed with Loctite and set to min idle speed by the factory.  This one is not replaceable and was not intended to be changed.  

Later versions have a second screw, if this is what you have then go at it and adjust away as that is exactly what it is for.  The dual screw version part number is shown in the 915 iPC along with the old version with the single screw.  The 055 was single screw and the 056 is the newer one with the second, adjustable, idle screw.

I hope that helps.

Cheers

See attached for reference. 

Howdy Rotax Wizard,

Hope all is well. It's  been a while.

One thing I have gotten away from are heat guns. They heat or may damage everything in the area and no pin point heat. Now I use a small butane torch that I can pin point my heat and do a better job of heat control and it keeps it from possibly damaging things in the adjacent vicinity. So far so good and no issues. Heat at times really helps break stubborn screws or bolts lose so you don't  damage things.