This is a quick & short guide on HOWTO set Idle RPM for Yamaha YZF-R15. Remember, the R15 is a fuel injected motorcycle and there is no carburettor. All we can set is the idle RPM. Further tuning like "Air-Fuel Ratio" or AFR can be set only with a Fuel Injection Diagnostics (FID) tool.
Remember, idle RPM should be set only on a warm engine. DO NOT do it on a cold engine. Please at least idle the engine for about 10 minutes (not exact numbers but something like a thumb rule) or even better run it for at least 1 KM.
Remember, Yamaha recommends 1300 to 1500 RPM as idle RPM on a warm R15 engine. Please refer to the users manual page 6-14 for the same. My personal experience has been that at 1350 to 1400 RPM the bike idles good and works pretty well for normal use. Anything more is useless and anything less can be harmful to the engine as it keeps lugging / struggling for breath to keep running. The Fuel Injection system however keeps the engine running without switching off. The FI also takes care of revving the engine higher when cold and for cold starts in winter too.
The image below shows a correctly set idle RPM on the console:

Tools Needed:
a) an eye on the RPM meter and an year for the beat
b) A long screw driver - flat one. The one that comes with the tool kit falls miserably short for this activity.
Please check the image below for the one I have used (green) and the one from the bike's tool kit (black):

Now, my R15 was running on low idle RPM from the past 4500 KMs. It came back like that from a service where they were not asked to adjust anything and then I was lazy enough to pull out the long screw driver to set this right. Here is an image of my R15's console before I have set the idle RPM right:

I shall even attach a video to this post. Bad quality but primarily made to make you hear how the engine beats with low idle RPM.
The Task:
0) Start your R15. Let the initial RPM burst settle down to the more stable position.
1) Please move to the right hand side of your R15 and locate the clearance provided for idle RPM adjustment in between the side panel and the chassis. Refer to the below image to where the screw driver is pointing to:

2) A Closer look at it - you can see a brass screw inside. That is the one you have to turn to set the RPM. Carefully place the screw driver's tip into the grove, hold it with your right hand (or even the left. use the hand that is more convenient to you) and stand up so you can see the console while turning. The below image would be useful:

3) To adjust the idle RPM you must have a warm & running engine. To reduce the RPM turn the screw clock wise. To increase the RPM turn the screw anti-clock wise.
Be gentle with your movements and don't just turn the screw heavily in one shot. It even helps to remember the original position & how many quarter turns you have made from the original position.
While turning, it would generally take a while for the change to be reflected in the console - so, be patient too. Make your turns in small increments, wait for the result (sometimes there would be none) and then proceed.
4) Once the idle RPM is adjusted to the desired level, revv the engine a little and see whether the needle settles back into the same position as you have set. If needed, do further adjustment. Based on the need you may want to repeat this process to your satisfaction.
5) Switch off the engine, fire it up again and see where the RPM settles down to after the initial burst. Does it settle down at the correct level you have set it to?
If yes, cheers, the task is done.
If no, make sure the engine is warm and try the process again. If you fail to get it right, take it to the workshop instead of further trials.
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Thank you.
HydBiker ([email protected])
Please excuse the out of focus photos. If you find some more inputs please post them or let me know and I shall incorporate them into this post.
I would actually like this thread to have the AFR settings DIY too. If some members can contribute the images with FID and contribute words (I can help with it if needed) it would be great and we'd get the thread renamed accordingly.
And finally, please vote for usefulness of this article.




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