Adjusting cold idle


Mediocre pilot - Average mechanic - Crazy tinkerer
Staff member
477 Owner
Nov 21, 2022
The following lines describe how I do approach this matter and it should be helpful to those seeking to make adjustments to their own bike.

These are general guidelines needed because every bike is slightly different and there is no a common value that can be used for every bike.
Stock bike rely on the correction from the lambda/o2 sensor but in my experience the red box can do a good job in controlling the crusing phase using o2 values, but it's not that effective at adjusting idle by itself.

This is going to be a pretty long post, so grab a chair, a snack and something to drink and make yourself comfortable.

So where do we start?
In order to adjust cold idle, first warm idle has to be set correctly.

Let's look at the map:

The cells that control idle are those within the square.
Adjusting warm idle:
Step 1: insert in those cells the same value which should be (approx):
  • For 411 stock: 2.1 to 2.25
  • For 411 with cam, filter and exhaust: 2.25 to 2.40
  • For 477 with stock cam but with filter and exhaust: 2.35 to 2.5
  • For 477 with cam, filter ane exhaust: 2.45 to 2.65
  • For 500 with everything: 2.55 to 2.75
Step 2: go for a ride of 7 to 10km should be ok to properly warm the bike up
Step 3: stop and check the idle. It should be at 1250 +/-50RPM and stable. If you don't reach 1250RPMs with any of the setting above relevant to your configuration, then act on the idle screw on the throttle body. Play with it to adjust idle RPMs. turning the screw counterclockwise would increase RPMs, clockwise should decrease RPMs.
Step 4: Try to adjust the values in the cells, lowering them till the point where the bike stalls and dies. once you reach that value, revert back adding 0.1 to 0.15. This should ensure the warm idle is set properly.

Phase 1 is completed, pat yourself on the back, turn off the bike, sit down and grab a beer.

Now to cold idle. For this adjustment the engine must be stone cold. Best if you do this in the morning. Warning: this process is very quick, you have limited time before the engine starts warming up so this might require multiple mornings. Be patient and read everything multiple times so you know what you have to do quickly, without thinking too much.

Foreword: the Red Box modifies the table above compensating for temperature. In order to do so it reads the value above, which will be called the BASE VALUE, then it superimpose on it the ECT comp maps. There are two of these maps: ECT comp INJ acts on the fueling (INJ VE table) and ECT comp IGN acts on the timing advance (IGN degree table). The philophy is the same, so we'll show how ECT comp INJ works for example.
In our example the base values for RPMS from 500 to 2000 is 2.5ms. Keep this in mind.
Now let's look at the ECT comp INJ table:


As you can see the rows are temperatures and the colums are RPMs. The numbers in the cells are a percentage. If it's positive it will add, if negative it will subtract.
So in our example, let's look at the 14C row:
At 500RPMs the number is +35 so the base value will be incremented of +35%, hence 2.5+35%=3,38ms
Same goes for 1000RPMs and 1500RPMs.
At 2000RPMs the number is +19%, hence 2.5+19%=2,98ms.
As it can be seen the numbers progressively go down as the temperature rises, this is because a cold engine requires much more fuel (a part of the fuel would condensate on the cold engine walls) than a warm engine. After approx 60°C the engine is more or less capable to sustain idle with the base values alone.

Keep this in mind, let's go to the procedure.

Step 1: connect the red box to the software before starting the engine and position the software on the ECT comp INJ table

Step 2: keep an eye on the ECT gauge (red square), the INJ gauge (green square) and the AFR gauge (yellow circle), although this one is just a reference, not a precise value. Once you start the engine you'll see a greyish square dancing on the table in correspondence of the temperature row indicated by the ECT gauge. E.g. if you're reading ECT 14C with engine off, the grey square will appear on that line once you start the engine. If temperature is, say 20C, the square will sit between the two row 14C and 28C.
Step 3: Turn on ignition (don't start the engine yet) and leave it on for 5/10 seconds to let the o2 sensor warm up a bit and have better reading (the values you'll see in the AFR gauge)
Step 4: Start the engine and see how it behaves. If it dies immediately there are good chances that the number in the table is too low. Try to increase the number in the cells "touched" by the grey rectangle that represents where the RB is reading. So in example if engine was 20C the cells touched should be 14C and 28C @ 1000 and 1500RPMs.
Step 5: change the values you deem important and press "Enter" on the pc, otherwise the mod won't be send to the RB. See how the INJ value changes looking at the INJ gauge.
Step 6: repeat this process iteratively to stabilize the idle. Keep an eye to the AFR gauge: it should be in the low 12s. Again this is just an indication
Step 7: keep doing this while the engine warms up. The grey rectangle will move upward toward higher temperature rows, check if the bike is idling properly or the cells need adjustments. The values above 56C should be fine.
Step 8: do whatever you have to do with the bike, come back the morning after and check if the new values can provide a better morning start. If not repeat the whole process.

The same applies to the ECT comp IGN table, where you can change the timing advance: in that table, however, the numbers are not percentages but pure number that add or subtract from the base values. Modify this table ONLY if you know what you're doing, changing the timing, without a clear idea of what you're doing, might lead to misfires and knocking. Be aware.

Final thought: due to the internal functioning of the RB a perfect "one push" start might never been achievable, specially with very modded bike. It might be the case that you have to learn to live with a little gas on the start up or the use of choke for few seconds. The aim here is to try to minimize the transient time in which these workaround are needed.

There are many other paramenters that play a minor role in idle adjustments but the discussion of these goes beyond the scope of this already very long post.
We are indebted to you @Sasa as are those to follow who dont know it yet.
We are indebted to you @Sasa as are those to follow who dont know it yet.
Your appreciation is more than enough to keep me going…
I’ve always been of the opinion that who acquires some knowledge should share it with others, otherwise there won’t be any progress…
@Sasa many thanks for all the effort put on this, you make our experience on Himas a true blast! I can tell you.

I'd like to discuss the ECT COMP INJ table, especially the part about "...changing the timing, without a clear idea of what you're doing", which incidentally is usually an Incentive for some of us!

Sooo, what could go wrong, right!? Sasa I remember your offering me some advice regarding this subject, but I cannot seem to find where we had that discussion, and I've check'd the WhatsApp & email discussions w/o discovering. Anyway it would probably be good to have it in the forum.

'I believe' that you told me that these values are Negative, so that any changes would for instance be brought into a higher value. So if @14c the value Was -3.8 I would, perhaps, change this to -3.6 and see how it performs at this setting. Is this correct?
Thanks again,
@RCruiser we discussed briefly about it in a mail, not so long ago!

Any ECT Comp INJ is the map to compensate for fuel, while the one for timing is ECT Comp IGN. Now I remember I said a long ago the values were inverted, but at time I still had to grasp completely the logic of the RB.
The values act as they are, so if you see -3.8 @14C, it means that the spark is "retarded" 3.8 degree at that RPM, compared to what it would be at, say, 80C.

Now my suggestion is to proceed as for the INJ (fueling) table. So start doing little changes in the region where you see the greish rectangle moving. You probably want to increase the advance so e.g. -3.8 -> -3.3

0.1 degrees increments won't be very noticeable, you can apply 0.4/0.5 per time to see some effect!

I hope that explains it better!