California idling speed

Well my thread regarding the shorai battery has provoked a lot of comments so, let’s see what you all make of this.

My fuel injected Cali Stone has a “choke” lever which increases the engine idle speed to prevent stalls immediately after engine cold starts. Seems to work fine although why this can’t be a programmed function of the ECU is beyond me (I sure some of the electrickery wizards will fill me in). Anyway, I sometimes forget to take off the “choke” and consequently ride around with the higher idle speed. When this happens I have often noticed that, in some ways, the ride is improved. Gear changes are smoother and the bike is more manageable in heavy traffic at low speed as there is no need to “set” the throttle when controlling the bike using the clutch and rear brake.

So, my question is this; what is the ideal idling speed and does leaving the fast idle engaged have any downsides?

As far as I know Idle speed should be 1000-1100rpm

Presumably you will use slightly more fuel.
As GB says if idle is at 1000rpm no need of the ‘choke’ when warm.

The factory spec idle for your machine is 1050rpm - although whether or not you can gauge that accurately from the ‘Vaguelia’ instrument is a moot point. If you have the perception that increasing the idle above that point makes gearshifts smoother then maybe it’s time for the TB setup and balance/synch to be looked at?What idle RPM are you currently seeing - you didn’t mention it.Leaving the fast idle lever ‘engaged’ does nothing more than riding with an advanced throttle - it just pulls a cable on the throttle linkage the same as the twistgrip does.
guzzijack2012-07-02 17:19:13

Mebbe the throttle cable slack needs taking in a wee bit

Could it be a matter of taste rather than a tech issue?Have to admit to experimenting with this on fast sweeping roads where a closed throttle can give toa lot of engine braking.All the bestSteve

It’s a Stone gentlemen. Moto Guzzi didn’t even stretch as far as a “Vaguelia” tacho on this one so I have no idea what the measured idling speed is. If I had to guess, I would say it idles slightly below 1000 rpm based purely on what it sounds like. Having said that, idling is smooth with no tendency to stall once up to normal running temperatures. Interesting point that the fast idle is just pulling on the throttle cable. I won’t worry about leaving it engaged by accident in future. I agree with Guzzibrat that closing the throttle with current idling speed can give rather too much engine braking for smooth riding (but at least I will be able to stop should the brakes fail!)

Not exactly. It’s separate cable that has it’s own attachment to the linkages between the throttle bodies and works entirely independent of the twistgrip cable(s).As GB has suggested, it might be that your throttle cable is too slack and the fast idle is compensating for that. You can download the full workshop manual from Greg Bender’s website and see how it’s adjusted if it’s not clear. Either that or the actual idle adjustment needs to be increased slightly - it’s a screw on the TB linkage.A strobe light or an automotive multimeter should give you a good reading for the tickover speed.
guzzijack2012-07-03 12:34:06

Yes have to say I’m somewhat surprised, seems an antiquated method, I presume an ECU controlled alternative would mean yet more gizmos to bolt on.

Like on me car (and I expect lots of others) has a ECU controlled idling valve, separate from the throttle butterflies (like a bypass), so’s it can set it’s own idle speed as it likes.

The last carburettor cars I remember had an orange warning light on the dash to remind choke is still on, no more complicated to do similar for this case shirley…

Mike & Others.The ECU does carry out an automatic enrichment during cold starting conditions by increasing the injector pulsewidth thereby enriching the mixture. It responds to the signal from the engine temperature sensor and an offset in the fuel mapping is engaged - there is also another sector of the mapping that deals with the engine cranking period and between the two it creates the optimum ignition and fuelling condition for starting. The later bikes also have an ECU controlled stepper motor.The above is why the bikes with the engine temperature sensor mounted in the L/H rocker cover can run rich in cold conditions. The ones with the sensor (it’s a Marelli fluid sensor) in a plastic pocket at the rear of the R/H head are particularly prone to rich running because there is an air gap insulating the sensor from the true temperature of the engine at all times. The ECU compensates to suit and the injector time is increased = increased fuel consumption. The fix is to fill the pocket with heat conducting paste or even copaslip grease. The earlier metal holder from the Hi-Cams makes the job complete.The cold start on a big twin with EFI is one of the most difficult phases of operation due to a combination of the invariably large throttle bodies, (50mm on the Centauro & Daytona), sucking in a relatively large mass of air, the need to squirt enough fuel in to match it, and try and get it atomised in the cold inlet tract at the same time.There’s also a fair bit more space available on cars for ancilliaries and EFI items like MAF sensors etc., but in this case more complicated might not actually be better.The WM EFI used on Guzzis - particularly the earlier models with the P8/16M/15M ECU - is a straightforward Alpha-N open loop system which actually works very well on V Twin motorcycles. Fast throttle response is one thing it gives, and because it’s not that sophisticated compared to later M/C applications, it can be modified and tuned quite easily. The fact that there is a manual fast idle lever is hardly a major imposition is it? It’s not like a traditional choke which will actually enrich the mixture so all that’s going to happen is the engine speed will increase slightly.On balance I think I prefer that system to the later closed loop generation EFI with stepper motors and lambda sensors.

guzzijack2012-07-04 11:48:04

Well! I invoked an electrickery wizard and one appeared! Thanks for the info GJ, I have now read your post twice and understand at least half of it. I agree that setting the fast idle speed is no great imposition and it is intriguing to get a little insight into the compromises designers are having to make when incorporating these systems into motorcycles. I will investigate the throttle free play this weekend and may well end up setting the idling speed slightly higher using the screw adjuster. Thanks to all for the advice and comments.

It’s certainly worthwhile getting the adjustment made as it can make the bike that much more driveable, (gear changes etc.), especially in the important just off-idle area as you’ve already discovered. It sounds as if the TB adjustment and balance are fine with yours so hopefully just a tweak on the idle screw to bring the speed up will do the job.Here are 3D representations of the EFI fuel, ignition and cold start mapping in Excel, (it’s from the MY16M ECU fitted to my Centauro).Although it appears to be now out of print, (and probably by now out of date), this book provides an excellent grounding in the EFI systems fitted to our and early EFI bikes secondhand might be a possibility?BTW. Going on from my post above as to why the relatively simple Alpha-N EFI might not be a bad choice for good 'ol air cooled V twins, (space considerations aside), have a look at this and scroll down to the comparison section.

guzzijack2012-07-04 13:40:25

my head hurts now

I’m a novice at reading these maps so, it seems the first two show throttle opening in arbitrary units against RPM against injected fuel volume (?) and ignition advance in degrees BTDC (?) respectively. If this is correct then the first map shows that relatively more fuel is injected at lower throttle opening for low RPM than high RPM (which seems to make sense)and the second shows that the timing is relatively less advanced for a given throttle opening at high RPM than low RPM (which again seems to make sense). Am I on the right track GJ?

You can read the motorcycle injection handbook here

I’m sure I once found a Ducati focused web page entitled something like “Everything you ever wanted to know about Alpha-N” but …

Anyhow, a useful article on M/C EFI can be found here

I’m with GJ, I like Alpha-N, I returned to Guzzi’s because I wanted a machine I could personalise and do all the maintenance, repair work myself. I couldn’t do that with a truly modern EFI system.

Fitted with K&N air filter, open (but civilised) pipes and a PCIII with custom mapping the Stone runs really sweet and provides >50mpg no matter what. That’s satisfaction


If this is correct then the first map shows that relatively more fuel is injected at lower throttle opening for low RPM than high RPM (which seems to make sense)

Yes, because there is less engine loading at high rpm/low throttle.

and the second shows that the timing is relatively less advanced for a given throttle opening at high RPM than low RPM (which again seems to make sense).

Yes, relatively more advance on a lesser throttle opening but mainly from mid-range upwards to help prevent popping/banging on the overrun as the throttle is closed.

Am I on the right track GJ?

Yup, but don’t forget that these are 3D renderings of the actual maps which are simple 2 axis grids. Although the datum points are spaced as indicated on the pics, the ECU processor will interpolate between them to give smooth transitions. The 3D renderings are good for getting a feeling of what the mapping achieves over the whole engine operating range. In addition they can provide a visual indication of any major anomaly that might occur in the programming.Here’s the fuel map posted above:and here I’ve increased the value of the injection duration at a single point about mid throttle/rpm.As you can see it has affected the area around it as well.Hopefully the ignition map in particular will illustrate what can be achieved with EFI compared to points or even electronic ignition. You are not limited to simple advancing curves with EFI and can tailor the sparks to 100% suit the engine - which makes all kinds of things possible - none of which would ever have been achievable before.Having now used Cliff Jefferies’ fully user programmable MyECU on the Centauro, and helped others with it for other Guzzi models, I can say that I’m not in favour of either the PowerCommander type ‘piggy back’ unit or re-chipping where possible, (P8 & 16M ECU), although I’ve had both before. The MyECU is a much more elegant solution and allows far better adjustment of the EFI.Case in point is the Centauro. As it came from the factory the EFI was not fully developed for the HI-Cam engine and left a massive hole in the revs at about 4-4500rpm. Although it makes the bike feel as if it pulls like a train as it comes back on the power it’s an issue that needed to be addressed. Ditto for the factory exhaust expansion crossover, it’s a great bit of kit which doesn’t have it’s true potential realised with the factory ECU programming. The easy thing to do is to ditch it in favour of a straight through X over which might make a tiny bit more power but mainly just makes the exhaust sound ‘better’ - unless that is you spend a fair bit on aftermarket exhaust, intake (filters) and even the factory upgrade ECU for the DaytonaRS to complement it.Thanks to the efforts of a well known Aussie who has spent a lot of time and effort on the dyno with his My16M equipped Centauro, (the mapping is his with my slight tweaking), the bike has a nearly 20% increase in torque at 2800rpm, with increases all the way through. In fact you end up with 92% of the engine’s torque available all the way from 2800rpm to 8200rpm, plus about 7hp increase in the best spots. The hole in the powerband is also virtually eliminated - I can’t detect it in real world use - and you can up the rev limiter should you so wish.All that from a change of ECU and a very slight modification to the airbox - the O/E filter remains. I’d say it was good value for money.

guzzijack2012-07-05 15:20:29

Food for thought,gentlemen. Food for thought. I think I will start off with the simple idling speed adjustment before getting in to these more exotic mods. Although 50+ mpg sounds very tempting…!

That’s a very smooth fuelling map. The one on my 1100 Sporti is remarkable for its similarity to the Cairngorm massif!At risk of being geeky CJs MyECU also allows data logging using an Innovate LC1 lambda sensor and gives an indication where more fuel should be added or conversely where it’s too rich.These sensors can be used to sort out carbs too; as my pal and his Norton 600ss can attest.p.s. this thread starts with recommended idle rpm and I have found that recommended rpm plus a hundred or 2 rpms extra gives smoother gear changes and better alround tractibility. Also worth checking is v/v settings - idle is far better with Raceco setting IMHO.

Mad Farquhar2012-07-06 16:11:04

Didn’t get to adjust the idling speed but did go for a brief ride on Sunday and deliberately left the fast idle half on. Definitely made the bike more tractable around town.

Interesting slant on this:-