revs on startup

[emel55]

when I first start my 2022 650 vstrom from cold the revs shoot up to 2000 revs  when I next start the bike even if has only been standing for three quarters of an hour in the sun with ambiant temperature of 21 degrees it still shoots up to 2000revs and stays at those revs until I pullaway  is that normal ?

[kwackboy]

Yes ... its the idle speed control, Even at current temps it'll fast idle for a short period.

You'll find in the winter, it may hang on a little longer.

[Joe Rocket]

Now that worries me kwackboy. From what you say it's normal but a bike that automatically over-revs by 800/900 without your control over it is OK? Apart from wasting fuel longer than necessary it must make riding a bit 'different', no?

Yes, it's bike computer or fuelling control but my AL5 has a brief 'choke' warm up then it settles to ridable idle. Anti-stall? That surely should be a skill learnt on a bike, not imposed. Is this dumb and dumber riding now then?

Your comments, respectfully requested of course. 

[kwackboy]

Not all, (not sure why) but Most modern bikes will fast idle for a short period when cold, the duration differs on various models, your AL5 should be doing the same.

As for wasting fuel, you'll have to contact Suzuki for those figures, it'll be minimal.

Injection systems all have a variation of a idle speed control valve, it will have influence over the cold start ,the idle and the anti stall, if it has it.

From experience when test riding I've not had to adjust my riding at all....

Surely the silliest thing on newer bikes these days is Hill start,  that should be learnt.. 

[Joe Rocket]

Thanks kwackboy. I got the impression that the OP was complaining that the high revs lasted until he (eventually) pulled off.

Yes, as I said mine has a brief choke but only a few seconds.

As for hill starts that surely isn't a bike problem? (In France car hill or sloping starts are done with the brake pedal so there's always at least a slight roll backwaeds. I was horrified when my son showed me the technique he'd learnt here.   

[Brockett]

The fast idle is very silly. My Z900RS used to rev it's nuts off 2000 rpm from stone cold. For the sake of the neighbours (and my mechanical sympathy, it could be slowed by twisting the throttle towards the closed position. However, when I let go the twistgrip the engine rev'd up to 3000 rpm as if to say "I want to be at 2000 and as you slowed me down I'm going to pile on the revs to make up for it".
So why does it do this?
It is a ruse to heat the catalytic converter as quickly as possible so as to become effective (they don't work much when cold) to satisfy the environmental requirements of certain countries.

[kwackboy]

Engines are at their most efficient at their optimum temperature so getting it there quickly is better for the environment I guess..

Some bikes go even further by using their radiator fans. The ECU spins the fan two ways, one way to c.o.o.l the engine and the other way which draws hot air through the radiator to warm the engine quicker.

[mr_diver]

The Varadero's fan draws cool air over the RHS radiator and blows it on my right leg.

[Rixington43]

As Kwackboy says, it's about getting the engine up to operating temperature and likewise the oil hot and circulating as fast as possible. No more "Letting her warm up" for 5 minutes before setting off. Overall it's better for the environment and for the lifespan of your engine. Cats are a big part of that equation as any catalysed reaction happens more thoroughly at higher temperatures. Cars often have a valve which causes the intake to pull air from around the exhaust manifold at first start just to get the block up to temperature quicker. It might seem counter intuitive but I feel certain the powers that be would stop it if it was environmentally unsound.

[Barbel Mick]

I just thought it was now that we have ECU's and fuel injection it was just a case of the ECU instructing the 'fuel system' to squirt a little more fuel in there to help it start easier, then open the throttle valve for more air to stop it running rich? 

@ emel55 how long do you wait to pull away?

[emel55]

I only wait about 60 seconds while I put my gloves  on when first starting the bike from cold. my original query was why it revs at 2000 when the bike is still warm

[Brockett]

Ah the old thread jacking routine. it often cuts in when the answer to your query is unknown but the door is open for old misery folk like me to have good old moan.

[Barbel Mick]

When warm(ish) does it stay at those higher revs for that full minute or go down after a few seconds.

[Rixington43]

Sorry, slightly more on topic, mine jumps to around 2000 immediately on pretty much every start up but drops back much more quickly (straight down to idle in maybe 20 or 30 seconds) on a warm day or if the bike has recently run. The fast idle is taken off coolant temperature so, if the coolant in the area directly around the sensor has cooled sufficiently in that short time, then the fast idle will still initiate. As soon as the engine runs and the coolant circulates, then the fast idle will drop back. On a cold day the fast idle on mine will drop back in steps, 2000, 1750, 1500, 1250 over the course of maybe 3 or 4 minutes.

[purplebikeunicorn]

if the coolant in the area directly around the sensor has cooled sufficiently in that short time, then the fast idle will still initiate

emel, have you double checked that you do actually have coolant in your bike? If that is where it's temperature sensor is, and you've no/low coolant, I guess it could take a while to warm up? Would some stubborn air stuck in the system maybe contribute to this too?

[jabmotorsport]

Unfortunately with the progressing emissions levels (currently EU5b for bikes), a lot of cold start feel and rpm is directly related to catalyst temperature. The sooner you can light the cat off the sooner the emissions trace plateaus. Lots of manufactures use this cold start period to increase load on the engine through various methods to try to increase the gas temp and therefore cat temp as soon as possible.