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My CBR 600 F4i idles at about 3000 rpm when the engine is cold, after about 2 to 3 minutes when the engine warms up, it settles back down to regular idle speed of about 1300 rpm.

Is this normal for this bike?

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5 Answers 5

Not too sure but this looks usefull;

http://www.bulkky.com/honda-motorcycle/cbr600/cbr600rr-03-04/honda-cbr600rr-2003-%E2%80%93-2004-fuel-system-lubrication-system-specification

Thought that might be the case, I suppose alternatively phone up your local garage or tuning specialist and they might be able to tell you?

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Thanks, but the link only shows the regular idle speed once the bike is warmed up. –  Ian Oakes Aug 23 '11 at 9:36
    
Thought that might be the case, I suppose alternatively phone up your local garage or tuning specialist and they might be able to tell you? –  CodeBlend Aug 23 '11 at 10:28

It is perfectly fine. Its much better for the engine to warm up on steady 3k RPM before you start reving it to maximum. This will make sure the oil has proper density and all components are well lubricated.

A friend of mine has a Fireblade and the behavior is very much the same. Until the engine gets warm its running on ~3k RPM and then drops to just a bit over 1k

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Almost all engines will idle faster when cold than when warm. My fuel injected ZGR-1400 does so. My car does so. My KLR 650 and my girlfriend's Ninja 250, both carbureted, idle fast with the choke on.

When your engine is cold, the fuel mixture needs to be richer in order to achieve combustion. That will cause the engine to idle faster, and that is why every engine recommends that the idle speed be set when the engine is nice and warmed up.

A fast idle for a cold engine in cold weather is normal.

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This is a (rather annoying, imho) characteristic with this particular bike. It doesn't happen with "all bikes", although some may be slightly higher when turning the engine on after a cold night.

The Honda CBR 600 F4i, particularly in cold weather, tends to rev it's nuts off for the first few minutes (it's the automatic choke) until it warms up and calms down. I had a 2005 F4i and I believe that was the last year they tended to do that.

So for this particular bike which is a bit old now, it's about right. Don't let it just sit there revving for ages though; you can set off within a minute of switching the engine on. Just take it slowly until the engine has warmed up and the idle speed is back to normal.

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I have a CBR600 F4 - which is essentially the same engine but with carburettors instead of injection. On cold start, just a small amount of choke adjustment will cause high revs (i.e 3000+) versus sitting at 1500-2000. As I have a manual choke, I'll warm it up at 1800-2000 RPM and then go easy riding it until temp gauge comes into the zone.

Factory idle for a CBR600 F4 is 1500 - which feels somewhat high but does let you pull off easier from a standing start as the engine makes all it's power above 4000 RPM.

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