No fast idle
 

Hi there,

I've been doing a fair of work to my CBR 600 F 2003 35K miles. It used to fast idle around 3k and then reduce to a normal idle. Now when I start her she just struggles until she's warmed up then seems OK (maybe a bit ropey up to 3k) and fine at all other ranges. I've cleaned and lubed the wax unit and added new seals, done valve clearances (all tight), new coils, plugs and air filter. Any help much appreciated. i was wondering about starter valves but don't know what to do with them or if this would be the issue.

Many thanks Nicky

I'm not familiar with the 600F, but if it's like the F4i there is not much to the fast idle. As it heats up, the wax unit expands and closes the Starter Enrichment valves. It idles fine when warm? Did you loosen the the Wax Unit adjusting nut or lock nut?

Hi,
thanks for response. Sorry yeah its the same bike as F4i I think but here in Scotland they call it CBR 600 F3 (3 for the year 2003) but its the first fuel injected one. Yep it seems fine when warm and idling. Although I'm not convinced about the power until after 3k revs but its not big issue and fine on open road. As you say the starter valves are open when cold and this seems to be when it is struggling so I checked shop manual and talks about synchronising starter values using vacuum gauge seems straight forward enough. The Haynes manual procedure however looks more complex for the starter valves and recommends Honda dealer for inspection clean and sync. I suppose I'm keen to know the symptoms of poorly performing starter valves (ones that needed cleaned and synchronised) ?
many thanks
Nicky

I have never heard nor seen these "starter valves" in all my years as a service writer for Honda or the following years of riding personally. I've always done all work myself to my bikes and have the factory service manual as well....
The only sync I've heard of is a throttle body sync. To me, this sounds like the wax unit is bad.

Who says you can't teach and old dog new tricks? :D
https://cimg8.ibsrv.net/gimg/cbrforu...8bfaa476b0.png

Just had my birthday last month you wanna rub it in huh? haha
How interesting. Now I want to take my bike apart and see these

:icon_bowrofl: Na, don't do it. If it ain't broke, don't fix it.