Issue: Cold Start and Idle rough

Still haven't given up. On another thread a user mentioned that they had heard of instances where the CAT was clogged up and caused very similar issues. So I swapped out the exhaust, this made no difference either.

 

Did you resolve this?

There are a couple of us with this very same problem pulling our hair out trying to figure out something even Honda can't fathom.

The only thing I can add as information into the mix; we found that if you electrically disconnect the MAP sensor it starts up as designed ie. wax idle takes it straight to 2k and brings it down as temp goes up. Plug the sensor back in and it does this bogging down business. MAP sensor has been replaced to no avail, wiring checked nada. Vacuums all check out.

 

Never did, replaced the entire exhaust as well, checked for air leaks nothing. There were two things I had not yet done before I sold the bike. It still ran fine and was a solid bike just had to let it warm up first. I stoped before I drove myself mad.

1) vtec valves could have been way out of spec
2) ecu issue, never found someone to swap me for a day

If you can check those off then truly there is nothing else.


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Well, I'm going to tentatively say....I've fixed mine. After 3 years of head scratching and getting nowhere I realised I'd never actually gone to the trouble of lifting the throttle bodies off completely. Anyhoo, whilst mulling this over it curiosity led me to think about the throttle body boot clamps. There are eight in total, four lower and four upper. Would you Adam and Eve it; all eight were loose enough to spin by fingers alone! Tightened them up and straight away the difference was marked. Took it out for a test ride and it felt like the bike had a new lease of life! Much smoother, engine braking changed, no more grumpiness at lower speeds/revs and just generally much more responsive.

It's been two weeks now and I commute every day on my VFR and she starts up straight away at 2k rpm no hesitation or bogging at all, every time. And what's more my mpg has gone up to 'normal' figures (I've had all the way down to 27mpg, that's UK gallons so for you yanks that'd be..err..23mpg!)

The startup issues will have been that the 'leaks' in the boots will have caused the MAP sensor to go wibbly and throw it off, hence why if I disconnected the MAP sensor electrically it would start up fine albeit in Alpha-N mode.

Needless to say I am delighted to put a long running mystery to bed.

 

Interesting... I've seen similar problems develop on small displacement-high revving bikes (the kind of bikes you have to rev the crap out of to make any horsepower/speed).

I still have two of them, a Kawasaki EX250 and a Suzuki GSF400 and the constant high RPM vibrations make every bolt and fastener want to loosen and bail out. When I'm working on these bikes just about everything gets Loctite threadlocker applied to it (I use the 242 Blue medium strength and the 222 Purple low strength depending on the item).