Hi guys

Recently I went on a ride one Sunday afternoon with a mate of mine who also has a VFR400.

His VFR400 is apparently a EX - Race bike which has had the HRC carb mod done as well having the heads skimmed. Obviously he only told me this after the run while I spent most of my day trying to keep up with him!

My VFR on the other hand is stock standard as far as the motor is concerned.

I would like to know what exactly is done with the HRC carb modification?

Had a chat to my local bike shop and they advised me not to do it as for around town driving and only taking the bike out on the open road once in a while that I will get very frustrated with the bike as it's really only helps out on your top end speeds... and is rather sluggish and rough on your lower range speeds with more of a flat spot at about 4 000rpm

so my other question: is this true?

I'm not sure that it would be great on the road - as you say the HRC kit gives mostly top end power. My race bike has the full HRC carb set-up though, and there's no flat spot to speak of - but that's after many (many) tedious hours to set it up properly. Also worth considering that there's no air filter used, so engine longevity may be shortened. There's a few on here that run the HRC set-up in various guises on the road though (filter/airbox, etc.), so it can be done. Maybe just don't go the whole hog for the road though - you'll still gain some handy ponies!

If it were my road bike and I wanted more power, I'd stick on a full/half system, HRC needles (from Rick O) and jet to suit. Then ride the tits off it

Thanks for that advice!