How yall doing, im new to forums so, sorry if i ask some rookie questions. But to start i bought a 1994 cbr600 f2 almost a year ago from a kid who tore it up splicing wires an removing a bunch of things. I bought it as a hobby and my 1st bike. Long story short i replaced a bunch of **** got it running alright but im not a motorcylce mechanic so im learing as i go a long. Currently im stuck. The bike falls on its face at any full throttle action or even half throttle, wont cold start without ether, ive adjusted carbs to best of my knowledge. Im at the point of trying to sell it for whatever i can if i cant get help/guidance. MISSING PARTS (Intake tubes from airbox to front of bike,most vaccumm lines, choke cable, choke slider that sits on back of all 4 carbs) have manual but as far as re-routing an setting up vaccum lines the diagram is had to figure out when i have almost nothing to go off of. Thanks in advanced.

 

Hi, welcome
I'm a complete newbie myself and can't help with your current issue, but I hope one of the more experienced peeps here can give you some advice.

 

I'd start with getting the choke replaced & working, I'd be willing to bet that's the issue.


Hopefully I'm not telling you what you already know but basically when an engine is cold, it needs a little extra fuel to help it start & run (Not sure the exact science behind it, but it is true.). With modern fuel injection, the on board computer (ECU) measures air temperature, oil temp, etc etc & adjusts the fuel/air mix (More fuel/less fuel) to allow the engine to run smoothly, slowly reducing the extra fuelling as it warms up.


With carb'd machines, there is no ECU, so the additional fuel is provided by the manual choke. It sounds like your problem is there is no additional fuel to help the engine start easily or get up to temperature. Any kind of throttle will be flooding the engine, causing it then to stall.


On the occasions you have got it started, have you tried leaving it 15 mins to warm up? If not, do that & then see if it'll accept throttle inputs (I.e. not stall when you rev it.). Should you find that getting up to operating temperature results in it revving normally, then you know it's the choke.


I don't own an F2 so can't speak specifically on you bike, but it might help to fit the intake hoses on the airbox, but I would 100% recommend rebuilding the choke mechanism before giving up as I suspect that is all the issue is.


Last piece of advice, when you have got the choke fitting & working, don't just ram the lever onto full, most engines don't need full choke to start. I'd suggest going with 1/4, attempt to start then increased it to 1/2, 3/4 etc if that doesn't work. The reason is an engine gets 'used' to being operated in a particular manner (Wear patterns etc) so you just need to work out how much choke your F2 wants.


As I say, hopefully I haven't patronised you by telling you things you already know. Good luck.

 

The vacuum ports for syncing on the carbs must be capped, otherwise it'll run like you're describing.


Welcome to CBRF!