So back in April I purchased a 1987 Honda CBR 600F Hurricane. When I purchased it, it ran fine, sounded fine, until I took the fairings off and noticed the fuel pump leaking. So one thing led to another and...well I disassembled most of the motorcycle.

The following are things I've done to the bike since I've owned it (some are irrelevant to my issue, but included just so you know how hard I've worked on it):

-New tires with powdercoated rims
-Rear and front pads changed
-Rear brake rotors
-Oil/oil filter change
-Spark plugs
-Carbs cleaned with new bowl gaskets and float valves
-K&N air filter
-NEW fuel pump (thank buddha for eBay!!!!)
-New fuel petcock
-tank got the Kream treatment (it was VERY rusted before)
-lubed the cables
-New yuasa battery
-Kickstand swapped
-New Delkevic CF exhaust

...and probably some other things, but I can't remember right now.

Now, for my question...I recently put the carbs, tank, air filter box, fuel pump, etcetera back and started the old girl. I put about 2 gallons of gas in the tank , turned the key, and hoped for the best. HAZAHHH it started, BUT it was very rough. Then when I tried to give it a little throttle, it would die. I repeated the procedure and come to find out the throttle only killed the engine SOMETIMES. At times, it would sound strong but eventually die down. Now, the only way I can get it remotely working is if the choke is on full blast.

Does anyone have any ideas as to what the issue is? I just hope it isn't anything major...and want to rideee already! Any help would be much obliged, thanks!

-JD

 

My guess, and it is only a guess but a halfway educated one, is that you have a vacuum leak, the carbs didn't get cleaned good enough, or they are way out of adjustment.

 

Is it running on all cylinders? You can check by checking the temp of the individual headers. Easiest to do with an IR thermometer, but you can just spray some water on them. If one cylinder isn't running right, usually the water won't evaporate as fast.

When you say "carbs cleaned", do you mean you sprayed a bit of carb cleaner here and there? Carbs are particularly fickle beasts. I've seen a set of carbs run fine, then the owner thinks they are being proactive and 'cleans' them, then the thing runs like ****. The orifices are so small, that even a tiny dislodge piece of crap will clog your jets.

That being said, did you pull your jets? Only running on choke is a pretty indicitive sign of too lean conditions. This can be caused by a vacuum leak (as demon said), or clogged jets.

IF the carbs are immaculate, your new pipe might have something to do with it. Hiflo pipes generally lean out the mixture. You might need to go up a few sizes of jets to correct it.

Because I am a cheap *** and do everything in stages, I never change multiple major items at once. This way it is usually easier to narrow down what caused the change.

 

If it only runs with the choke fully on it's probably running lean due to one of the 3 things 74demon suggested would be my first thought.

You might still have junk in the fuel lines from the rusted tank that worked its way back into the carbs and blocked something.