F4 Running Issues
 

evening,

After some help and advise on what to try,

Basic rundown, acquired a ruined CBR600 F4 2000 a few months back managed to get it running before i started to commit to trying to restore it, everything was going well till about two weeks ago when it refused to start, suspected the fuel pump had gone bad.
tested the fuel pump with direct 12v, no issues but it refuses to prime when ignition is turned on, after a little reading around i was led to believe it might be that the fuel system was pressurised and that was why it wouldn't prime.
Did some more reading managed to work out the carbs might be bogged down and flooded ( refused to start and was backfiring) found a post yesterday that suggested trying full throttle attempt to start, ran a start attempt for 10 seconds ish, turned ignition a off then on and tried to start again, it fired straight up and was running for around 2 minutes, tried again tonight and nothing still resisting to start.

So far the bike has had the fuel filter changed, Oil & Oil filter, new fuel line, fresh fuel, Spark plugs Changed, K&N Air filter cleaned, dried and re-oiled. All weeks prior to the starting issue. I have checked all fuses and confirmed the fuel pump does work when connected to a 12v supply. Unable to currently find my multi meter to check the relays so that's my next port of call But wondered if anyone else could chime in and offer any additional things to check was hoping to try get it going to get it through a MOT in the next few weeks.

Thanks

Hi there, welcome to the forum.
Sorry to hear about your issues. As it is a carbed bike, it does not prime when the ignition is turned on. The pump will only operate when the engine is running.
I suspect that your issue will be with the carbs and that they need a thorough strip and clean.
As it did start and run it suggests that the pipe is functioning correctly and its just crap in the carbs / tank. How long was it sat?
Lets see some pics.
Cheers
Al

Carb needs restoration. Not “cleaning” with useless sprays, might as well squirt perfume through. Have to completely disassemble down to every last nut, bolt, individual component. Scrub with PEA-based fuel system cleaner. Especially secret hidden passages in carb body. Ultrasonic soak everything and micro soda blast for reassembly.

Replace all rubbers: float valves, pilot screw O-rings, fuel-rail O-rings, float-bowl seals, even slide diaphragms if needed. Set float levels, sync carbs, etc.

We’ve all heard of people having to pull carbs 4-5x for ever deeper cleaning before carbs would run right. If you do complete job 1st time around, it’ll save you from having to pull carbs another 3-4 times.

While in there, verify all jets are OEM sized. If not, replace with factory OEM from authorised Honda dealer.

https://lh3.googleusercontent.com/d/...AD3oCdOwrs1QlC

thank you both,

Rebuild kit ordered will pull and strip the carbs tomorrow.

picture of the bike when it first arrived 😅
https://cimg1.ibsrv.net/gimg/cbrforu...7e7aaf906.jpeg

Rebuilt kit from Honda? Well, if not, those can be used for the rubbers.

But should still get hard-parts like jets from Honda dealer. Don't really need to anyway, metal doesn't get worn-out by petrol. All those can be cleaned by scrubbing. Should definitely use factory OEM jets that came with carbs than stuff that comes in kits. I've seen so many that comes with non-matching jets of different sizes. I've seen 4 different sized jets in single kit! Unmarked of course, so I had to measure them to confirm their size and none of them were correct!

unless there is something wrong with my bike, I believe you are mistaken. I have a 1999 CBR600F4 and when I turn the key to the on position on a cold start, I can hear the fuel pump prime.

starting to think the issue might not be carb related as the carbs were fairly clean internally and might be fuel system instead, I know the pump itself if good, going to try checking the relays as I have finally found my multi meter to measure voltage being received through the harness.

Regardless the carbs have been off, stripped, cleaned and are now waiting on new seals before being assembled and replaced to the bike, Only seals have been replaced original jets have been cleaned and reinstated in the carbs.

What relays should I be checking and what output should they be measuring ?

this is a very confusing statement. if you think the carbs and fuel pump are fine, there isn't much of anything left that could be fuel system related. do you think you are having electrical issues?

What happens when you spray starting fluid into the carb throats while trying to start it? Does it try to fire?

stupidly didn't check the relays till i tore my carbs out as i couldn't find my multi meter to check the relay harness feeds and the relays themselves

i don't currently have and starter fluid available to try + the carbs are currently off the bike