Hi all, first of all any help given will be massiveky appreciated 👍🏼.
Just went to start my CBR1000f for the first time in about 2 months (usually left longer and starts and runs perfectly). Started it as normal with full choke for a few seconds before starting to back the choke off to let it warm up. Well it now seems to start normal and run as it normally should with full choke but as i just get past about half way of backing the choke off it starts to run on 3 with the occasion backfire. If i put the choke back on then it runs fine again. Thought maybe getting some heat into the carbs might help so i run it a while on half choke but still coughing and spluttering with anything less. Any ideals?

 

First thing to check is plugs, I notice you fitted new in 2020.

D.D.

 

Thanks for the response, I service it every year without fail, it had new plugs about 200 miles ago. Could check them yeah but surely the fact its running fine when on full choke would eliminate a plug issue?

 

Probably a blockage in your idle jet, when did you last (or ever) have the carbs cleaned.

 

Never 🤣, Never really needed it to be honest mate, always run the float bowls dry before putting away for any long periods and only ever ran on 98. Synced the carbs up last year and was running perfectly. Last time i rode it was a couple months ago and it was running as normal. I've booked it in for the carbs to be stripped and cleaned now anyway as its clearly a fueling issue. Just surprising how it runs fine on full choke but splutters and runs on 3 when the choke is backed off.

 

Whatever downpipe is cold when you start it and let it run for a moment is the blocked one, but you might as well clean the jets on all four. It probably won't clear up even if you put a bottle of cleaner through it, unfortunately - those jets are extremely fine and fickle.

Takes about 40mins to flip the carbs and clean the jets.

 

Yeah thought that mate, Cant say ive worked on carbs before to be honest but im sure i could work it out aha. Guessing i just flip the carbs, open up the float bowls then unscrew each jet and give it a good blast out with some carb cleaner?

 

Yep that is correct, biggest challenge will be to get the carbs off in the first place, rubbers might need some gentle heat to soften them.
You should use some carb cleaning brushes (or nylon brush bristles) as most carb cleaner has had the chlorinated active agents removed.

 

Yeah ok mate cheers for the advice, would you say its worth replacing the rubbers regardless or as long as they come off fine then just leave them alone?

 

If they come off fine, leave well alone. You can get some oil that will help to soften the rubber and recondition it, unfortunately I can't remember the name of it.