Hey guys, had this CBR F4 for a couple months now & haven't really had anything to compare it to but my buddy just picked up a 01 Zx6r & I'm noticing more & more I have an issue. Basically it starts up perfectly with the choke on, takes less than a minute & I can turn the choke off & start riding if I want BUT in first gear, if I'm accelerating from a stop, I need to really feather the clutch to get going otherwise it will stall on me. Also if it helps to know, when I try to quickly rev while sitting in neutral, it kinda stumbles over itself & takes a second to actually rev up, though if I go slower or do it while riding it tends to be a bit smoother. Lastly when I'm riding if I let off the throttle the try to roll on again its a tad jerkier than my buddies Zx6r.

Also when engine braking it's not really the smoothest process in terms of the engine sound. None of these things really mess with me while riding as my throttle control is alright, but If they're not normal I'd like to fix them. I plan to change the air filter, fuel filter & spark plugs in January after my bank account recuperates from Christmas but if there's anything else you recommend let me know.

 

It sounds like the carbs might be dirty or not set up right.. if you're not sure the history of the bike it might be a good idea to take them out & clean them. Or at least add a can of seafoam to the fuel and see if that improves anything. Also make sure they are synched correctly after cleaning them.

If you turn the choke on partially after warming up do any of those symptoms get better or go away?

 

Alright will do, hit a bit of a rain streak up here in Norther Cali as you probably know so the bikes tucked away in the garage at the moment. She's also due for her first valve check/adjustment, I don't hear any ticking but you think that could possibly be the issue?

 

It could be possible, but they would have to be pretty significantly out of adjustment to start causing problems like that. Without seeing it in person my bet would be on a fueling issue from dirty/misadjusted carbs, or possibly an ignition misfire. If the bike runs better with the choke on a bit it's probably going to need the carbs cleaned & synched. If you have access to an infrared temp gun you can measure each header pipe individually.. the misfiring cylinder(s) will not be as hot as the good running ones.

 

Alright sounds good, I'll start pricing some gaskets and what not so I can pull the carbs and give em a cleaning and check the valves as well while I'm in there. I'll let you know how it goes. Thanks for the help!

 

Hopefully that fixes it for you.. a tip for cleaning the small passages in the idle jets: spray some carb cleaner inside and use compressed air to blow it out. It's much more effective than trying to use a piece of wire and will not damage anything. Also you don't have to completely disassemble the carbs. Just pull the whole rack out in 1 piece and take off the bowls. You should be able to access everything then without having to split them all apart.

 

Hey there was just one more thing I wasn't clear about while researching. Do you HAVE to do a carb sync if you take off the carbs, or is it only if you separate them? I ordered the carbtune sync tool but I wanted to clean the carbs prior to receiving the tool but not if I can't ride the bike as I don't know how long it will take to ship and get here from the UK.

 

I always do a sync any time I pull mine off to do any work to them including cleaning, but it shouldn't stop you from being able to ride it afterwards. Any adjustments to the throttle linkage or butterflies, or separating the carbs, and you'll definitely have to sync them to get it to run right afterwards. But just cleaning them and putting them back in shouldn't change the adjustment much if any at all.

 

If a shop is going to do your valves,they most likely sync your carbs as part of the service.

 

I'm a total DIYer lol. Rebuilt and modded my civic engine from the oil pan up along with suspension bigger breaks etc. just my first bike and my first carbureted vehicle so not used to some of this stuff yet. Also since I never added this for Tahoe rider. When I turn on the choke while the bike is already running and warmed up it just dies lol. It seems to get a bit sketchy after I've recently turned it off and turned it back on. Like I stopped to get gas and it seemed to be riding ok. Then as I left it tried stalling as I was backing out in neutral and I really have to keep it revd up to keep moving off a stop. Actually stalled pulling outta the gas station lol