Hi All, this is my first post, so I will make it short.

My 92 F2, stumbles when you accelerate from a dead stop. Nothing can be done to prevent this, not feathering the clutch, slowly giving it gas, nothing. Jumping on it helps, but it kills my clutch. Having only 30,000 miles on it, I am at a loss as to the cause. Maybe plug wires, they are 14 years old afterall. But the bike pulls strong after the initial stumble and runs great all at rpms except for around 1500 to 2000. It starts to go, bogs down briefly then goes as normal. All stock except for an oil airfilter and Yoshi Slip On. Anyone have any thoughts as to a possible cause? Maybe unsynched carbs? Plugs look ok, a little dark but otherwise ok. Oh, does anyone know where I can get a set of plug wires cheaper than the dealer?

Thanks ...........

Krokus

 

carbs need inspecting?

fuel lines?

When I got my f2....at 20,000 miles it stumbled a lot at idle and even when rolling forward.

I even stalled it and dropped it...not my fault I was turning out of a driveway and it stalled mid-turn.



After a while it fixed itself...I think the carbs were gummed up and over time they got better.

A mechanic added some additive to the gas tank for the carbs

 

Good call on the carbs possibility being gummed up.

Along those same lines, your pilot jets may be gummed up as well. It sounds like you get hesitation at low RPMs but it goes away when you get the revs up. This might suggest that your pilot jets are plugged but your main jets are fine (main jets are what feeds fuel into the carbs at higher RPMs).

Someone feel free to correct me if I'm wrong.

 

Thats the same thing my mechanic told me....the lower speed jets were plugged or something so at low speeds you get problems...at higher speeds the other jet kicks in and it's ok

I wish I remembered what he poured into my gas tank to clear it....it was a bottle of clear liquid.


It didn't help right away but over time got better

 

Hmmm, now I am curious about these pilot jets. I didn't consider the jets originally because when the bike is cold it runs fine, even with the choke off. It doesn't start stumbling until after it gets warm. But, even when hot, it will rev up and down fine in neutral, just when in gear and you try to pull away from a stop does the bike stumble. A roll on start, no problems. My plug wires are Original, so I will change them as well as the plugs and go from there. I have always run Techroline through every tank of fuel so that I don't think I have gummed jets, but it is something I will now consider just to be safe. I have always got between 47 and 50 mpg with this bike....now it is all I ride because of the current fuel prices. So it would be nice to get it running 100 percent again.

My bike does get hot, tipping the gauge at around 3/4 of the scale at times in traffic or riding two up. I think my radiator is going south now too.........but first things first, the stumble needs to be taken care of before the heating problem.

 

Well I removed my Yoshi Slip-On and the stumble all but disappeared. I guess dispite what they told me when
I bought it, the CBR did need to be rejetted. Now running the stock muffler, though it seems to have cost me
some power, especially mid range, I can now pull away from a stop light and not look like an idiot.

Thanks to all who gave their advice, it was much appreciated. Problem is now solved. Let's end this thread before
we end up making a sweater or something

 

Glad to hear it-- or we can all sing "Kumbaya" together

 

I have the same problem, I actually fell because I stalled halfway through a turn . What is Techroline or this Yoshi Slip-On you mention? just asking because if it helps I would like to start using it as well.

 

Techroline is the detergent additive found in Chevron gasoline. You can buy little bottles at Autoparts Stores, or big bottles at Costco for a better price. Techroline cleans the intake, anywhere gasoline flows, Techroline is supposed to clean. It is similar to Gumout or STP or any type of Intake Cleaner I guess.

A Yoshi Slip-On is my Yoshimura Slip-On Exhaust that replaced my stock muffler. It is called a slip on I guess because you don't remove anything but your old muffler and SLIP ON the new one. You retain your stock header when using Slip-Ons.

My problem was my bike was never rejetted by the previous owner when he installed the Slip-On. I am running the stock exhaust and my stumbling problem has gome away and my MPG's are actually up, to 55.83 on my last tank.