What does it run like under 3000rpm, or at low speeds?Do a quick TPS check and see if it's in the correct position, they gradually break down and a misfire at any speed is one symptom, but the main symptom would be rough or jerky running at low speeds where you'd need to use more clutch and throttle to compensate. It's something that will take a minute to check, and needs to be ruled out.Also, when was the last time you changed/cleaned your air filter? A badly clogged paper air filter for example will eventually affect running. K&N filters tend to be a lot more forgiving as they let more air through but they can still get dirty as well.
If start by ditching those iridium plugs, I've had them break down in under 1000 miles. Only buy plugs from a dealer or m and p (somewhere reputable) as there are tons of fakes out there on eBay. Then check caps, leads and coils. There are only a few things in the ignition system to cause a miss fire.
Thanks for the replies, i would say it is definitely an electrical issue.I didn't add fuel stabiliser ... but at the time i last started and noticed the misfire the fuel was 2 weeks old, but i agree old fuel will not help the matter.I need to go back to the garage and inspect the leads,caps etc, I have ruled out the plugs due to the fact they are only 1000 miles old,however i will still pull them and inspect.ok so i guess it a case of starting at the plugs and working backwards, so i'm guessing the suppressor caps are screw on ones?? so is it just a case of chopping a bit off and winding them back on?I'm hoping that i dont need new caps as money is tight right now.Regarding the TPS it has those tamperproof screws on them is there away around this??
I'll put my flag in the ground. 😝It's a Yamaha, if the obvious plugs, fuel and filter are eliminated (and should have been first) then it's a coil. Stake your guesses now.