• Topics: 38
  • Replies: 447
Nov 30, 2017
North UK

Hopefully someone can think of something I haven’t thanks again


The pilots are too big. Size 15 front and rear is plenty. (You said you up-jetted, this assumed to be higher than stock. You did not say what size.)

Pilots control IDLE & slow running. Your problem could be this too.

Air mixture screws must not be tampered with by any garage (They are idiots if they did) as the service manual discourages air screw messing , and for good reason.

Main Jets should be 90 & 92.5 = Unless the bike is doing 90-100mph, it won’t need size 95 which is 250cc

Some of the information below is copied from other topics which I replied into. (other topics have pictures & much deeper replies, so have a browse too.)

πŸ”§ Hyosung Technical Help

Start your bike. Rev to 4k rpm. Your battery “must” say 14.5v at the meter , otherwise change the regulator. All electrics depend on how healthy the regulator and stator is.
Anything 13.xx is not good. So bare minimum is 14.5 up to 15v as specified in manuals.
This is your charging system (& sparking juice)

Big sparks come from better electric supply.
Speaking of sparks. Remove your spark plugs. If they are “RICH BLACK” (Your jets were too big or the diaphragm slide needle may be on the rich setting, if the garage touched this)

, a healthy bike will show “DARK BROWN” plugs. No sign of ash blacks anywhere.

Before you start the bike again, grab a multi meter. Switch to 20K OHMS (20,000), then follow this…
1. Red wire of your meter INSIDE the HT CAP
2. Black wire of your meter on the FRAME (NO PAINT) (Find a shiny area!)
3.—>Your meter must say UNDER 7k ohms max!

Hyosung says your ignition coils must be 5 – 6.2k ohms max. If its higher, you found your sparking / bogging issues. This is way too common, I digress! – I’d ditch the stock coils at all costs & the bike will be a lot happier (AND less annoyed spark plugs).
Kawasaki units win.

Lastly, Grab yourself some “Platinum Laser” racing plugs. No other plug beats this , period.
You WILL have a better throttle with such instant plugs.

The stock plugs foul up too easily & hence the peformance of your bike wanes quickly.

Lasers last 2yrs / 50k whichever comes first, if your fueling system is nice and good too.

Sorry I took ages to reply, let us know how you get on. Good luck!

// Meditation doesn't mean you have to sit still....

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