Reply To: new bike runs bad
Hello,
Set the mixture to 2.5 turns each pot. Take out the pilot jets and look in the sky with them, if light does not shine thru the pilot jets. This could be a problem and also a sign that carb needs more aggressive cleaning (Yes , sometimes CV carbs not just hyosung, but may need cleaning 2x) unless it has been in a good ultrasonic bath + air compressor afterwards (there many holes inside the carb)
Also check fuel filter for any debris coming from the tank.
The fuel should be E5 (it may be called different in Norway) but here in UK , E10 fuel is generally bad for bikes (nothing great about extra ethanol)
Also when bike is running, spray carb cleaner to carb rubber intake pipes and also rubber holes for airbox, if any revs change, you have air leak. Sometimes changing “manifold orings” under the carb pipes helps a lot.
If you can, wait for bike to be 10 minutes hot, then test compression for cylinders.
1. Take out spark plugs (both of them)
2. Compression tester (a good one!) inside cylinder one (front engine)
3. Twist throttle to full throttle.
4. crank the bike for 10 seconds and look at compression numbers and tell us.
5. Repeat this for rear cylinder.
Clearances when bike is overnight ice cold (that means let it cool down overnight, then check in the morning) all intake valves will be 0.12mm-0.15mm optimal (0.10-0.20)
All exhaust clearances will be 0.25mm optimal (ish) but range is 0.20 to 0.30 max.
Did you also set the floats when carb was upside down on the table ? to 7mm ?
I would also caution that if there is any doubts about the “fuel valve” that’s under the float, its okay to replace it with some rebuild kit or even just get new floats.
The float area can also cause big issues from starting bike to full throttle if its not behaving well.