Reply To: Put some upgraded coils and sprake plugs on my bike now goes 64
Hey,
It looks like you have a standard exhaust on it too, i will assume the bike is very young,
A. is it under 5,000 miles miles ? and do you have any proof history of these 2 critical jobs (as Korean’s mention it on service manual if the bike speed drops)
- Valve clearances done and shims changed ?
- Compression test ?
B. Also since you changed the coils and filter, your speed will drop also again if you;
- Changed the Jets yet ?
- Clean the carb with air compressor (must be done believe me) or ultrasonic bath.
If using a rattle can carb cleaner, you will probably go through 4 small cans.
C. Air System checks (because you changed the filter)
- Spray the carb manifolds to see if revs change (speed drops also if the orings under the manifolds are caked up or too old by years not miles)
- Spray under the air box holes where carbs sit on, if revs change, you have a leak.
D. Fuel System
– If it’s a 66 plate. Korea says change the stock lines and the filter after 4yrs (whatever miles she is on now) – Old rubber can rot inside, old fuel filter can cause weird issues, it’s mentioned in the service manual. – Change lines and use a giant fuel filter that’s trusted , not china things.  Lest the carb gets clogged up and your fuel pump won’t push hard if you want to ride faster
– Open the fuel pump, clean it with carb cleaner only .Do not use compressed air, as it has spring loaded mechanism inside.
– Fuel Tap that’s directly under the tank —> It should work as normal. If using a big filter, when you stop going for a long ride, you will ALWAYS see half-full or 3/4 full filter means the tap is working. Emtpy filters after a ride always suggests starvation is likely.
– Use e5 fuel only. E10 will cause a lot of problems even as much as bog downs , eats up manifolds eventually, eats up rubber bits, extra ethanol in the e10 can be corrosive to metal parts etc… it’s just a devils juice.  Stick with E5 and use WYNNS XTREME GOLD (this brand only) from halfords , pour all of it in a 3/4 full petrol so that it will soft-clean your whole fuel system (it will try!)