Reply To: Carburetor GV 125 Year 2012
12 Bar is very good, that is like 175 PSI for a 125cc Hyosung twin. So engine is OK.
For the engine, now if the top speed is poor, i would definitely check with service manual these 2 because it is also true;
- Valve Clearances
Get a feeler gauge and follow instructions and see if any valve is out of spec?
Tight valves = hard starting / overheating / poor speed.
Loose valves = noisy / poor speed / dangerous if too loose, it will annoy the chain tensioner. - Clutch Plates
Get Venier Calipers and measure clutch springs and measure plate thickness vs manual oem limits.
Bad clutch = bad speeds.
Beautiful big (heavy!) girls the Korean bikes are but they like to eat clutch and brakes!
So if engine is sorted, next step try these tips:
– Show us which caps did you get ? If they are NGK CAPS, then no problem, ignore this message.
– Next tip, replace ignition coils. (Better ones , like these we have )
Do not buy rubbish chinese knock offs.
If you do not want to wait for us to ship coils, then you can go to your local junk yard (scrap yard) and find SUZUKI SV650 1999 (1999 only!) good condition working coils and try them.
They are BIG, so they may cause issues fitting it!
Hyosung GT650 (2003 iirc) and SV650 use same coils because they are japanese and made by Mitsubishi. These are the “only” korean coils we don’t mind keeping haha. After 2003-2005 iirc , Hyosung used different coils
Fuel System next,
– check air filter is new and clean ? If i have already send you new air filter, then ignore this
– Carb cleaning by ultrasonic will help.
– Did you replace manifold ORINGS rubbers ? (intake pipe o-rings) ? Maybe i have already send you new ones ?