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hello everyone....since swapping my old micron exhaust to a delkavic with a viper end can I seem to have lost all power from 3000rpm and below....now I know that 600's dont have much torque at low revs but it used to pull cleanly from 3000rpm in 5th and 6th but now the motor bogs so badly I cant open the throttle wide if the bike is any gear above 3rd and in fact I tried to take my son pillion up a steep country lane with some nasty 90 degree corners and obviously I had to keep the speed sensible around the blind bends so I kept the bike in 3rd at 4000rpm but as the bank got steeper the revs fell to 3000 and before I could change down to 2nd the motor had bogged so badly I had to ride the clutch at 6000rpm just to keep the motor alive....I  have been asking advice and most people think its running rich low down but there is no way of altering the needle position because the standard honda needle has only the one groove....the bike is a 1992 600F2 with a new standard air filter, 20,000 miles, new plugs and oil everything is in very good condition. The carbs have just been sync'd and it has the standard 135 main jets..............could it be rich? or is it running too lean? the plugs are a pale tan to light brown in colour and its never overheats......all help appreciated guys

stock jetting, full exhaust, and pale tan spark plugs does not really say too rich to me.  bogging can go either way, too lean or too rich, and without actually riding the bike its hard to tell which.  if the top-end A/F ratio is fine, how bout u richen the midrange up a bit and c how that works.  its really an ez change.  i kno the needles dont have grooves... however, u can easily go to a hardware store and buy some tiny 2-3mm washers that will fit under the needles and space them upwards.  start with small changes first to c if things get better.  of course, if things get worse and the bike actually too rich now, ull need to go down a main jet size and re-tune the midrange.  but as Honda's usually come lean from the factory, i cant c this happening. 

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Naked 93' F2...... RIP -- 04/12/07
04' 600RR Black - currently stuck between track and street usage
- Brembo Master, Sato's, & Ohlins out back