Not running right below 5000rpm RVF400

[mylessheehy]

Hi,

I've had this problem with my RVF for a while now, Basically, Below 5000rpm its very slugish, not much power, its takes a few sec to pick up. I've cleaned the carbs, Done the hrc mods (drilled the air hole to 2.5mm, Put a 0.5mm washer between the needle and the vacume piston) But still no change. Im replacing the plugs and air filter tomorrow. Also, im using 107 main jets, the circlip on the needle is set to the second notch from the top, does this sound correct???

Thanks for all the help!!

Myles

[Neosophist]

Pilot screws too lean?

[mylessheehy]

When i cleaned the carbs out i set them to 1 5/8 turns. Thats what the haynes manual said. One of the pilot screws was closed, but there all equal now. Do you think i should try 2 turns out?

[Drunkn Munky]

RVF's dont need the slides drilling to 2.5mm, just VFR's iirc
107's aint standard, i think 108's are but dont quote me

i always use to think my rvf was sluggish below 5k and i tried a number of things only improving it slightly and some things making it worse. in the end i put it down to jumpin off my other bike gsxr 750 and expecting too much from the rvf

[mylessheehy]

Your right, 108 is standard. I would love a bigger bike but insurance would kill me!!

[Jon]

Mine NC30 with NC35 carbies and full Ethos system is like that.

I fiddled with it for a while, ran an O2 sensor on it and the mixture was ok, programmable ignition from Rick helped as there is a dip in the timing advance around there (emmisions testing).

Eventualy found a cure for it, the gear shift, never had any problems with it since.

If you have drilled the slides in RVF carbies they may be opening too quickly and bogging, is it better if you roll the throttle slower rather than bang it open?

Is it better on a warm day or on a cooler night?

regards
jon

[Cammo]

Also, im using 107 main jets, the circlip on the needle is set to the second notch from the top, does this sound correct???

Your needles aren't standard if you have grooves in them, they could be largely responsible for the problems. Do your needles have any markings on them?

Try getting hold of some standard needles and seeing how it runs.

[mylessheehy]

Think i found the problem... The float heights were way off, meaning the pilot jets were only barely touching the surface of the fuel in the float bowl, they'd work for a sec then starve themselfs (flat spot) when the level went below the jets, as there was not enough petrol in the bowl,as it filled itself up with fuel it slowely continued on to 5000rpm, Once the engine slowely reached 5000 rpm, the needle jet would kick in and this jet was submerged in the float bowl and had enough fuel to power on, (above 5000rpm the bike always had plenty of power)

Also, as i adjusted the float heights, i set the needles to there original position (2 notches from top) and set all the pilot jets to 1 7/8 turns out. the bike now has plenty of power below 5000rpm but now, when it reaches 5000rpm its a bit slugish... I think this is because i set the pilot jet richer than it should be, the setting by the manual is 1 5/8 turns, (I tried a higher setting because the other day 1 5/8 turns was still sluggish, bearing in mind the float height had not been set then) So i think now when the needle kicks in its getting too much fuel. Tomorrow i'll set the pilot back to the manual setting (1 5/8 turns) And let you know how it goes.