Low down fueling issues with RVF HRC carbs

[Drunkn Munky]

Those of you at cadwell at the weekend will have seen my frustration with the low down fueling on my bike and im all set to pull them off and fit stock carbs again but i cant help but try and resolve it first, this is what i concluded from the weekend,

From cold the bike would start and rev cleanly, infact no choke is needed.
Once warm it would struggle the rev cleanly until 8k, riding it through that rev range it would bog badly.
Above 8k the bike is fine.
Starting the bike when warm was also difficult.

Once home ive pulled the carbs off and the pilots were all slightly out in varying amounts from the recommended HRC setting of 1.5 turns out. I rectified this and checked the float heights which were all bang on the 12.5mm stock setting, i cant find any HRC setting for this.

Carbs back on and started from cold (no choke) it starts and revs cleanly, once warm the problem is back however a little better IMO which maybe due to the pilot screws all being set correctly, it ticks over fine by the way and always has. So i leave it running and turn the fuel tap off to simulate a lower float level. Sure enough after a minute or so the bike starts to rev cleanly again until running out of fuel. So am i right in assuming this is a float level problem? and if so does anyone have any float level settings for HRC RVF carbs?

[richyrd5]

dont have/know any settings sorry tony but sure does sound like float level/settings.maybe to rich? as it doesnt need choke and is difficult when warm..but only guessing here chap

[arsey30]

Did the engine ever run well with the current set up, if so settings are correct.
Pilot circuit will have little effect at 8000rpm [1/3rd throttle?]

Is a float valve leaking in one carb raising the fuel level over time.
Drain and measure each float bowl contents and compare each to see if one is greater.

[Drunkn Munky]

Yes dave it did, only had it out on track once before this and it was fine through the lower part of the rev range and the only thing changed is the system from a single can to the current twin system. Will check the amount of fuel in the bowls tomorrow.

One thing that might be worth mentioning when it did run fine was that the float bowl gaskets were knackered and pissing fuel.

[Drunkn Munky]

I let the pump fill the carbs switched it off and left it for 30 mins before removing and emptying the bowls and all seem near as dammit bang on the same,

[Jas RVF]

Just guessing here, have you checked the choke linkages are closed, sounds like its over fueling untill its pulling in the right amount of air for the fuel going in. pull the plugs clean then start untill warm then pull them again and see the colour if its burning clean.

[vfrman]

What position are your needles in? Sounds like they are too rich, and the needles are what affect full throttle below 8k.

[Neosophist]

that range is transition form needle to main so perhaps a lean / rich dip, have you had it on a dyno to get a fuel air graph.. its the easiest way to see how oyur bike is fuelling and you can compensate accordingy

just dont forget race bikes dont fuel as well as street bikes and designed to run at full throttle all the while..