Rvf 400, still not running well

[Mcconnellnc30nc35]

Carbs have been ultra sonic cleaned, standard airbox, new carb rubbers,new plugs tried increasing main jet size, tank, tap and all breather tubes are clean and clear, cant understand this bike, next step is pulling the engine out i think? Anyone got any suggestions please?

[Malc]

What are your symptoms? Pulling the engine is not going to help unless you know why you are pulling it!!

Sounds like you have all the fueling covered, so... Battery healthy? There's more to a healthy battery than voltage. Are your earth connections good? Are you plugs good?

[Mcconnellnc30nc35]

Hi mate, just put a new batt in as bike has been standing for about 2 years, i have checked every electrical connection i can think of, checked voltage at batt, is 13.5 at 5k, spark plugs are new but are coming out pure white( lean ), getting lots of poping and banginging on the over run and engine seems to run very hot,( lean ) but carbs are spotless and internaly as new, i have 115 mains in at the min, i tried a nee ignitec ignition cdi, and new ignition pic up also, to no avail

[skinnydog0_0]

Are all the plugs the same as the one in the pic?
That looks very very lean.
Does the bike start okay?
does it tick over okay?When you say popping banging on the overrun, is that in every gear or just when you are nailing it?
How old are the vacume tubes?
The tubes could be colapsing at speed and making the bike run lean, but not enough to make it stall or missfire?

[Mcconnellnc30nc35]

Yea mate all plugs are the same, bike starts straight away and ticks over like a swiss watch, what do you mean buy vacume tubes? All the tubing that i can see looks as new with no splits or cracks, the bike just feels very under powered and very flat, , 100 mph is a struggle, this is my 3rd rvf and all the others have been little rockets

[Mcconnellnc30nc35]

Sorry just sounds the same in every gear, just as you roll off the throttle it pops and cracks, i would say it shoots flames, realy cant under stand( new carb rubbers also fitted ) tried a set of nc30 carbs and cables off my nc 30 and it still runs much the same,

[skinnydog0_0]

The vacume tube opens the fuel tap to let fuel through, when they get worn, (they can look in very good condition - but they get soft) they can colaps when warm and stop/restric fuel flow. this can cause similar issue sto what you have. the vacume tube is from the cylinder head to the fuel tap. get a new tube and try that. it might not work, but it will only cost 50p

[Mcconnellnc30nc35]

Worth a try mate i like cheap fixes :-)

[isca1987]

The vacume tube opens the fuel tap to let fuel through, when they get worn, (they can look in very good condition - but they get soft) they can colaps when warm and stop/restric fuel flow. this can cause similar issue sto what you have. the vacume tube is from the cylinder head to the fuel tap. get a new tube and try that. it might not work, but it will only cost 50p

I done this and it made a big difference.