Fuel not flowing fast enough?

[hawk2993]

Aight guys,

Mon RVF400 seems to be not getting fuel fast enough, here's the scenario:

I haven't ridden the bike in a month so its obviously dried out, so I try starting and there's no fuel getting in the engine, on like the 5th try it started but it was lethargic and it cut out even though i was trying to rev it to keep it up, akin to running out of fuel. Eventually my battery died, so I charged it, put it back in, and kept on cranking, I then tried cranking it WITHOUT choke, and after 3 tries it came to life, but was lethargic so i revved it hard and then fuel really started flowing and it started revving freely and idling. (What baffled me most was why it started without choke, in cold weather....and wouldn't start with choke)

All the lines are good, I recently had the carbies overhauled as well. I had the tank repainted as well, and when we put the fuel back in, as the bike was dry, it took FOREVER to get the bike started, and when I run out of fuel, it also takes FOREVER to get the bike started, the fuel doesn't seem to be flowing freely :/

[porndoguk]

Have you checked your float heights?

Also check vacuum hose and tank vacuum diaphram

[Cammo]

I had the tank repainted as well, and when we put the fuel back in, as the bike was dry, it took FOREVER to get the bike started, and when I run out of fuel, it also takes FOREVER to get the bike started, the fuel doesn't seem to be flowing freely :/

That sounds pretty normal to me, it can take a long time for the carbs to fill with fuel if they've been empty.

The fuel tap diaphram is opened via vacuum (i.e. engine cranking), each time you try to start the bike only a dribble of fuel will get through into the carbs. If the diaphram isn't in great condition it will worsen the situation. Rick Oliver sells replacement diaphrams.

I use a few syringes full of fuel to fill the carbs (down the fuel inlet pipe) before hooking the tank back up, will start instantly and not strain your battery/starter so much.

[magg]

Might be worth checking the fuel tank breather too, no air in means no fuel out.

[hawk2993]

Aight I'm going to rebuild the diaphragm, what tools do I need? Other than the rebuild kit. Is it hard? Going to change all hoses as well. What about the non idling when cold?

[magg]

You could do the HRC mod and remove the vacuum control on the fuel tap so that fuel flows as soon as the tap is turned on. If you do the mod do not forget to plug the vacuum hose and turn the tap to off when the engine is stopped.

[Neosophist]

as above, fuel is vacuum fed. it wont flow unless the bike is cranking.

best thing to do is crank the bike for 5 seconds and then let it rest for at least a minute or so, this will allow time for the fuel to drain down into the carbs.

if you keep cranking away it doesnt do anything until the fuel has gone down.

also full choke and no throttle

[hawk2993]

as above, fuel is vacuum fed. it wont flow unless the bike is cranking.

best thing to do is crank the bike for 5 seconds and then let it rest for at least a minute or so, this will allow time for the fuel to drain down into the carbs.

if you keep cranking away it doesnt do anything until the fuel has gone down.

also full choke and no throttle

Yup I did that...Its just ridiculously hard to start, I remember it wasn't as bad when i first had the bike last year, but it just progressively got worse over time. Now it takes 2 recharges of the battery to start (I might just use starter fluid or fuel down the carbs) I literally left the bike for 4 days...and it started but fuel was not flowing freely and i had to keep that throttle on but couldnt and it died....sigh....It had a carby overhaul done earlier this year but after that, i noticed it was a lot harder to start the bike....and i got a mega flat spot at 6000 rpm.....when its cold, it won't idle....when starting when its hot, it's harder to start (gotta hold the crank down for a bit longer) but it'll hold idle.

[bikemonkey]

Plugs fucked?

[dobbslc]

Plugs fucked?

Could be the plugs, they are very small on these 400's and can foul up quickly even if only after one poor start that flooded the engine slightly .