Bandit 250 High Revving After Overhaul

Hi All

Been reading for a while and learning but I have hit a problem.

I am rebuilding a 250 Bandit (4 Cyl x 4 Carbs) and as part of the rebuild I removed the carbs, cleaned the Jets and vacuum etc.

I have re-assembled the whole thing, attached fuel and when it starts up it goes to 7-8,000 revs and wont come down

Notes - I have checked:
* The Throttle is fully closed
* The Air box is currently NOT attcahed
* the Needles are lowered when its revving
* Choke is dis-engaged

My guess is an Air Issue (as opposed to fuel issue)

The Carbs are 4 x Mikuni in a row and have two rails - top and bottom. Now Im sorry if I sound like a dick when I dismantled it - for the life of me I dont remember wher the top hose attached to (See Picture)

The bottom rail / hose is the fuel line. the top one according to the workshop manual is a breather hose

Questions:

1) where doe the top hose attach to or does it just sit loose

2) Can any one shed some light on why its going up to 8k and unable to go down in revs?





Thanks all

Marc

Sounds like you've got a massive vacuum leak.
Sorry i can't help you with where the top hose goes, is it sucking air through that? Try plugging it and see what happens.

madmax wrote:Sounds like you've got a massive vacuum leak.

Yep, agree with MM there

The top hose probably runs to the air box if its a breather.
For it to be doing those revs the throttles cant be closed (well i'd be surprised anyway)
It does sound like a vacuum leak but to be turning those revs its getting a fair quantity of fuel as well.
I'm no expert but I think you might be better off starting again after just plugging the hose woth a bolt to see what happens.

I know that on my VTR its easy to accidently reverse the throttle cams if the carbs have been stripped down and have them open when the throttle is closed and as the throttle has spring tension it makes for an interesting first fire up. Dont ask how I know this

Is the hose a vacuum hose to your petrol tap ?

The hose is a vent mate, can't help on the revs it could be any thing. What happens when you choke it?