South West Bikers | Motorcycle Forum

hi all well iv just got myself a zxr 750 race bike.It needs abit of work doing to it as the last time the last owner rode it he came off it and it hasnt been ridden since and that was nearly 5 years ago.i payed £350 fot it and the last owner said i need a vacuum switching valve to get it started as it doesnt have one.Iv already cleaned the fuel tank out and stripped the carbs down.is this true or can the bike run without one.

Is this the piece that now replaces the "Throttle Bypass" - use to be a small spring flap set into the butterfly valve inside the carb body?

It should have the same effect as opening up if/when the butterfly shuts during tickover allowing air in for fuel mixture.

If it's the same thing [or similar in function], I'd imagine tickover would be difficult without it.

Don't think you said if the engine runs...

well i dont know if the engine runs as i havent tryed it yet.plus i was told that it wouldnt run with out the vacuum pump but thats wot im asking as i dont wanna try it and get no where

Thought you were asking about a valve - not a pump

I had an old gpz 550 and that had a vacum value on the fuel switch. If the bike had been stood for a while the trick was to turn it to reserve and it bypassed this value.
Could be worth a try to see if that works first.

I reckon the bike could run without one mate, if u can get a Haynes manual there is a diagram for it in there. I cant see any reason why its hould not run without without it having look at the diagram.

yeh ur right i did look in the manual its only for usa bikes.thought it was weird him asking as my bike doesnt have one and it runs

hi there it was me asking after the vacuum valve swith as i was told i needed this to start it but iv now found out y it wont start because the fuel pump is nackerd.Fuel was getting to the fuel bowls and that was it so i blow down the rubber tube and then i saw fuel going out of the carbs so i hit the start button and the bike started for about 20 sec as thats when the fuel ran out.Are the fuel pumps from zzr`s and zxr400 and zx7r work the same as they look all the same

mate i dont know whether the others will fit but there are several for sale on ebay, all around the 30 quid mark.

any luck with getting the zxr started yet gsxrsi

not yet mate awaiting my fuel pump from speedy

it'll be a long wait mate, barnstaple post officer are still using horse and cart

i hear they thought of using a ducati to speed up the delivery times, but found the horse and cart more reliable, less tempramental and easier to live with

lol