1980ish gsx250 revving problem

andington · L Plate Warrior Joined: 25 Jun 2005 Karma :

hi all..i resently bought a 1980 suzuki gsx 250 that had been stood for a few years.well when i got it home i cleaned the carbs out put some petrol in the tank.when i bump it it starts ok ticking over but as soon as i rev it it cuts out? i thought it was a petrol problem at first but ive double checked the carbs and there not blocked.another thing is the battery is not holding its charge and wont even turn the engine over when i press the start button! all it does is lights the ignition lights up. could it be the battery not giving it enough power to rev? or does anyone no what else it could be? cheers

loply · World Chat Champion Joined: 24 Mar 2004 Karma :

I would suggest a new battery as an old one might have past its best.

I bet if you put a new one in, it will start first time.

Not sure about the revving problem though.
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imadoofus · Renault 5 Driver Joined: 03 May 2005 Karma :

Did the battery discharge after you bough it or was it discharged when you bough it? I would suggest keep it on a charger to see if it is really the battery problem.
Else it could be anything with the electric including duff regultors, broken brushes , corroded or loose connectors etc. So before you get a new battery, I would suggest you charge the battery to see if it
1) holds charge
2) works the electrics and starts the bike
3) recharges while in motion

It might not make sense to just get a new battery in if it is problem with something else electric

regarding, the cutting out on revs.. I am not quitre sure and there was something very recent in the discussions about this
But i think it might be caused by the mixture being too rich or too lean.. probably a leak or loose connection in the rubbers from the airbox or to the manifolds. If the rubbers are really old, they might be cracked causing the mixture to become too rich when you open the throttel because the air leaks
i am still lerning. so cross clarify

ZaphodBeeble · World Chat Champion Joined: 10 Feb 2004 Karma :

If the battery is a bit duff then there will not be enough power to ignite the richer mixture of fuel when you open the throttle. That's one theory. Another problem could be a blocked/fouled air filter choking the engine. Thumbs Up

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Current bike: VTR1000F Firestorm. Previous: Firestorm (written off) - XJ600 Divvy - NSR125 - DT125 and a load of offroaders.

andington · L Plate Warrior Joined: 25 Jun 2005 Karma :

cheers guys for replys
i had her started today and it accually revved up so i took her for spin round the block..however still spluttering i now think its a mixture problem..does anyone know how many turns on the mixture screws from fully screwed in? cheers

andington · L Plate Warrior Joined: 25 Jun 2005 Karma :

ive bought a new battery today and its starting fine now just still abit spluttery when i rev it? now ive looked at the carb and the fuel pipe is conected but there is 2 more tubes for pipes to go on..on the carb would this be anything to do with it?
and yes i have put new plugs in it and drained the old fuel.
i also noticed that the airbox was loose and there was a slight gap between the carbs and the box so it must be gettin to much air
i think im gonna take it to a bike shop to get the mixture set properly.
1 more thing is theres 2 pipes coming off the tank 1 is the main fuel outlet and the other seems to do nothing? ive blown down it and it seems blocked?

imadoofus · Renault 5 Driver Joined: 03 May 2005 Karma :

that is proabbly the vacuum tub that conencvts to the carbs which decides the amount of gas going in when the throttle is opened, as it creates a vacuum. make sure that pipe is not cracked and such