1980 GS25X refuses to start

[DarrenC]

Hi all being the owner of 2 old Suzuki’s I decided it was about time I joined this forum.....I’ve been a Car/Truck mechanic for the past 26 years but I do find bikes sometimes very frustrating so I’m just putting this out there I’ve got a 1980 GS25X (GSX250E) I dragged it from a barn where it had been lying for years, the carb linkages were badly corroded and seized so I decided to fit/modify 2 Bandit 600 carbs onto which I just happened to have on the shelf in my garage......currently the engine is cranking over with a nice bright blue spark on both plugs.....compression is 110 psi on the left cylinder and 140 psi on the right.....both silencers have been removed as badly rusted up inside.....no air filters on the carbs yet.....if you leave the throttle and just crank over with the choke out it pops and bangs/back firing through the carbs and exhaust otherwise it just cranks over until the battery goes flat.....almost making me think the ignition timing is out but looks to solid state timing with no adjustment.....any advice would be great before I start any major stripping.....thanks in advance 

[Gixer1460]

Is it a parallel twin or a 180 deg. twin? Sounds like its 180 degrees out hence backfires - try swapping the low tension coil connections - assuming it has two coils? Of course Blandit 600 carbs maybe too big for a little 250 twin which won't help!

[DarrenC]

Thanks for ya reply yeah it’s a parallel twin, yeah you have a point there alright about swapping the coils around.....yeah I too thought about the carbs maybe being a bit on the big side but it’s one of those projects that I wouldn’t mind spending a few quid on if could I could at least know she’s a runner....parts seem hard enough to get for these old Suzuki’s 

[Blubber]

Hi and welcome to OSS 

 

Let me be the first to tell you .. you will end up with an EFI conversion and a turbo if you stick around here