1988 GSX R250 engine troubles

**Flashjammin** · 28th September 2014, 18:25

I've been having a play with my bike, it hasn't been running correctly lately...
Seems to be missing on 1 cylinder but randomly.

Things we have done on it so far
* checked the compression
* checked the valve clearances
* adjusted the carb floats levels
* cleaned out and checked the carbs (needle, seats and jets)
* checked over and replaced the spark plugs (some had arcing marks)
* checked the spark from the leads through the spark plugs

After doing all this it is defiantly running better however there is still a funny thing happening...
When the bike is running and let it warm up a bit, when its standing up straight it idles fine and revving it a little (up to about 5000 rpm) it sounds fine, then if we do the same laying it over (somewhere around 20 degrees) it starts to run rough and miss firing (not to an extreme).

I haven't been able to take it for a proper run since playing round with the carbs etc last night however I'm hoping that one of you will have some ideas or maybe ask some questions that will point me in the right direction.

**FJRider** · 28th September 2014, 18:42

Originally Posted by Flashjammin

I've been having a play with my bike, it hasn't been running correctly lately...
Seems to be missing on 1 cylinder but randomly.

Which cylinder is it NOT running correctly on .. ???

Originally Posted by Flashjammin

After doing all this it is defiantly running better however there is still a funny thing happening...
When the bike is running and let it warm up a bit, when its standing up straight it idles fine and revving it a little (up to about 5000 rpm) it sounds fine, then if we do the same laying it over (somewhere around 20 degrees) it starts to run rough and miss firing (not to an extreme).

Don't rev it up when it's on a lean ...

Originally Posted by Flashjammin

haven't been able to take it for a proper run since playing round with the carbs etc last night however I'm hoping that one of you will have some ideas or maybe ask some questions that will point me in the right direction.

Sounds like fuel flow issues ... check the fuel line(s) (and vacuum line) for blockages or kinks ... and fuel filters for gunk. This includes the one in the tank above the fuel switch.