massive frustration

okay i hate to repeat something a lot of guys have asked but i'm at my wits end. my brother inherited a 80 kz250 with only 700 miles. it had been sitting with fluids in it since 85 so we cleaned the carb retimed it changed the oil but we still cant get it riding. it idles fine but when riding it stumbles around 4k and after a half a mile it fouls the plug right up. it jumps a bit through the whole range but mostly at 4k. i don't suspect any mechanical failure such as valves because of the low miles. i just have no idea. is it possible i'm just operating the choke wrong? i am a new rider but i know close it off to start and slowly open as it warms up. either way we keep getting black spark plugs.

Welcome to KZR!
I'm not too sure on the 250,but does it have a mechanical timing advancer that might need to be cleaned and lubed?(a good starting point).
Did You use compressed air to blow out all the passages in the carb,when You cleaned it?
There's a few Members here with 250's...

Timbo...where are You?
:whistle:

sounds like you still have something going south in the carb area, float level maybe

that's a good start actually i havent checked the advance havent even seen it, a lot of stuff was sticky when we got it, the carb float is fine, but thank you. does anyone know where the advance is? i know on my cb450 it's behind the points breaker plate.

Should be in the same area,Dan...in with the points(right-hand side,sitting on bike),if the 250 HAS points,and not electronic ignition.
Small cover with 2 bolts to remove?

i already timed it and gapped it though, dead on in idle. i don't know if the advance is sticking as i don't know the location of it. and i don't really wanna remove anything till i do so as not to upset the timing. and the carb boots are fine look like new and even seat like it, the carbs a tough one to put back in the boot so no air leaks. hey tim your carb looks a lot different than mine.

You mentioned something about opening the choke as it warms up? On my 650 I open it to start then slowly close it as it warms up. Maybe we're talking about doing it the same way just with the names backwards. Like Sandy said theres alot of minute passages that can make a world of difference. Hopefully this will help. Just keep on trying. Good luck. -Bobby

my Classic Motorcycle Mechanics mag came in the mail today and includes this Q&A. the magazine is a bit expensive but pretty good. they've got a special series of articles on the z250 coming up in the next few months.

www.classicmechanics.com

so maybe my oil punp is plugged? it makes sense since the oil was never removed as well as the fuel. we did change the oil and it drove for a day but very roughly. may have to look into this, the carb ports a very clean as i've removed it several times and constantly rechecked every port. i've been trying to get it running since last winter in feb.

so maybe my oil punp is plugged? it makes sense since the oil was never removed as well as the fuel. we did change the oil and it drove for a day but very roughly. may have to look into this, the carb ports a very clean as i've removed it several times and constantly rechecked every port. i've been trying to get it running since last winter in feb.

so maybe my oil punp is plugged? it makes sense since the oil was never removed as well as the fuel. we did change the oil and it drove for a day but very roughly. may have to look into this, the carb ports a very clean as i've removed it several times and constantly rechecked every port. i've been trying to get it running since last winter in feb.