Project GSX250 restoration

Thanks guys I will certainly try to clean the jets and check specified orings.

Trying something just then, if I block the end of the vacuum hose that doesn't go to the petcock, the idle comes down. Does that confirm that it's just a breather port? This is the vacuum port on the right carb that is horizontal.

 

Ok cool, just a breather, thanks.

After setting the choke to half, to get a lower idle, applying carb cleaner everywhere didn't really seem to effect the rpm. Maybe a little on the right engine boot. Started to run out of fuel at the end there! Waiting for WD40 to loosen up the engine boot bolts so that I can get them off to check the o-rings.

https://www.facebook.com/video.php?v=10212786368632802

Anyway, stripped the carbs, all looked good but gave all the brass parts a cleaning; main jet, pilot jet, emulsifier tube, bronze screw on carb intake opening... no blocked holes anywhere.



Does this brass nipple-y thing look ok? Looks like it's not draining residual fluid, if that's what it's supposed to do:



Thanks guys.

 

God those engine-carb boot bolts really don't want to come out... and they're soft as ****. I'll give them a few days of WD40 then failing that might just have to spread some RTV around where the boots could be leaking =/

 

Was reading another thread, could it be the carb diaphragm covers are leaking and causing the high idle? The user said putting some RTV on the carbs to seal the covers fixed their issue. My diaphragm look to be in good condition but air seal might not be great after 30 years.

 

That's how I'm diagnosing it at the moment, vacuum hose to petcock plugged. I'm not seeing much of a change in the idle speed when spraying the carb intake and exhaust seals though.
Could be to do with choke position though, I have no idea (I have had it half 'on' when testing today).

Haven't tried spraying the diaphragm covers so was wondering if that was a possible culprit. Also confused why reducing the amount of choke reduces the idle speed. Less choke = higher air to fuel ratio which should increase, not decrease, the rpm?

 

If the 250 model carb follows the 400 model carbs, the diagram from the service manual shows part 13 being a breather, inferring the same should be true for the 250. I will have to do further analysis that the idle coming down was directly tied to blocking off this hose, as it wouldn't make sense to have two vacuum hoses coming off carb #2 doing the same thing. There are only 2 vacuum ports/hoses on my carbs, and one fuel hose.

 

If someone can confirm on their bike part 14 goes to the petcock and 13 (both from the 400 carb diagram) hangs loose as aforementioned by @Johnny that would be much appreciated. @Joker? Did you have one of these bikes?

So confused haha! Just trying to understand why it idles better with less choke but still needs at least a little to keep running. Will have to just hope the carb clean and sealing everything up resolves the issue!

 

Ah ok my bad

 

I'm missing the washer shown in the manual for both main jets, could possibly be problematic.

 

I also wonder whether it is running lean because of the position of the butterfly valve. Should it be fully closed or partially open w/o throttle input? I can't find the bit on how to set the butterfly valve position with the idle throttle screw I found previously dangnabbit

 

It's possible the valves were too far open, not sure if the could be the sole cause of the high idle, but I've now set their idle position to be like this:

https://www.google.com.au/search?q=...UICCgB&biw=1920&bih=1070#imgrc=XfYuH7uKi_FCkM:

 

Yep I understand that, I was wondering if they were to far open whether the idle could get as high as I'm seeing?