[GPZ500_UK]

Hi, I've owned a 2002 EX500 for around 6 years. Runs great and been very reliable.

This winter it sat for about 6-8 weeks in a garage with freezing temps & I came back to a sticky throttle. Aside from that, the bike runs fine. However, I've traced the sticky throttle back to a sticky butterfly valve on one of the carbs (it moves, but not freely).

I've removed the carbs and tried pentrating oil overnight on the shaft from inside. Also tried carb cleaner. No changes, remains difficult to move.

From my research, I understand you're not supposed to remove the butterfly valve & shaft, but it can be done.

I'm far from an expert on Carbs - Is removing the butterfly & shaft my only option as a next step and anyone have guidance / advice on the steps for how to go about it? (the screws on the butterfly worry me as understand they're non-standard and thread locked in some way so they can't vibrate out - would I have to drill them and find replacements somewhere?)

Thanks!

 

[yorkie]

hi, it's not the butterfly but corrosion on the carb body that the butterfly shaft runs through had this once on a old set of carbs. plenty of penetrant perhaps a little heat and keep working it open and closed. perhaps a strip down and a session in the ulta sonic tub might help, but I would not attempt removing the screws on butterfly.

 

[[email protected]]

Just to reinforce what yorkie said, those screws are there to assemble the carbs in a controlled factory environment, not for taking them apart. We all know its tempting, but the chances of getting that butterfly back in the same position is zero, meaning that even if you can free the shaft, the carb will never be right from that point on.

Your best chance is a thorough cleaning, gentle heat, and working back and forth. If that doesn't fix the problem, then another, uncorroded carb is the safest solution.

The trouble with the "the carb is defective, I've got nothing to lose, I might as well take it apart and see if I can fix it" logic is that upon reassembly those screws have a good chance of working loose and being swallowed by the engine, turning a small problem into a much larger problem.

 

[ducatiman]

From my research, I understand you're not supposed to remove the butterfly valve & shaft, but it can be done.

Yes, but be aware, no internal shaft parts are made available by Keihin, demanding mandatory reuse of same. Best o' luck to ya'.

 

[fog]

anything man put together. can be taken apart by man, it's all a matter of force

FOG

 

[ducatiman]

anything man put together. can be taken apart by man, it's all a matter of force
FOG

and forcing decisions to be made such as....should I? Do I actually need to do this?

 

[yorkie]

anything man put together. can be taken apart by man, it's all a matter of force

FOG

yeah sure, as well as dexterity, knowledge, skill, and the right tools. sadly most or all are lacking in the average amateur.

 

[[email protected]]

The problem isn't getting them apart, the problem is putting them back together and working properly.

 

[ducatiman]

The problem isn't getting them apart, the problem is putting them back together and working properly.

Been there....certainly can be done....witness a set of 4 Mikuni CVK I split back in 2016. Not easy, but necessary to enable a full split in order to clean/replace/ renew leaking rail seals.