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Carburetors and their various parts,internal and external with pics.STICKY PLZ

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This write up pertains to the 1989-2000 GS500 Mikuni BST33SS carbs.These carbs are on various motorcycle makes and models.I am going to point out the various parts that we need to know.

Here are two good links to help understand our carbs better.

This link is really good at explaining things.Same carbs as ours just in a rack of four instead of two.Ours would be like the two center carbs.

This link explains what each circuit of the carb does and how to tune them.There is some false stuff on our forum and this should clear some of it up.,CV,high_rpm_engines.html

Here is the air filter side of the carbs.

Here is the top side.

Here is the engine side of the carbs.

Here is the bottom side.

Here is the right side.

Here is the left side.

Now for what's on the inside.Starting at the top.

When the top of the carbs are opened up,be sure not to loose the vacuum port O ring.These things cause all kind of running issues.

The top.

The top removed.Be very careful not to loose any of the parts

Here is the slide needle laid out.

The slide has been removed.You can see the slide guide and emulsion tube.

The slide guide removed as an assembly.

The emulsion tube seperated from the slide guide.

Please be aware of the seal.I can not find these any where and I have a set of carbs with bad seals.

Now for the bottom side.This is the area that gives the most grief,especially to new people working on the GS500.

Here it is with the float bowl removed.Note that the jets are missing from this set.

Here is the float bowl.You can see the drain and drain screw better in this pic.

Here is the inside and this is where dirt and gunk settles.It's also where it gets sucked into the carbs,clogging them.

Float assembly has been removed.If the needle's seat O ring doesn't seal tight,it will flood the crank case with gas.

Float assembly.If that O ring or needle doesn't seal tight,it will cause running issues and flooding.

All those little passages need to be cleaned and blown out with compressed air.I used gunk brand brake cleaner on my carbs.
To use it,ever rubber part has to be removed from the carb.I didn't show the chokes being removed.They are rarely an issue and
usually a couple sprays with WD-40 will free them up.

Here is a link to the album with more pics of the carbs.This is my parts set.

Can you post this on the GS wiki page?  :dunno_black:

Would be great to have it there permanently. Good job by the way  :thumb:


--- Quote from: Twisted on June 08, 2011, 10:53:48 PM ---Can you post this on the GS wiki page?  :dunno_black:

Would be great to have it there permanently. Good job by the way  :thumb:

--- End quote ---

Thanks and I am unsure about how I would do that.


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