Carb identity wwhat are you

[funky]

Hi all Hope you are well
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Are these Mikuni Carbs 34s or 38s When I stripped them down to clean them and put them back together i missed somthing I have been reading about these carbs and looking at exploded views of the components and have noticed that the mixture screws are missing the little washer which sits at the base of the spring and more importantly the rubber "O" ring which I presume acts as an air seal. My Bike is back firing on occasion so I need to know where and what to buy. The back firing my be a characteristic of the engine but i am sure that these parts missing are not helping the issue...
All the best Funky

 

[DogBunny]

Those are BS34s.
Lots of things can be causing the back firing, but I doubt it is missing washers and o-rings, which would more likely simply cause fuel to leak out the mix screw openings.
It is very possible that the o-rings and washers are stuck at the bottom of the mix screw holes, they can be hard to see and hard to remove.

 

[fredintoon]

Hi funky,
what DogBunny sez about the washers and o-rings still being down there.
Fish them out with a home made hookything.
Take a ~8" length of 1/16" gas welding rod and stick it in a vise with ~1/4" sticking up.
Pound the sticking up part over at 90º and then smash it flat.
Shorten the flattened end on the grinder so it's only sticking out enough that it'll go down the needle's threaded hole and hook out the washer and o-ring.

 

[funky]

well I looked and there not there

 

[angus67]

http://www.mikesxs.net/product/48-5011.html