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KA1J,
Welcome to the club.
Before you start shredding metal, why are you replacing all this stuff? Are the needles, jets, and throttle shaft seals actually worn or are they just dirty and need cleaning? The only parts that actually get any physical wear and tear are the floats, float valves, enricheners, slides, slide diaphragms, needle jets, jet needles, and throttle shaft seals. Unless you totally hammer the parts trying to get them out of the carb bodies almost everything can just be cleaned and re-used.
The jet needles (slide needles) and needle jets (emulsion tubes) are no longer available anywhere. There is no link to those parts or I'd give you one. Your best bet for replacing the rest of the jets is your friendly neighborhood motorcycle dealership. You can buy them online if you really want to but I like to bring the old jets with me and eyeball the new ones personally right there on the counter before I give up my money to make sure they're the correct size, type, and that they're actually Mikuni jets.
I haven't used them myself but I think the carburetor shaft seals from Mike's XS are okay. If you're going that far into the rebuild you'll also need the carburetor throttle plate screws:-
Mike's Throttle Shaft Screws
When you clean the slides and check the diaphragms for leaks pay attention to the length of the slide return springs and try not to mix them up. Since you're diving in deep with your carburetors, what are the markings on your XJ's jet (slide) needles? You can remove the retainer clips holding in the needles but memorize, photograph, take notes or carve hieroglyphs on the wall of the mancave if you have to but do not mix up the order of the needle clips and washers. Assembly has to be the exact reverse of disassembly or the needle height will be wrong and you'll drive yourself crazy trying to tune the engine.
For reference, here's a picture of two different Mikuni needles that shows the part numbers. The one with five slots is from a set of '78/'79 carbs and I think the second one with the single slot is an '80/'81 Standard needle that shows the Genuine Mikuni logo:-
Click to download the original full size picture
I don't remember the numbers on the needle jets and jet needles in my XJ carbs (they're on my '80G right now and I'm not going to take them off and pull them apart to look at them) but if yours are marked 300FJX-7 they are:
Mikuni 300 Series needle jets
Size X7
I never did find out what the letters 'FJ' in the part number meant. It might be the size, number, and location of the air bleed holes in the sides of the jet but I've never found it documented anywhere so just I pulled that wild guess right out from underneath my keyboard.
Do not 'mess' up your carbs.
If you do you'll be trolling eBay like everyone else looking for a new set of used carbs that you hope is in better shape than your old set of carbs.
.
Welcome to the club.
Before you start shredding metal, why are you replacing all this stuff? Are the needles, jets, and throttle shaft seals actually worn or are they just dirty and need cleaning? The only parts that actually get any physical wear and tear are the floats, float valves, enricheners, slides, slide diaphragms, needle jets, jet needles, and throttle shaft seals. Unless you totally hammer the parts trying to get them out of the carb bodies almost everything can just be cleaned and re-used.
The jet needles (slide needles) and needle jets (emulsion tubes) are no longer available anywhere. There is no link to those parts or I'd give you one. Your best bet for replacing the rest of the jets is your friendly neighborhood motorcycle dealership. You can buy them online if you really want to but I like to bring the old jets with me and eyeball the new ones personally right there on the counter before I give up my money to make sure they're the correct size, type, and that they're actually Mikuni jets.
I haven't used them myself but I think the carburetor shaft seals from Mike's XS are okay. If you're going that far into the rebuild you'll also need the carburetor throttle plate screws:-
Mike's Throttle Shaft Screws
When you clean the slides and check the diaphragms for leaks pay attention to the length of the slide return springs and try not to mix them up. Since you're diving in deep with your carburetors, what are the markings on your XJ's jet (slide) needles? You can remove the retainer clips holding in the needles but memorize, photograph, take notes or carve hieroglyphs on the wall of the mancave if you have to but do not mix up the order of the needle clips and washers. Assembly has to be the exact reverse of disassembly or the needle height will be wrong and you'll drive yourself crazy trying to tune the engine.
For reference, here's a picture of two different Mikuni needles that shows the part numbers. The one with five slots is from a set of '78/'79 carbs and I think the second one with the single slot is an '80/'81 Standard needle that shows the Genuine Mikuni logo:-
Click to download the original full size picture
I don't remember the numbers on the needle jets and jet needles in my XJ carbs (they're on my '80G right now and I'm not going to take them off and pull them apart to look at them
) but if yours are marked 300FJX-7 they are:Mikuni 300 Series needle jets
Size X7
I never did find out what the letters 'FJ' in the part number meant. It might be the size, number, and location of the air bleed holes in the sides of the jet but I've never found it documented anywhere so just I pulled that wild guess right out from underneath my keyboard.
Do not 'mess' up your carbs.
If you do you'll be trolling eBay like everyone else looking for a new set of used carbs that you hope is in better shape than your old set of carbs.
.
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