Rebuild parts help

Hey! happy winter,lol.
I own an all original 79 xs650 special, I ride it occasionally and it runs great just difficult to start sometimes, lots of cranking fires (once) right away then lots of cranking to fire again.. I would like to rebuild my carbs this winter but have read here that some re-build kits are better than others, can someone please tell me which kit is the best and most complete to purchase, my bike only has 6000 miles from new but things get old and dry-out like me, also I am considering a switch to electronic ignition and will be seeking advice on that this winter so thanks in advance, Sam.

About the only thing in a kit that is usable are the gaskets. Most everything else isn't.
Mikuni used this basic carb to build a carb for a lot of different bikes. The manufactures of the bikes had different requirements. Mikuni made mods to match these requirements.
Aftermarket suppliers just picked a set of internals and gaskets that fit some uses. Our XS650 wasn't on the list.
I as well as others don't recommend kits just for this reason.
www.amckayltd.com/carbguide.pdf was written by our carb guru's. If you follow the steps in the guide to tear down, clean and inspect what you have then you can decide just what you need to buy. If you are careful during tear down you can reuse the gaskets. When assembling the carbs don't use any sealer on the gaskets. You may need to go back in.
With so few miles I doubt you need to buy anything. Just a good cleaning should work.
Once everything is clean, follow the steps to reassemble. Making adjustments as you go.
Once fully assembled they should work fine.
The guide has a section titled "Tuning For Mods" this section can help you check your carbs adjustments. Even a fuuly stock bike needs a bit of tuning.
Leo

We usually don't recommend carb rebuild kits. They are aftermarket and the quality of the parts can be hit and miss. Sometimes the included jets are the wrong size too. Best you just replace anything that needs it individually, and use genuine Yamaha or Mikuni parts. The original float bowl gaskets are very good and as long as you're careful not to tear them as you remove the float bowls, they can be re-used. You needn't disturb and/or remove the choke housings from the sides of the carbs, just take the plungers out of the top. The passageways in the choke housing are quite large and rarely, if ever, plug up. You can swab them out if you like but like I said, they're usually not an issue.

There are very few rubber parts in your '78-'79 carb set and they don't come in the rebuild kits. Even though you have low miles, they are old so some of this rubber stuff may need replacing. There is an o-ring on the needle jet. If it's good, the needle jet will be a tight slip fit into the bottom of the carb body. If it's gone bad, the jet will be loose. Replacement size is 1mm x 4mm .....



Your mix screws also have an o-ring on them. Check it's condition. If a replacement is needed, here's the size .....





The only other rubber bits in your carbs are the butterfly shaft seals. I'd let them go for now.

Your hard starting may be related to the choke operation. The jet that feeds fuel to the choke when you turn it on may be plugged or partially plugged. The choke won't work if it is and that makes cold starts difficult. Here's how to check it .....



This jet is pressed in place so about the only way to clean/clear it is to blow cleaner through it with compressed air.