help with carbs

[paper scratcher]

Hello everyone I am obviously new at this and I'm rebuilding the carbs on an XS650 that I just bought and any help would be greatly appreciated. I'm not sure what year the motor and carbs are but they appear to be the Mikuni BS38 with an E stamped on the bottom. The floats are brass and they have straight pins that fit flush with the sides of the posts which I think dates it between 76 and 79. One question I have is that on one of the slides (the one on the right) that in addition to the hole for the needle, there is a second hole in the slide, which I think is normal but on the other slide (the one on the left) there are 2 additional holes. Is that normal? also the pilot jets don't have bleed holes, is that right? and lastly my main jet has the number 152.5 on it, is that the size? Also I'm not sure if it helps or if it matters but the the main air jet does not have an "M" cast into the carb mouth next to it. Thanks

 

[5twins]

Take a closer look at that main jet. Are you sure it doesn't say 122.5? That's the stock size for a '76-'77 carb set. 135 is the largest main ever put in any 650 carb set so a 152.5 would be way, way big. Too rich really to run correctly. Go to the tech section and read the carb guide. That will help you I.D. the carb set you have.

The brass floats and straight flush pivot pins were common to all so that's no help. You need to go by jetting and certain characteristics. If bolted together as a bank and using one throttle cable, that would be a '76 through '79 set. Earlier carbs were separate and had individual throttle cables. Here's a chart I put together with stock specs .....

The slide was changed in the '78-'79 set. It retains the needle with a snap ring. All earlier sets held the needle in with a large plastic disc or washer and the large slide return spring was all that held it in place. Pilots with no bleed holes were used in some of the carbs, notably the '76-'79 sets. I'm not sure about the extra hole in the slide.