ciaostupido
XS400 Member
Hi there. I recently purchased a 1977 XS360 for my first bike. I've worked on small displacement 2 strokes and mopeds before so i get some of the theory behind it. Anyway does anyone know what jets, mainly idle and main jets I should be running on a stock xs360 with Mikuni BS34 Carbs?
I ask because recently I've been doing some much needed maintenance to this lil' guy. It sat in a barn in Nh for the first 1/4 of its life. Then the previous owner got it running abit roughish but running. Now i have it and have been slowly bringing back to the 21st century. I replaced the friction discs in the clutch. But my problems started after I replaced the intake boots.
I had ultrasoinic'd the carbs like four times. The main jets in the float bowls weren't coming out so I had to extract them. Now the first round of jetting I followed the xs360/400 service manual and ordered 135's off of MikesXS. Little did i know those jets aren't genuine Mikuni jets and caused the bike to run suuuuuuuuper lean.
So I got proper Genuine Mikuni jets and installed them, the 135's. Also another discrepancy I'm trying to figure out is the Idle jets. The manual calls for 17.5's, but Mikuni doesn't make 17.5's without the air bleed holes anymore. They only make the 42.5's range that the XS400 jetting specs use. So I put in some Mikuni VM 17.5's that have the air bleed holes but the bike is still running lean and my idle does go up from time to time unless I blip the throttle.
Soooooo should I run an XS400 jetting spec on these carbs? I heard they were jetted lean from the factory. So that would mean I would go up to either a 137.5 or 142.5 main, and a 42.5 idle, as thats what the manual calls for on all the models of the XS400's but calls for obsolete 17.5's on the XS360. Anyone with any experience think this is the way to go?
Also what should I do about the fact that Mikuni doesn't manufacture any 17.5 Idle jets with no air-bleed holes anymore. Should I run regular vm 17.5's, or go up to the 42.5's with the non air bleed holes?
Any help would be awesome, as im starting to turn into this guy:
I ask because recently I've been doing some much needed maintenance to this lil' guy. It sat in a barn in Nh for the first 1/4 of its life. Then the previous owner got it running abit roughish but running. Now i have it and have been slowly bringing back to the 21st century. I replaced the friction discs in the clutch. But my problems started after I replaced the intake boots.
I had ultrasoinic'd the carbs like four times. The main jets in the float bowls weren't coming out so I had to extract them. Now the first round of jetting I followed the xs360/400 service manual and ordered 135's off of MikesXS. Little did i know those jets aren't genuine Mikuni jets and caused the bike to run suuuuuuuuper lean.
So I got proper Genuine Mikuni jets and installed them, the 135's. Also another discrepancy I'm trying to figure out is the Idle jets. The manual calls for 17.5's, but Mikuni doesn't make 17.5's without the air bleed holes anymore. They only make the 42.5's range that the XS400 jetting specs use. So I put in some Mikuni VM 17.5's that have the air bleed holes but the bike is still running lean and my idle does go up from time to time unless I blip the throttle.
Soooooo should I run an XS400 jetting spec on these carbs? I heard they were jetted lean from the factory. So that would mean I would go up to either a 137.5 or 142.5 main, and a 42.5 idle, as thats what the manual calls for on all the models of the XS400's but calls for obsolete 17.5's on the XS360. Anyone with any experience think this is the way to go?
Also what should I do about the fact that Mikuni doesn't manufacture any 17.5 Idle jets with no air-bleed holes anymore. Should I run regular vm 17.5's, or go up to the 42.5's with the non air bleed holes?
Any help would be awesome, as im starting to turn into this guy: