All good, we're on the same page, Cheers.

 

Hey Guys, I'm still having difficulty sorting out the 1/4 to 3/4 throttle range performance.  I've had this '74 360 for 52 years.  About 10 years ago I let my younger son use it and ran it out of injector oil...piston seized...honed bore, new piston and rings.  Ran poorly after.  Dove into the carb tuning, bought a set of jets, and was randomly trying them until I sent DEET an audio...he guided me just on sound...found the right one and she started to sing again.  My older son had it after and decided to "adjust" the carb but ended up taking it to a shop where they did a "rebuild" on the carb.  So, every time I tried a new jet 10 years ago, I had to take the float bowl off and screw the new jet into the bottom of what I'm wondering now was an emulsion tube (top of the photo) and not a needle jet...is that possible?  I know there were some "one off" things Yamaha did just in 1974 with the 360  I also have a 159-Q-6 needle jet and a lot of needles (although I don't really know what needle goes with that needle jet).  Just trying to do what works and would very much appreciate some help.  I love working on the old Enduro but I've spent too many hours with too little progress.  Thanks, Pat

I don't know, maybe get back to totaly original carb settings with the side mounted main jet & Oring on the jet setter which you might not have now if the shop changed main jet to needle jet base. Emulsion tube & needle jet are the same thing just different wording. Be sure the idle air screw hasn't been screwed fully home as that mucks up things & when closing throttle from well open it'll richen up as you go to open it again. Is exhaust possibly a problem. Is the piston a reed hole piston not a full skirt rt1 type. Is piston the right way around. Just thinking back to why it went pair shaped after the running out of oil trick. Lots of guesses by me likely way off the mark sorry. One more random thought--is the choke closing, be sure the little stick cap seal thing isn't off its locating ridge & stopping the choke fully closing. Is the slide guide pin ok because if slide turns 180 you'll get all sorts of blubbering running--.

For the Q6, I think 6DP17 from a VM32 and P5, 6F5 from a 30-83. Thats going by memory and lately, watch out.

RT325 - thanks very much for your thoughts on this.  What I'm calling "emulsion tube" is the one at the top on my previous post.  The main jet is accessed from the side of the bowl.  I'm planning to use the 159-Q-6 needle jet with jet setter/O-ring and try either a 6F5 or 6DP17 needle (thanks pabdt!).  Last time I disassembled the carb I noticed the needle was very loose in the needle jet.  The air screw is 2 turns out and seems to idle well.  The exhaust WAS DEFINITELY a problem.  The right side crank seal had blown out and it was smoking very badly.  After much tinkering it turned out that the oil injector pump was stuck on max flow.  All of that has been resolved including a thorough cooking and clean out of the exhaust.  After the seized piston repair 10 years ago and finding the right jet the bike ran great for a few years.  The choke seems fine...starts on the first kick and after about 30 seconds starts to lag but returns to smooth idle when I raise the lever.  The slide pin and the needle jet pin are in good shape.  All good thoughts and sincerely appreciated!  Pat