Rat650
XS650 Enthusiast
Roger that, I was just looking over some of that carb info. Love the photos, I'm visual learner. And I will check into a timing light locally here. Thanks for taking the time to help!
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Noob here, 1972 xs650 not firing on right side
- Thread starter Rat650
- Start date
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- carburetors electrical engine
Rat650
XS650 Enthusiast
Going through the right side carb I have found that the float level is at 26.16 millimeters, is there any reason they would be set that high? After looking through the tech section I have found guides that says it should be 24 and one that says 25, Which one should I shoot for? I am measuring with the gasket removed. Also I have attached a picture of the carb, I'm not having any luck identifying the hole on the top left by the butterfly and it's the only one I can hit with carb cleaner or air and can't find it coming out someplace else. I don't think it's a blind hole because if I pool a little carb cleaner on it there's a slow bubble that comes from it. Thanks again everyone for your help and patience!
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Rat650
XS650 Enthusiast
Since that hole at about 10 o'clock on the top left is located in front of the butter fly I'm assuming it is part of the pilot circuit. I am still unable to get carb cleaner or air to pass through it however. Should I try to clear it with a small wire?
That may be the feed from your mix screw. Remove the mix screw and air or cleaner should go through then. The mix screw should be removed anyway for a proper cleaning. That hole and a cluster of 3 small ones covered by the butterfly plate are fed by the pilot jet. Blow carb cleaner through the pilot inlet on the bottom of the carb .....
..... and watch for it to come out the 4 feed holes in the main bore .....
Hold a finger over the mix screw hole to block it off so all pressure is directed out the 4 holes. To back-flush to the pilot feed hole, blow carb cleaner through the mix screw hole while blocking off the 4 little holes in the bore. That will force all the pressure back through the circuit and out the feed hole.
..... and watch for it to come out the 4 feed holes in the main bore .....
Hold a finger over the mix screw hole to block it off so all pressure is directed out the 4 holes. To back-flush to the pilot feed hole, blow carb cleaner through the mix screw hole while blocking off the 4 little holes in the bore. That will force all the pressure back through the circuit and out the feed hole.
Rat650
XS650 Enthusiast
From what I can tell the small hole next to the large hole in my picture is the feed from the mix screw. I get carb cleaner coming out of it when I shoot it through the mix screw hole or the pilot inlet with the mix screw hole covered. Still no luck clearing that other hole in question though. The bubbles I'm getting from it when I puddle cleaner on it are moving a little faster today however.
The large hole on the right is the choke feed. I don't know what that small hole on the right is. Something else I noticed in your photo is you have #115 butterfly plates. From this link, I was under the impression they should be #125s .....
http://www.xs650.org.au/XS-TX650 Carburetor Evolution.htm
I don't know how or if that would effect carb function but it might indicate those aren't even 650 carbs to begin with.
http://www.xs650.org.au/XS-TX650 Carburetor Evolution.htm
I don't know how or if that would effect carb function but it might indicate those aren't even 650 carbs to begin with.
Rat650
XS650 Enthusiast
Hmm... well bummer. I guess what I'll do is pull the left side carb where everything is running properly and see if all the little ports/hole respond the same and go from there.
Rat650
XS650 Enthusiast
Yes it's also a #125 plate on the left hand carb. And that mystery hole acted the same, just bubbled. So I will reassemble and install and see what I get. I will also adjust the right side float to 25 millimeters since that's what it measures on the left (working) side.
OgreOwner
XS650 Member
The big one is the choke communication line. The smaller one is the fuel communication line. The fuel line makes it so that both carbs have access to fuel even if only one petcock is giving fuel to them. It is vitally important that both of them be hooked up between the two carbs. Since the geometry is so tight between the carbs, I put hose clamps on one side and then press the hoses on as I mount the other carb.
OgreOwner
XS650 Member
The large one is the choke fuel entry. The small one is the idle fuel entry.
Well, if you have a #115 butterfly plate installed in one carb and a #125 in the other then the carbs are mismatched. You may not be able to get both cylinders to run the same like that. Have you compared jetting carb to carb (main, pilot, needle jet and needle) and is it the same? It looks like either someone has installed the wrong plate in the right carb or the whole carb is from another bike.
Rat650
XS650 Enthusiast
Well I installed the carbs last night and she fired right up! Sounded a lot better and both pipes heated pretty evenly. Took her for a quick spin and everything seems good. Not sure if it was the cleaning, float adjustment or both that did it but what an improvement. I can't thank you all enough for your guidance and patience! This has been a truly enjoyable learning experience. So for now the plan is to keep riding her this summer (fingers crossed she keeps running well) and then do some upgrades and a topend rebuild this winter. And maybe even a build of my own in the future, so I'll be reading up on some of that and be bugging ya with more Noob questions soon 
Rat650
XS650 Enthusiast
Oops! I'm sorry 5twins, I miss typed they are both 115 butterfly plates. Everything is the same side to side. Thanks again!
