paultsmith Posted October 29, 2008 Author Share Posted October 29, 2008 If you have the transistorized ignition you can check the resistance of the pick up coils resistance. It should be about 700 +-150 Ohms Link to comment Share on other sites More sharing options...
Special Man Posted October 29, 2008 Share Posted October 29, 2008 Thanks to all for all the input (and patience!! ) I haven't got a chance to check the resistances yet, but will do this weekend. Thanks again. . . glad this club is here. Not many people know much about old bikes!! Special Man Link to comment Share on other sites More sharing options...
XRayHound Posted November 1, 2008 Share Posted November 1, 2008 Was playing around with it some more tonight, got it running with MUCH effort, to discover it had switched sides, again. The right cylinder was now the strong one. Kept fiddling with it, tried some of my other coils on the left side (the one that was on it checked high on secondary resistance, both my spares checked good) to no result... until the bike finally got warm and lo and behold both cylinders were firing. I took it for a short ride to blow it out and burn the residue off the plug on the side that wasn't firing... before I got back to the driveway, it had switched sides AGAIN and the right cylinder was gone. Will check the pickup coil resistance later as per pault's advice, but the side swapping has me completely mystified. Also, the hovering spark plug wire boot trick has stopped working. I'm almost ready to take back my assertion that it isn't carburetion, because there IS spark ALWAYS. But I don't get how the carburetors could spontaneously just decide to take swing shifts, either. They both work or one works but they never BOTH give it up. Halp. Link to comment Share on other sites More sharing options...
Cy Welch Posted November 1, 2008 Share Posted November 1, 2008 Was playing around with it some more tonight, got it running with MUCH effort, to discover it had switched sides, again. The right cylinder was now the strong one. Kept fiddling with it, tried some of my other coils on the left side (the one that was on it checked high on secondary resistance, both my spares checked good) to no result... until the bike finally got warm and lo and behold both cylinders were firing. I took it for a short ride to blow it out and burn the residue off the plug on the side that wasn't firing... before I got back to the driveway, it had switched sides AGAIN and the right cylinder was gone. Will check the pickup coil resistance later as per pault's advice, but the side swapping has me completely mystified. Also, the hovering spark plug wire boot trick has stopped working. I'm almost ready to take back my assertion that it isn't carburetion, because there IS spark ALWAYS. But I don't get how the carburetors could spontaneously just decide to take swing shifts, either. They both work or one works but they never BOTH give it up. Halp. Make sure they are clean (not just the bowl but the passages and jets as well) and make sure that you have no leaks in the carb mounting rubbers. Also make sure that your needle valve seats are not leaking (very likely on a bike this age) as the o-rings that seal the needle valve seats into their holes flatten out and wear out and the WILL leak gas around them making it run rich (which is what it sounds like could be happening.) I ended up getting complete rebuild kits that came with all the parts (including the needle valves and seats) from MikesXS and that solved MY problems. After that it was just a matter of getting them dialed in properly, and that was actually pretty easy. Of course, glutton for punishment that I am I just got a 1980 XS1100G that has the same carbs on it, and I suspect all the same problems, so I'll be getting 4 carbs kits and redoing 4 carbs (and I don't look forward to balancing them, but I will). Link to comment Share on other sites More sharing options...
G-man Posted November 2, 2008 Share Posted November 2, 2008 Lucky you, wish I could say likewise. Paul, I'm going thru exactly the same thing as you, same side as well. Gonna try swapping the plugs and see what happens. Hey, I dunno if this will help y'all, but here's what I stumbled on. I stripped the carbs, pulled the needle valve assembly, and woohoo, lotsa junk behind the filter screen, evidentally gas tank crud, probably got there before the previous owner installed a gas line filter. So I figure the gas supply was restricted into the right carb, backing up into the left one. That may explain (in my case, at least) why the right plug showed it running a bit lean, and the left plug rich. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted November 2, 2008 Moderator Share Posted November 2, 2008 I'm having the same problem as Special Man. It is NOT in the carbs. Here's my story: I rebuilt the carbs, set the valves, sync'd the carbs, everything was nice. It started easy, ran good. Let it sit for awhile since I had accomplished what I set out to do. When I next try to start it, no joy. Nothing works. I get it running with brake cleaner and notice the right pipe is cold. Pull the plug wire, it's still loping along, nothing changes. Here's the goofy part: if I pull the wire off and hold it way off the plug, to where the spark is arcing to the plug, the cylinder fires and the bike runs great! I figured this was a bad wire, so I swapped in an extra wire I had. No change. After I caught onto the pulling the boot halfway off making it fire thing, I swapped the plugs side to side, and sure enough it moved to the left cylinder. Two new NGK plugs later and after a short period of running well it's back in the right cylinder. I'm stumped. Again, carbs, the cyl runs rich fouls up the plug, moving the cap away a touch increaces the gap therefore increaces the energy needed to jump the gap hence bigger spark blows the cr@p off the plug. Every thing hokey dokey till the cyl chokes again. IT IS THE SODDING CARBS i have been through this with a XS650 hard tail (dont ask, not mine) a cb175(69) and a cb125(83) and in EVERY CASE it was the carbs. They are either set wrong or cr@pped up but they are causing the engine to go rich. NGK plugs dont go for being run rich either. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted November 2, 2008 Moderator Share Posted November 2, 2008 Again, carbs, the cyl runs rich fouls up the plug, moving the cap away a touch increaces the gap therefore increaces the energy needed to jump the gap hence bigger spark blows the cr@p off the plug. Every thing hokey dokey till the cyl chokes again. IT IS THE SODDING CARBS i have been through this with a XS650 hard tail (dont ask, not mine) a cb175(69) and a cb125(83) and in EVERY CASE it was the carbs. They are either set wrong or cr@pped up but they are causing the engine to go rich. NGK plugs dont go for being run rich either. use irridium plugs, they fire under extreem conditions Link to comment Share on other sites More sharing options...
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