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I'd like to say "Hello" to all, and to let you know that because of this forum, last Friday (4/23) I purchased a '78 XS.
First a bit about the bike, the second my question.
78, XS, 11,060 miles on it, bought from the original owner, pristine, garaged all the time, 3 years ago went in for about $1000 of work (at the dealer he bought the bike from)(new tires, Carbs cleaned, new Battery, new fork seals and oil, replaced all the fuilds, and tune-up.) Other than the obvious, I don't know the specific reason he did the carb overhaul. I can speculate that
since he hardly rode it, he thought the carbs were gummed up and had poor performance. After all that work, he's ridden it about 50 miles in 3 years. I don't think the dealer fixed his problem and he became frustrated. At the time of sale, all he could do was complain about the carbs.
Anyway, it started, but was obviously running on only #2, & #3. Following different posts, I figured the pick-up coil issues talked about would cure most of the mis-firing.
Now to the problem:
First what I've done, (I consider myself a fairly good wrench, and by the constant stream of mechanical devices through my garage, others do also)
Changed the oil, new plugs, (Previous owner had put Stabil in the tank), cleaned the tank and found no problems, fixed the pick-up wire,(it was broke), disassembled #1 & 4 carb (on the bike) by pulling to top cover, and bowl. Didn't touch the floats, but everything else was pulled and cleaned (jets, emulsion tubes, all of it) Carb cleaner thru all of it and found no sludge, dirt, or varnish. Cleaned air cleaner, and checked for critters in the intake tubes.
Fired right up, and in the driveway, ran on all four for about 2 minutes. Found the plugs completely fouled. Replaced plugs, and started up and ran. Synched the carbs at 1000rpm, and got all of them at 6" vac, but the vacuum advance plate was oscilating quite a whole lot (About 1 1/2" of travel at idle, no wonder the wire breaks). And I was getting some poping back into the intake tubes. Checked the valve train the next morning and found the clearances to be a bit tight, about 1/2 of what the factory manual says, but they're all consistant, and I don't have any reason to suspect the shims have been changed.
Anyway took the beast out for a ride to test my progress. Wasn't good. Went great for about 3 miles, then bogged down to 20mph, and no manipulation of the throttle would do anything else. Ended up about 6 miles traveled, and used near 3/4 of a gallon of gas. Heavy black smoke out of both pipes, plugs fouled, and removal of the air cleaner didn't change anything.
This is where I'm asking for help.
Do I need to do a complete tear down of the carbs? Could the enrichment circuit be "misadjusted" and dumping fuel? Floats to high? I don't understand how a CV carb can dump that much fuel. And do it to all four cyclinders.
Any help or experience you can lend would surely help.
A frustrated
Doo-Daa.
First a bit about the bike, the second my question.
78, XS, 11,060 miles on it, bought from the original owner, pristine, garaged all the time, 3 years ago went in for about $1000 of work (at the dealer he bought the bike from)(new tires, Carbs cleaned, new Battery, new fork seals and oil, replaced all the fuilds, and tune-up.) Other than the obvious, I don't know the specific reason he did the carb overhaul. I can speculate that
since he hardly rode it, he thought the carbs were gummed up and had poor performance. After all that work, he's ridden it about 50 miles in 3 years. I don't think the dealer fixed his problem and he became frustrated. At the time of sale, all he could do was complain about the carbs.
Anyway, it started, but was obviously running on only #2, & #3. Following different posts, I figured the pick-up coil issues talked about would cure most of the mis-firing.
Now to the problem:
First what I've done, (I consider myself a fairly good wrench, and by the constant stream of mechanical devices through my garage, others do also)
Changed the oil, new plugs, (Previous owner had put Stabil in the tank), cleaned the tank and found no problems, fixed the pick-up wire,(it was broke), disassembled #1 & 4 carb (on the bike) by pulling to top cover, and bowl. Didn't touch the floats, but everything else was pulled and cleaned (jets, emulsion tubes, all of it) Carb cleaner thru all of it and found no sludge, dirt, or varnish. Cleaned air cleaner, and checked for critters in the intake tubes.
Fired right up, and in the driveway, ran on all four for about 2 minutes. Found the plugs completely fouled. Replaced plugs, and started up and ran. Synched the carbs at 1000rpm, and got all of them at 6" vac, but the vacuum advance plate was oscilating quite a whole lot (About 1 1/2" of travel at idle, no wonder the wire breaks). And I was getting some poping back into the intake tubes. Checked the valve train the next morning and found the clearances to be a bit tight, about 1/2 of what the factory manual says, but they're all consistant, and I don't have any reason to suspect the shims have been changed.
Anyway took the beast out for a ride to test my progress. Wasn't good. Went great for about 3 miles, then bogged down to 20mph, and no manipulation of the throttle would do anything else. Ended up about 6 miles traveled, and used near 3/4 of a gallon of gas. Heavy black smoke out of both pipes, plugs fouled, and removal of the air cleaner didn't change anything.
This is where I'm asking for help.
Do I need to do a complete tear down of the carbs? Could the enrichment circuit be "misadjusted" and dumping fuel? Floats to high? I don't understand how a CV carb can dump that much fuel. And do it to all four cyclinders.
Any help or experience you can lend would surely help.
A frustrated
Doo-Daa.
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