Bike dies after a few minutes

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pdedse

XS650 Enthusiast
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I have a very clean 1983 xs650 with 7400 miles. Purchased it early July of this year. Bike had sat for a number of years unused and the carbs were synced and cleaned by an independent mechanic right after I purchased it. It has run 1200 miles flawlessly until today.

Started bike fine as always, it has 1/2 tank of gas, took off w/out warming it as much as I usually do cause I was in a bit of a hurry, drove less than 1 mile and it died while in second gear. Pulled over, started again right away, ran fine for 2 miles and it died while in 4th. Pulled over, starts fine but then dies right away. Waited 10 minutes, started fine, drove back towards home for 2 miles and it dies again. Starts every time, but dies right after. I push it 1 mile home. Two hours later it starts fine, idles, I go around the block 2 times, it dies. I switch to reserve, it starts and idles fine, I go 2x around the block again, it dies again, starts easily each time, but dies 1-2 seconds later. I leave it at this point. Later in the garage it starts, idles, but after 1 minute dies. Zero starting issues, it just dies after a bit.

To me it seems as if there is fuel delivery issue because it starts and runs for a few minutes after sitting for an hour. Didn't have time to look at it this afternoon, but before I look at fuel lines, carb tomorrow, any specific culprits come to mind that I might think about? Thanks.
 
i'll second the fuel flow as likely problem.

this sounds like a gas cap that is not venting properly which shuts off fuel flow due to vacuum build up. if problem goes away by opening cap, you found it. not a very safe test while riding however.

if that's not it, with engine cool disconnect the line(s) from the carbs and check flow into a container. keep working downstream...
 
barncat said:
i'll second the fuel flow as likely problem.

this sounds like a gas cap that is not venting properly which shuts off fuel flow due to vacuum build up. if problem goes away by opening cap, you found it. not a very safe test while riding however.

if that's not it, with engine cool disconnect the line(s) from the carbs and check flow into a container. keep working downstream...
Click to expand...

I like trying the easiest things first...so I added about 3-4 oz of Sea Foam to the gas. I opened the gas cap and started the bike, it started fine, ran...I let it run for 5, 10 minutes, rode it around in circles around the cul-de-sac with gas cap open and it died once but I think because I killed it. I let it run some more with cap closed, another 5 minutes. Road 3 times around the block, cap closed, no hesitation, no stalling. road 3/4 mile to gas station, put a gallon in, rode home about 1/3 mile and it died. But differently than yesterday, it started and ran just fine afterwards. I rode it around the block again, but it didn't stall. So maybe the SeaFoam opened up something so a little more gas gets through, but not quite enough to keep it from stalling out completely? I didn't have much time this evening, but the fact that it started up and ran after stalling this time makes me think it's gas starvation.

Question re fuel cap. If it were to run w/out stalling with cap open, what would be the fix...a new cap? Or is there an 0-ring inside the cap that one replaces? thanks for the idea...I'll try again tomorrow and if the problems persists, I'll start with fuel line out of petcock.
 
i'm not sure what the exact construction of the '83 cap is. probably a C-clip to be removed and then check for crud, clean any passageway(s), clean the spring, shoot it with WD40, etc... there are other guys here who have more info on specific parts and/or you could perhaps find a diagram online.

that's just the first check i'd do. you'll zero in on it. how clean is the tank internally? doesn't take much crud in an old tank to create problems. external fuel filters also clog easily that appear to be working, if it has one...
 
Could it be that easy? Pulled the gas cap off, removed the 3 screws, removed the rubber seal which does probably need replacing due to cracked condition, used a thin wire to run through the vent holes, blew it all out with air and put back together. There didn't appear to be much blockage, but why not see how it runs after.

Bike started fine like it always does, went once around the block, 3/4 mile, another time, a third time, out into the streets a bit, all told 4 miles around 20 minutes...no problems, no engine dies. Stopped about a mile from home, let it sit for a few minutes. Started again no problem, ran fine, rode it home w/out issues. Not convinced it's only the gas cap yet, but who knows, I'll try again this afternoon when I know someone will be around in case it dies farther away from home.
 
Hi as fuel is used from the the tanks it has to be replaced with air if these holes are blocked then it will result in fuel starvation as a vacum is acumilated in the tank the carbs are gravity fed theres no pump so air needs to pass into the tank vis the filler cap.
What probably is happening is that a partial vacum is caused which slows the feed of fuel to the carb this probably caused the splutter and pop when it first did it, you stop fuel is still being fed into the carbs but slower that it should be carb bowl fill you drive of 2 miles and it cuts out.
By clearing the holes you have cleard the vacum thus allowing fuel to flow as it should at the right rate.
All the best funky
 
funky said:
Hi as fuel is used from the the tanks it has to be replaced with air if these holes are blocked then it will result in fuel starvation as a vacum is acumilated in the tank the carbs are gravity fed theres no pump so air needs to pass into the tank vis the filler cap.
What probably is happening is that a partial vacum is caused which slows the feed of fuel to the carb this probably caused the splutter and pop when it first did it, you stop fuel is still being fed into the carbs but slower that it should be carb bowl fill you drive of 2 miles and it cuts out.
By clearing the holes you have cleard the vacum thus allowing fuel to flow as it should at the right rate.
All the best funky
Click to expand...

I was trying to explain to a friend why it could be the fuel cap and this explanation works better than what I was trying to say! Rode another 8 miles w/out incident so maybe that's all it was...
 
Apparently it wasn't the gas cap after all...I was able to ride it 4 miles 2x with no issues, then another 2, made a stop, then after less than a mile it died again going about 30mph. No sputtering, just shut down quick like. Left the bike on the side of the road and came back a few hours later. At first it wouldn't start, but eventually it would with petcock turned over to "prime" and I made it home.

Decided that I would clean the tank of any rust before going to the carb. I could feel a little on the top, nothing terrible, but I removed the tank, did the shake thing with nuts and bolts, naval jelly, flushed it all out and it's looking great. Went through the petcock and, vacuum tube and fuel line to carbs. Thought about tackling them as well, but they were cleaned and synced 1200 miles and two months ago so I thought I would see what I had first. Yesterday road 5 miles around the neighborhood. No issues. After stopping briefly at the gas station, road another 8 miles no problems. Let it sit a couple of hours and road it another 4 miles, stopped for an hour, then another 4 miles back home, no stalling at all. Rain today--my KLR650 gets the rainy days : ) -- so I'll try again tomorrow, staying fairly close to home, but time will tell.
 
these things aren't always an easy fix... cap was just first thought.

if you did not treat your tank internally with a sealant after using the nut/bolt chemical flush, it will quickly develop more surface rust. i've had good luck with the one part Eastwood brand sealer.

hope you've got it sorted.
 
PDEDSE,

Does your bike have vacuum operated petcocks? I experienced a similar situation on my 79. I replaced the vacuum hose that operated the petcocks and it curred the issue. I believe that as the engine warmed up and softened the old hoses, the vacuum thru the hose caused them to collapse thus closing off the vacuum and also closing the petcocks. New sturdy vacuum hose didn't collapse as easy when warmed up and seem to fix the issue. Just a thought.

Jon
 
barncat said:
these things aren't always an easy fix... cap was just first thought.

if you did not treat your tank internally with a sealant after using the nut/bolt chemical flush, it will quickly develop more surface rust. i've had good luck with the one part Eastwood brand sealer.

hope you've got it sorted.
Click to expand...

Rode it 50 miles yesterday and today, varying distances from 2 mile to 8 mile rides, left it sit for 10 minutes, a couple of hours between some stops, seems to run just fine.

I had planned to seal it either with Red Kote, Por 5 or Caswell, but a few forum members here and others I've talked to said I might just leave it because the liner materials can flake off and cause problems too. So I left it unsealed and if it runs ok for some time and then I have the same problem, well, I'll know what to do and seal the next time. It doesn't really seem all that difficult now that I've taken tank off and cleaned it once.
 
Last edited:
alwaysmonday said:
PDEDSE,

Does your bike have vacuum operated petcocks? I experienced a similar situation on my 79. I replaced the vacuum hose that operated the petcocks and it curred the issue. I believe that as the engine warmed up and softened the old hoses, the vacuum thru the hose caused them to collapse thus closing off the vacuum and also closing the petcocks. New sturdy vacuum hose didn't collapse as easy when warmed up and seem to fix the issue. Just a thought.

Jon
Click to expand...

It does have one vacuum operated petcock that controls both carbs...the previous owner installed the new petcock to get the bike running again. Interesting comment about the vacuum hose. The hose looks to be new, as if installed at the time the PO did the petcock. But the vacuum hose is quite flexible and soft, maybe a harder one would be in order. On the other hand, the bike hadn't been running very long when it died the times it did, between 1-3 miles. When I cleaned the tank and petcock, I used the compressor to spray air through the vacuum line, maybe that helped as well. Could be a combination of things such as gas cap (it did last a little longer after I serviced the cap), soft vacuum line that collapses a bit, somewhat clogged petcock screen...but so far in two days and 50 miles, no issues. Still not convinced, seems like I'm holding my breath just waiting for it to happen again...maybe I'll exhale tomorrow.:)
 
Rode the bike over 40 miles today with no incident, regaining confidence. Tomorrow I'll stretch its legs even more and if there's no more issues, I'll consider it fixed.
 

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