Hi out there, a couple weeks ago I took my bike for a ride. Pulling onto a hiway, accelerating but not hard and like a switch was flipped the bike starts running bad, but still running. Kept going thinking out of gas, nope, so after a short while I realize it's running on one cylinder. Having no tools or parts I just kept going, about 10 miles to home. Once parked, I noticed fuel and carbon weeping at the left side muffler/head pipe connection and the inside of the left muffler outlet was damp with fuel. After a couple of weeks I now have time to investigate further. Checked for spark, both cylinders have spark, of note I do run the Pamco system with e-advance and have a fairly new dual output coil. Removed the valve covers and checked for whatever I might find, all looked good and the valve/rocker gaps were right on. Did a compression check, although the compression is low at 130 left and 135 right, this is really no different than when I first got the bike and it has mostly ran good since I first started it a couple years ago. Next step was to button everything back up, install new plugs (B7ES, gap .026) and see if it would start, first kick and it fired right up and ran as I would expect when cold, both cylinders firing. After about 3 minutes things started going south again and the bike died and didn't want to start after a few more kicks. So here I sit scratching my head, thinking carburetor problem. Is it possible for a carb to flood so bad that a cylinder stops firing? Or maybe it just seems like that and it is so fouled with fuel the one cylinder can't make power? Am I missing something? All your thoughts are appreciated.
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
XS1b running poor
- Thread starter Ipa62
- Start date
I'll give the strongest likelihood is the left carb...
Short answer.... yes. It's called flooding.
Sorry, didn't mean to be a smart ass.... shoulda put a wink in there....
But yeah.... sounds like the carb is dumping gas in there. As good a place as any to start....
Well.... live and learn. When I rebuilt my carbs they needed new diaphragms, bought a couple from JBM and followed their video on how to do the replacement, pretty simple. In this video there is no mention of using glue to attach the new diaphragm to the slide, however on their website there is some mention of using super glue for this, but they don't say it is a requirement. I can tell you now, it is a requirement. After a maybe a 1000 miles and exposure to fuel the diaphragm became loose to the slide allowing it to rotate enough so that the angle on the bottom of the slide was no longer facing the carb air inlet, effectively choking off any airflow. I'm sure this subject has been discussed somewhere here, but I didn't find it, thanks for being patient with me. Back on the road now
Nice to know you got it worked out
post #22 Has some addition info on what can cause a slide to twist........Also post #18 on page one
http://www.xs650.com/threads/carb-slide-rotating.11829/page-2
post #22 Has some addition info on what can cause a slide to twist........Also post #18 on page one
http://www.xs650.com/threads/carb-slide-rotating.11829/page-2
Good reading. I do appreciate BlueBiker's comments on dirt and varnish being the culprit. However, if you consider the way that original diaphragm's and slides are assembled, there is no possible way the slide could rotate. So for now I'm good with super glue, at least until it fails.
Welcome to the "superglued diaphragms" club.
I'm also monitoring mine...
http://www.xs650.com/threads/jbm-industries-bs38-diaphragms-fail.51656/
I'm also monitoring mine...
http://www.xs650.com/threads/jbm-industries-bs38-diaphragms-fail.51656/
Interesting 2M, my observations were almost identical to yours, both diaphragms were enlarged with the left side more so than the right, also noted small amount of fuel on the spring side of the left diaphragm. The left side slide had rotated, the right side was still in its proper position. Glued both.
Last edited:
Something that may warrant a revisit.
Using an o-ring to fill the gap below the JBM diaphragms.
Post #17.
http://www.xs650.com/threads/bs-38-carb-diaphragm-replacements.999/#post-312556
Using an o-ring to fill the gap below the JBM diaphragms.
Post #17.
http://www.xs650.com/threads/bs-38-carb-diaphragm-replacements.999/#post-312556
