I was riding the other day and after about 2 miles the engine began to bog down. I had to give it extra gas to maintain a speed of about 40mph. If I give it more gas it has a burst of normal power and then bogs down again and the exhaust seems to pop a little. When I got to my destination I stayed there for about 5 hours then I went home and had the same problem, after about 2 miles the engine began to bog down. I thought maybe dirty carbs, but I just got the carbs last year along with a new tank, petcocks and gas lines. Would bad gas do this maybe a hole in the floats, but again I just got the carbs new from 650 central. If anyone can point me in the correct direction it would be great. I did try seafoam. 1981 xs650 w/750 tank on it and 2 to 1 exhaust.
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Patches
XS650 Junkie
Are you running a fuel filter? Sounds like a clogged pilot jet. The main jet takes over when you are past 1/2 throttle and that would cause the birst in power. Have you gone through them? Some more info is needed. What carbs? What year bike? What mods?
Q Tip
mad bomber
It sounds like it may be dropping a cylinder....does it chug like it is on one cylinder? The burst of power sounds like the cylinder coming back online.
Patches
XS650 Junkie
It could be no spark, or no fuel. After the bike is cold let it idfle for a minute then check the exhaust to see if one is hot and one is still cool. I have a 78 that had the same problem. When I tested the plugs they were both getting spark so I didn't think to replace them. I couldn't figure it out for a while until I decided to swap the plugs and the dead cylinder changed sides. Turned out that I had a plug with too weak of a spark. Went to the store and got some new autolites, and problem solved.
The bike would pick up that dead cylinder randomly at higher RPM's for some reasonnbefore I replaced the plugs, and I really never figured out why. This would cause a surge in power. You can tell a cylinder is dead from both listening to it compared to the good cylinder, and the exhaust will be cool.
The bike would pick up that dead cylinder randomly at higher RPM's for some reasonnbefore I replaced the plugs, and I really never figured out why. This would cause a surge in power. You can tell a cylinder is dead from both listening to it compared to the good cylinder, and the exhaust will be cool.
Q Tip
mad bomber
You could have a coil going bad. Or it could be a plug issue...have you checked your plugs? I can tell you of one crazy thing that happened on my Suzuki GS500. It has a tank petcock and a frame mounted vacuum petcock. The vacuum petcock on the frame has a diaphragm in it and this diaphragm was super old (almost XS650 old) and it finally tore. This allowed too much gas to get to the left carb, flooding out that cylinder....sometimes under full throttle that cylinder would be able to use that much gas and would suddenly "come to life"! So be sure to check your petcocks on your bike, if you are running the later model vacuum petcocks you might have that same issue. Rare but possible. Only after much searching the GS500 forums did I gather enough info to check mine. I switched to a manual frame petcock off a honda dirtbike and never a problem since.
Patches
XS650 Junkie
I just run good ol Autolite #63's per XS John's recommendations in previous threads before his unfortunate passing. This is with the factory points on this particular bike.
shotgunjoe
XS650 Hunter
Kev1
XS650 New Member
I have the same problem. Not sure its a kinked fuel line tho...It first started i was accelerating to 50 mph at about 3.2k rpms and it started to sputter and the bike sufficiently lost power and you cant get he rpms over the 3k range. After shutting off for a five to ten minutes the bike returns to normal. Problem also happened when i accelerated too hard...recently put in new spark plugs (they are the correct ones). Does kinda sound like a cyllander gives out but i could feel exhaust from both pipes.
aktive0
XS650 New Member
@kev1 - I just had the same exact problem as you. Was on the highway, 4th gear, rev'd pretty high(no tach to tell me...), and then all of sudden loss of power, some sputtering from exhaust. Pulled off the highway, turned off the bike and inspect things for a few minutes. Turned her back on and everything was ok, but I stayed on local roads on the way home...
I just got her back from the shop after fixing an exhaust leak. Don't know if that's relevant.
@kev1 - did you ever figure it out?
I just got her back from the shop after fixing an exhaust leak. Don't know if that's relevant.
@kev1 - did you ever figure it out?
One of the gas line was bent or crinkled. So it was only running on one cylinder
Posted via Mobile
Kev1
XS650 New Member
One of my gas lines was not pushed all the way into the fuel petcock, and there was little or no vacuum sucking gas out of the tank. After i fixed that everything was great!
Sweet nice find!
