XS650 not running right =(

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XS650Cafe

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Ok, so here's the deal - I bought myself a '75 xs650 last summer, when I first got the bike, it seemed to run okay, but then after the first few days things started to go downhill, if I remember correctly the first thing that went wrong with it was that one of the cylinders wasn't firing for some reason, so i replaced both of the spark plugs and it started to run alright again for a while. but it was soon discovered that the spark plugs were being fouled after about 30 or so minutes of driving time. The next thing to happen was that it stalled on me and wouldn't start again until it had time to cool off (I did manage to get it running while the engine was still hot but it wouldn't hold an idle and died right away)
While waiting at the gas station for it to cool off a few people approached me and claimed to know what the issue was, both having different ideas - one guy said it was vapor lock and another told me that the xs650's had faulty wiring and that it was an electrical problem?
After that I was out for a ride when it was running alright and it stalled again, i tried to kick start it, but either there was something wrong with my kicker or the engine had no compression because the kicker just kinda flopped around. So I ended up parking it for the winter after that.
I know I've probably left out some key details but I really just can't seem to remember everything that happened... Basically I've had a bunch of different diagnoses for the problems - being - faulty wiring, dirty intake/fuel system/ carburetor, a crack in my engine case that's causing loss of compression =S, too rich a fuel mixture.

Basically I need help, does anyone know what could be causing these problems? has anyone ever had these types of troubles with their xs650's? any input would really help me out. I'm fairly mechanically inclined but I have little knowledge on how to diagnose problems.
Thank you to anybody who responds and again I apologize for the lack of specific information I've given.
 
Hello 650cafe! Welcome to the forum

Have you done a compression test already? I'm not an expert at all but I'm pretty sure that could help give a measure of how bad you're compression really is.. ya know?

chef
 
Thank you.

I haven't done a compression test yet >.< I'll see if I can get one done on the weekend
 
not too sure, I'll check that this weekend too.. although I don't think it does, every time I tried to use the electric start it usually didn't have enough power until it had ran for a bit then the electric starter would make it go.
 
This probably isn't the whole problem but maybe part of it. My bike kept dying after a bit of riding then I would let it sit and it would run fine for a bit, gas tank wasn't venting.
Has nothing to do with the kickstarter thing but I have had multiple problems before. It is easy enough to check. Sorry I can't help more. Good luck.
 
If it was my bike I would start with the ignition system.U should get a manual if you don't already have one. Then go through each system starting with the easiest things first,like checking coils,carbs for richness et. I don't know what you mean by the kick start flopping around????? check compression Check stator and rotor make sure it's putting out the right numbers. Rich carbs and weak spark can both cause plug fouling.
 
Wow, so many problems....so many solutions!! Here's a good one (or bad one).

If your oil level is low or not getting picked up by the sump, that would explain the running till it gets hot. In other words, it's seizing up when its hot because there is no or insufficient oil. Also difficult to turn over a hot engine with no oil on it.

Same thing if the oil is very old and needs to be changed, or contaminated with gas, so change the oil.
 
I agree with pete about changing the oil but If it seized up the kick start wouldn't become mushy or as cafe puts it floppy?? I know that the rotor on these bikes and the coils don't like it hot;however I'm not sure if the coils or the rotor would just die immediately from overheating or if the would work on and off for awhile before they died.We need more info any updates???These bikes are really simple to work on and trouble shoot it wouldn't hurt to spend a couple of bucks and go through it up dating things,perhaps a pamco ignition,new coils,carb rebuild kits,check out charging system(the biggest weakness on the xs in my opinion).There"s other simple things that wont cost u alot of money but will really make a huge difference with reliability and performance.There"s also alot of good xs guys here like pamcopete,xsjohn,myself and others who will be glad to take the time to help you.
 
well what i meant by floppy is that it just kinda swung there - not sure if there was something wrong with it like teeth not grabbing or slipping, or if there was absolutely no compression
 
The kick start does that on my bike, might grab at the bottom of the swing sometimes but will return. Just wont grab at all other times, yet starts with the electric and runs fine
 
Because of the age of the wiring on these bike's,the connectors get very corroded. What you seem to be describing with it dying on you is the kill switch losing a good contact. Very common on these machine's.
One of the first thing's I did with mine was to clean ALL the connection's in the wiring harness. I was chasing a reason for burning up the rotor's, as I went through 3 before I found the problem. But, with all the connections clean, I now have a very dependable bike.BTW, the problem with the rotor's was a bad ground, from the engine to the frame. Made a cable from the engine to the negative battery bolt on the frame.
Aside from what I've said, what the others have stated could also apply. The vent on the gas cap's get cruddy, battery's are weak to start with, bad set of point's,coils,wire's,(spark plug and/or plug cap's). Oil is a good one also, fresh oil won't hurt. Smell the old oil for gas, then your too rich on the carbs, or a bad air filter.
On the home page there is a shopping list on what to inspect on these bike's BEFORE riding. I think it was from Jayel. He give's alot of insight to what to look for.:thumbsup:Otherwise, you could end up banging your head for nothing, & coming up with nothing...:doh::yikes::wtf::shrug::banghead::mad:
 
If it seems like there is no compression after engine gets warm, and then returns after it cools, it sounds to me like you got one or more valves sticking open. I'm an aut tech, and have seen this causing misfires on certain engines. We have repaired those with an engine flush and using synthetic oil. Check your compresion when the problem occurs.
 
First off drain the oil and check for chunks of plastic and filings from the cam chain guide, refill the oil to the correct level........... Do the compression test if it is not good do a leak down test next to see if it is rings or valves......If compression is good check the oil system, if the guide has disintegrated some might have got through the oil pump so check that for damage then through the oil delivery system for a partially blocked pipe to the head,............If all the above checks out ok i would then make sure the vent in the gas cap is clear..........go into the electrical system and clean up all connections, make sure you have a fully charged battery and check for spark .............then the carbs and fuel system............ This is the order i would be doing, if it was my problem.....the kick start shouldn't have any thing to do with the running problem, may be a broken spring
 
something else I forgot to mention, when I opened it full throttle and it got to about 4k rpm it just kinda bogged down and lost power, but I'm pretty sure that's a fuel/carb problem
 
- relationship between jets and throttle

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