BlindSight Posted June 16, 2008 Share Posted June 16, 2008 My 1980 yamaha xs400 special will start up and run for 1-3mins and then die. usually if I try to start it right away it either wont or it takes alot of effort but if I let it sit a few mins it will start again and run for a short while and die again...when it dies it just idles down, kind of putts, and then dies...also its smoking a bit...white smoke so burning oil? I was thinking maybe its the CDI unit or the coils? what about possibly moisture in the tank or carb adjustment? This is my first bike to play with but ive been an automotive tech for 2 years...thanks for any and all help Link to comment Share on other sites More sharing options...
xtonyx Posted June 16, 2008 Share Posted June 16, 2008 is your fuel tank venting? my bike smoked when i first got it. it had been sitting a while. i changed the oil, ran it a bit as i worked on things, changed the oil again, and now i'm riding it daily. no more smoke since the motor has 'woken up' again. if the bike has been sitting a while just check over things, make sure everything is up to par (tires, lights, etc..) and just RIDE. after you ride it a bit see if there is still something goofy going on and then start to diagnose problems. Link to comment Share on other sites More sharing options...
BlindSight Posted June 17, 2008 Author Share Posted June 17, 2008 yeah I have already replaced most of the normal stuff and it had been sitting up for almost 2 years..will check the venting on the tank this weekend when im home but I cant ride it to work the kinks out when it dies every couple of mins Link to comment Share on other sites More sharing options...
ndtben Posted June 18, 2008 Share Posted June 18, 2008 I am having just about the same problem with my bike. I just cleaned and reinstalled the carbs, put new seals in the petcock valve. The bike will start and run for about 1 minute with full choke, then dies. If I try to give any throttle or change to half choke it dies instantly. Were you able to find out the problem you were or are having? Link to comment Share on other sites More sharing options...
BlindSight Posted June 18, 2008 Author Share Posted June 18, 2008 Nope I havn't gotten any help...will be working on my bike later this week a little bit though. I was going to start by rebuilding the carbs but if it didn't fix your problems I might go ahead and replace the ignition coils and CDI and see if that makes a difference. Link to comment Share on other sites More sharing options...
socalyamaha Posted June 18, 2008 Share Posted June 18, 2008 is your alternator working? Link to comment Share on other sites More sharing options...
BlindSight Posted June 18, 2008 Author Share Posted June 18, 2008 is your alternator working? my dvom just got rained on and wont work anymore but do you think that could cause it? I mean after it dies and sits a min I can still use the electric start and it will crank over so I figured it wasn't battery/charging related. Link to comment Share on other sites More sharing options...
BlindSight Posted June 19, 2008 Author Share Posted June 19, 2008 OK so cleaned the cabs up a bit, and added some b12 fuel system cleaner to the thack, I got it started and adjusted the idle all the way up, rode it around a bit and it stayed idling in my driveway for about 30 mins this time before it died. any suggestions now? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 19, 2008 Moderator Share Posted June 19, 2008 Hi could this post apply? http://www.yamahaclub.com/forums/index.php...c=10488&hl= Link to comment Share on other sites More sharing options...
BlindSight Posted June 20, 2008 Author Share Posted June 20, 2008 after messing with it yesterday im leaning heavily towards it being an ac generator problem (darnet I need to go buy another dvom :-/)...after it died I was having problems getting it started again and wouldnt stay running but I stuck it on the battery charger for a few hours and when I went outside it started first try and ran for awhile. so if I test it and the generator isn't charging the battery properly what should I replace and how hard is it? Also I noticed it wont rev over 6krpm, once I get going it will climb to 6 and if I dont let back on the throttle it will start to bog down a little bit. Also I can get it into first but it doesnt want to shift up to 2nd, I switched to a straight bar and the clutch cable is run kind of funky so it is really hard to squeeze the lever but even squeezed all the way back it doesn't want to go into any other gears, any suggestions on that one? THANKS FOR ALL OF THE HELP Link to comment Share on other sites More sharing options...
socalyamaha Posted June 20, 2008 Share Posted June 20, 2008 lube the clutch cable and make sure there are no kinks or sharp turns in the line. i'm running straight bars and i'm not having any problems. Link to comment Share on other sites More sharing options...
BlindSight Posted June 20, 2008 Author Share Posted June 20, 2008 well I had bought a brand new clutch cable, there aren't any major curves or anything but it curves more than id like...anyone with straight bars have pics following the cable from the bar to the case to show me how its supposed to run? Link to comment Share on other sites More sharing options...
Gnash Posted June 21, 2008 Share Posted June 21, 2008 So did you concur that your dying problem is electrical? I have the same problem in that the motor runs on full choke for a couple o seconds, but dies with a hit of the throttle or letting off the choke. I cleaned the carbs, but I'm thinking of sending them for a rebuild. I cannot find a rebuild kit or any parts for the carbs yet. Have you found a place to buy your alterantor yet? Link to comment Share on other sites More sharing options...
socalyamaha Posted June 21, 2008 Share Posted June 21, 2008 sending them in???!!! honestly you can rebuild your carbs yourself. don't pay for it. you can always find carb kits. what are you looking for? Link to comment Share on other sites More sharing options...
Gnash Posted June 21, 2008 Share Posted June 21, 2008 Your right. I don't know what a bad part looks like in a carb though. I cleaned the gunk out of em, and I also noticed the last guy stripped the screw head on the bottom of each of the float bowls. I'm gonna clean them once again today, and try again. Those damn airbox intake boots are a bitch to get back in place! Mine is an 83 xs400. Link to comment Share on other sites More sharing options...
socalyamaha Posted June 21, 2008 Share Posted June 21, 2008 look for worn needles, slides, cracked rubber diaphrams, if you have rubber floats you should check those too. check your springs (out of shape), hoses for cracks. get yourself a jewelery ultra sonic cleaning machine. that gets out more dirt from the little bits than anything else. Link to comment Share on other sites More sharing options...
Gnash Posted June 21, 2008 Share Posted June 21, 2008 SHE'S RUNNIN!!!! I cleaned the carbs again. I had a float sticking. RUN'S AND RIDES GREAT!!!!!! The front brake is sticking though. Thanks Socal! I almost gave up on those carbs. Link to comment Share on other sites More sharing options...
socalyamaha Posted June 22, 2008 Share Posted June 22, 2008 anytime. are your brake pads in good shape? my XJ's front brake was sticking because it was worn out. pushed the piston in and changed the pads, and now its all good. sorry for jacking this post. Link to comment Share on other sites More sharing options...
Gnash Posted June 23, 2008 Share Posted June 23, 2008 The brake is fine now. It just hasn't been ridden in a couple years. Man, she screams! I certainly didn't anticipate this bike to be this quick. It rides smooth too. The diaphrams on the carbs are in good shape, but a spring was bent out of shape, so I straightened it up, got the floats working and just cleaned the hell out of it. Now I can't get off of it! Sorry to jack your thread, Blindsight. It got my bike started though! Good luck with yours. Cheers! Link to comment Share on other sites More sharing options...
BlindSight Posted June 23, 2008 Author Share Posted June 23, 2008 No problemo, glad you got it running right. yeah I think its electrical, im sure the carbs need a good cleaning but after 2 days of riding it for about 45mins until it dies...not being able to restart it until it charged for a couple of hours...and then after a good charge it starts right up and runs for awhile...pretty sure its the alternator...will probably just ebay the parts. im hoping that the not going over 6krpm is just the carbs need to be cleaned, it was sitting for almost 2 years. still dont know what to do about the clutch issue though. anyone with pictures of how there cable is run with straight bars? Link to comment Share on other sites More sharing options...
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