KFunk Posted May 8, 2009 Share Posted May 8, 2009 Yep, just as the title says. It's a 81 xs400 with 2600 miles, and I haven't yet taken the engine covers off. The oil/filter is fresh, and the only work I've done is rebuilding the carbs and checking valve gaps. At first it just randomly stalled and died right after leaving the house and while sitting at a stop sign. I went to the coffee shop, then I noticed a weird metal on metal sound a few times during start-up, might be coming from something loose inside the engine. I took it for a brief drive, and under load it stumbled/surged several times and generally ran like crap. It ran ok while at a stop. I'm a bit afraid to drive it much, as whatever is bouncing around might get lodged somewhere bad. I figure take the right side cover off atleast and investigate stuff, then go for left, and so on till I find something bad. Any ideas? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted May 9, 2009 Moderator Share Posted May 9, 2009 Hmmm, as you may know, I know not a lot about XS's, but I would check out the generator rotor ? woodruff key arrangement first. Link to comment Share on other sites More sharing options...
JimR Posted May 9, 2009 Share Posted May 9, 2009 Yep, just as the title says. It's a 81 xs400 with 2600 miles, and I haven't yet taken the engine covers off. The oil/filter is fresh, and the only work I've done is rebuilding the carbs and checking valve gaps. At first it just randomly stalled and died right after leaving the house and while sitting at a stop sign. I went to the coffee shop, then I noticed a weird metal on metal sound a few times during start-up, might be coming from something loose inside the engine. I took it for a brief drive, and under load it stumbled/surged several times and generally ran like crap. It ran ok while at a stop. I'm a bit afraid to drive it much, as whatever is bouncing around might get lodged somewhere bad. I figure take the right side cover off atleast and investigate stuff, then go for left, and so on till I find something bad. Any ideas? Hi, I would guess the metallic noise is when the starter is engaged (turning) and/or on release of the button ? If so it maybe time to service the starter motor. If you take off the r/h c/c cover you will be looking at the clutch & primary gear, the starter chain/clutch are under the l/h c/c cover also this cover would be removed in order to remove the starter motor and you would have to drain that new oil ! Your running problems sound like you need further servicing to the carbs & engine, to start setup the ignition (if you have access to a dwell meter set the dwell to 22½% if not just gap them but you will not get such a smooth running engine) & set the timming up. Then cast your eyes to the fuel supply & carb balance. When the bike was new the vaccum fuel tap gave very little problems but as now its old it may start to play up and not supply enough fuel to the carbs causing them to to run 'weak'. Check that the vaccum take off pipe (from the tap to the R/H manifold is in good condition, if it has gone hard (the pipe ) or split/cracked replace it. While the tank is off,balance the carbs using vaccum gauges the spin off from this will be the readouts will give you a good idea as to the state of the top end of the motor (Head & Cylinders), a good level would indicate that part of the motor to be fine, the inability to get the motor to run with carbs balanced (same vacuum) would indicate a problem with the valves (the lower reading cylinder being the culprit) low readings, bike running ok when balanced, would indicate piston/cylinder problems. And lastly set the mix screws so the bike idles fine & the idle speed does not increase/decrease when the lights are turned on or off. Regards Jim Link to comment Share on other sites More sharing options...
KFunk Posted May 11, 2009 Author Share Posted May 11, 2009 OK, I'm tearin into it now. The starter is suspect, yes. Since I've gotten it, the bike has often made weird wheezing noises on shutdown that sound like a spring unwinding, and most people say its related to the starter and it might have trouble disengaging. I've got the left side cover off, and think I need to remove the crank bolt and pull rotor to access the parts of the starter clutch. I can't figure out how to keep the crank from spinning to remove the crank bolt. The repair manual says to put a bar thru the little end bosses. Does that mean on the connecting rods? I don't want to remove the cylinders.... any better way? I don't have an impact wrench here.... So yeah, haven't found anything obviously wrong on left side. Until I figure out crank bolt, might was well take right side cover off. Oh, and I shouldn't be able to adjust dwell and such since this bike supposedly has electronic ignition. The carbs should be just fine, as I recently went thru them and tuned them up good. The loss of power doesn't feel like a fuel issue, it was just too rhythmic, and felt like it like it has to do with crank rotation. If nothing else... wondering if a valve is screwed up. The vacuum check might help. I recently synched them, so it should still be balanced close. If thats changed majorly... then off comes the valvetrain I suppose. Also wondering If I can tell anything by just looking in the valve adjustment holes... Link to comment Share on other sites More sharing options...
JimR Posted May 12, 2009 Share Posted May 12, 2009 OK, I'm tearin into it now. The starter is suspect, yes. Since I've gotten it, the bike has often made weird wheezing noises on shutdown that sound like a spring unwinding, and most people say its related to the starter and it might have trouble disengaging. I've got the left side cover off, and think I need to remove the crank bolt and pull rotor to access the parts of the starter clutch. I can't figure out how to keep the crank from spinning to remove the crank bolt. The repair manual says to put a bar thru the little end bosses. Does that mean on the connecting rods? I don't want to remove the cylinders.... any better way? I don't have an impact wrench here.... So yeah, haven't found anything obviously wrong on left side. Until I figure out crank bolt, might was well take right side cover off. Oh, and I shouldn't be able to adjust dwell and such since this bike supposedly has electronic ignition. The carbs should be just fine, as I recently went thru them and tuned them up good. The loss of power doesn't feel like a fuel issue, it was just too rhythmic, and felt like it like it has to do with crank rotation. If nothing else... wondering if a valve is screwed up. The vacuum check might help. I recently synched them, so it should still be balanced close. If thats changed majorly... then off comes the valvetrain I suppose. Also wondering If I can tell anything by just looking in the valve adjustment holes... Hi, So the bike has after market electronic ignition fitted or is it an early DOHC 400. this may have some bearing (excuse the pun) on the problem Regards Jim Link to comment Share on other sites More sharing options...
redbug2 Posted May 12, 2009 Share Posted May 12, 2009 Sounds like the starter rollers. Had a similar problem on a yamaha 4 wheeler. I have an old XS400 that I parted out, still have the engine and the starting mechanism.... Link to comment Share on other sites More sharing options...
KFunk Posted May 12, 2009 Author Share Posted May 12, 2009 Hi, So the bike has after market electronic ignition fitted or is it an early DOHC 400. this may have some bearing (excuse the pun) on the problem Regards Jim huh? some of the guys on this forum told me that this model/year didn't have breaker points, since it has a plug that has to be drilled out to access anything, so I should just leave it alone. From my car knowledge, dwell angle is only something that only can be adjusted by changing the point gap. unless you can adjust the dwell angle on a non-breaker point type system? Link to comment Share on other sites More sharing options...
JimR Posted May 12, 2009 Share Posted May 12, 2009 Sounds like the starter rollers. Had a similar problem on a yamaha 4 wheeler. I have an old XS400 that I parted out, still have the engine and the starting mechanism.... Hi Redbug2 can you translate :- I have an old XS400 that I parted out, still have the engine and the starting mechanism.... I would guess this means you have broken the bike and still have these parts on hand ? I would guess the rollers out of the starter clutch are not causing the problem, unless the whole lot is knackered, but of course models from a different country may be different. Regards Jim Link to comment Share on other sites More sharing options...
KFunk Posted May 12, 2009 Author Share Posted May 12, 2009 Sounds like the starter rollers. Had a similar problem on a yamaha 4 wheeler. I have an old XS400 that I parted out, still have the engine and the starting mechanism.... which rollers and how can you tell if they're damaged? I've got the rotor out now (used strap wrench to hold rotor still to remove crank bolt), and now have the starter clutch and starter out. I don't see anything too wrong with the little rollers inside the starter clutch. Seem to free-roll fine in one direction and stop the other direction. There's some scoring where those clutch rollers sit on their metal plate that I'm thinking about smoothing out with some fine steel wool. There seems like there's some slop in the shaft of the starter itself, but I don't know how much there's supposed to be. I've also got the right side cover off for the heck of it, along with kick start mechanism, and nothing seems odd. There are some oil passages on the bottom right that look kinda like busted metal around the edges, but I'm thinking those are just really sloppy casting marks and edges. Link to comment Share on other sites More sharing options...
JimR Posted May 12, 2009 Share Posted May 12, 2009 which rollers and how can you tell if they're damaged? I've got the rotor out now (used strap wrench to hold rotor still to remove crank bolt), and now have the starter clutch and starter out. I don't see anything too wrong with the little rollers inside the starter clutch. Seem to free-roll fine in one direction and stop the other direction. There's some scoring where those clutch rollers sit on their metal plate that I'm thinking about smoothing out with some fine steel wool. There seems like there's some slop in the shaft of the starter itself, but I don't know how much there's supposed to be. I've also got the right side cover off for the heck of it, along with kick start mechanism, and nothing seems odd. There are some oil passages on the bottom right that look kinda like busted metal around the edges, but I'm thinking those are just really sloppy casting marks and edges. Hi, I guess from the posts, your motor is the same as the UK one .. the rollers are unlikley to be damaged (along with the clutch) . I would guess you would need to look at the starter motor. Regards Jim Link to comment Share on other sites More sharing options...
KFunk Posted May 12, 2009 Author Share Posted May 12, 2009 Hi, I guess from the posts, your motor is the same as the UK one .. the rollers are unlikley to be damaged (along with the clutch) . I would guess you would need to look at the starter motor. Regards Jim and what am i looking at or measuring in it? I tried hookin it to 12V and it spins... Link to comment Share on other sites More sharing options...
KFunk Posted May 12, 2009 Author Share Posted May 12, 2009 anyways, i've checked out the clutch and stuff as well, still nothing obvious. i mostly like taking all this stuff apart just so I can get familiar with it. i ripped the cover gaskets in a few places, so im thinkin i should go get some new cover gaskets from the dealer (unless yamabond would work instead?), and put it on back together. other than cleaning up the starter clutch roller surface, there shouldn't be much difference. if its just something in the starter itself, i'll keep on using the kick starter most of the time. then i'll have to get checkin out if the power loss is still there, and if it might be a valve problem.... Link to comment Share on other sites More sharing options...
JimR Posted May 13, 2009 Share Posted May 13, 2009 and what am i looking at or measuring in it? I tried hookin it to 12V and it spins... Hi , it spins at what sort of speed & when you do this test do you get the noise you describe ? Regards Jim Link to comment Share on other sites More sharing options...
KFunk Posted May 13, 2009 Author Share Posted May 13, 2009 Hi , it spins at what sort of speed & when you do this test do you get the noise you describe ? Regards Jim I just hooked it up with jumper cables straight to the battery, and lots of sparks flew and it just spun a little before I doubted whether it was safe to hook it up that way and quit doing it. I didn't hear that sound, but I doubt I would if it had no chain tension or resistance... Link to comment Share on other sites More sharing options...
KFunk Posted May 19, 2009 Author Share Posted May 19, 2009 OK, its back together and runnin OK now, not sure why... I haven't heard the metal sound again. My best guess is that maybe one of the two screws holding the starter together was loose. One seemed way loose, but maybe that was just because I had already taken the other one out, and it took the tension of the other... hell if i know. The scoring where the starter rollers do their rolling also seemed suspicious, and I smoothed that out on one side and just flipped over the keeper plate on the other side. I probably didn't need to take the right side cover off, but oh well. I had a chance to measure the clutch discs/springs and check out the kick starter. When I got it back started, it randomly died again and stalled/surged some. It turns out that it was just a loose main fuse, I think. I gotta get some more butane for my soldering iron and put in a more rigid connection. Link to comment Share on other sites More sharing options...
JimR Posted May 21, 2009 Share Posted May 21, 2009 OK, its back together and runnin OK now, not sure why... I haven't heard the metal sound again. My best guess is that maybe one of the two screws holding the starter together was loose. One seemed way loose, but maybe that was just because I had already taken the other one out, and it took the tension of the other... hell if i know. The scoring where the starter rollers do their rolling also seemed suspicious, and I smoothed that out on one side and just flipped over the keeper plate on the other side. I probably didn't need to take the right side cover off, but oh well. I had a chance to measure the clutch discs/springs and check out the kick starter. When I got it back started, it randomly died again and stalled/surged some. It turns out that it was just a loose main fuse, I think. I gotta get some more butane for my soldering iron and put in a more rigid connection. Hi, sounds like you have removed the carbon deposits from the starter motor .... should run ok now untill the brushes wear out Regards Jim Link to comment Share on other sites More sharing options...
KFunk Posted May 22, 2009 Author Share Posted May 22, 2009 Hi, sounds like you have removed the carbon deposits from the starter motor .... should run ok now untill the brushes wear out Regards Jim ack, think that just happened.... starter started makin similar weird sounds again.. then went to just clickin... might spin a little and click a little... Do I just need to buy the two brushes (8 and 9) that are in this pic, or do I need other things too? The kick start can work for now, but I can't always count on it. Plus its difficult to find secure footing to kickstart it sometimes.... Link to comment Share on other sites More sharing options...
JimR Posted May 22, 2009 Share Posted May 22, 2009 ack, think that just happened.... starter started makin similar weird sounds again.. then went to just clickin... might spin a little and click a little... Do I just need to buy the two brushes (8 and 9) that are in this pic, or do I need other things too? The kick start can work for now, but I can't always count on it. Plus its difficult to find secure footing to kickstart it sometimes.... Hi, also check that part 10's are still springy, clean parts 5 & 6. not forgetting to remove all the carbon from the grooves in part 5. Regards Jim Link to comment Share on other sites More sharing options...
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