KFunk

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....

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.

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...

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....

and what am i looking at or measuring in it? I tried hookin it to 12V and it spins...

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.

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?

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...

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?

The engine sure looks like a 50cc. Could it be a YF5?

Yeah, I was wondering about that.... perhaps a vacuum cleaner attachment or mechanics magnet would help if you could get it in there....

ahhh yeah... i guess just about any decent solution would require head removal. you can try JB Weld or some other sloppy fit, which would work for a while, until it shoots the spark plug into your leg. They can fire out with enough speed to put dents in cars.

I think one of those has been in my RX50 for the past 12 years.

look up 'heli-coil'..... or there's other types of thread sleeve inserts.... not ideal, but worth a try.

hmmm, my 81 xs400-SH had cast alloy wheels with the original tubeless tires on them when i bought it.....

If you look back thru the forum, you'll see there's several threads about xs400's starting up and only running on one cylinder, and often taking a while of warming up before the second cylinder kicks in. It's usually due to clogged passages inside the carb for that cylinder. A very thorough cleaning/rebuilding of the carbs may take care of it. I haven't gotten mine quite working on both yet at first, but I'm new. It still takes me a while to warm mine up and like 50 feet of riding before the left cylinder kicks in, then I'm good to go all day.

nevermind, Jason is somebody I know that posts on some car forums as the screenname 'eurotrash.' It doesn't seem like a common name, so I was wondering if he was following me. Sorry, i know nothing about the dt125 stuff. Hope somebody else does....

uhhh, Jason?

Oooh, that looks really tempting. Only $46 for an all new mechanism, instead of getting an old mechanism that will be due to break again. I might just do that when I get some extra cash. Doubt the extra $3 for chrome would be worth it.

Yes, thats one of the reasons I'm hanging on to mine! I love teaching and getting to see the thrill people have when they try a motorcycle for the first time. I've taught several people, and even had some fairly big guys riding it. You wouldn't believe the amount of attention you get with the thing as well when you take it into town and ride up next to the big bikes. Just rev it to 10K and laugh along with 'em.

Awesome! Everybody is buggin the hell out of me wanting to buy mine ever since I got the bigger bike, but I don't want to let it go. It just starts too easy and is way more fun in town than the bigger bike. I've got a brand new battery sitting here, its a Yuasa 6N4-2A-5. Keep in mind its 6V too, in case you want to charge it. It's fine to ride it with no battery, as I do most of the time. You just can't get the turn signals or horn or lights to work very well at an idle. Gotta keep in mind your brake light won't be as bright while waiting at a stoplight, so I rev it sometimes if its dark and someone is coming. I just haven't gotten around to getting a lighting coil and such for mine to charge the battery. Last time they sold me the wrong coil, I think. Have fun with it, and keep in mind you'll find lots of info online for YSR50s that share the same motor and most electrical and other stuff.

i checked the valve gaps recently, and all was fine. i was hoping you'd say it just needs some using, as thats what I'm workin on doin. Would different oil help the clutch? Right now I've got Valvoline 20W-50 VR1 non-syn racing oil in it that I had sitting around. But I just got a new oil filter and want to change it again soon while I change that, and get some extra crud out. I should probabbly look into just getting a new cable... the housing where it meets the throttle grip is horribly rusted... I used the plastic bristles from a toothbrush and can see plain as day light visibly thru all the holes... don't know how much there is left to clean. Cool, I'll check that later. Maybe, but I figured since both was out it might be a connector somewhere? Anyways, yes its the original fuse box still... I've cleaned it up some and tightened the connections for now. I'd rather wait on jumping into that project later. Thanks all! It's sitting outside idling/choked right and sounds like its ready to go!

OK, I've ridden the bike a couple hundred miles now, and have got several problems I need tips with. -Really hard starting when cold. Even if it sits for only a couple hours, I've gotta crank on it a while. Kick starting is sometimes a bit easier, but not after the first couple kicks fail to keep it going. Then I just gotta spin the starter and choke it for a really long time. I think its because the left cylinder doesn't want to get going, and exhaust pipe stays ice cold for quite a while, and doesn't get firing until I warm it up and ride it like 100 ft. You can really feel a POOF as it finally kicks in and gets going. When its cold there's spark and theres fuel in that cylinder, but I couldn't really get any compression when cold. This bike only has 2250 miles on it.....but all I can figure are the rings just aren't sealing till I get it moving. -Throttle cable often pops out of linkage when I go full WOT. This has been a real pain a few times to take off the tank on the side of the road while the engine is hot.... Sometimes too when I try redlining it in every gear, it'll slip gears and slip to 10K rpm... oops, maybe its telling me not to run it that fast.... -Turn signal switch, horn button, and starter button are all busted up. Everything works if you jam a screwdriver in there. Any ideas on best place to get decent buttons/switches? -Still won't idle on its own for more than like 15 seconds once I get it warmed up unless I choke it, even after rebuilding/cleaning pilot jets/tuning the carbs best I can. Air filters have big holes in them.. wondering if the excess air is hurting things. edit to add more: -neutral light doesn't work. oil light works occasionally for no apparent reason. turn signal light seems to work OK. It'd be really nice to have the neutral light working, as I can't quite tell if its in neutral sometimes and might stall it while thinking its in neutral. wheres the switch/connections for it? -no lights for guages. kinda sucks not being able to tell my speed/rpm at night.... where to start? Thats all I can think of right now. All in all its a damn fun bike and pulls strong once I get it warmed up. I've been having a great time with it, and even took a passenger for a ride the other night and it was awesome. Any ideas for these little problems would be appreciated! Thank you, Kevin

Nah, as long as the other one is hooked up. One of the two vacuum ports should run to the petcock, which serves to open and close it (its a safety measure to keep you from dumping fuel into the bike while not running). The other vacuum port should be capped off, but will help you with synching the carbs. I would say if you don't want to embarrass yourself with the boss, then ride the damn thing as much as you can between now and then. You'll soon find out any problems. And have you ridden motorcycles much before? Just be sure you're used to the bike and don't stall it or stumble and drop it for some reason.

heh, where in Ohio? I'm gonna guess the Zanesville area. I'm down in Athens myself, and had this on my bike when I bought it: I cant help much with the other stuff myself, since I'm fairly new as well. But Synching is easy. You just need to use the screw that connects the throttle linkage on the two carbs, and adjust it until both carbs are sucking an equal amount of vacuum on both (i.e. the throttles are open at the same position on both). There's a thread a few days back on making a synch tool with some tubing and a yardstick, and that worked for me. You've gotta connect the hoses to the vacuum ports on the top of each carb. Since the one is needed to operate the fuel petcock, you'll have to find another way to get fuel. Some people just connect a hose to a separate bowl of fuel. But I just set the petcock to 'Prime' and wiggled the fuel tank to the side to give me just enough room to access the synch screw with a stubby screwdriver.