KFunk

How do I get the needle jet out of this '81 xs400 carb? I took out the main jet and the washer underneath, and I see the hollow needle jet and there's a little open tab on the side, and its too narrow to get a screwdriver in it. The Haynes manual just says to push the needle jet out, and doesn't give any specifics. It seems like its pretty tight in there. I just want to clean out any crud in it, while I have things apart. I was runnin around on it today, and it started runnin like crap, acted like it was down a cylinder, then would die and eventually didn't restart at all. I pushed it on home. It'd fire and run for a bit with starter fluid, and the fuel strainer was recently cleaned off, so yep its time to tear down the carbs. This bike only has 2000 miles on it, so its been sittin and rusting a long, long time. Both pilot jets look clogged up, but I think the main problem was a float needle valve was stuck shut. I can force it in and out by hand...but its stiff and clicks. any idea how I can smooth up its motion? It should run awesome as soon as I get stuff cleaned up and back together. I just put the new brake shoes in it yesterday (yes the pad material came off the shoes, and I ended up takin an angle grinder to hack up the spacer just to get the axle out.) I also replaced the footrest bushings yesterday, and it feels great to have a solid footing. I had been missing the washers on the inside too, so that made it really floppy.

I guess I got confused on the 'S' thing, and thats just the speed rating like any other tire... So anyways, I'm thinkin of goin with this: Rear: DURO HF261A 120/90B-16: $41.41 Front: DURO HF918 90/90B-18 $37.04 +$19/shipping from http://www.americanmototire.com/ Both are belted/tubeless. Bike Bandit doesn't have the same brands/prices. I also thought about ironpony.com (Ohio preference for me). They've got similar Cheng Shin Hi-Max tires for almost identical price, but they're regular bias ply. I thought the belted Duro tires might be a bit stronger... plus they want to add an Ohio sales tax. I could cut shipping cost and buy from the store, but thats a long drive and I don't have another excuse to go up there... So yeah, AMT for 100 bucks. As soon as I secure some extra funds, I'll prolly place the order.

both my tires on my bike say 'tubeless' on them. not sure if thats odd for an'81. but anyways, perhaps i just need that adapter. i did some research, and the 3.00S-18 is just an older system. 3.00 is the width in inches, and apparently the S means an aspect ratio of like 82%. If there were no S, it would be an aspect ratio of 100%. I've seen the bridgestones listed, but seem a bit pricey. I just want something a little bit better than cracked tires, as i can't afford much more really, and will end up just running on the cracked tires if i have to.

its for the ugly '81 Yamaha XS400-SH, and my current tires are all dry rotted and cracked. I'm really picky on my car tires, but I'm new to motorcycle tires. I just want something safe... The rear is a 120-90-16, and front is 3.00S-18. It's got 'mag' wheels or whatever (not wire), and it currently has tubeless tires. It looks like all I can find are chinese/taiwanese brands unfortunately... and I'm pickin from Cheng-Shin, Duro, and IRC. I'm thinkin of goin with Duro from http://www.americanmototire.com/ It's $41 for rear, $26 for front, and $11 for a tube for the front. ...but, that leads me to.... everything I can find is for tubed front tires. Can I put tubed tires on a tubeless/mag wheel? ..and my front would be bias ply, while the rear is belted, is that OK? I've found that its wrong to mix a radial front with a bias ply rear, but not sure if its bad to mix bias ply and belted. I'm tryin to stick with both as Duros instead of mixin brands, should I worry about that? Other affordable brands don't have the 3.00S-18 (apparently the S means lower aspect ratio of like 82%). and... is it possible for me to change any of these myself? Local bike shop wants $20 per tire, if I bring them in just the wheels. Thanks if you can help! Kevin

I managed to find a PDF online for the repair manual of the YSR50, so thats covered most everything I need. Yeah, I rebuilt my engine once too.... It appears that both gas tanks mount in a similar way, but it would depend on if the front mounting pins are too apart on the 400, but you could maybe rig something up. When I get the chance I could try fitting one on the other. The 400's gas tank holds about 3 gallons while the 50's tank holds 2 i think, so it would be a bit big.

I've moved on to a slightly bigger bike (400), but I think I'll keep the 50 around for cruising in town. It's just so light and fun, which you can't have with a bigger bike. You know you can get higher top speed and less shifting by changing the front sprockets? Stock is a 12-tooth, and I bought 13 and 15-tooth sprockets from bikebandit (they've got 14 too). With the 15 I can get between 55 to 60mph on a hill, but it feels too light, and it can't pull me to those speeds on flat ground. (I'm 175lbs. or so). I've been running the 13-tooth most of the time since it cuts down on having to shift in the middle of turns, and gets a little better top speed. I really run it on small city streets most of the time. I've taken the RX50 to the twisty backroads here, but it feels dangerous when you're expecting cars to come up behind you going 65+. So yeah, thats why I got the 400... for some nice backroads cruising.

Wooohooo, someone else with a bike like mine! An '83 RX50 is my normal bike for running around town with no worries. I only found one other post about an RX50 from back in 2006 when I did a forum search. I wish I could help you with the gas tank, but I really don't know any sources. I believe its a part specific to only RX50s, and you know these are really rare bikes, right? Most websites say that only 2,000 were ever made. Most are probably behind someones shed rusting away by now. Your best bet is checking ebay regularly, but I've never seen a gas tank alone come up on there. If not that, some kinda patch is probably all you can do. Bikebandit.com lists a price of $321 for a new one, but it doesn't list them as still being available. Oh, and theres lots of support for the engine and electronics on YSR websites. The YSR is a small sport bike that shared most of its engine and components with the RX50, and they're still raced quite a bit and are much more plentiful. Obviously though, they have way different gas tanks. Good luck, Kevin

OK, I couldnt wait, I painted it! texture doesnt show up well in the pics, but its rustoleum's 'hammered' gray: and yeah, mapp torch didnt help, gonna have to take angle grinder to it once I can find a spare spacer. I tried takin it for a ride again, and rear brake is still doing nothing but just sliding around.

yeah, i might get there soon. I may just hack at the spacer till it submits, which is basically whats gonna have to happen anyways. I still havent tried heat, so I'll try to buy a torch in the next couple of days. There's an axle for cheap on ebay right now, or i can just get a new one for like $36 online. I don't know where to get the spacer though... nobody shows them in stock.

yep, tried that. I'm afraid of squeezing it too tight that it pinches in against the axle even more. I'm now workin on diggin in deep with a cold chisel, and beating the spacer sideways to spin or move it, but no go yet. I had to put away the sledge because its late and the neighbors wont be happy. Don't get me wrong, I'm not gonna trust this brake at all till it works reliably for me for many miles. (no matter what form its in)

Well, I rethreaded the axle end... put the nut back on there, and tried whacking it with a hammer. Still no go... I'm thinkin i could try cutting a notch in the spacer, then beating it with a cold chisel/hammer to try and rotate it around the axle, and get that rust broken free. But in the meantime, I'm wondering if i can put it back together and see if the rear drum will work. It seems like it works fine when you operate it by hand on the stand. Would yours do that, Cy? I'm wondering if maybe rust between the backing plate and/or pin and the shoes was keeping my brake from operating smoothly. I sprayed some PB Blaster and lubricating oil around thru the side of the drum, and maybe with the adjuster freshened/tightened, and some more use, I could get lucky and it'll work? But in any case, still gotta get that spacer/axle out someday to change tires....

Well, I need some assistance trying to figure out how to get this rear axle out. I finally got it to rotate by using a big line-up bar thru the hole in the end, and hitting it with a hammer. But, the axle is stuck inside the big spacer just on the other side. Every time I rotate the axle, the spacer just spins with it, and its stuck in there so that it won't let me slide the axle out the end. I can't get a solid whack on the line-up bar to get the axle outward. I tried holding the spacer with channellock pliers while rotating, and still no go. I've got the adjuster freed up finally, and sprayed some grease inside the drum, and maybe it'll be enough to get rear brake functioning alright. I'll have a re-threading die tomorrow for the other side, so I may just try putting it back together as is.. but I'm still gonna have to get that axle out someday if I want to change the tires, which it needs really bad.

aww poop, I messed up the threads on the end of the rear axle. I was trying to get the rear wheel off and to check out the rear drum, and the axle didn't want to come out. So yeah, I whacked it on the end with a sledge hammer to try to drive it out, and it smashed in some on the end. I guess its too hollow because of the big cotter pin holes. Well, I figure I'll try a re-threading die tomorrow and hope that works. 12mmx1.5? I also gotta figure out how the heck to get that axle out of there... Need some kind of bar thru the hole on the other side and a way to pull on it from that side....

It's cold here in Ohio, but I couldn't resist takin it to town. It's still really sketchy and I don't trust anything, though. Biggest problem is the rear brake: I got nothing, except occasional noises of shoes bouncing around and occasional full lock. Yep, gonna have to tear into that. Must be a spring or something broken in there. I still need to lube that clutch cable before it breaks on me, as well. I've also got other little things here and there missing or damaged, like the rubber supports for the gas tank and the horizontal bar that holds the seat down. But, I did finally find a patch of road where I opened up the throttle all the way. Damn, this thing is pretty strong! Now I just need to make it comfortable so I can do more of that.

I did a google image search, and couldn't find any decent pics, but the engine looks extremely similar to the one on my 1983 RX50 street bike (which is very rare as well), but the engine is also shared with the YSR50, which is a very popular mini-sport bike used in racing, and has good aftermarket support (www.teamcalamari.com, etc.) Here's a YSR50 engine, is this what yours looks like?

well, it propels itself! Front brake seems to work OK. Drug a little bit at first, but now it seems to be doing OK. Rear brake... not so much. Gonna have to take that adjuster off and beat the crap out of it. I've either gotta get used to it, or the clutch is worn out, or it just needs fresh oil and re-broken in, or its just a really stiff shifter too. Just took it around the block, stalled it and had to walk it back home. Time to go get the license plate and battery I hope.

hmm, just a light film of red brake grease, the kind that you put on wheel bearings. is that what you mean, or should i clean it off?

hmmm, maybe when it was running w/o battery power, I was just thinking about my car battery connected with jumper cables. The bike's old long dead battery was still connected in circuit, and despite being dead as a doornail, it contributed something to keeping the field coils going.... Anyways, I got the front brake bled and operating! I tried compressed air thru passages, and then lots of brake fluid pumping from both sides, and it still wouldn't go. But then I tried hooking my hand vacuum pump directly up to the bleeder (without the bottle in between), and gave it about 30PSI of suction, and some clod of dirt finally broke loose and it got fluid thru it. Then I pumped a good bit of fluid thru it, sealed it up, squeezed really hard on the handle, and it actually got the caliper piston to push out. I pushed it out almost all the way and added a slight bit of grease to it. It was really tough to get it squeezed back in, so I'm not gonna trust it fully at first. I think its gonna take a lil bit of operation to work smoothly. Now I just gotta bolt the whole front brake back onto the bike itself, hah.

ahhh, im still refusing to shop at wal-mart. they've wiped out way too many small businesses here in appalachia. I know autozone is still a national chain, but I just don't like wal-mart. I'm somewhat a hippie I guess in some aspects, but not nearly as hardcore as I should be. And yeah, don't know how, but my bike will keep on idling and revving just fine after I disconnect all battery power. My RX50 has been runnin for years without a working battery.... but its easy to kick start.

Yes, it now runs ok in the 'ON' position. So, the major problem on my master cylinder seems that there's no fluid going from the reservoir to the brake line. I've tried spraying it out with brake cleaner thru the little holes, but still fluid just sits in the reservoir and never goes into the line. Tried pumping the brake a whole lot, and leaving the brake squeezed in overnight. I might try some compressed air tomorrow to blow out any blockages, and do the same with the front caliper to get piston out. Any other easy way to get it working? I started to take out the piston itself out to further investigate things, but it seems I can't remove the rubber seal without damaging it. I don't want to order and wait on a m/c rebuild kit if its not necessary or won't fix the problem. Oh, and I figured out that I can start it simply with a screwdriver into the starter button hole (apparently jumping ground from switch case to button). Plus, I get a solid 14.5V when idling or revving, so I figure that the charging system and voltage regulator are OK. I also figured out it'll run fine without a battery connected to it, despite dying the other day whenever I disconnected the battery. what up with that? I don't think I've got enough foot power to get it to start with just the kick starter though. Still, I might take it for a ride at least around the yard or the block in the next couple of days, with or without a battery or front brake. Autozone wants 50 bucks for a battery, and local yamaha dealer was closed today so I havent asked them yet.

I just did a forum search, and found the simple explanation of the automatic vacuum powered petcock. I saw that vacuum line earlier today, and noticed it was broken. Not sure when that happened... but it sure would explain things. My '83 2-stroke bike isn't like that at all, but I guess its because theres no risk of fuel runnin down thru an inlet valve into a stopped 2-stroke bike. I'll try the 'on' position again tomorrow and see if it'll work. Oh, and I got the rear brake working somewhat.... The nut on the adjuster rod refuses to turn at all, and is now bent, and might break off if i keep messing with it. So I did something redneck... I removed the lever arm from the splined shaft, and then spun the splined shaft with needle nose pliers such that the shoes were closer to making contact, then slid the lever arm back on. Not ideal... but maybe it'll work for now. I may try a ride atleast around the yard tomorrow, if I buy a battery for it.

on second thought, i'm just an idiot. I didn't understand the markings on the fuel petcock, and still don't. For some reason in the 'on' position (straight vertical), which I had been using, gives me no fuel. If I set it on PRI (i guess thats the prime you were talking about), it pours fuel all over the engine. So yeah, I set it on RES for now to run it. Could my 'on' outlet be just clogged up, or is that really what you use to shut off the fuel? In any case, SHE RUNS! Starts right up and idles just fine. Time to throw in a new battery, get the brakes working, get a license plate for it, and get this bitch on the road! I've got plenty of other things do of course... but all in due time.

fire in the hole! yeehaa, forgot i had a can of starting fluid. yeah, definitely fuel problem. won't go after starting fluid is gone. sounds good when it is going, though. fuel strainer looks clean, and fuel in float bowls poured out clean after i poked a chunk of dirt out... there's not much gas in the tank though. I bet that cheap bastard drained as much as he could and put it in his truck before he sold it to me. I don't have a gas can, but think I might just take the tank off and walk it around the corner to the gas station. yeah, thats how i roll.

so does this motor have points? I've got a dwell meter, because I still have points on my BMW car. what do you mean by running prime? So I just went out and played with it some more. I noticed that the plug wires didnt hold on tight at all. It appears the plug wires are the kind that hold onto bare threads, but the Champion spark plugs are ones that have the round nubs on them that won't come off. I really couldn't get them to hold on at all, don't know how he got it to run before. Anyways, I dug in my toolbox and found some nearly new NGK BP5ES from my BMW, and they look like they match up perfectly with the same threads and reach, and you can pull the nubs off. So I put them on instead, and the plug wires held tight on them. Stole the battery from my miata, and got the starter spinning pretty good, but still no fire. Hooking 12V to positive post of dead battery and key in vertical position should turn ignition on, right? The brake light comes on, and oil light. But no neutral light (would it not fire if it thinks its not in neutral?). I assume its in neutral because it doesn't roll forward when I turn the starter or kick it over. Oh, and I tried arcing the plug wire to block, and couldnt get a visible spark, but maybe just cuz its weak and I had lights on. Yes, I'm going to tune everything properly eventually. But I'd rather do it one piece at a time on a roughly running bike, just so I have a baseline to work with. Thanks for your patience and help!

yeah, I've tried the kick start, but it takes a whole lot more work to kick it over than on my 50. The carbs are so out of whack that it took a whole lot of starter spinning to ever get it to fire and run the other day, that I don't think I could ever turn it that fast or enough with my leg. Yeah, I figure the carbs and such will be coming off soon for a cleaning. But it should run somewhat as is... Oh, and the rubber 'carb joints' where the carb connects to the head are badly cracked, so thats probably part of the reason the PO couldnt ever tune the carbs right. Any idea for a cheap source? Best I can find is $43 on bikebandit.com. In the meantime, I was thinkin of goin redneck and smearing some RTV over the cracks. For the rear brake, I tried using the nut on the end of the horizontal rod, but thats rusted together tight. I think I'll go ahead and take that rod off and soak it in something, or just replace it. Oh, and to top things off, I really need to avoid spending any unnecessary cash right now on it (yes, economy has gotten to me bad..., probably dumb for buying the bike but I couldnt resist). So yeah, its best that I thoroughly diagnose things first and fix them if possible instead of just buying all new stuff. Thanks for the help.