Another newbie. It's ugly...

[KFunk]

Yep, just picked it up for $150, and I'm not sure if it was worth it. It's pretty rough.

I don't know much at all about these bikes, but I'm searchin the forum, readin the manual pdfs, etc.

I heard it run before, but I'm not sure how they guy started it. Starter button is gone, and battery is dead. Hooked up a car battery and jumped the big starter switch under the seat with a screwdriver, but couldnt quite get it to go yet.

Before I go though, need atleast some brakes. Front master seems to do nothing, tried flushing things out, now doing the trick of holding in handle over night to get fluid thru it.

Rear brake does nothing, havent torn into it yet.

I know a little about old Yamahas because I have a 1983 Yamaha RX50 (very rare lil 50cc 2-stroke street bike), but this 400 is a much bigger animal with a lot more ugliness. I'm also more of a car guy, but I have dual weber sidedraft carbs on my 74 bmw 2002 daily driver.

Oh, and the title says its a 1981 Yamaha XS-400 SH-R. Is that just a typo on the the title, or is there an -R model that I can't find any info on it. Oh, and the engine code starts with 4R4... whats that mean?

Here's the pics of the ghetto pimpness:

and here's the little bike with its new abusive step-father:

the odometer says 1975 miles, but like I'd ever believe that....

I really don't want to make this thing pretty or new. Just simply go so I can run the crap out of it on backroads. The RX50 can't quite get over 55mph safely, so i can't take it out of town.

Thanks in advance, and I'll keep on searching this forum....

Kevin Funk

[steve m]

Hiya,,

Noticed the bike has a kick start,have you tried kick starting the bike with the battery hooked up ? use full choke and no revs.

Looking at the state of the bike, the carbs will be full of crap and need a clean out and the fuel tap filter will be full of crap,the brakes will more than likley need a master cly overhaul kit and new caliper seals, the rear is a drum brake, so have you tried adjusting it ? if that don`t work a new set of brake shoes will be needed.

[KFunk]

Hiya,,

Noticed the bike has a kick start,have you tried kick starting the bike with the battery hooked up ? use full choke and no revs.

Looking at the state of the bike, the carbs will be full of crap and need a clean out and the fuel tap filter will be full of crap,the brakes will more than likley need a master cly overhaul kit and new caliper seals, the rear is a drum brake, so have you tried adjusting it ? if that don`t work a new set of brake shoes will be needed.

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.

[JimR]

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.

Hi

its a good old xs400 sohc motor, it should be fine but without doing tappits/dwell/timming & carbs you dont stand a chance of getting it to run like it should. Also looking at the ruff state of it I'd check the vac pipe from the fuel tap to the r/h intake is ok.. without that no fuel unless you do prime !!! runnnig prime will give you fuel but perhaps a r/h cylinder running well weak. the inlet manifolds may be cracked from the outside but their internals may seal ... unless the carbs are sat on the crankcaes just let me know where the bike is at

Regards Jim

[KFunk]

Hi

its a good old xs400 sohc motor, it should be fine but without doing tappits/dwell/timming & carbs you dont stand a chance of getting it to run like it should. Also looking at the ruff state of it I'd check the vac pipe from the fuel tap to the r/h intake is ok.. without that no fuel unless you do prime !!! runnnig prime will give you fuel but perhaps a r/h cylinder running well weak. the inlet manifolds may be cracked from the outside but their internals may seal ... unless the carbs are sat on the crankcaes just let me know where the bike is at

Regards Jim

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!

[KFunk]

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.

[KFunk]

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.

[mark h]

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.

Hi KFunk, I have the same deal with the fuel tap on my XS, Scratched my head a bit with that one,

Good luck with the old girl.

[bralkan]

make sure there is a house coming from the top of the petcock to the inlet boot of the engine.

The petcocks on the xs400 are vacuum. Meaning, that as the piston moves up and down it creates the pressure (via the hose from the inlets to the petcock) needed to drain fuel out of the tank and into the carbs.

There is on - normal vacuum. RES - normal vacuum, however the fuel comes from a lower position in the tank. PRI is for "prime". This is free flow. Used to refill the carbs after working on them.

[KFunk]

Hi KFunk, I have the same deal with the fuel tap on my XS, Scratched my head a bit with that one,

Good luck with the old girl.

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.

[KFunk]

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.

[Cy Welch]

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.

Try walmart, they have a good price on the right battery (it's what I have in my xs400). It won't run without a battery, it's required for the charging system to work and the battery MUST be good.

[KFunk]

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.

[KFunk]

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.

[steve m]

Good news then souunds like you are on your way !!

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.

Hope you used the red rubber lube ?? cos normal grease or oil ain`t good for brake parts and can cause the seals to expand and lock the pistons...

[KFunk]

Good news then souunds like you are on your way !!

Hope you used the red rubber lube ?? cos normal grease or oil ain`t good for brake parts and can cause the seals to expand and lock the pistons...

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?

[drewpy]

its usually red in colour and is quite "pasty" in viscosity.

[KFunk]

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.

[drewpy]

need to lube the clutch cable methinks, its not that bad

[KFunk]

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.