New guy with a 400

[06CCDMAX]

Hi everyone. I just picked up an 81 xs400H with 4165 on the clock for cheap, and I got the Owner's Manual, factory toolkit, and a Reggy, I am rather happy with the purchase. Actually it's in excellent shape (Not Craigs List excellent). Exhaust has a ding from the kickstand, I'm gonna guess this is common based on that rubber pad's ease of sliding down (at least on mine). The paint has a few minor blemishes, but the tank has NO dents or dings, the bike's damn near rust free. No pitting, and overall, for 31 years old looks about as close to new as I'd expect to find. It's been off the road for 2 years. I bought it Sunday, knowing nothing about these bikes, and started on it today. Drained old gas, see tank isn't rusty on inside . Drain carbs, just stale gas no crap coming out. Put in some fresh gas, put to prime, then Res, and try to start. Get nothing. Snort of Ether. (No, I don't overdo the stuff, just a shot not a blast) I get a backfire loud enough the neighbors are asking each other if they're OK. (It was .50cal rifle loud) Both cylinders have compression so I'm not looking at stuck valves(I HATE stuck valves...) I'm expecting crapped points are causing spark way out of time (BTDT 50 times this year). Search leads me here where I see it should not have points. I'm going to pull and clean the carbs over the weekend, but wondered if there's any other ideas here. I have Comp, I have spark, I got a bang But no sign of wanting to run.

Owner's manual has nothing helpful really. I'm not by any means new to engines or repairs in general, but I've been around enough to learn to look for someone who's BTDT before I go crazy on some stupid problem. So I'll entertain thoughts/ideas/info. And tear into it Saturday.

 

[xs400newbie]

Hello and welcome. Fantastic deal! Definitely want to get those carbs clean. Also make sure you've got a good battery or you could be cranking her over 'til armageddon and still get nothing. Also download the service manuals from this site. Good luck!

 

[06CCDMAX]

Thanks. Yea, when I heard the price I figured it was worth a look. I'll have the Battery on a tender for a couple days, It cranked quick but are these known for weak spark or something like that if the battery isn't at it's best?

 

[63-Coupe]

Thanks. Yea, when I heard the price I figured it was worth a look. I'll have the Battery on a tender for a couple days, It cranked quick but are these known for weak spark or something like that if the battery isn't at it's best?

It's more like these bikes are known for NO spark if the battery is bad. You need a good battery to get spark when you are first turning it over, kicking it over, or even trying to bump start it.

Also, for the gas, if the vacuum hose from the carb to the valve is bad or not there you will not get gas to flow in the "On" or "Res" position. The valve needs vacuum to open it to let the gas flow in either of those positions, but the "Prime" position should allow unresticted flow from the tank to the carbs by gravity alone and without needing the vacuum.

Welcome to the forum, sounds like you got a great deal.

 

[06CCDMAX]

Thanks 63. I had it in "Prime" long enough to fill the carbs many times over, so it shouldn't be the problem. I will pull the line and crank to be sure I am getting fuel flow in "on/res" while the motor is spinning, as I DIDN'T do that yet, and would like to be sure I'm not facing an issue there. I'll also hook up a jump-box so I know I've got good volts when starting. I can't say I like the idea of needing battery even when kick-starting, that should be in case of starter failure OR battery being drained.

I DO need the Carb boots. They are dry-rotted and cracking. I doubt they're through yet, but it'll be an issue so when I hear it roar, I will look to buy them. Anyone got a source? The rubbers for the headlight/turn signal mounting, I need those too. Also a seat. Mine is like new, I actually would like a cheap one (Ripped cover, etc) as I will recover it over a different shape/size foam pad, I'd like to keep this one in case I don't like my idea....

I'm quite sure I got a good deal on the bike, but then again, most all my toys I have were bough for pennies on the dollar

 

[06CCDMAX]

It runs. Sort of.... Since apparently good battery volts are needed for spark, I put it on the tender, but then tried kick-starting it instead of the starter. (No starter Battery draw-down.) It took a "Few" kicks resulting in 1/2 to 2 second runs to get it running but it finally ran and idles sorta-ok. Warmed it up and tried to give it a little gas... No bueno. I'll be cleaning the carb, and replacing the fuel line and vacuum line just for the heck of it when I can, but expect progress at the speed of continental drift, I have a "Few" more pressing measures. Plus I started hearing today about a little visit I can expect from Sandy, being I'm a North-Easterner. Once that wonder passes, I'll get back to this project. (Hell, maybe I'll motivate myself to take a picture or two...)

 

[arfstrom]

Good deal on the purchase. Our model has some know troubles, unless the PO previous owner, did anything with the bike.

1. Dirty Carbs, put a inline filter onto her sooner than later, (Ultrasonic cleaning preferred, Boiling in light acid (lemon juice worked for me)) (every one cleans their carbs 2 to 5 times before they get it right) You want the carb spray to come out in 3 sprays in the one end of the carb by the butterfly valve. (its been a while) look it up under Tech section.
2. take the guess work out of the plugs, lines, and caps. get new ones. http://www.oreillyauto.com/site/c/detail/NGK1/5534.oap

3. Electrical problems, The wire are shot under the motor. if you look at the drive sprocket, and find the wires where the come under the motor right there, they are shot right there, so if the green wire doesn't get electricity to the stator then it wont charge. seems to be a lot of us replacing Voltage regulators (test it first, instructions in the manual on the download from here) Go though the tech section for more tips. I did some photos, and copied them to my album. Most of us have done the "Rewire How to" by Drewpy with success on just the stator part.

4. Safety check the master cyclinder for DOT fluid in the MC. I had Cake. My wifes bike sat around for 8 years before I started working on her.

If the PO had been riding it this year hopefully he fixed some of these and has been driving, otherwise good luck!
Tobie

 

[l4ne4]

I've got a seat from an 81 special I'd sell cheap. I'm going a different route with it, already hacked the rear frame off.

 

[arfstrom]

so how is that going to help 6CCDMax start his bike? If you have some thing to sell sell it in the right place. If this is your first, then do what others do, wait for someone to get in a spot, and then attempt to sell it. Thats what the "Classifieds" are for. Click on Forums up ontop of here, and its right there.

or start your own new thread. others will jump on a chance to get oem parts.

 

[l4ne4]

so how is that going to help 6CCDMax start his bike? If you have some thing to sell sell it in the right place. If this is your first, then do what others do, wait for someone to get in a spot, and then attempt to sell it. Thats what the "Classifieds" are for. Click on Forums up ontop of here, and its right there.

or start your own new thread. others will jump on a chance to get oem parts.

No disrespect intended. I know how forums work and know they have classified sections. The OP stated he wanted a seat to expirement with so he didnt have to cut up his pristine original seat.

Also a seat. Mine is like new, I actually would like a cheap one (Ripped cover, etc) as I will recover it over a different shape/size foam pad, I'd like to keep this one in case I don't like my idea....

I have exactly what he is looking for so I offered so sell him mine, I am not asking a huge dollar amount (which the PO and I could discuss over PM).

 

[arfstrom]

Sorry, I glanced over it, I didn't see that on the double check, my bad!


next time I will have to triple check

 

[l4ne4]

Sorry, I glanced over it, I didn't see that on the double check, my bad!

next time I will have to triple check

\

no blood no foul!

 

[06CCDMAX]

Thanks guys. I seem to always start some sort of s#*t where ever I go.
I've actually had it running and rode it around yesterday and again today.

It's an XS400H so no master cylinder. Cable actuated drums... I'll check the points you mentioned arfstrom for damage and maybe catch it before it causes issues. But there are no current electrical issues. It is definitely charging. And it runs pretty well now. But I do have to clean the carbs still I'm sure, it does occasionally cough and I think it should run a little better, but not a bad idle overall...
I'd love to have a sonic cleaner, it's on the tools list but not yet. I'll soak and spray them out, and I'll look for the "3 sprays" you're referring to, which I assume are the low speed passages cast into the throat of the carb body. (Pretty common setup if this is what you are referring to).
Plugs caps and wires are like new, the only spark issue is I guess a common one. It doesn't seem to fire much if at all while I crank it with the starter. But if I spin it for a couple seconds and let go of the starter, it will fire as soon as I let off. Is there a fix to get spark even when battery volts are drawn down a bit by the starter???

Bike is fun to ride though. Not that much in the power dept, but I can say it's a fun ride, and when I start doing some work I hope to make it even more so. (And to be fair, my other bike I am comparing it to weighs only 220lbs and has a 60hp 300cc 2-stroke. )

l4ne4. I am interested in the seat, I'll PM you, or PM me. But don't expect a reply for a bit. Sandy will most likely leave me working 24-7 and powerless for a good bit.

 

[l4ne4]

No hurry. Get back to me when you're ready

 

[arfstrom]

I'd love to have a sonic cleaner, it's on the tools list but not yet. I'll soak and spray them out, and I'll look for the "3 sprays" you're referring to, which I assume are the low speed passages cast into the throat of the carb body. (Pretty common setup if this is what you are referring to).

Yup, youtube has vids on this I am sure there is shots of that on this forum some where. Plenty of references. Speaking of http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf doesnt show the 3 streams, but it does have excellent pics

It's an XS400H so no master cylinder. Cable actuated drums...

Hmmm Drum brakes, Ahhh Drum brakes

Is there a fix to get spark even when battery volts are drawn down a bit by the starter???

Seems to me that even if you were on top of a hill, and push start the bike over the without the battery fully charged, and that when the battery hits 7volts, it will kill on you. There is a thread about switching to smaller AGM batteries, and using a capacitor for immediate power needs, etc... I haven't hit that point yet. I have on my wish list is to put on a Voltage monitor/Ammeter. I haven't settled for which one yet. I just want some thin/smaller than what is commonly available. Okay that might not be what your loooking for, I hope this will help you in your googling good luck!
Tobie

 

[16VGTIDave]

Plugs caps and wires are like new, the only spark issue is I guess a common one. It doesn't seem to fire much if at all while I crank it with the starter. But if I spin it for a couple seconds and let go of the starter, it will fire as soon as I let off. Is there a fix to get spark even when battery volts are drawn down a bit by the starter???

Check the ground cable from the battery to the engine casing. With the high current load from the starter, the ignition may not be able to fire if the ground has a poor connection.

You can test this by connecting a booster cable from the battery negative terminal to the engine and trying to start the bike with the starter. If it fires up better, you know that the ground connections are poor.

HTH,
Dave

 

[06CCDMAX]

Well, I sure didn't plan to off this bike, BUT I AM a Die-Hard 2-stroke fanatic, so when the chance to trade for an RD250 in still pretty nice shape came up, well.... As stated I HAD an XS. Pics of the bikes for you pics guys. As I said it was a damn clean and 100% original bike. It was fun but I can't pass a 2-dinger. New owner will enjoy his winter project I'm sure. And I'm gonna enjoy mine

 

[Flexeril]

Nice bikes.

 

[Scorpio1963]

My bike also back fires sometimes when its trying to start.Im sure why yet but I will be looking into it over winter.

 

[Lou Ranger]

... I DO need the Carb boots. They are dry-rotted and cracking. I doubt they're through yet, but it'll be an issue so when I hear it roar, I will look to buy them. Anyone got a source? ....

This guy has received some rave reviews: http://jbmindustries.com/index.html

Best of luck with your swap. How was Sandy's visit to your place?