North FL Build

[phanowel]

Well, I had some real success tonight. And so I'll start to document the build a bit.

Back story: I'm going to try and see what I can do with this xs400 (purchased for $70). I'm going to try and involve Sam, my 13yo, whenever possible.

He is out of town this weekend, so I wanted to try and get a sense of whether or not we should move forward with this particular bike. I didn't know if the motor was seized, and so on.

So I took everything apart, removed the motor, etc. Now I have the frame, the motor, and a pile of ugly parts. On the plus side, I figured out where the electric starter is (since I don't have a kick start lever) and bumped it over a few times with an extra battery I had. It fought to turn things a couple of times, but then started rolling over, so the motor isn't frozen. I thought that was a real good sign. I could see the intake and exhaust valves moving up and down on both sides. I had earlier taken both plugs out and sprayed a crap load of PB Blaster in the holes.

Anyway, some pictures...

And finally, my other bike for grins...

I've got forks and a rear wheel (with rotor, caliper).

Needs:

Kick start lever (coming, purchase in process from another member here)
Front wheel w/brake setup and axle
Hardtail stuff (I haven't decided if I want to go with a kit or try and piece something together with DOM tubing, sand, and a bender...)
Bars, controls
Minimal wiring
Carb (I'd really like to go with a single carb and fab up an intake)
Exhaust

I've found a couple of xs650s nearby for cheap, and I am sorely tempted to try and convince my wife that I should buy them to try and scavenge parts. I'm not sure what would come straight over to a 400 though... Thoughts?

Thanks! -Peter

 

[Arclight88]

Great project to start. From what I have read, some parts from XS650 are common to the XS400, but not much. The motors do not share much in common at all. The front and rear axels are different diameters on both models, thus little from the that area is common.

But 650s are way cool! I would be tempted to go get them and get your wife involved too, if she'll have any of it.

 

[drewpy]

good start so far, I would have tried to start the bike when it was in the frame so you know what needs doing. Now you probably have to strip the top end at least to see what's worn or not!

 

[xschris]

I would get all of the old oil and pb out of there I have been told that when left for a bit of time pb can eat at aluminum parts. Then do a compression test.

 

[phanowel]

I like the way you think xschris, that was my plan. Old oil (what little there was) is gone, new 20w50 in.

And the compression results are:

Left - 115
Right - 135

Sounds like the left side is a bit off, which is also the side that had a plug that was a real bear to get out. I've been reading about pouring in a bit of auto tranny fluid for 'ring rejuvination.' What exactly does it do?

By the way, compression test was done with plugs out (i.e. the plug on the side that wasn't being tested), no carbs, no exhaust.

 

[drewpy]

perhaps your valve seats are pocked/rusty ATM and just need re-grinding in. rings will loosen after a while!

no carbs on was a good move as they should be open anyway!

 

[phanowel]

So it runs.

I put on the coils, new plugs, and a battery. Sprayed some fuel in the intake, and it fired up for a few seconds. While I'm sure it isn't in tip top shape, it'll do for Sam and me, I think.

Now some questions:

1. Where does the clutch cable attach? (Sorry, I know this is a dumb question. I can see in pictures that the cable goes in to the sprocket cover, which was missing on my bike. When it goes in there, what happens?)

2. Tell me about the carbs on an xs650 in comparison with the carbs on an xs400. Are they wildly different? Would it be worth the effort to clean and rejet a pair from a 650 if I have relatively easy access to them?

3. Where the heck does a person buy DOM or ERW tubing? I asked at Home Depot and the guy looked more clueless than me. I guess I can look up steel suppliers in town - I just thought there would be a vendor with weekend type retail hours.

Thanks for any information you might be able to shed on this stuff!

Peter

 

[Arclight88]

1. Where does the clutch cable attach? (Sorry, I know this is a dumb question. I can see in pictures that the cable goes in to the sprocket cover, which was missing on my bike. When it goes in there, what happens?)


The clutch cable attaches inside the sprocket cover to a belcrank that is mechanically fixed to a cam actuator. The actuator has the job of transferring the grip pressure exerted by the rider into a force that pushes the clutch pushrod against the clutch plates so you can shift. The sprocket cover therefore is essential to the design because, without it holding a fixed position relative to the pushrod, the clutch lever force will not be transmitted into the clutch plates.

I just tried to find an image of the inner workings of all of this, but Yamaha parts catalogs do not appear to have images of the interior view of the sprocket cover and its moving parts. The clutch pushrod is installed in the crankcase and is visible about two inches away from the 8-o-clock position of the drive sprocket on the motor. The pushrod just rides around in that hole and you can pull it out. Be careful if you do, because I think there is a ball bearing on the far end of it that can just roll out of the engine. The pushrod is about a foot long and spans almost the width of the motor.

Good news - sprocket covers (with all their parts) are relatively cheap on eBay and other places.

2. Tell me about the carbs on an xs650 in comparison with the carbs on an xs400. Are they wildly different? Would it be worth the effort to clean and rejet a pair from a 650 if I have relatively easy access to them?

The Mikuni BS34 model carbs were used on both the XS400 and XS650 (and it varies by model year). XS650 also used a Mikuni BS38 model (and some others I think). I also think that all the XS400s can operate on the BS34 models, so if that is what is on the donor cycle, you're in good shape. Check out BCWARES 1978 Carburetors For Beginners videos here on XS400.com for good videos on BS34 parts and cleaning.

3. Where the heck does a person buy DOM or ERW tubing? I asked at Home Depot and the guy looked more clueless than me. I guess I can look up steel suppliers in town - I just thought there would be a vendor with weekend type retail hours.


Consolidated Pipe & Supply in Tallahassee was the first location I found, but I would check with welding supply companies as well.

 

[OleDoc]

welcome aboard.you have a good start

 

[Reaper]

I been gettin all my DOM from speedymetals.com. Prices ain't bad, shipping is a little high, but they're quick. And about Home Depot, them morons look at you funny if you ask for anything. I go there only when necessary.

 

[phanowel]

I been gettin all my DOM from speedymetals.com.

Thanks for the heads up on this source.

After some reflection, Sam and I have decided to leave the swingarm. This is in part to save money, but also when I asked him to take a look at pictures online of xs400s he liked, the first one he showed me was this:

I also think this bike looks great, so this is the *general* direction we are going. Not to say that we are even remotely trying to re-create this. In fact, I'm going with stock cast wheels, and I think I'll go with big dual purpose tires like this:

(IRC TR1 dual purpose, front rear, 4x18)

We will be extending the swingarm by about 4". We attached the frame to a worktable (sorry about the horrendous quality of the photos, my phone is about as cheap as they come):

We also screwed in a firm cross piece between the swingarm prior to the cut to - hopefully - keep some of the axis from turning.

I've got a small section of DOM tubing coming for the extension, but I haven't though about plugs yet... Any advice there? We will also have to obviously modify the existing brake caliper holder-thing, but I think we can just re-angle part of the brace and weld it up.

Some other parts I have coming now:

Sprocket cover, exhaust headers with flanges, and kick lever (thanks to scoutnaround here on this forum)
Front wheel with axle and spacers
A 38mm Mikuni carb (from a snowmobile)

We are going to fab up an intake manifold for the single carb.

Future need (as far as parts go):

Front brake cylinder
Bars (our thought is to make our own, probably 12" rise window bars)
Everything on the bars (clutch lever, brake lever with master, throttle, any electronics we might want up there...)
New brake lines front and rear
Clutch cable
Throttle cable
Probably jets to tune in the Mikuni
Tank (probably a 90s sporty peanut)

 

[phanowel]

Well, I guess someone should have informed me about the acquisition sickness that immediately afflicts a new xs400 owner.

And then there were two:

When I emailed the guy about this bike, it was just a parts-seeking adventure. I had no intention of buying a complete bike... Oh well.

 

[scoutnaround]

lmao thats great!! i am looking for amother to cafe. did those parts come yet? sent you the exhaust, then needed it for my forward controls had to cut my 2 into 1 into eight pieces. but it worked .

 

[xschris]

You can never have to many.

 

[phanowel]

Scoutnaround - yes, I did get the parts. Thanks man, I was glad to see them. Sorry you needed 'em after the fact.

xchris - Yeah, tell my wife that. Actually, though, when I showed her what I got after Sam and I went to 'get parts,' she really liked it, and is claiming this one. So, it is back to hunting parts for the '79, and the '81 will remain whole(ish).

For the '81, the PO claims that the carbs need reworked, but I haven't had a chance to really try and start it yet.

 

[Flexeril]

If you ever want to get rid off that seat, let me know... I need one.

 

[OleDoc]

warning!!!!!!!!!!!!!!!it is not a sickness but an addiction.three ways to curb the fix for a little:1. keep buying bikes 2.keep riding them and 3. keep building them

 

[xschris]

Agree! Sometimes I ask myself why do I need seven engines in my basement?

 

[Reaper]

You guys with multiple XS's are lucky. I found mine and have been looking for another for parts and can't find anything thats reasonably priced. I'm a firm believer in having machines and spare parts for the original machines. It's always nice to have something to grab a stud, bracket, nut or bolt off of in a pinch.

 

[xschris]

Took me 13 years to find all of it