My ‘80 Yamaha XS400 Special build thread..

[Itschrisb]

Hey y’all I figured I’d start a thread to keep track of the progress on this ‘80 XS400 Special I picked up not long ago.

Friend of mine had this bike sitting around and he asked me to clean it up and sell it for him. After looking it over I decided I wanted to fix it up for myself instead. This was the day I brought it home. It has a little over 14k miles on it, seemed to have been some what maintained over the years but definitely needed some freshening up.

First time messing with an XS400 but I’ve had a number of XS650s over the years and am currently working on the ‘76 xs650 that’s pictured.

The plan for the 400 is to be my go to daily/city bike. Living in Philadelphia having some small like this is perfect for getting around.

I’ll keep you all updated with my progress.

 

[tstidham]

Nice! That's pretty much what I use mine for and also live in the Philly area, in the NE, near Huntington Valley.

 

[CaptChrome]

Welcome to the forum! Nice looking bike (the 650 as well as the 400). I can't wait to see what's in store.

 

[Itschrisb]

Threw a new front tire on it and cleaned up the wheel.

Then I moved to the carbs which ended up being a huge headache. The carbs themselves cleaned up pretty good, I wish I had taken before photos. I replaced the carb boots and air filters while I had it all apart. After putting it all back together I chased my tail for awhile with one cylinder running rich and one cylinder running lean. I replaced plugs, plug wires, caps etc. kept messing with the carbs with no real solution. I believe the problem was the float height listed in the manual was too low. I raised the floats and also put new idle mixture screws in and it seems to be way better.

Then I took it on its maiden voyage to get gas and give it a shake down.

I’ve put about 200 miles on it since getting it back on the road. At this point a few more maintenance issues have came up. So next I’ll be tackling the steering head bearings and bronze swingarm bushings.

I also need to refresh the front fork. Are progressive springs worth the money or should I just add a heavier oil and some preload? I’d love to eliminate the brake dive as much as I can.

 

[CaptChrome]

Ohhh, Avon front tire.... You XS400 owners in Philly know how to roll! You have to stop rubbing this stuff in my face.

I believe the problem was the float height listed in the manual was too low.

On the '80 and later SOHC bikes, Yamaha specified setting the float height using a piece of tubing from the drain port and measuring the level down from the bowl/body seam:

I have a black dot on the bowl as the reference in the picture and the spec is 3+/- 1mm down from the body flange.

Things are looking pretty good! I can't comment on the springs as I am using the stock springs and 20wt fork oil. I do like the "gentleman's ride" it provides over the pothole challenged roads I seem to enjoy most.

 

[Itschrisb]

Ohhh, Avon front tire.... You XS400 owners in Philly know how to roll! You have to stop rubbing this stuff in my face.


On the '80 and later SOHC bikes, Yamaha specified setting the float height using a piece of tubing from the drain port and measuring the level down from the bowl/body seam:
View attachment 38385
I have a black dot on the bowl as the reference in the picture and the spec is 3+/- 1mm down from the body flange.

Things are looking pretty good! I can't comment on the springs as I am using the stock springs and 20wt fork oil. I do like the "gentleman's ride" it provides over the pothole challenged roads I seem to enjoy most.

That’s a really trick setup you have there, I’ve only ever measured float height via a caliper with the float bowl off. My XT350 also recommends checking the float height like you’re showing so I’m gunna have to try it out.

 

[CaptChrome]

That’s a really trick setup you have there

¼" clear vinyl tubing is the best tool I have in my tool box. When I saw the factory manual used this method, I was all over it!

 

[Itschrisb]

¼" clear vinyl tubing is the best tool I have in my tool box. When I saw the factory manual used this method, I was all over it!

I think it’s time I overhaul my toolbox a little and get some motorcycle specific tools. I came from working on cars mostly but now motorcycles have taken priority haha

 

[Itschrisb]

At this point I’ve put about 350 miles on my xs400 since getting it back up and running. The original swing arm bushings were so bad I could feel the rear end shifting in turns so it was time to replace them with bronze ones.

Overall the process was pretty straight forward. I did end up having to buy a press to get them all the way in. Worthwhile tool to have in my shop anyway considering how many projects I have going on.

Before tearing it apart my buddy and I went on a long 100ish mile ride. It was nice to see how it felt riding for long periods of time. I have to say overall this bike is really comfortable.

As I take pieces off the bike I’ve been trying to clean them up as best I can before putting them back on. This is the first bike I’m really doing that on and I have to say it’s very rewarding. Here is an example of the chain guard I polished up.

What’s everyone favorite polishing method or products. This was a combination of some Never Dull, 0000 steel wool and Mothers chrome polish. I am pleased with the results but I’m always looking for more tips/tricks when it comes to detailing.

Next up on the agenda is rebuilding the front forks and replacing the steering head bearings finally.

 

[tstidham]

I think my 78 is in need of swing arm bushings as well. Every now and then I feel a weird movement in the tail, but was never sure if it was bushings or just some gravel or other slippery stuff on the road. How did your shaft look?

 

[CaptChrome]

It was nice to see how it felt riding for long periods of time. I have to say overall this bike is really comfortable.

Surprising, right? I can ride this bike through a tank plus and still feel great afterwards. I was definitely not expecting that.

Disclamer: I don't try to crush miles on the Interstate on this bike. I expect it would not be at all comfortable for that task.

 

[Itschrisb]

I think my 78 is in need of swing arm bushings as well. Every now and then I feel a weird movement in the tail, but was never sure if it was bushings or just some gravel or other slippery stuff on the road. How did your shaft look?

The shaft itself didn’t look that bad and even the original plastic bushings didn’t look bad. I took the bike for a ride yesterday with the new bronze bushings and could immediately tell a difference. I’d recommend replacing them.

Surprising, right? I can ride this bike through a tank plus and still feel great afterwards. I was definitely not expecting that.

Disclamer: I don't try to crush miles on the Interstate on this bike. I expect it would not be at all comfortable for that task.

Yeah I try not to spend much time on the interstate on mine either, I much prefer back roads.

Yesterday I finished up installing the rear wheel bearings and got the bike back together. Mechanically the rear of the bike is now 100%. I’d like to eventually do some cosmetics to it, the big bulky taillight and broken license plate holder is bothering me.

I got the front of the bike torn down to do the head bearings and fork rebuild. Front wheel will also get new bearings. Don’t worry I supported the dangling mess after the photo haha

The old bearing races had so many notches in them the steering stem felt like a switch. I can’t wait to feel how much smoother the new All Balls tapered bearings are.

 

[CaptChrome]

I’d like to eventually do some cosmetics to it, the big bulky taillight and broken license plate holder is bothering me.

What? That lunchbox tail light is an '80s classic! Don't toss the tail light, mine has a crack in lens and if yours is in good shape, I buy the thing off of you - because I love a good lunch box tail light.