My ‘80 Yamaha XS400 Special build thread..

Itschrisb

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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.

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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.
 
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Welcome to the forum! Nice looking bike (the 650 as well as the 400). I can't wait to see what's in store.
 
Threw a new front tire on it and cleaned up the wheel.
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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.

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

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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:
Carb reassembly7.JPG

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.
 
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.
 
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
 
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