1978 XS400-2E Intro and Build

can cut the bolt off then drill a hole in its place.basicaly inverting t/ /onhe bolt where it goes down from the top and uses a not on the bottom to hold the tank?
The seat is kind of universal. The hotwingglass sit claims it fits an xs400 and it nearly does, but the front few inches of the pan is too narrow for the frame. I've seen more than one person make it work, but they had the later model with the rounded gas tank and that tank mounts differently; there is no bolt like on my '78.
I thought about this, but the bolt is so high that if I made a hole or half-circle cutout for the bolt to pass through the pan it would still be so tall that I'd have to cut a hole on the seat cushion itself. :(


Hmm yea that doesn't sound like the best idea then. Perhaps the solution lies in a combination of making the tank mounting bolt sunken or smaller (by grinding down the bolt and/or removing the washer) just so it's low enough that your seat padding can still fit over it. Then cut a semicircle out of your seat pan and make it all fit :)
I'm in a bit of a hurry; still more exams this week. Here's an update with a crappy quick picture.

Inaugural ride 2014!

First impressions:

Progressive fork springs 11-1109 with 15w oil feels great.

The seat feels good; very comfortable cushion.

I'm running an NGK R5672A-10 plug on the right cylinder now; it started first kick after winter storage with old gas. Win!

Switched to 10w40 oil for giggles; seems to work well in this cold.

More to come later. A few bugs left to work out, but nothing major.


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Hey I've got a bike pretty well the exact same and im looking around for engine rebuild kits. Anyone know where I can pick one up for the xs400j for cheap? Having a hard time coming across one

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Here is a recent photo of the bike; a few minor things done to it, but there is more to come in the near future!


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figured I butt in a bit on this thread as I have what could be the twin to the one shown in the first post.

The question(s) for today are is there a preferred source for carb kits these days? Also will they come with float valve and seat and the "butterfly seals"?

OK found these online, anyone try them? Price sounds almost too good compared to others I have seen:

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Butterfly seals? no, no kits come with those. I found it very difficult to find a "complete" carb kit with all of the innards, but eventually located a Keyster brand one after a lot of searching. The float valve and seat are usually included in the common "basic" kits. I don't know if there is a preferred brand. I am sure Keyster is not the best; Mikuni is the best, but it is what I used and it worked.
New paint. I used tan truck bed liner. It's a bit ghetto, but at least the bike matches now and there is some color. I think it is an improvement. It cost me just under $20 for two cans.


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Meh, the fender isn't going to stop a whole lot, but I'm sure it does something. Its main purpose right now is to act as a cable-stay for the speedo and front brake cable :laugh: Thanks for the kind words.