1982 XS400 (J)? - Cafe'd


XS400 Enthusiast
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Aloha from the mild north pacific of Vancouver Island.

Picked up an 82 XS400 yesterday. My first bike was an 82 XJ650 that got stolen, so when this came up locally it called out to me. That said, my 650 was all stock and this bike has been tinkered with just a touch. This is my first 400 and first modified bike.

The whole thing looks very clean, and I'd guess a recent PO has gone through just about everything. New turn lights, battery, partial wiring. Some kind of custom seat. Starts right up, runs strong, but doesn't love being in the low RPMs, seems to bog down more easily than I remember from the 650.

The ODO says 46k, but the frame and engine have non matching VINs and the ODO doesn't look original so I'd say that number is a guess at best. The PO who cut it up modified it listed it as 20,000 on the nose so I'd bet that was also a guess.

Fork seems a bit on the soft side, so might look at replacing that. Since it's already been chopped up I'm not too concerned about keeping original, so if there are good suggestions for after market options I'm happy to hear them.

PO also put on some extraordinarily loud pipes on this thing. My 650 was loud, but this is deafening. I live in a quiet residential neighbourhood and my reputation for noise -- having jackhammered 25 tons of rock out of my basement -- is already good enough so I'd like to put something much quieter on here.

Lastly I'm wondering if there are any reasonable options for getting this thing back to being a 2 up bike. My neighbour has a welder and between the two of us we're handy enough. I'm guessing it may be more work than is wise but though I'd check. I'll be reading through everything before I come back with any specific wrenching question.

Edit: Link to quick youtube of bike startup and working the choke



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Great bike!

For the forks, you can try heavier weight oil (15wt?) to stiffen it up a bit. I've also upgraded to progressive springs and noticed a good improvement. More controlled in corners, and much less brake dive. Check out XS650 direct and the springs that are 24mm dia by 484mm long. You'll need a 3" spacer (PVC pipe works). I think they're the same as Progressive Springs model 11-1119. Also, your forks are missing the top caps to keep dirt and moisture out.

The bike doesn't really have any power until it gets over 2k, so the bogging is normal to some extent. It might be the carb setup though, given that it has aftermarket exhaust. The stock exhaust is much quieter if you can find a set. Some have done 2 to 1 exhaust on this bike, I believe.

For riding 2 up, the stock seat works fine if you can find one. It bolts down to a rear grab rail, which bolts to the frame. Not sure how much of your rear frame is left though. There are also some side plastic fairings that match the contour of the rear seat, and cover the rectifier and electronics on the left side of the bike.

For reference, here's a shot of my bike in the mountains just past Seattle a few weeks ago.


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Thanks for the suggestion on the forks Jared. Will check that out.

One other modification that I'll want to change is that po removed the side stand, so it only has center stand. Are side stands fairly standard between the xj and xs bikes from this era? Would other makes our a generic also fit easily?
Took it on my first "real" ride today (~40km) before I leave town for a month. Writing this mostly just so I remember everything when I get back, but of course any ideas/help are appreciated.

First half of the ride everything seemed good, then the idle started to stick high, around 3,000. A little while later I though I heard a bit of a changed sound coming from the engine. Stopped for an errand, engine felt quite hot. Got it started though no problem and headed to the highway to head home, heading down the first hill I suddenly lost throttle response and all power (engine still running, just no go). I coast to the shoulder (big one fortunately) and with the clutch out the motor died. Still rolling I dropped it into second and got it to turn over and run again, but still no throttle response. Pulled it right over and stopped, check petcock, leaks, etc, nothing obvious. Still over half a tank (I did stupidly put in 87 with ethanol...). I waited a minute or two before trying to start it again. When I did it would turn over and half fire before dying right away. There was an exit 100 m ahead so I pushed the bike there, just hoping to get it off the highway to call a tow. When I got to the exit it was a downhill slope so I hopped on and coasted it. Popped it in second just to try it, and boom fired back up and throttle response is back. So I'm just limping it home at this point but a couple things are obvious as I go.

Idle still high, I can get it down by leaving it in gear and giving it no throttle so that the engine starts to die.

I did three simple things. First I messed with the idle screw. It was probably set a bit high to compensate for something else. Just changing that seemed to help, but didn't solve the problem. I reset the idle fuel mixture screws on both side to three turns out. Also tightened up the hose clamps on the carbs. Running much better now, high idle seems to be gone. I suspect two issues really at fault, 1) small vacuum leak on the airbox side carb boot, those screws were a bit loose. 2) The fuel idle mix screws were, I think, set randomly. At three turns out now. That may be a touch rich, but engine pulls strong now and no hesitation or high idle. However, I still haven't had it on a really hard highway ride.

A strange noise started, my exhaust is very loud so hard to hear, but sounds to me like a "rotational whine". Would come and go. Hit a bump and it went away, downshift or something and it would come back. Seemed to me that power was lower when the noise was present.

Fairly sure this is just a noisy speedo cable. I talked to PO and apparently he rigged up off a CBR...

Overall power seemed lower.

Only thing I can think is that the high idle may have caused it to slowly start overheating which led to other issues... Does that make sense?


[Edited with diagnoses/solutions in red for future reference]
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