Special Man

Okay, cool. I'll give it a run. Thanks!

I removed the retaining cotter, the springs, the . . . aw hell, I took apart the valves like the service manual said. Basically removed everything, then the one valve stem I was able to pull right out. The other three I can pull all the way down, but they wont come all the way out of the valve guide. It's almost like they get stuck right at the end.

There was some smoke out of the exhaust at the head, however, the pipes were loose at the head too. I didn't want to run the engine too much for fear of screwing something more up. Plus the plug had fouled out and that cylinder wasn't working. I think maybe a good fix from here would be to re-seat the valves, change out the gaskets and put on a new exhaust system (as the old one is pretty bad). What do you guys think?

Awesome!!! Thanks so much for the details! So. . . I don't actually have to replace the valve stems or the valve guides!! Is this process considered "re-seating" the valves? What I meant about the valves not sliding out was. . . three of the four valves are still in the valve guides that are still in the cylinder head. One slid out easily, but the other three won't come out. Now, I haven't tried very hard to get them out as I didn't want to bang them up and what not. Should I just put a nail punch on the ends and pop them out or. . .??? Thanks again.

No oil in the air boxes, and I'll check the pistons too. One thing I noticed when I took apart the valves. . . the valve stems do not come out of the valve guides, except for the one exhaust valve that was blowing oil, the valve stem slid completely out of the valve guide. Any thoughts on that? Can you shed some more light on re-grinding the valves? I imagine this is something that I need to take to an actual mechanic to fix as opposed to me fixing myself??

Hey all! I've had my XS400 up and running well for the past several weeks now thanks to all the input here in the forum. I've got a new problem now though. Was running it the other day and the left cylinder shut down and oil started blowing out the exhaust at the head. Got all over my purty little engine too!! I figured maybe a blown head gasket or something. To make a long story short, I broke the engine down, pulled off the valve cover and the cylinder head. The cylinder head gasket (metal) looks fine. The valve cover has no gasket! Weird! Here are some things that are noteworthy: the tops of the pistons are dry, just some charring; the cylinder walls are smooth; the valve openings on the left side are very charred; and the spark plug on the left side was fouled and charred pretty bad. Talked to some grease monkeys and they think that the valves are leaking and need to be re-seated. Any thoughts?? I don't know if this (re-seating the valves) is taking me in the right direction or not. Thanks!

Well, that was it!! I checked the points and sure enough, the main bolt was loose! Took it apart, cleaned it up, put it back to spec. . . and she cranked right up. Thanks all!! This club rocks!!

Hey all. Ive got my XS400 up and running then all of a sudden it died! It cranks and cranks but won't fire. I grounded out the plugs and no spark. Changed the plugs (New NGKs), still no spark. Changed the ignition switch and the coils. Still no spark. I do however get a spark out of the plugs when they are grounded if I turn the ignition switch on and off. . . What's next in line to change out? The voltage regulator? Rectifier? Ignitor unit? Any thoughts?? Thanks!!

Thanks to all for all the input (and patience!! ) I haven't got a chance to check the resistances yet, but will do this weekend. Thanks again. . . glad this club is here. Not many people know much about old bikes!! Special Man

I have read Cynic's posts, any my diaphrams are good and I know nothing about float adjustments or valve clearances. Is there any literature or manuals that explain how to check these things in detail? Thanks.

I have read Cynic's posts, any my diaphrams are good and I know nothing about float adjustments or valve clearances. Is there any literature or manuals that explain how to check these things in detail? Thanks.

Hey all. I also have a 1981 XS400 and I am having very similar problems. I've got the bike running and cleaned up, carbs torn completely apart, cleaned and put back. New plugs. . . the whole nine yards. I've noticed that when it is running, the left pipe is blowing hot and the right pipe is blowing cold. After a while the right pipe will start heating up and it spits and sputters. When it is revved up, I can hear that the right side is working but having trouble keeping it going. If I pull off the right spark plug wire, the engine continues on unaltered. If I pull off the left spark plug wire, the engine shuts down. I have swapped the spark plug wires and it won't start at all. One more thing I did notice is that the right spark plug wire shocks me slightly when I touch it. I figure that if it is a bad wire, when I swap the wires, the left wire should fire the right side, right? I have not done any compression tests and I don't really know too much about that. Any thoughts on what's going on?? and what direction I should go?? This may take some explicit instructions as I don't know much about valves and compression etc. Thanks for all your help!!