My XS400 Leaks and Burns oil like Crazy

[Jamin Smitchger]

So this is the deal. I bought an old XS400 for 250 bucks. The bike was not running. I tore the carbs apart and rebuilt them. The bike started fine, but it was leaking and burning oil out of one of the exhaust pipes. I went through a 1/4 quart of oil in just about 10 miles, and the bike would just randomly die after a few miles. There was black smoke coming out of the exhaust pipe and oil leaking from the top of the exhaust pipe.

I decided to tear the bike apart this past weekend. I spent a couple nights last week removing the engine and just cleaning a lot of things out. The previous owner did not take care of the bike. I did a compression test and found that there was about 140 psi in each cylinder and that they were pretty much the same compression. I took the engine to a cycle shop and had them do a leakdown test. They said the results were inconclusive. The bike would go 60 mph on the highway so I don't think that there is bad compression, but where else would the oil be leaking from?

I tore off the head and found that the spindle of one of the rocker arms was missing on the side where the smoke was coming from, meaning that the exhaust valve was probably not opening? This is itself a serious problem, but not unfixable (i just bought a new valve cover for 16 bucks on ebay). However, I don't see how this is related to my oil leak problem.

At this point, I have decided to change the valve seals and maybe get the engine rebored. However, I have not found anyplace that carries piston rings. Bikebandit.com does not have them in stock. Anyways, tell me what you guys think about my oil leak problem. Feel free to call me random names like idiot, genius, fool, or potlicker. I promise I will not take it personally. I am very new to working on bikes, but I really do enjoy turning bolts.

By the way, what is the best way to compress the valve springs in order to change the valve seals? I already bought those so I might as well put them in.

Sincerely,
Jamin Smitchger

 

[ahale2772]

jamin, if your exhaust valve was not opening that can cause some serious head gasket pressures...I work on diesels alot and they use exhaust brakes that close off the exhaust and essentially force pressure back into the cylinder, lots of times guys will blow headgaskets because the gasses have nowhere to go....I would check the headgasket

 

[drewpy]

jamin,

you can make a valve spring compressor with a G-clamp and a couple of plates welded on to it for keeping the collar from slipping.

http://xlforum.net/vbportal/forums/showthread.php?t=395586&page=2

give the end a bash first to break the collar's grip

 

[lhaolpa]

I have a banjo type compressor,an overhead valve type and one made in the'30s for flathead motors.The type you need would be the banjo or C- clamp type,or make one like the link shows.Man,that guy really has a knack for improvising lha.