Top End Troubles

[LtBadass]

Hello everyone!
So, I rebuilt the top end of my 1982 xs400 Maxim, and have been having some troubles. Pulled her apart and found that my intake valves have been banging on pistons, and the rubber end of my cam chain tensioner has been shredded. I had a lot of trouble on the rebuild getting the rear cam guide in correctly, and am not totally confident that I did so, even though the engine chain was tight. This probably accounts for the head of the tensioner being shredded (unless I installed it incorrectly.) As for the valve/piston collision I can't help but think that my timing is off. I struggled a lot with my vague service manual instructions, and no matter what I did couldn't get the markings on the cam shafts to perfectly line up with the markings on the cam caps @ top dead center.

In addition, on of my valves exploded and embedded itself in the top of the right piston after about 30 miles of riding (running very well aside from the tapping).

I'm going to be re-rebuilding the top end and would love some advice/assistance with the following:

1. Read cam chain guide/cam chain tensioner installation.
2. Cam sprocket/chain installation/timing.

Let me know,
Much thanks!

 

[LtBadass]

Still lookin for some help.

 

[BBS360]

My engine is probably more than a little different but I would speculate that if the chain guide were not seated all the way down/in it would be too tight against the chain right away instead of letting the tensioner take up the slack.

 

[LtBadass]

Yeah, that's what I'm thinking.
Good advice, thanks.

 

[LtBadass]

Any advice on timing?

 

[BBS360]

I timed mine with a multimeter set to test continuity between the ignition points and a nut on the frame. It'd beep when the points close.
You probably have an electronic ignition though. I don't think that technique would apply to your bike.

 

[arfstrom]

Hi there, I ended up doing that this last spring. My bike is not an 82 version. So there is obvious differences. I was able to get a seal/rubber gasket set from ebay. Get a torque wrench, I set up a couple of saw horses, then I also did. I got some replacement parts, a guy that I took my head/cylinder apart, I found out that I can not do the valves. my mechanic could pop them off fast. tested out the cylinder for circlur circumference, (what ever that test is called.) perhaps run a glass beads though it. I had a hard time with the acorn nuts, and some people didn't like my video. (thought it was irresponsible) If anyone follows my advise, I hope they have strong tools that can handle that abuse.