Unusual wr400 valve cover wear?
Posted September 19, 2010 - 12:55 PM
For your reference, I installed a rebuilt head a couple hundred miles ago, and the first time I checked the valves, I wanted to be sure my timing was spot on, and I ended up taking off the tension-er. When it was reinstalled I was sure to re-torque everything to spec. I do not recall the worn section on the valve cover as being there before. The only thing I do not torque is the valve cover itself which I can highly suspect is the cause of this problem, should I just not tighten it up as much?
I have also heard these bikes have poorly designed tension-ers that are prone to failure, is there an aftermarket replacement that works better?
Posted September 19, 2010 - 01:30 PM
Posted September 19, 2010 - 03:52 PM
When the OEM tensioners go, they tend to wear the chain due to too much tension, a worn chain whips (and eventually, can jump a tooth).
Posted September 19, 2010 - 04:10 PM
Posted September 19, 2010 - 04:16 PM
At the least, I'd replace the chain. Normally, it is swapped out every time the head is pulled at a minimum. Cheap insurance.
Posted September 19, 2010 - 05:03 PM
Also, what would cause such an exact line in the valve cover? I would think that if the chain was popping up like that, the scrape would be wider. I suppose this also explains some of the metal in my oil
Posted September 20, 2010 - 07:43 AM
Posted September 20, 2010 - 10:03 AM
Posted September 20, 2010 - 11:47 AM
Yup, head stays put. You pull the flywheel off, valve cover and cams. Job takes like 30 minutes to do, tops.
I'll be pleasantly surprised if the chain can be replaced without damaging it without pulling the head. If I remember the layout correctly, the threaded tip of the crank sticks out too far and it would take some serious forcing/bending of the chain to get it around the tip (if dropped from above).
To the OP - let us know how it goes.
Posted September 20, 2010 - 11:55 AM
Posted September 20, 2010 - 02:47 PM
Three broken links all within a couple inches. Was it just an old chain? Is there a bigger problem I should worry about? You can the middle links are broken and can turn up which would gouge out the valve cover.
Ordering a chain and APE manual tensioner tomorrow. Combined with the re-shimming of the exhaust valves, it should hopefully quiet things down and perform better.
Edited by nnamssorxela, September 20, 2010 - 04:23 PM.
Posted September 21, 2010 - 06:12 AM
Posted September 22, 2010 - 11:40 AM
Posted September 24, 2010 - 03:58 PM
Posted September 25, 2010 - 02:07 AM
Valves typically tighten, not loosen. You need to investigate further.
Posted October 13, 2010 - 01:41 PM
The orange pencil is flat across.
Posted October 16, 2010 - 12:32 PM