[Bosshog272]

Bought a non running 2006 VN900 after new fuel pump and coil got it running. Noticed a lifter tick most fourms said this was just a noisy engine but decided to check valve lash. Was surprised to find front cylinder was missing one shim on intake side and two on rear had 2 missing shims on intake side. Looked everywhere for them not in oil no metal shavings has anyone ever come across this didn't look like anyone had taken it apart before me only has 6000 miles on it.

 

[jbiggers]

Interesting. I don't know if there are oil return passages large enough to pass shims down to the bottom of the oil reservoir. If there are, then I might drain the oil, then remove the oil screen to try and find them. That screen is on the bottom of the engine on the left side.

 

[BikeMadPete]

shims

I wouldn't think it was possible for the shims to come out under normal operation by themselves.
I would think either they've been taken out or they were never fitted. :surprise:

 

[Bosshog272]

Found two of them in oil near the drain got them out with a magnet but still looking for the 3rd. Do these bikes have oil screen ?

 

[jbiggers]

Yes it does. It's on the left side of the engine, at the bottom of the engine. It's located right next to the frame. The frame appears to interfere with the screen's removal, so you need to bend the screen down just a bit to clear the frame. The screen is fairly long, so be patient getting it out. I forget the nut size to remove the screen cover, something like 14mm, which you will probably needs a wrench for. Also, no need to replace anything when you reinstall it, just lube the o-ring on the cover with oil, before putting it back in.

 

[jbiggers]

It suddenly dawned on me this morning what could have happened to cause the valve shims to come out. The only scenario I can think of, would be over revving of the engine, causing valve float. That's the only way enough clearance could have been temporarily created, that could allow the shims to fall out. However, I thought the Vulcan 900 engine was protected by a rev limiter. Am I mistaken about this?

 

[jbiggers]

After some research, this makes sense. Apparently the rev limiter on the 900 works like this. The cut out limit is 7200 rpm. However, when it cuts out, it does not stop the fuel flow, but cuts fuel flow every other cycle. If there is no load on the engine, then it can rev higher than 7200 rpm. This is unlike most sport bikes that have a hard rev limit, where you see riders in videos announcing their presence to other traffic with the rev limiter. It would be unwise to do this on the 900.

 

[BikeMadPete]

Surely shim mishtake.

That's what I was thinking, overrevving is the only possibility besides malicious/negligent removal. Maybe the spring loaded rocker arms move aside at high revs! :frown2: