V11 Sport with strange metallic rattle

[coreytrevor]

 

Also put my finger on the crankcase vent for a while during running, but she does not seem to build any pressure really.

 

You would have to plug the drainback line also. The pressure would get out that way if you plug the vent.

[luhbo]

You should find quite a remarkable pulsing, somewhere, as both pistons move in and out rather synchronous.

[Tinus89]

 

Hey all,

 

Took out the check valve, ran the engine: silence. The rattle was the little ball jumping up and down on the crankcase pressure.

 

I looked back at the 1999-2001 parts diagram, and no "check valve" ball. Tinus89, how about a brief video of how she runs and idles without this thing? Photos of what you found and where?

 

Are we thinking it was fitted between the  [metal] "breather pipe" #14 and the [rubber] "breather pipe" #18?

 

 

Yes, correct. Interestingly, I cannot find any bike drawing (any year) where that check valve is in place. It is a short metal bushing with a ball bearing in there, which slips into the metal breather pipe (14). I can imagine that if hose (18) is very tight, it could also remain stuck in the hose once you pull it. I will get some pics of it online hopefully tomorrow, busy day/eve tonight.

A video I will be able to do Wednesday earliest, but will do!

 

 

 

Also put my finger on the crankcase vent for a while during running, but she does not seem to build any pressure really.

 

You would have to plug the drainback line also. The pressure would get out that way if you plug the vent.

 

 

Why exactly? The crankcase, frame tube and drainback line are an enclosed system, of which the only exit is the vent line (directly behind the headstock bearings) which (normally) goes to the airbox.

 

You should find quite a remarkable pulsing, somewhere, as both pistons move in and out rather synchronous.

 

Yes, I did find the pulsing. But when I kept the hose closed for say 30sec, and then let go of it, there was no pressure release (thus no buildup)

[luhbo]

Your engine isn't that bad. Maybe once it's done 200000 or more. Maybe.

 

One thing I remember after I've put in new rings was that the water/oil foam agglomeration under the valve covers went down to nil. Nearly as good as a leak down test

[coreytrevor]

 

 

Also put my finger on the crankcase vent for a while during running, but she does not seem to build any pressure really.

 

You would have to plug the drainback line also. The pressure would get out that way if you plug the vent.

 

 

Why exactly? The crankcase, frame tube and drainback line are an enclosed system, of which the only exit is the vent line (directly behind the headstock bearings) which (normally) goes to the airbox.

 

 

I misunderstood you. When you said crankcase vent I took that to mean the hose from the crankcase vent to the frame. The way you did it is valid.

[Tinus89]

I misunderstood you. When you said crankcase vent I took that to mean the hose from the crankcase vent to the frame. The way you did it is valid.

 

 

No problem:) Happy we agree!

 

So I took a video of the bike running (she was cold though, the valves are a bit louder then normal.

 

Initial video with rattle: https://www.youtube.com/watch?v=4chn9SpxJQM

New video without rattle: https://www.youtube.com/watch?v=xkaRpMgOKxA

 

Here is what I took out (no, not the soda cap, that's for perspective):

 

 

Actually, the "cap" on mine was loose, which may explain the rattle, but I don't really feel like putting it back if I don't need it.

Disassembled:

 

 

 

So, with the second compression test being good, I will still take her for a test ride somewhere this week, but I expect this topic could be marked "solved" soon:)

 

 

UPDATE: Took her for a spin. Filled her up with 102 fuel and drove her. Hard. In the dark. I mean real hard, almost drove myself off the road missing a corner .

But seriously... It's interesting how after more than a year of misery and mistrust in the bike, the love comes back so fast. WOW I love this machine.

After the rather spirited ride, I left her idle for minutes while readjusting the headlight (up, don't want to miss corners again) and then revved her a number of times real hard. No oil out of the breather vent, so I call it:

 

FIXED!

 

Wonderful community. Thanks all for all the help!

[Lucky Phil]

Compression test worked out then, very good. Removed breather valve appears not to be an OEM component.

 

Ciao