No FCV Piston!

[swerver]

I dropped the oil this morning on this bike because when I started it up with the dash now attached I was getting the oil pressure warning light, so I thought I'd investigate the FCV as there is the correct amount of oil in there.

FCV Bolt came out, followed by the spring and the oil, but no FCV piston in sight. Waited for all the oil to drain out and then shone a torch up inside the FCV aperture and there is no piston!

Slightly worried about the implications - anyone know if this would damage the bike not having it in there while the engine is running?

Finally, anyone got an FCV piston kicking around they want to sell?

[Diverence]

alice has lots of them i bet!

[king karl]

ive got some fcv jobbies new... are ya sure its just not got stuck up there

Get something small like ya cock and see if ya can feel owt

[cr500erider]

I think your valve will be still stuck inside.
I am curious on what thoughts about damage done if run bike with no valve installed as I recently ran my bike with the retaining nut sheared off

[swerver]

my cock's too small kk

Pretty sure I'd be able to see it if it was just stuck up there, I can see right up inside with a torch shining in there and it defo isn't there - more likely that it fell out in a previous oil change and wasn't put back in?

[swerver]

I am curious on what thoughts about damage done if run bike with no valve installed

Me too, although all the FCV does is regulate pressure - to paraphrase Jim Hubert: It simply shunts excess oil flow from the outlet side of the pressure pump back to the inlet side of the pressure pump. Dunno if having the piston missing can cause any damage though?

[usherp_250]

Pm sent..

[swerver]

Going to pick up a new one from Corsa Italiana tomorrow.

Would be good to know if it is even possible for the piston to get dislodged and wind up somewhere else inside the case though? If that's impossible I'm pretty sure it isn't in there, cos I'd be able to see it.

[Markee]

I would think it's still in there. Get something like a 8mm bolt that's about 100mm long, stick it up the hole, till it tops out and push it sideways (using the threads to grab the threads on the inside of the FCV) and pull down.
I bet it's just stuck in there. Mine just doesn't "fall out" when the spring is removed.

[amauri]

Me too, although all the FCV does is regulate pressure - to paraphrase Jim Hubert: It simply shunts excess oil flow from the outlet side of the pressure pump back to the inlet side of the pressure pump. Dunno if having the piston missing can cause any damage though?

Yeah, and if the oil pressure is flowing from the outlet side of the pump and back into the inlet side, then there're isn't any oil going to the bearings is there?

If you run the motor for more than a few seconds without oil pressure, especially under any kind of load, you can kiss goodbye to your bearings and crankshaft.

The bottom side of the FCV piston is threaded for a 10mm bolt that you can screw in to remove one that is stuck.

Let's hope your is just stuck in there.

[SXVINWA]

Also, it's a 10mm X 1.0 not a 10mm X 1.25 if you plan on buying one.

[J_B]

A little off topic, when should the FCV be replaced? How much scoring is too much?

[swerver]

Thanks for the comments guys, I'll try a M10 x 1.0mm bolt but I really don't think it's in there - I can see up inside the case further than I would be able to if it was in there. I'm hoping the previous owner just forgot to put it back after the last oil change which was done after the last time the bike was under any kind of stress - since then it has just been started for a few seconds a few times.

Markee: on my old SXV the FCV piston used to fall out most times I changed the oil

[jay dub]

A little off topic, when should the FCV be replaced? How much scoring is too much?

I wouldn't get too uptight about it unless it's pretty scarred up, but I kinda doubt it is. There's mixed feelings about replacing them, but I've never had issues w/ them besides trying to remember if I put it back in. There super cheap so it never hurts to have a few new ones lying around for ease of mind.

[amauri]

Scorring on the side of the piston is normal and not a concern.

When the motor is running, the piston can move up/down as the pump buids up pressure and overcomes the spring pushing on the piston.
The only time I replace them is when I see wear or scoring on the sealing surface of the piston, that is the flat top side.