Can't adjust my valves cos its stuck

I'm trying to adjust my valve clearences today on my scooter. Got it tdc and done the top valve no problem but the bottom valve which I assume is the exhaust wouldn't open. I loosened the nut and turned the screw. But there is no gap no matter how much I turn the screw out please help

 

sounds like you have it on the wrong stroke, turn the motor over again and it should be right

 

I've tried that mate still no joy

 

sounds like something is very wrong then. i can only guess the camchain went loose and you have bent the valve. is the cam turning with the motor?

 

Yes mate the cam is turning as it should and also the timing is ok. Just seems like the valve is stuck or blocked. Don't understand it cos it's a new head that was out on about 4 months ago

 

Oh and the tension on the cam chain is as it should be. Nice and tight

 

must be sooted up in the port, has it been burning oil/running rich?

 

Sound's like it's burnt the valve seat out!

 

turn the engine by hand while watching the cam pushing the valve down, if it does nothing either up or down then off comes the head for inspection.

 

Took the head off today to inspect it and couldn't see anything wrong with it. My cousin is coming to look at it later and he's a time served mechanic

 

Put a new barrel,piston& rings and also a new head. Put the cam on and made sure the timing was ok. But when I've come to the last job of adjusting my valves the exhaust valve is closed and I can't get a gauge behind it no matter how much I screw it out?! Please help. Is it my rocker arms bent? Replaced everything else apart from them and the camshaft

 

maybe the cam is REALLY worn? like totally round...?

 

No mate cam is egg shaped

 

how strange? cant think what else it could be!

 

might sound daft but is there a possibility the cam shaft is bent or damaged in anyway? even the smallest of bends could cause issues. seen it a lot in cars.

 

Haven't got a clue what it is at the moment lads. I've left it with my cousin who's a time served mechanic. Bought new bore/piston. New head and new rockers so hopefully when all the parts come and he puts it together it should be ok?! If not there's only the cam to change lol. Don't think its that tho it looks perfect at close inspection

 

Alright guys my cousin fixed the bike today. Put a new head. Piston/rings/barrel and new rockers on and it's running great! Thanks for the help