Hi all,

I'd like to remove my 499cc cylinder head to look at the valves. I've taken all the 6 head bolts off and exhaust bolts etc but it seems well bonded to the lower engine. I gave it one whack with a rubber mallet. The engine is still in situ as is fan tinware.
Any tips to get round this admittedly basic problem?
Thanks, David

Have you taken off the 2 'hollow' bolts--1 each end of the engine underneath the exhaust manifold? These allow the exhaust gases to escape should the head gasket blow (as does the machined ring in the cylinder head)

Yellblob said:

I've taken all the 6 head bolts off

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Hi David...I hope you've actually taken all 8 nuts off the head studs...two under the carburettor?

I would try a more solid mallet such as a copper one or a hard plastic one wth lead shot inside.

what you can do.. is put a couple of bolts back in if it' still stuck...
but leave them a little loose...
presume carb removed..
spark plugs in..no plug leads
and turn the engine over
the compression should be enough to break any gasket seal...
if not... then something else is stopping it....

Thanks, all your tips were useful. I did mean 8 Peter although I said 6! I found that one blow off nut was missing at the back, can't have been helpful. The insides are carbonated and orange in places. Im going to borrow some spring compressors shortly. How best to clean the deposits off? Thanks again

David, in my humble opinion that looks quite healthy.

I may well be wrong but is that a crack from the bottom exhaust valve towards the outer edge? You'll see it better once you get the carbon off.

Paolo66 said:

I may well be wrong but is that a crack from the bottom exhaust valve towards the outer edge? You'll see it better once you get the carbon off.

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Got my glasses on and looking at it enlarged on the laptop....I see what you mean now Damian . Let's hope it's just a casting mark because there's no obvious signs of damage on the valve.
Images are hard to read for things like this, the valves might be a little recessed, may be slightly oval but I things it's just the angle of the camera and distortion of the lense...but the colour tells a good story for me.

I was thinking the valves looked recessed as well but easy to diagnose from afar

Updated pictures after a bit of cleaning. Eagle eyed of you Damian, but is it significant? It has rounded edges to it the "crack". That was the side missing the hollow nut. I'll remove the valves soon, but they seem to be OK as does the combustion mixture? David

Have a look at my "crack".

MAL_4814 by Peter Thompson, on Flickr

For guidance, this is the same head with the valves seated not too badly.

MAL_4810 by Peter Thompson, on Flickr

It doesn't look too bad to me. Rather than a crack it looks like a casting mark. If you compare it to Peter's picture it looks to be in the same place and if you follow it up in David's picture you can see the end of the line where the gasket is.

Tony

Yes, I don't think its a crack so that is good. The exhaust valves after twirling with some grinding paste still seem to be pitted. I'd be grateful for advice on how significant that is. In comparison the inlet valve and collars are very smooth. Cheers, David

I would replace those exhaust valves, they are not expensive and if you cannot get a good seal then the hot gasses will destroy the valve and possibly the seat.

I took my cylinder head to cylinderheadservices in Bilston today. They reground the exhaust valves and vacuum tested them. He said there wasn't a crack, just a casting mark. They noticed the cylinder head was well warped and so skimmed it flat and also honed my cylinders - all for £40, which was a good value. Unfortunately there was a vertical gouge line in both cylinders which he said looked like overheating damage. It looks like I should replace with new pistons and cylinders.
If I go for a matching set should I look for any particular size other than for a 499cc? Thanks,
David

Sounds like you got good value and service there, hard thing to find these days at least in my neck of the woods. The only option you have with the standard 500 crankcase (unless you have it bored out) is for a rebore or the Nanni 540ccs kit which will give you a modest increase.

Thanks. The Nanni 540cc kit looks interesting. Also saw a very nice all in one stainless exhaust....
I wonder why my engine overheated in the first place (before I got it), oil wasn't changed?