valve guides
 

Hi all
I am in the middle of a full engine rebuild on my girlfriends 640 adv it a 2003.
I am reconditioning the head, new valves and guides,
I have reseaved the new guides from ktm and they don’t fit the valves.
The internal diameter is too small, after speaking to the dealer he said that they come unfinished and they need to be machined to the correct diameter after being fitted.
I have never come across this before on a rebuild, so is this correct?

Thanks Iain

Yes its quite common.
 

I'm not certain about how common it is for bike engines - but for other petrol engines it is quite common. The guides are an interference fit into the cylinder head and this causes them to close up slightly on installation. They are then 'reamed' out to the correct finished size. Any cylinder head place should be able to do this (and also press fit the guides - much safer than the alternative large hammer method)

thanks for the reply Martin
going to drop cylinder head off today to get the work done. then on to putting the bike back together, (with no large hammers ):mchappy:
thanks
Iain