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NC30 Valves won't reach TDC
Posted: Thu Sep 15, 2011 6:28 pm
by Adderboy
I'm undergoing a valve clearance check on a new engine before fitting it to my bike, but when the T2 mark is in the right position I cant get the lines on the camshaft to line up properly. I havent taken the cams out on this engine before, but i dont know if a previous owner has, does this mean the timing is out?
Any help greatly appreciated.
Re: NC30 Valves won't reach TDC
Posted: Thu Sep 15, 2011 7:55 pm
by CMSMJ1
One which camshaft is this?
Re: NC30 Valves won't reach TDC
Posted: Thu Sep 15, 2011 8:39 pm
by Adderboy

Just realised I have drawn out a sheet to write the clearances out on, and your comment made me look at it again and realise I labelled the pistons upside down - so my piston 1 is actually piston 4 - schoolboy error!!
Thanks for your help

Re: NC30 Valves won't reach TDC
Posted: Thu Sep 15, 2011 8:51 pm
by CMSMJ1
lol, no worries. It seems complicated but it actually isn't.
Are you running them closer to tolerance or a touch on the open side?
Re: NC30 Valves won't reach TDC
Posted: Mon Sep 19, 2011 10:18 pm
by Adderboy
No, I was just confusing myself, i do valve checks pretty often on various bikes, hence me feeling so stupid
And I was aiming for tolerance, but the shims i need are going to have to be bigger than i had hoped [The clearances were further out than anything I have measured before] so it looks like using the shims i have available will leave them a little on the open side - your comment makes it sound like this could be benificial? I have only ever aimed for tolerance before so I wouldnt know.
Re: NC30 Valves won't reach TDC
Posted: Mon Sep 19, 2011 10:22 pm
by CMSMJ1
I always aimed for .17 rather than .15 on the inlets and the same on the exhausts - .2 loose.
Open is not as bad as too tight IMO. The HRC manual has them at .20 if I remember it right...
Re: NC30 Valves won't reach TDC
Posted: Tue Sep 20, 2011 8:00 pm
by Adderboy
You are absolutely right, aiming for the more open end of the tolerances has given me a little more room to play with, and made it much eaisier to find the right clearances - Thanks!
Also i'm presuming the gaps naturally tighten over time but I cant find it mentioned in the manual I dont suppose you could continue to enlighten me please?