Hello,

I'm just doing the valve clearances on my nc30. Cylinders 1,3 and 4 are all in spec but there in no Clarence on the valves in cylinder two.

I've not removed the shims yet but the rocker arms are free enough to slide across to remove them but there's not enough clearance to get a gauge in to see how much I would need to reduce the shim by.

Has anyone come across this before? Any advice would me much appreciated.

Whats the smallest gauge your trying to slide in there? If there really that tight then something is a miss

Can't get a 0.05mm in there but the rocker arm will slide off. Can't see any excess wear on the cam or anything untoward. I hope its not a head off jobbie...

If it is could it be valve seat wear?

More likely Valve stretch i would think, had really tight clearances on mine i then rebuilt the heads to find the seats where ok other than the obvious carbon build up and i think one was as low as 0.04mm. Luckily the worst head was shot due to a slightly dropped valve guide so i sourced a better condition one and swapped a few valves around and it was much better.

My advice is to set the clearances at the looser end of the scale and check again in a few thousdand KM, if its tightened up loads then whip your heads off and give them a refresh.

If you cant get a feeler in there just reduce the shim size by the maximum clearance given in the manual, I've always set my bikes on the slack side. Bikes usually tighten up clearance, unlike cars which go the other way or they used to before hydraulic tappets came about.
Cheers
Ian

May be a silly question, but have you got the timing mark right for that cylinder?

Thanks guys, as you said it seems like the valve clearances had gotten tighter rather than loose. Whipped the shims out and after measuring them they where toward the larger side of the scale. Re-shimmed all the valves to the slacker end of the tolerences now all have a correct clearance.

Will the bike run any better now that all the valves in cylinder two have the correct clearance (rather than none!!)? Bike is still in bits whilst I do other maintenece so can't see for myself yet.

If there was no clearance in that cylinder then it won't have been running well at all, so yes it should be much better now.

Doubt you will notice a huge difference but the motor will tick and tap a little bit compared with before but that's nothing to worry about.