No Valve Lash

[hudson]

I am losing my mind, so I am trying to step back and also get your input. I am installing my rebored cylinders and head. I have done top ends before, but I can't figure out what the deal is - probably very simple. I will skip the piston, cylinder installation. After the cylinder is drawn in to the engine wall evenly, when I put the head on, and slide on the rocker assembly, I have no valve lash on the input side, even with the adjustment valve screw backed all the way out.

The side I am working on was the side that had no problem, but I rebored to match the other side that was smoking and had a deep nitch in it (my previous post not too long ago on reboring or rehoning. BTW, I had to get them rebored and to the second oversize piston and rings).

The side I am working on is OTC - it was left in tact on this side when I removed the parts- (but carefully rotated anyway just to verify), the "vorn" is facing forward (and the larger groove on the piston is for the input valve), pushrods are even and free through the head, the cam followers are seated properly and lubed, the pushrod tube seals appear all the way seated. The exhaust side is totally fine? What gives? What stupid mistake am I doing? Not thinking clearly due to frustration. Any obvious steps I am forgetting?

[Kurt in S.A.]

About the only thing I can think of...are you sure that the pushrods have dropped into the indention on the cam followers.

Kurt in S.A.

[hudson]

I can feel the pull on the exhaust side, but mildly on the input side. Wouldn’t the rod stick out farther though if that were the case?

[Rob Frankham]

I can feel the pull on the exhaust side, but mildly on the input side. Wouldn’t the rod stick out farther though if that were the case?

Is your engine one of the models that has spacers between the rocker arm support and the head casting? and have you forgotten to fit them?

Rob

[hudson]

Yes they have the o-rings that slip on and the spacer sleeves, then the rocker slides on against it. I will recheck to make sure the spacers are definitely pushed all of the way back. It has to be an assembly issue error - the darn thing fit before! LOL.

[gspd]

You must do TWO full crankshaft rotations to be back where you were when you took things apart.
What's OTC?
Don't you mean TDC ? (top dead center)

On which side of the engine are the valves 'rocking' (overlapping) at TDC.
you can determine this by turning the crankshaft forwards and backwards a few degrees from TDC (0 mark on flywheel ) while watching the valves open and close.
The easiest way to nudge the crank back and forth is to move the rear wheel with the bike in top gear.

set proper clearances on the side that IS NOT rocking
then do one full revolution of the crankshaft and set the other side clearances.
hope this helps

[hudson]

Yeah, I mean TDC, but I think it is marked OT on the flywheel . Gotcha on the rotation. I've been using the rear wheel to nudge. I haven't gone back to it yesterday, but will do so when I get home from work today. I know it is something simple that I overlooked -either the TDC is off or the spacers mentioned. Thanks!

[Rob Frankham]

Yeah, I mean TDC, but I think it is marked OT on the flywheel . Gotcha on the rotation. I've been using the rear wheel to nudge. I haven't gone back to it yesterday, but will do so when I get home from work today. I know it is something simple that I overlooked -either the TDC is off or the spacers mentioned. Thanks!

With the adjusters wound right out, the rockers will be free to move no matter where in relation to TDC the crankshaft is positioned.

The easiest way to move the crankshaft is with an allen key in the bolt at the front of the alternator rotor... preferably and allen key socket on a ratchet socket wrench.

If I were in your position, I'd first assemble the heads without the rockers, insert the pushrods and turn the engine pressing the ends inwards. This would prove that (a) the rods are seating in the tappets and (b) that the tappets aren't stuck in the crankcase.

Have you replaced any relevant parts?

Rob

[gspd]

Rob said:

The easiest way to move the crankshaft is with an allen key in the bolt at the front of the alternator rotor...

I find that turning the crankshaft via the rear wheel (in top gear) is easier/quicker during routine maintenance because you don't have to remove the front engine cover, which on some models requires removing fairing parts, splash shields, horns and/or crash bars. Also, there is a chance of shorting the cover on the diode board if you don't be very careful or disconnect the battery.

Also, sometimes the rotor bolt will sometimes unscrew instead of turning the engine backwards, even with the spark plugs out.

[Rob Frankham]

Rob said:

The easiest way to move the crankshaft is with an allen key in the bolt at the front of the alternator rotor...

I find that turning the crankshaft via the rear wheel (in top gear) is easier/quicker during routine maintenance because you don't have to remove the front engine cover, which on some models requires removing fairing parts, splash shields, horns and/or crash bars. Also, there is a chance of shorting the cover on the diode board if you don't be very careful or disconnect the battery.

Also, sometimes the rotor bolt will sometimes unscrew instead of turning the engine backwards, even with the spark plugs out.

Fair comment, but you can be much more precise with an allen key and, when the bike is on the ramp, it's likely that you're going to want the front cover off anyway. If the allen key comes loose... tighten it... but, as a general rule, it is considered bad form to turn an engine backwards anyway.

Rob