A Question about reassembling crankcase halves

I have yet to decide if I will pull my crankcase out but I am thinking ahead to questions I may have if I do so.

If I am reassembling the crankcase halves with sealant, should I put in the four through bolts (that secure it to bike frame) and tighten them as the sealant sets?
And then take them out before engine is reinstalled in frame?

It might be that if I use a non hardening sealant, this may not matter because not using the four through bolts when putting halves together
just means that when engine is installed in frame with four through bolts, there may be a little more squeeze on the sealant forcing a bit out of the
joint.

But if I use a sealant that sets flexible, say a Loctite anaerobic flange sealant, there could be squeeze against the hardened flexible sealant
if I only use the four through bolts when putting engine back into frame.

I would appreciate your thoughts or am I over thinking and it will work fine either way

Dennis

DennisMo said:

I have yet to decide if I will pull my crankcase out but I am thinking ahead to questions I may have if I do so.

If I am reassembling the crankcase halves with sealant, should I put in the four through bolts (that secure it to bike frame) and tighten them as the sealant sets?
And then take them out before engine is reinstalled in frame?

It might be that if I use a non hardening sealant, this may not matter because not using the four through bolts when putting halves together
just means that when engine is installed in frame with four through bolts, there may be a little more squeeze on the sealant forcing a bit out of the
joint.

But if I use a sealant that sets flexible, say a Loctite anaerobic flange sealant, there could be squeeze against the hardened flexible sealant
if I only use the four through bolts when putting engine back into frame.

I would appreciate your thoughts or am I over thinking and it will work fine either way

Dennis


View attachment 124003

Click to expand...

You already know the answer....

I like to get reassurance!

I would also put the cylinder in place and bolt it down at the same time. Then you are sure the cases are aligned along the crank axis and there is no step at the base flange

Thanks Andy and Concours. I have never pulled apart a Norton Crankcase so this makes sense. I figured there would be locating dowels on each half that locate into the other half so cylinders on is not needed?

DennisMo said:

I figured there would be locating dowels on each half that locate into the other half so cylinders on is not needed?

Click to expand...

Correct, only way to get rid of any step (which there should not be as they were machined together but things happen over time) is to remove the dowels and clamp the cases to the barrel, or machine the cases buttoned up with dowels in place. Note the dowels should be registering the main bearings in line, so by removing them to get rid of the step you risk having a flat barrel base but a crank not spinning freely.

That makes sense.