Hi. I am installing new H.D. stock piston/ring kits in cylinders with 10,000 miles on them.
Do the STD rings need gapped or are they pre-gapped for the stock cylinders?
What should the gap be?
If anyone has tips or info that will help me on my top end overhaul, I'm all ears!
Here's pics of the DME heads that will go on also...
Thanks

 

If you don't have a shop manual for your bike, get one. Money well spent. The manual, and probably the white paper for the rings you bought, will usually state the gap specs. Normally it runs about .004 per inch of stroke, which puts most setups at between .010-.025 of gap - but I would trust the manual or the ring documentation first. If you don't have a ring spreader, be careful if doing it by hand. It's easy to twist/break new rings when doing it by hand, aside from the small cuts you usually get on your fingers from the sharp edges.

Also, whenever I remove a top end I like to take a ball hone and "deglaze" the cylinders before I reinstall. This gives a fresh cross-hatch pattern and allows the rings to seat better on a new surface.

Have fun! It's not rocket science...

 

I'm sure you meant to say bore not stroke...

 

Them are some pretty heads ya got there.

 

You're absolutely correct Chuck, and thanks for catching that. It's what I get for trying to add value by making a quick response to a thread while at work - and it ends up being of no value at all because I rushed.

To the OP - My intent was to say .004 for every inch of BORE as Chuck states above. My bad...

 

Thanks for the info.
My gap is just over .015. I can't run a .016 through and the .015 has just a touch of play.
And a manual is as important as any part you can buy! My local dealership said 5-7 working days to get one from H.D. I found one in Ca. on Ebay and it should be here by the 8th.
The arrows on the pistons for a "V" twin face the intake valves or do they face forward like a single cylinder?

 

https://www.uempistons.com/catalogs/...le_catalog.pdf

some very useful info here^^^
end gap also depends on type of piston and intended use.