I use Go-No-Go gauges so yes you can get pretty accurate..
Yes forged require more cylinder clearance than cast..
I'm sure Fuel Moto has a lot of experience with these 110" kits so it just might be by design.. look at it this way with a liner thickness that's 1/2 of what a stock 103" cylinder is @ .130" and what I measured the 110" cylinder sleeve at .066", maybe there's more expansion (growth) of the cylinder which would close down on the bore a little more requiring the bigger gap.. We all know how hot these twin cam's get..
As a cylinder gets hot, the aluminum outside along with the steel cast in sleeve of the bore gets larger too. (The bore hole gets bigger)
The aluminum piston grows bigger diameter around. The compression drives the ring down on the ring groove of the piston and outward on the cylinder bore.
Especially the ring with the bevel. It's my understanding the ring gap doesn't get measurablely smaller while running.
Last edited by Jackie Paper; 03-11-2023 at 05:00 PM.
Well just my experience and opinion, but I'd get another top ring set. Yea it'll run at that dimension, but why bother? It would probably run at .030 too... You're over .006 per inch at .026 total.
Ring gaps close with temperature, thats why boosted apps will run looser
I had a hard time believing the measurements so in better lighting I redid them and found it a little different.. I measured both sets of rings in both the cylinders and this is what I found.. These were extremely accurate measurements or should I say the best I could do...
Last edited by 98hotrodfatboy; 03-11-2023 at 08:54 PM.
I found some more interesting info on ring end gaps in the following links.. https://www.enginelabs.com/engine-te...-ring-end-gap/ https://static.summitracing.com/glob...m-1000-125.pdf
Both list the standard setting for a Naturally aspirated motor at .0065"/inch.. But not sure if this includes Air cooled Harleys.. We do know that Harleys retain more heat because they are not liquid cooled.. So could my gaps of .024"/.029" be correct??
Still confused a little cause when I was fitting 3.5" Evo's gaps were .016"/.020".. without issues..
KB info for their forged VTwin pistons have same specs as CP. That's a good article, and further down they state JE specs as the same too.
It'll run fine, but I'm picky. It would be different if I were doing my own rings and went a touch too far with the gap, as opposed to being handed a set with no room to change gap as I desired
KB info for their forged VTwin pistons have same specs as CP. That's a good article, and further down they state JE specs as the same too.
It'll run fine, but I'm picky. It would be different if I were doing my own rings and went a touch too far with the gap, as opposed to being handed a set with no room to change gap as I desired
That's just it.. I always set my gaps.. This is the first time it was done for me..
03-11-2023, 04:50 PM
