E: Engine Cylinder Liners
- Thread starter Cyborg
- Start date
Just wanted to confirm that you really did spoil my day. My wallet is a little lighter now. BTW… how could they be round? The thinner area around the pushrod tubes obviously moves more than the rest. Reminds me of my connecting rod bigends.
I recall Greg saying that… or was it new liner muff assemblies? I was just trying to block it out.
The problem is there are several things to measure and double check........not just the bore/liner condition.......Obviously the bore size is important, but also the height of the muff or both for a twin.......These new are 3.062" I've had some that were down to near 3.00" and some that one was 0.040" more than the other........But the absolute vital one is the height of the liner hat at the top...... So the head recess should be 0.125" depth and the liner should be more......0.127" or similar.......Once the liner/head joint have been lapped in once or twice, this figure is lost. I have a large glass surface plate that I rub the head face down, but it is quite difficult to remove a couple of thou off the head face. You can turn the barrels with an expanding mandrel in a lathe, and this will work. The oil feed hole is again another issue, most factory liners, the hole is too high up injecting oil into the rings. Once I check all these things, it is often easier and better to simply replace the complete assemblies........With modern pistons and in our hot climate, I give the twins 0.0035" clearance and singles around 0.005"........ All in a day's work........ Cheers.
Having just done that job (with a bit of help) I machined the liner "hat" at .125. Next the heads go in the lathe and get just a clean up tickle on the liner hat face followed but a .123 step to the head face. No coarse/fine/lapping involved, on these heads (unused since 1956) it was a very small tickle on the head but nice to see it all clean up running true.
Like you .0035 clearance seems to work well on twins.
Like you .0035 clearance seems to work well on twins.
Even with new, machined surfaces, at the least I still like to lap the top of the liner/head surfaces only with fine paste. Some of the new liners the top face is not flat........in this case I dress this off on my surface plate first.........The new top end kits from Terry that use to be available were prone to leaks at this joint, mostly where the cutter for the head recess came around full circle back onto the start...... on these I lap the liner to the head before the liner is installed into the muff.
Just got pistons (rings and gudgeons ) liners and muffs for my rapide engine rebuild from Neal Videan a little over A$1300 Happy Days
Wow, cheap! That's about the same price as one 90mm kit from Conway. Nikasil and Omega piston.
