I contemplated heliarcing both or just putting the threaded insert on the other side to even them out, but I got a little tired of the constant issues and knew I would need to do another valve seat regrind if I TIG'd the holes up and tapped them. I really hate these butterheads, I always wondered why my bike didn't get the LK heads. Maybe they were replaced long ago before I got her.
I have been using a few repro pieces from Uli's Motorrad in Frankfurt for many years. Valve covers and a deep oil pan. The quality of the aluminum always seemed excellent to me. I can tell from just pushing a nail into practically any point on the metal that it is much harder than the original. The machining seems impeccable to me, tolerances are very tight.
So I decided to bite the bullet and get a set of repro heads. These are available from Bobs for only $550, but they only had one in stock and had to special order the other side. I didn't want to wait (with the lockdowns in Germany my cousins there are telling me its slowing everything down) so I ordered from vintagebmwparts (spike buck on ebay) for $1500 for a set shipped. Pricey, but it came to me in 2 days. 1 year warranty (I know, not much to tell in 1 year).
I called Uli's and spoke to Uli in Frankfurt, very nice guy. I wanted to know where these were made, he would not say. I kept asking "are these made in Germany?" and he kept saying "These are made for Uli's Mottorad exclusively". I asked if they were made in Europe and where and he would not say.
The quality on the heads is up to par with other things I have seen from Uli's. Tight machining, seems like damn good metal. No porosity in the aluminum anywhere I can see, even in webbings and around edges. The valves seem more like stock valves than any of the aftermarket "black" valves I have seen that sell for so much money. Can't tell much about the springs or the guides, they look good. Seats are ground without any apparent flaws, I regrind my own seats so I can tell this is professionally done and isn't some kind of hacked hand lapping.
They head design itself is kind of interesting. It's definitely not patterned off the LK design. The fins aren't as thick as a butterhead but they are not as thin as an LK. Also, the bottom of the cylinder is not "tubed" and is filled in, like the butterheads. It uses a short reach plug, and of course the threads are tapped directly into the aluminum (no insert at all, like the LK's). So I am liking this- a always thought the LK's were a little too thin and had broken fin potential. Seems like a good mix of designs.
Exhaust threads are nice and stout, no hard edges. Studs are all new with zinc plating, came with the valve cover stud as well. No markings or clues anywhere these are made, but I suspect either Germany, Czech Republic, or Poland if its Europe. I doubt these are South Korean, just a feeling though. I have had some experience with South Korean Harley head copies and they just don't stack up to this tolerance.
I used my special vacuum tester to test the seats. My standard is to apply vacuum to the combustion chamber side, with only the valve spring pressure holding the valves closed. I just think this method will scrutinize any setup considering it's not pulling the valve closed but pulling it open. I read 26 inches on one and 27.5 on the other, all good and within my spec for this. The old heads I have, which were reground and hand lapped by me, pull around the same.
Popped everything on and then ran a cold compression test. I reused my Nural pistons because they were solidly in spec, just deglazed and new rings. 120 psi on both cylinders. Pillow blocks went right in without any shimming or adjustment, all good. Torqued then and waited 24 hours and torques again, they didn't budge at all.
So, so far so good. I'll be putting around with these and seeing what's up. Hopefully I can get some serious mileage on them to tell if things are good. So far impressed.
