Now with the first approx. 300-something kilometres (200 miles) done, it's time to look back a bit, report some of the mishaps and also ultimately evaluate whether all of this was actually worth it. (Hint for the impatient: Hell yeah.)
As can be seen in the picture below, yours truly didn't skimp on oiling up the cylinders properly, which resulted in a massive smoke cloud inside my workshop. It might have been so bad, that this Winters mouse problem might be a lot less substantial than the years before.
The first 30km of run-in were generally rather uneventful, it was a very hot day and due to the increased internal friction and some (admittedly) rather tight clearances the oil quickly got to 120 degrees celsius.
Interestingly enough, for some odd reason, the front cam cover just didn't want to seal properly, even though it was fine on the old motor and not even a new seal would cure it.
I also installed the wrong oil-pressure switch (a closer), which meant the warning light would light up instead of go out. The Volkswagen-part-number below will get you a blue 0.35bar opener, which is an acceptable substitute until I can get a switch for the correct range. It starts flickering at around 0.6bar, which is quite a bit lower than you'd want to go in terms of oil-pressure on such a crank.
... and then there was a little rideout with my dad, when spontaneously the rear plug decided to call it quits and I had to get some H*nd*-branded BP7ES plugs. Aside from that I could feel the engine starting to free up at around 100km on the clock and it became apparent that the old girl is actually quite a bit faster.
Because I didn't want to drill holes into the cylinder heads, I originally opted for BT1100 inlet rubbers. This sounds like a clever idea on paper, but it isn't as the retaining lip is a different shape and the carbs aren't held in very well. At this point I also started to tweak the carbs and installed #185 mains, instead of the #175s I had in there before. I also had to tweak the air-screw a bit and increase the idle speed as those welded up heads just flow A LOT more air.
As one forkleg of the originally installed XS1100 forks was a bit bent, a good used stanchion was acquired. This was also the moment to do the long overdue fork-oil-change on the other leg.
230ml of 15W fork oil was used and in hindsight, next time I might go with a 10W again as it's a bit stiff.
... and a little dab of molykote to decrease the break-away stiction.
The airfilter got a bit of cleaning and re-oiling as well.
And even the oilchange revealed no nasties.
This is BEFORE cleaning the magnetic drain plug.
The only leakage left at this point was the seal around the clutch actuator arm. Fortunately this is a generic industrial item with 14x25x5mm dimensions and a single lip seal and it sets you back a whopping 3 Euros at your local bearing shop.
Removal can be done in situ, you just have to screw the adjuster bolt all the way out, then you can insert a flatbladed screwdriver and just pry it out when the cases are hot. A bit of vaseline or petroleum jelly on the in- and outside of the new seal make installation a lot easier.
So what's the verdict, how does she go? Well, she goes like stink. Initially I worried that the bigger ports and valves would lead to losses down low in the rev-range, but there weren't. Objectively I would actually assume, that there's even the odd extra newton-meter/pound-foot happening, but as the whole engine now revs a more linearly you don't feel it as much. The biggest difference is from 4000 rpm onwards. The old girl now just SHIFTS. With the 750 heads you could feel that she was running out of breath somehwere around or shortly after 6000rpm and the last thousand rpm to the redline were only to be used as a buffer. Now she happily revs to 7500 and would probably even go a bit higher, if I hadn't set my limiter accordingly. I did notice that sucking through the frame is now definitely holding the engine back a bit.
On the whole I am very happy with how the engine turned out and she goes just as I would have hoped, I admit that it will be a couple more weeks until I am able to harvest the full potential of the engine, as I am still dialing in the carbs and with only approx. 300km on the clock there's quite a bit of freeing up going to happen.