Missing a shift used to be the death knell of my engines. I was running the x4 camshaft with a head built by, well I won't say. Every missed shift was bent valves. Then I went to the x20 cam, wasn't quite so bad, every other missed shift was a bent valve.
Then I had the head done up proper. I've missed shifts and just buried the 12k tach..had to be 14k rpm. Everytime I would cringe, just knowing when I back off the throttle it would die and not run below 4 or 5k rpm. But to my surprise it takes the abuse just fine. Despite the fact that the valves are larger and heavier! Just goes to show you what proper spring rates and heights and bronze guides will do.
This Mike Rich guy does not fuck around. If you want genuine, pro race quality mods made then he's the guy to see. No guessing, nothing half assed or cobbed together, he does the kind of work you see on AMA superbikes. Computer flow bench, all kinds of engine simulation work, matching valve rates to rpm, valve weight and cam profile. He even flows the head to a specific camshaft profile. You gotta send him the whole head, assembled, preferrably with intakes and carbs attached. No just sending a bare head and have someone hog it out based on some kind of wives tale voodoo. Mike will break all the rules if the flow bench says that's what you have to do.
He told me one bit of very valuable information about the 175's vert heads. It's not the ports that are the problem, it's the valves. Mildly ported heads will flow about as much as the valves can pass. You gotta go with bigger valves if you want the big power.
What I can't believe is that so far the rockers and cam lobes seem to be holding up great. I have no doubt that if one wanted to throw the dollars at one of these engines you could see a usable 14k rpm. It would require Ti valves and new seats to keep the spring pressures down. But it's doable, and would sound great.
A project for another year I guess.
PS. I know...a lot of talk to respond to a simple statement about a missed shift..but there you go..the wonder of modern medicine.