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You are correct, I found the discussion.He said that the stock RH10 made around 3 or 4 horsepower more than the RH4 at 4000 rpm and that the heads were about tied for peak hp.That is roughly a 10 percent gain at 4000, so quite substantial.There is very little information out there on tuning for more midrange. Almost everything I have found on tuning Commandos is all about the top end, often at the expense of the 4000 rpm stuff. Dunstall's book comes to mind. It makes sense, without extra top end you won't win. If the midrange suffers, just use the gearbox and keep the revs up.That's fine for racing but not great on the road.I have a spare RH10 head here. I was going to have it ported for the 920 but might just try it in stock form on the 850 on dyno hill. The head needs rebuilding first.Glen
You are correct, I found the discussion.
He said that the stock RH10 made around 3 or 4 horsepower more than the RH4 at 4000 rpm and that the heads were about tied for peak hp.
That is roughly a 10 percent gain at 4000, so quite substantial.
There is very little information out there on tuning for more midrange. Almost everything I have found on tuning Commandos is all about the top end, often at the expense of the 4000 rpm stuff. Dunstall's book comes to mind. It makes sense, without extra top end you won't win. If the midrange suffers, just use the gearbox and keep the revs up.
That's fine for racing but not great on the road.
I have a spare RH10 head here. I was going to have it ported for the 920 but might just try it in stock form on the 850 on dyno hill. The head needs rebuilding first.
Glen
