He's a better mechanic/engineer than he is a sound engineer for sureThe Commando in the Henshaw videos is clean. Too bad it sounds like an underpowered rototiller running in a field of rocks. Too harsh?
Mine sounds like an overpowered rototiller running in a field of rocks when idling. I would imagine it would probably sound pretty awful running down the road if I recorded it with whatever gear Henshaw was using.He's a better mechanic/engineer than he is a sound engineer for sure
Most road bikes are probably jetted too rich for a velocity stack to make a difference, An air cleaner might slow the motor but how would most people know it was happening ? Most people are not riding around on race tracks trying to go faster. When I tune my bike, I progressively lean-off the jetting until the motor lets me know that I have gone to far, then I richen the jetting the minimum amount possible. I do it by making my own needle jets then drilling half a thou out of the leanest ones. It is not possible to do it, if petrol is the fuel - the errors in needle jet sizes are too significant. A Commando with a computer controlled fuel injection system would probably be much faster. Petrol has a higher calorific value than methanol, but Amal carbs can manage methanol better than petrol. The sightest bit too rich with any fuel in any motor, causes loss of power - except when nitromethane is used.
I found with two strokes that when road racing in 5 lap races on short circuits - the motor got slower as it warmed-up, and the drum brake used to fade at the same time. So one thing compensated for the other, - you cannot ride faster with a fading brake , to compensate for the slower motor. With a two-stroke, warming the motor before racing is stupid - the crankcases are part of the inlet tract.
Meant to say "More so "than" 4-strokes."
The single cylinder 2 stroke engines I tuned were definitely quicker warmed up. If the engine got slower when warmed up a minute, the tuner was probably not that experienced and the engine was getting close to seizing up. An engine should never run slower warmed up.
Methanol fuel makes two-strokes become much faster, it cools the bottom end as well as the inlet port. When the motor eventually gets hot, it slows because of the reduced supercharging effect. Petrol does not have such a large latent heat of vaporisation. But the effect is still there. Same with running it too rich, but with petrol - too rich is twice as bad. One of the things which upset a lot of people when the two-strokes arrived was the criticality in tuning them. My brother runs 3 cylinder Kawasaki motors in speedway sidecars. He was Australian Champion in one class in 2001. Winning is all about the jetting -getting it lean enough is much easier with methanol. There is an extremely small margin in fast and slow - with methanol, twice as much is used - so the errors are halved. Most guys believe Phil Irving's book - it is misleading.' If you run rich, you still get good power' is true, but you don't get the best that way. It is the reason my Seeley 850 is reasonably fast. Most of the other guys are probably jetted too rich. It makes a big difference. The Suzuki T250 racer I built was faster than my Seeley 850. I won a race with it and immediately sold it. By 2003, it had won 28 races and 4 championships. I think doing that with such a bike proves nothing. I actually encountered it in a race when I was riding my Seeley. I beat it, but the guy who was riding it might have been a bit slow. Most of the guys did not have my level of experience and I did not give them a hard time. It is silly - road racing is not what many people think - the fastest guys are often the old wrinklies. One of my friends was a top A grader in the 1970s - the guys with the big Hondas will not give him a ride. I once saw him chuck a TZ750 away when he was halfway down the front straight at Phillip Island. I was never in that class, and never wanted to be. Most of those guys are dead now.
