Joined
·
2,837 Posts
I like to read as much on performance engine building as I can afford to. Sometimes a little info here or a tidbit there can help put together a previously cloudy subject. While paging through "Tuning for Speed", by Phil Irving, he says, "At slow speeds when valve inertia is low, almost the full spring pressure is acting on the cam nose, and since lubrication is often very scanty when starting up a cold engine, more wear can be caused by frequent starts or slogging around in top gear, than by hours of fast running when the valve inertia is almost balancing the spring-load on the cam nose".
This got me thinking about another article I saved off the internet detailing the building of Todd Hennings cb500 race bike, which to my knowledge is the pinnacle of these machines. In it, top race tuner, Kenny Augustine states, "There are some pressure angle problems in the geometry, which is why the valve train rockers wear out, especially on the short side radius on the exhausts. People think they just plain wear out, but there's more to it than that. It wears out on the closing side of the exhaust valve because the pressure angle is so rotten. Nobody can tell you what the pressure angle is except somebody who designs cam shafts".
So, slogging around in top gear causes more spring force over the nose and down the closing ramp which is especially bad news for this engine. I think when Honda designed this "Super Sport" bike, there were a lot of compromises made from the technology at the time. The oil pumps and four speed gear boxes were as good as it could be done and paired perfectly with the Super Sport Bike they gave us and expected us to use as such. The problems started when people insisted on cruising and parading, and not wanting to rev em too much for fear of damaging them. I try not to cruise below 3500-4000 on mine, and when in slow traffic, I'll fall behind and then rev it up to 7 or 8 and then let er slow enjoying the music the whole time.
This got me thinking about another article I saved off the internet detailing the building of Todd Hennings cb500 race bike, which to my knowledge is the pinnacle of these machines. In it, top race tuner, Kenny Augustine states, "There are some pressure angle problems in the geometry, which is why the valve train rockers wear out, especially on the short side radius on the exhausts. People think they just plain wear out, but there's more to it than that. It wears out on the closing side of the exhaust valve because the pressure angle is so rotten. Nobody can tell you what the pressure angle is except somebody who designs cam shafts".
So, slogging around in top gear causes more spring force over the nose and down the closing ramp which is especially bad news for this engine. I think when Honda designed this "Super Sport" bike, there were a lot of compromises made from the technology at the time. The oil pumps and four speed gear boxes were as good as it could be done and paired perfectly with the Super Sport Bike they gave us and expected us to use as such. The problems started when people insisted on cruising and parading, and not wanting to rev em too much for fear of damaging them. I try not to cruise below 3500-4000 on mine, and when in slow traffic, I'll fall behind and then rev it up to 7 or 8 and then let er slow enjoying the music the whole time.