- Apr 22, 2020
Making sense might not be in my wheelhouse.I hear you, but it doesn’t make sense as when new there wasn’t any need for aftermarket crankcase breathers. My new ‘72 combat in 1973 had no problem blowing past 100mph. What has changed with regard to crankcase pressure as the engines got older?
Nobody really knows what the cumulative changes are on the OP's bike. It's possible the breather plumbing was modified so that it is now ineffective. IMO if nothing was changed, this thread asking for help would not exist, and the bike would be running great using your experience as an example. At least this example, not so much the next one where you were fighting this problem for years. I resolved this issue in about a week before the interweb existed. Got a tip from an old road racer at a motorcycle show and swap meet at the San Jose fairgrounds, and made something up that worked on my engine.
I don't need to be right about anything. I'm just trying to help, and stay in my own lane whenever possible.