Working on a 75 CB750. It's all stock except for the pipe. Carbs are freshly cleaned, 3000k tuneup. Fresh plugs & caps. Bike runs pretty darn good.
But...It has an aftermarket 4 into 1 pipe. Very, very similar to one of my motogp werks pipes. Pretty straight - not much of a baffle
I'm having a little problem starting the bike. When the motor is cold, it will start with the choke - no biggie. Usually, within 1-3 tries. I'm used to my bikes firing immediately on the first touch of the button. If the motor is HOT, it starts pretty easily with no choke. Still, 1-3 tries. If it is warm, sometimes it starts immediately, sometimes it seems like wants more fuel.
Timing was set statically, and then fine tuned with a timing light. Advance is cleaned and operates properly.
The 4 into 1 pipe has a baffle (not much of one) The inside diameter of the baffle is right at 1.5" You can see straight through the pipe. The pipe sounds great, but is ridiculously loud. Been considering a different baffle or maybe even a different slip on muffler (cone engineering)
What diameter should I be looking for on something like that? I am in no way a exhaust specialist, but it seems to me that there's not much slowing the exhaust down ? When it doesn't start, it just seems like everything is just blowing out the exhaust - horrible description, but I can't think of how to describe it.
