PRIMEWORKS
CB750 Enthusiast
so I'm in the process of test riding my 1981 cb750k every other day because I've just recently completed a rebuild on it and have run into a bit of a running issue and I wanted to run it by some of you. So to break down my current set up, I have 4-1 aftermarket MAC exhaust with a baffle in it, I've bench tuned my carbs, I'm running pods, have large jets (98's & 125's), and have the mixture screw at about 1.75 - 2 turns out. I've noticed that when the bike gets to operating temperature a couple odd things tend to happen:
1. When decelerating I often times here cracks and pops from the exhaust which to me implies that I still have to much fuel entering the combustion chamber and not being ignited. I've heard that this could potentially be bad?
2. When I pull in the clutch to shift gears my RPM spikes slightly between shifts and when I pull in the clutch when I'm coming to a stop my RPM rises and stays high as long as the clutch is in. When I'm at a stop i'll adjust my idle knob on the carbs to lower the idle and the RPM drops but then the bike basically comes close to dying/does die because the rpm is to low at that point.
The odd thing is that when I first test drove my bike with this set up it ran like an absolute dream! I'm yet to have a chance to do a full inspection myself just yet (check spark plugs or a potential air leak) but i figured i'd post and see if someone might think it's something else/ know exactly what this might be.
Build thread in case anyone is curious : http://www.dotheton.com/forum/index.php?topic=73590.0
1. When decelerating I often times here cracks and pops from the exhaust which to me implies that I still have to much fuel entering the combustion chamber and not being ignited. I've heard that this could potentially be bad?
2. When I pull in the clutch to shift gears my RPM spikes slightly between shifts and when I pull in the clutch when I'm coming to a stop my RPM rises and stays high as long as the clutch is in. When I'm at a stop i'll adjust my idle knob on the carbs to lower the idle and the RPM drops but then the bike basically comes close to dying/does die because the rpm is to low at that point.
The odd thing is that when I first test drove my bike with this set up it ran like an absolute dream! I'm yet to have a chance to do a full inspection myself just yet (check spark plugs or a potential air leak) but i figured i'd post and see if someone might think it's something else/ know exactly what this might be.
Build thread in case anyone is curious : http://www.dotheton.com/forum/index.php?topic=73590.0