People have told me, I think even on this forum, that with big carb set-ups, you need big exhaust to compensate.
Well, I am running a single Mikuni VM34 roundslide carb on my KZ400. My mufflers are a set of stock Sportster mufflers.
I am afraid that they are too restricting and I need a more free flowing mufflers.
Here is my reasoning...
1) Even when my engine appears to be running lean, my plugs are still black. I know this could be a number of other tuning issues, which I am trying to solve, but I feel like the mufflers could be contributing.
2) My headers don't seat to my engine head perfectly. I know this because whoever had the bike before stripped the bolts on the head a bit so I can't get them completely tight. They are pretty tight but not perfect. Where my mufflers attach to my headers I didn't have a perfect seal either, so some exhaust was leaking. Finally last night I wrapped my headers with exhaust wrap which sealed any leaks where the mufflers meet the headers. But today, when I got to work, there was quite a bit of smoke/exhaust fumes escaping from where my headers meet the engine.
Since this is the first time this has happened, and all that changed from yesterday to today is the header wrap, is it safe to assume that my mufflers are creating too much back pressure and are forcing the exhaust out where the headers meet the engine?
Or do I have a bigger issue on my hands?
1979 KZ400 - 2-1 Manifold - Mikuni VM34
