All stock 79 KZ1000LTD kerker header

Hey everyone,

So for a while now I've been debating whether or not to put a kerker or vance and hines header on my bike. She's all stock nothing has never been replaced except the tires. But idk it seems to quiet, I've heard lots of kerker header videos on youtube and that thing sounds awesome, I want my bike not only to kick any bike on the roads ass, but sound better while doing so. I don't want to screw around with the bike and the mixtures, I'd just like to know if I were to take the stock pipes off and put a kerker on if it would sound awesome with it on there and not screw with the engine or anything, the bike runs awesome barely ever been ridin. Sorry I'm only 15 so if I say things wrong it's because of my age lol, I don't know much, but I do know that bike goes like hell.
Trevor

It will sound cool but you may run hotter. I did this myself when I was younger because there was no internet to find out from experienced folks how to adjust the carbs for the loss of exhaust back pressure.

I'm not technical enough to explain how loss of exhaust system back pressure affects the combustion cycle in the engine but the bottom line is, the header pipes on that new chrome Kerker I put on back in the day turned blue. At the time they told me "it's not a bad chrome job on your new exhaust, you're running hot."

Others on the board here can probably explain the technical side of how loss of back pressure affects the combustion/firing process in the engine.

Most of the time you have to re-jet the carbs or (1) you can 'blue' the chrome headers, and (2) you lose horespower

Although at that time it was worth it because the bike sounded righteous.

You were misinformed, newOld. They turned blue because you were running too lean. You must install larger main jets, usually 2-3 sizes larger than stock when you install a pipe.
The same applies to you, 80kz. It is a fairly easy task to complete, btw.

Hi -- actually, running lean causes 'running hot'.

On a 2-stroke engine, if you run it lean, it will also get hot, but unlike a 4-stroke motor, a 2-stroke engine will get so hot that the piston will fail due to the heat. While that can happen also on a 4-stroke, the 4-stroke piston has an extra stroke to cool off whereas the 2-stroke piston is firing every time and no chance to cool down.

What the guys meant back then, and they told me as much, was that I needed to rejet. That was so far beyond my ability back then -- and no internet to help -- I could never convince myself to try it. Good thing too, rejetting is a bit tricky.

When you run hot, in both 2 and 4 stroke engines, you're either running lean due to an air leak somewhere in the intake and/or you're running lean due to non-stock intake side or modified exhaust back pressure.

I didn't mention it because I still don't have the technical know-how to understand why a loss of exhaust back-pressure in an aftermarket exhaust can cause the same 'running lean/running hot' condition as removing the stock airbox and replacing it with K&N pod filters.

My guess is that during the exhaust stroke with a less-restrictive aftermarket exhaust, nearly the entire volume of air/exhaust on top of the piston is pushed out due to the loss of backpressure, and then on the down-stroke the cylinder ends up with more air than normal -- because normally with stock exhaust back pressure, the down stroke of the piston after exhaust cannot pull in the same amount of air because the exhaust stroke didn't totally empty it.

That's my 100% guess, I have no idea if that explains why, with a reduced-back pressure exhaust, the fuel/air mixture leans out. Sounds plausible enough to me but like I said I lack technical knowledge to be sure.

Let's look at it a different way, newOld.
When you changed pipes, you allowed the system to flow more air. However, you failed to introduce more fuel. Thus, you lowered the air to fuel ratio , commonly known as AFR. This introduced a lean condition. When an engine runs leaner, the combustion chamber temperatures rise, since fuel has a side effect of cooling the combustion chamber. This heat is passed out to the exhaust system on the exhaust stroke. In a 4 stroke, running too high combustion chamber temps can burn your valves, generally considered a bad thing.

When chrome gets too hot, it turns blue. Thus, it is a side effect.