open headers?

crazykz, what kind of cooling does your bike have, because even with my baffles I made and good jetting, my short pipes and such tend to make my bike run hotter than it should. enough to the point where I dont want to ride it in town in the summer for too long. I'v heard that the increase of performance from the drag style pipes properly tuned adds a good amount of heat. My KZ750 doesn't even have an oil cooler available so i've been trying to figure out a way to make one work

sry kzcool, kinda dropped of the face of the earth for awhile, i run it all day 100 degrees out, no problem so far, but im running rich, think that would help out some, but honestly im pry not the best qualified to be giving advice

KZCool wrote: :laugh: you've got a good point. Love your bike like it is the most expensive thing you own and it'll run fo eva!

No wives are..

Save up for an exhaust..

actually readytoryde fronted me a set, but i was only gonna chop em up, couldnt bring my self to do it, so i wielded washers at the end of each pipe for a lil backpressure, when i get a new block i might, but as for now shes quite enough to think. running a lil rich on acount i jetted it for open pipes, with no backpressure.

and ready to ryde, sry buddy ill be down to visit soon bro.

Quit worrying about burning the valves.
As long as the pipe is 20" long off each cylinder you'll be ok.

With really short or no pipes what happens is the cold air can get to an open valve after you shut it down while hot, causing a valve to warp. Since a warped valve no longer seals, the exhaust getting by the warped valve will burn it.

Might hole a piston running it so lean though.

i jetted up to, 122 main jet? i think, might be 122.5 cant remember, it was still running lean, but since i wielded those washers on its a lil on the rich side, which im fine with


warping a valve it what i was worried about, i just try and keep in mind not to let off the throttle suddenly,

ill have to measure them, there atleast two foot

steell wrote:
Might hole a piston running it so lean though.

Yup, it's called un-metered air in the fuel injection world.

Basically the exhaust pipe is going to take in air through "reversion" (like a vacuum), since that air isn't flowing through a carb or air flow meter no extra gas is accounted for so you facilitate a lean condition. Same thing can happen on with a cracked carb boot on the intake manifold side of a carb or a vacuum leak.

Hollywoodmx wrote:

steell wrote:
Might hole a piston running it so lean though.

Yup, it's called un-metered air in the fuel injection world.

Basically the exhaust pipe is going to take in air through "reversion" (like a vacuum), since that air isn't flowing through a carb or air flow meter no extra gas is accounted for so you facilitate a lean condition. Same thing can happen on with a cracked carb boot on the intake manifold side of a carb or a vacuum leak.

Are you saying that cold air is going to travel up a 20" long pipe, plus a couple more inches of port, and hit the valve while the motor is running?

steell wrote:

Hollywoodmx wrote:

steell wrote:
Might hole a piston running it so lean though.

Yup, it's called un-metered air in the fuel injection world.

Basically the exhaust pipe is going to take in air through "reversion" (like a vacuum), since that air isn't flowing through a carb or air flow meter no extra gas is accounted for so you facilitate a lean condition. Same thing can happen on with a cracked carb boot on the intake manifold side of a carb or a vacuum leak.

Are you saying that cold air is going to travel up a 20" long pipe, plus a couple more inches of port, and hit the valve while the motor is running?

I didn't pay attention to the pipe length in the thread just read they were short, 20" should be ok but too many factors for me to say, just call it a risk when you run short pipes no collector, etc.

I recently read interesting theory about running open pipes with no collector. There was no concrete evidence to support the theory, but nonetheless it is an interesting thought.

The theory goes like this: With no collector there is no scavenging affect. Scavenging helps pull exhaust gases through the pipe, and this helps draw hot gases away from the exhaust valves. With no scavenging affect the valves tend to run hotter and depending on the engine, valves, and state of tune, the valves can overheat and warp leading to burned valves. While one sees open pipes with no collector on some types of racing engines they are not intended to run thousands of miles without being stripped and rebuilt, so the open pipes and the possible burned valves are not a concern (the valves don't burn in a quarter mile). Ed

Remember a top fuel motor with zoomie headers only has to run about 1 min.
then it gets rebuilt between rounds.

At 10,000 rpm for under 4 seconds it only turns around 800/1000 rev.'s
per pass.