YFZ Central banner

1 - 14 of 14 Posts

·
Registered
Joined
·
836 Posts
Discussion Starter #1
Was riding yesterday, and saw another YFZ at the park. Could tell right off, that it had an aftermarket pipe on it-from the sound. Well, I chased it down and talked to the owner. He had a GYTR complete system with one of those Go-Now intake things. He said he was really happy with the performance and all the stuff was added to the bike pre delivery at the dealership. So, he never really got to ride it stock. As I was checkin out the pipe, I noticed that the header pipe was much smaller in diameter than the stock pipe. Is there a good explanation for this? I was under the impression, that the whole idea was to flow more air, instead of restrict it. What gives?

Oh yeah, it's pretty cool ridin one of these things. As everybody that rides anything else, are completely checkin YOUR ride out. I've been out four times since I picked mine up, and I've only seen 3 other YFZ's at the OHV park. :lol
 

·
Registered
Joined
·
773 Posts
Are you certain you are not confusing the guard (on yours) as part of the pipe? I'm not running they GYT-R system nor have I seen any, but I'd dare say they have not decreased the header diameter.
 

·
Registered
Joined
·
625 Posts
actually I remember seeing that the GYT header flows less than the stock header.... Dyno tests have proven it appartently.
 

·
Registered
Joined
·
836 Posts
Discussion Starter #4
It was way before the "end of the day toast". The header pipe on this guys system, was definetely smaller in diameter than my stock exhaust.

"Are you certain you are not confusing the guard (on yours) as part of the pipe? "

Yes, I know the difference between a heat shield and exhaust tubing. I didn't say anything to the guy about it. But thought, it was odd that the header was smaller than the stock unit. Maybe, somebody that has the GYTR pipe could make a measurement -and post it. Not that it really matters, but maybe this guy got boned at the dealer ship (in sacramento)
and they used a non matching header pipe.
 

·
Registered
Joined
·
836 Posts
Discussion Starter #6
selector,

Sorry, didn't mean for it to sound like that. No harm- no foul.
 

·
Registered
Joined
·
773 Posts
Originally posted by vorra65@Sep 8 2003, 09:04 AM
selector, 

Sorry, didn't mean for it to sound like that. No harm- no foul.
Agree. :D
 

·
Registered
Joined
·
126 Posts
The GYT-R header makes more HP then the stock header (2HP more). The GYT-R header has a welded step up, that is how you can tell the difference.
 

·
Registered
Joined
·
6 Posts
I'm running a complete GYT-R exhaust. the header pipe I bought and installed from the dealer was much larger. It is large enough to need a "dent" from the factory to clear the frame. I have the SS header pipe and aluminum pipe.
 

·
Registered
Joined
·
97 Posts
After discovering the diameters between my stock YFZ header and the Yoshi header on my KFX400 are virtually the same, it's hared to understand how any aftermarket header could be worth much of anything. The stock slip on piping is smaller in diameter than the header, so it doesn't seem very necessary for an aftermarket header??
 

·
Registered
Joined
·
836 Posts
Discussion Starter #11
YFZRob

So, what your'e saying is- that in your opinion is to keep the stock pipe from the head back and go with a slip on ? I'm curious, as a complete system really looks nice, but 1) I'm not racing (other than my bud's) 2) I can buy more goodies if I don't dole out the extra $200 +
 

·
Registered
Joined
·
97 Posts
vorra65,

All I am saying is that the stock head pipe is the same diameter as my yoshi head pipe on my KFX 400. Granted the YFZ will make more HP, but you can only go so large on the head pipe anyway. The stock KFX 400 head pipe is much smaller than the Yoshi I have now, but even on that quad, there is only a 1-2 HP addition from the head pipe. From the photos I have seen, and from other posts in this thread, it seems like all of the aftermarket headers are either smaller or the same size up to about 3" before the slip on, where there is a step. The only way I can see an aftermarket header making more power is if the stocker has some restrictions inside that we cannot see. The stock KFX header has a large weld bead inside the collector ring at the head, making a big restriction. So, maybe there is something like this in the stock YFZ header???
 

·
Registered
Joined
·
836 Posts
Discussion Starter #13
YFZRob,

Thanks for responding. I agree with the theory, that the header will flow only so much air. Also I have noticed that the exhaust manufacturers state gains of 6-9 hp (example). I'm assuming the lower # is indicative of just adding a slip on and retaining the stock header pipe. I will probably just add a slip on and work on jetting-save the other cash not spent on the header for other accessories. As far as the restricter in the header pipe, I will definetely take mine off to check. I can't imagine why the factory would do something that silly. Maybe someone here that has installed a complete system, could check their stock header and let us know if there is any type of restricter/reducer in there. Thanks again
 

·
Registered
Joined
·
111 Posts
I have the yamaha complete system on mine. The step in the pipe from smaller to bigger gives a real bottom to midrange pull. If you take a look at some of the other pipe builders u might see most of them are stepped to. Yamaha has a lot of r&d into there products they did for the best results. I took a look at Tim Ferry's race bike the other day and he has a gytr pipe and muffler on it and the header is the same exact way.
 
1 - 14 of 14 Posts
Top