FZRSupport: the FZROnline Archive

Now that my track bike is somewhat running (Working out a few carb issues)

I need to try and make a complete transfer from stock to track ready.

To me this means:

a better exhaust, dyno jet kit velocity stacks or individual air filters and maybe a light polishing of the ports.

I don;t want to go too crazy with this bike as its for training mostly.

So what are my options to improve flow regarding an exhaust.

The stock one I have is great (As a boat anchor)

I talked to Dave Sadowski the other day and he said that he found that is you take the exhaust and expand its diameter just a bit it helps. he gave me a few numbers.

but the question is who has what and what works for the track with a simpel stage three dyno kit.

Does the r6 conversion work on a 400?

Any input appreciated

a) forget "polishing" ports. Counter-productive. If anything, grind the protruding valve guide stems off(the intakes) and rough the ports up with 120 grit without expanding them any. Or go whole hog and do the mototune/velocity port choke point port job.

Ok Excuse teh ignorance but....


What is this?

reelrazor wrote: ......Or go whole hog and do the mototune/velocity port choke point port job.

China_Racer_1 wrote:Ok Excuse teh ignorance but....


What is this? reelrazor wrote:
......Or go whole hog and do the mototune/velocity port choke point port job.

http://www.mototuneusa.com/think_fast.htm

http://mototuneusa.com/homework.htm

Thsi guys sight is a bit hard to read with all the multi colored garbage.
However I went through every tab and read the entire sight front to back.

He offers some good insight and I will take it to heart.

My other buddy locally was trying to tell me less is more as well so I think I will try this on the h400 and see how she goes.

Steve

Yeah, the concept is pretty well proven....in fact that research paper Geo posted up about a week ago went into flow vs. velocity quite extensively.

And, for quite a while it was recommended to port for velocity on small bore, but big flow on large bore, but the folks dealing with high end H-D engines (Zipper's and others) and others are seeing the same good results with 'd-shaped' ports.

Yeah, Pat's site is pretty obnoxious, but he WAS kinda the guy a normal guy could get to build a killer engine for an FZR in their day. Got a lot of experience with Yamaha4s, 6s, and 1k's. I remember he was the guy who figured out the Ontario's replacement valve seats were an AMA legal replacement for stock, even though they were radially thinner by .012" (which equals quite a bit more valve area)

R6 headers with scorpian slip-on...
best performance mod I did to my bike...