[mixxer]

http://www.yfzcentral.com/forum/32-yfz-powertrain/115722-porting-theory-tools-techniques.html

If anyone was interested in learning or doing some porting of their own... I took the time to compile a decent amount of photos and some information as to what is behind it all...

I am 55 years old and work full time in radiation physics for cancer treatment... But I have a lifetime of doing performance engine work on both 2 stroke and 4 stroke engines... 10 years of dyno ownership and development under my belt too..and have been responsible for engine work on everything from engineering school FSAE challenges to pro flattrack winners and everything in between... Even took a 5 year break from my day job to run Venom Performance...

Just letting everyone know a bit of background on who is presenting the how to import info in case someone was curious....

Anyways.... I have also put a similar tread on Honda.heads up on a Honda ATV forum...

The link here is for the 5 valve Yamaha head info...

Hope it is enjoyed and is of use to some of you...

I have had a lot of great mentors and have been appreciative of info shared with me... So I wanted to take some time and pay it back to other curious gearheads....

 

[toten]

Thanks for the link, I'll have to read through it.

How different are YFZ heads than YZF heads? Not sure what they changed on the quads.

 

[mixxer]

The quad heads have the same configurations as the dirt bike heads ...

The different styles are seen in both.... Mostly different in the intake tract volume/velocity... The fuel injected version of the quad head has way too much port volume /low velocity ...it was designed more with meetimg emissions standards than with power output... Easy enough to fix though...

 

[mixxer]

04-05 quad heads have a large intake port volume with a good port floor height

06 and up FCR carb quad models have a lower volume higher velocity intake port with a good height to the port floor

And the fuel injected quad heads have an intake port with too much volume and a terrible port floor height to work with .... Epoxy changes all of that

 

[mixxer]

Nobody interested in the real deal of port work??

The big deal is that no matter what you do to mod your engine...

It all has to breathe through the ports to make it work.... so the ports are the gatekeeper to power... they can handicapp all your other components, or they can add power at every rpm...