2014+ YZ250F GYTR intake boot review

[MJP68]

https://www.shopyamaha.com/product/details/gytr-air-boot?b=Off-Road+Motorcycle&d=20%7C20

Click the link for product description, It is intended to complement the GYTR ported cyl head

This product came up in another thread, decided to give it a try.

https://www.thumpertalk.com/topic/1145568-2014-yz250f-top-end-which-piston/

The boot can be removed without taking out the entire airbox frame.

Stock and GYTR boots.

The instructions also call for opening up the airbox a bit.. Yes I actually read the instructions for once.

Before..

You are supposed to remove the sections out of the back of the airbox with a utility knife.. someone removed mine from

our toolbox. Had to just drill a few holes with my cordless and a UNIbit till the battery died

I decided to do the switch in between rides in order to give a more accurate seat of the pants comparison.

Bike details.

2014 YZ250F

Williams Motowerx complete "Package" Porting, valves, cams, combustion chamber, cyl decking ect.. set for pump fuel.

FMF full Ti exhaust, Megebomb header, power core slip on with the sparky screen removed.

No Toil air filter kit (removes backfire screen) using the red No Toil oil.

2015 piston kit with roughly 5 hours on it.

Bottom line..

This airboot works VERY well with my current "package" I was expecting to lose torque in the lower rpm's

But honestly I don't think I lost any torque or response at all, Gains were felt from the lower mid range on up

with the main focus being upper mid all the way to rev limit. For a somewhat simple mod I think It's a good value

That has improved performance on MY machine..

[Ctown208]

Great review. I've been looking for that boot for my 16yz450.

I can't seem to figure out how to locate it (yet)

[MJP68]

Great review. I've been looking for that boot for my 16yz450.

I can't seem to figure out how to locate it (yet)

Thanks

The airboot tested is model specific..

God help you if you really need more power from a YZ450f ?

[Ctown208]

Thanks

The airboot tested is model specific..

God help you if you really need more power from a YZ450f ?

Lol It's not a matter of needing. It's about tinkering at this point.

[MJP68]

Lol It's not a matter of needing. It's about tinkering at this point.

Copy that.... been there done that, big bores hurt me.

small bore= less pain and more tinkering. hope that makes sense

[Ctown208]

Copy that.... been there done that, big bores hurt me.

small bore= less pain and more tinkering. hope that makes sense

Yeah I hear you. I'm just dying to play with this head to be honest. I was wondering what people were doing for intakes, once they were to that stage.

I come from the yfzr 450 quad. That thing was a must to port and build some ponies in. When Yamaha released the yz450r with the front intake set up we all got excited and prayed for it to come to the quad scene. Since then I returned to bikes and picked up a yz450r 2016. I'm more than pleased with it in stock form. I'm just dying to play with this head tho. I will keep the bike stock stroke and stock bore.

[Ctown208]

How in the heck did you find that intake lol. I can't even find the 250 one. Without using your link. Let alone find the 450 one

[MJP68]

Yeah I hear you. I'm just dying to play with this head to be honest. I was wondering what people were doing for intakes, once they were to that stage.

I come from the yfzr 450 quad. That thing was a must to port and build some ponies in. When Yamaha released the yz450r with the front intake set up we all got excited and prayed for it to come to the quad scene. Since then I returned to bikes and picked up a yz450r 2016. I'm more than pleased with it in stock form. I'm just dying to play with this head tho. I will keep the bike stock stroke and stock bore.

Ahh, the 450 runs an intake boot very similar to the GYTR 250F boot, some were using the 450 boot to boost flow at high rpm, guess Yamaha

noticed.. Aside from the Twin Air or NoToil backfire eliminator kits I know of nothing for the 450. Sorry you had to ride a Quad before, at least it was a good one. If you insist on head mods to your big boy bike contact Jesse Williams or Derrick Harris, way more performance per dollar than ANYTHING MXA tests.

[MJP68]

How in the heck did you find that intake lol. I can't even find the 250 one. Without using your link. Let alone find the 450 one

yours came free of charge with your new bike.....

[Ctown208]

Thanks man for everything.

[harrperf]

It appears to taper larger?

Is the tract more straight on this than the 250 oem?

[MJP68]

It appears to taper larger?

Is the tract more straight on this than the 250 oem?

Not sure I understand the question about the taper.

Air flow has a much straighter shot into the throttle body

[davbrucas]

Copy that.... been there done that, big bores hurt me.

small bore= less pain and more tinkering. hope that makes sense

 

Ditto...I am almost 45 and the 450 is just too much bike for the limited play riding I do. 

 

The link says this item is not available for sale online. 

[MJP68]

Ditto...I am almost 45 and the 450 is just too much bike for the limited play riding I do.

The link says this item is not available for sale online.

Copy the pt# and google it. Rock river Powersports

Has them listed on eBay

[fgrote]

Copy the pt# and google it. Rock river Powersports

Has them listed on eBay

thanks for the link , my dealer said backordered still, so i ordered one there, had to pay more but what heck its only money

[fgrote]

there is a app you can load on your phone that will give you gps acceleration grafts , speeds,etc, i plan on doing some testing in the next weeks ,with some combinations of exhausts, maps, gas,and this boot, we have a big race series coming up ,and i'd like to find some more power

[harrperf]

there is a app you can load on your phone that will give you gps acceleration grafts , speeds,etc, i plan on doing some testing in the next weeks ,with some combinations of exhausts, maps, gas,and this boot, we have a big race series coming up ,and i'd like to find some more power

You will find it very hard to get consistent data...

To ensure your testing methods are sound, repeat the same test multiple times and see how closely they overlay, say ten tests, if all the tests are within 1-2 percent, thats usable.

Throw out the worst test and the best test, then average the results.

Then move on to the new test of whatever part.

Unfortuneately any mapping changes, intake boot, or pipe changes have such minor gains or losses that it falls in the 1-2 percent range.

Sadly any testing on a dirt surface is nearly meaningless. Often less powerful engines will register faster acceleration rates because they hook up more. The get ignition with its traction control all the way up makes a motor feel slow. And you dont think you are pulling hard like when its off... But then you realize you cleared a jump easier or turn faster laps and it all comes down to traction.

And we found knobbies totally worthless on the street for accleration tests. Spinning the tire occurs all the time. Even when you dont think it is!

And even worse its nearly impossible to apply full power during acceleration on the street because even a 250f will wheelie in 3 and 4th.

Hence... The dyno. Its just a rolling road that measures time and speed... And then via same technique of the concept of calculus... Calculates the change in speed per measurement point vs time to get acceleration, thrown in a know inertia value for the drum... And you have power.

[harrperf]

Not sure I understand the question about the taper.

Air flow has a much straighter shot into the throttle body

Sorry i got off topic.

So this boot has noticeably less turn than stock?

And taper... Does it get progressively larger diameter the further it gets from throttle body. It appears to.

A pic as if looking from the throttle body lookig towards filter (that orientation) of both would be killer!

[MJP68]

Sorry i got off topic.

So this boot has noticeably less turn than stock?

And taper... Does it get progressively larger diameter the further it gets from throttle body. It appears to.

A pic as if looking from the throttle body lookig towards filter (that orientation) of both would be killer!

Compared to the bend in the stock velocity stock, there is very little bend at all.

Taper, Yes there is about a 1" aluminum spacer clamped into the boot right at the throttle body "junction" and from there it gets

wider progressively.

Sorry that's the only angle I never thought to capture. You can see the aluminum collar/spacer in the first pic and the last pic from the bottom

might help with taper. all the bulges in the stocker are just to add volume around the velocity stack I'm assuming.

[harrperf]

The straightened turn is a huge help, and the taper is as well. Probably runs quite well, ill dyno one as soon as a boot can show up.