GYTR Head for 2010-2015 YZ450f Upgrade


3 replies to this topic
  • Mighty_Whitey

Posted January 21, 2016 - 09:58 PM

#1

Looking for those with personal or knowledgeable experience swapping the stock YZ head with a GYTR complete head assembly with valves. 

My question is regarding the oil squirter, there may be a correct technical term for it, but I was told by a Yamaha tech that Yamaha will add an extra oil squirt nozzle which requires splitting the cases, but some people choose to do without it.

It's been 2 years since the conversation, but I want to say the logic was if running a high-comp piston + race fuel, must add the extra squirter.

If running standard compression piston + pump fuel, don't need it.

 

Application is 30+ B/Expert rider racing 10-15 times a year. or about 1+ race a month.

 

Anyone out there have clarity on this?

Thanks a lot!

 

 



  • grayracer513

Posted January 22, 2016 - 07:57 AM

#2

I'm assuming you mean the 14:1 GYT-R kit for the '14-'15?  Their web page does say that the updated nozzle is required, but the design is different from the '06 type, and the nozzle may (maybe) be replaceable without splitting the case.  It bolts in with an Allen screw, and it's possible that if you shorten a hex key enough you could position the crank in such a way as to access it and remove.  

 

You might also be able to drop the whole works into the engine, so discretion is necessary.  

 

https://www.shopyama...umber=&req=true

 

Whether it's really required or not, I don't know, but they do seem concerned about it. 



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  • Mighty_Whitey

Posted January 22, 2016 - 11:01 PM

#3

Grayracer, i must have misunderstood my contact. Instead of adding an additional nozzle, the task is to replace the nozzle from the OEM/Non-GYTR head with an updated, GYTR spray nozzle that has a special 2 hole design. It's a swap. That makes sense.

The tip about a shortened hex key in lieu of splitting the cases would be fantastic if true. 

 

The real shame is this head was part of a trade almost 2 years ago and has been sitting in a box doing nothing for me. If Yamaha does not release an electric start YZ450f for 2017, the plan is to buy the 2016 YZ450FX or WR450, break it in and when I do the race setup: suspension, clamps, air-filter, pipe, ignition with O/2 sensor, the GYTR head will be a new and first time mod for me. I'm very interested in a racing season with a GYTR head, considering the most modded bike i've owned had pipe, air-filter, Hot-cams and Yosh ignition kit ECU and Data Mapper; i've never run a high-compression piston or modded head. Understanding race fuel will be required, and I"m ok with that.

 

Thanks so much for the reply. You're on-point as usual, much respect.

 

Doug


Edited by Mighty_Whitey, January 22, 2016 - 11:03 PM.


  • grayracer513

Posted January 23, 2016 - 09:51 AM

#4

If it was me, I would do everything you have planned except the high compression piston.  That decision would be based on two main points:

  • Using the OEM standard 12.5:1 compression is both less expensive and more reliable than 14:1, and eliminates the need for special fuels and the problems associated with high compression.
  • The power gains from extra compression are generally at lower speeds, and high compression can actually impede high RPM power.  Based on my own YZ, I don't really feel any shortage of low end grunt, and the FX, with it's heavier crank assembly will have even more.  I would miss the top end if it was reduced, though. 

The GYT-R head and cams will add a lot of power potential to the bike anyway, and I really don't think you're likely to find too many instances where you wish you had much more than you're going to end up with.  OTOH, it is true that raising the compression can help "civilize" the low speed behavior of aggressive cam timing, so it might turn out to be worth it.  Hard to say for sure without trying it both ways, but it's a point to think about.







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