gytr pistons


4 replies to this topic
  • motodadjlg

Posted August 11, 2016 - 04:11 AM

#1

Anyone using a 14.1 gytr piston ? Did not realize you had to split case to add aftermarket oil nozzle recomended.Any thoughts?JE makes the piston for GYTR they offer there own piston 14.1 but don't require a oil nozzle change.



  • stevethe

Posted August 11, 2016 - 06:32 AM

#2

I believe someone said you can put the oil jet in without splitting the cases. However you need to realize 14.1 compression is very hard on cranks and timing chains. I believe it is for serious racers that mechanics. 



Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted August 11, 2016 - 06:50 AM

#3

The timing chain has no more idea what the compression ratio is than the front tire, actually.  For that matter, the load added to the crank by the compression itself is insignificant compared to the load on the power stroke with any piston.  Having said that, I agree that there is no need for 14:1 compression unless you're loosing races only on the basis of inadequate power.  It's just kind of extreme at that level, and you'd need to think about fuel cost and availability.

 

The difference is Yamaha's view of what's good for the engine versus the view of an aftermarket supplier who wants more to sell their stuff than to make the engine last.  Their reputation does not hinge on the reliability of one particular brand engine.  Yamaha's does.

 

And having said that, it's a little bit debatable as to whether the nozzle change is really necessary in the first place.  The history of it is that it ws added to the quad engine to help keep the piston crown cooler.  Quads are heavier by more than 50%, so the engine is far more likely to run under continuous loads, and crown heat became a problem.  The nozzle was added to the YZ a couple of years later because it was cheap and easy to do during the redesign for '06. 

 

Either way, I'm not certain that the nozzle could not be changed with the crank in place, but it would be a challenge.  You'd need to cut down an Allen wrench for access, and you'd need clearance to remove both the screw and the nozzle.

 

Alternatively, you might be able to drill out the existing nozzle to match the new one.



  • stevethe

Posted August 11, 2016 - 09:01 AM

#4

The bike I am acquainted with a very high compression piston producing around 65 RWHP gobbles up cam chains and cranks. However it is spun higher on a road race track but doesn't get many miles put in it.

  • grayracer513

Posted August 11, 2016 - 08:41 PM

#5

The bike I am acquainted with a very high compression piston producing around 65 RWHP gobbles up cam chains and cranks. However it is spun higher on a road race track but doesn't get many miles put in it.

 

And you don't suppose that the aftermarket cam profiles and valve springs necessary to produce 65 RWHP from 450cc had considerably more to do with the timing chain wear than the compression ratio, do you?  Operating resistance in the valve train, the power needed to turn the cams against the valve springs, etc., is the only load the cam chain carries apart from speed.  As far as speed goes, higher compression generally works against higher RPM, providing the biggest gains in the low and mid range, there's not even an indirect effect on the chain from that. 

 

Good job on 65HP, BTW, whoever that was.  Never mind the cam chain, I'm surprised something like that doesn't eat itself.







Related Content

Forums
Photo
Supercross

Wilson the Blue Privateer by jetfuel


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies
Reviews

Yamaha YZ450F 2017 by Chris.GVS


Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017
Forums
Photo

YZ450FX OR YZ450F by MESSMAKER


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies
Forums
Photo

Megabomb Fitment by 288yz450


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply
Forums
Photo

James Stewart back on a YZ450F by YamaLink


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.