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You should see gains in torque with a high-comp piston. While you have the head off, you should at least clean up some of the ridges and casting flash with some form of abrasive. Even if you don´t change the port shape at all. At least clean it up. As far as what piston is best, every manufacturer will likely claim that theirs is best, but it´s really up to you to determine which is best for you. I prefer to go with an OEM piston, and headwork, personally. The headwork doesn´t wear out, and OEM pistons are less expensive than the aftermarket stuff. Just my opinion.
 

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Discussion Starter · #3 ·
Ok good input. Well then how are you upping compression then wi th an oem piston

And im nervous to do a slhg mod on the 14 since my rod is longer than the other rs
 

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You can do the SLHG mod, or you can achieve the same results in a safer manner by machining the base of the cylinder. If you measure the head gasket, the compressed thickness should be 28 thousandths of an inch, and there are three layers, which equates to roughly nine thousandths per layer of the head gasket. If you machine eighteen thousandths of an inch off the base of the cylinder, you should achieve the same results as the SLHG mod, without taking away the reliability of the OEM gasket. You´ll need to measure your gasket thicknesses to make sure you´re not changing anything else, especially if you use aftermarket gaskets.
 

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Discussion Starter · #5 ·
Ok. So since my rod is .009 longer I can do a double layer hg to achieve the same results as a slhg on the 09-13s?

Also if I machine it would I be taking off the base of the head or of the block?
 

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You have a 63.4mm stroke with a 2014, and the same with a 2009-2013. The difference comes in the form of a longer rod and larger bearing. The rod being longer (.25mm) will put the piston closer to the head, by .25mm (or about ten thousandths). It looks as though I may only be able to safely remove about eight or nine thousandths. This will all be confirmed when I measure everything.
 

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In the end you still just have a pump gas oem piston that isn't as reliable as the CP. The oem pistons are more prone to cracking and don't have the wrist pin oiling benefits of the CP pistons. If you want a top of the line high compression piston get a custom cut MMAD 14:1 piston
 

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Discussion Starter · #9 ·
You have a 63.4mm stroke with a 2014, and the same with a 2009-2013. The difference comes in the form of a longer rod and larger bearing. The rod being longer (.25mm) will put the piston closer to the head, by .25mm (or about ten thousandths). It looks as though I may only be able to safely remove about eight or nine thousandths. This will all be confirmed when I measure everything.
right so either mill off 9 thousands or remove only one layer of the head gasket. Since the rod and bearing is 9 thousands longer than the previous models..correct?
 

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its best to check the squish yourself when you take it apart. its easy to do, just use a couple small pieces of solder. youtube it, most vids will be for two strokes, but same principles apply.
 

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If the rod is longer on 14 models shouldn't that just move the wrist pin up higher in the piston and not change the squish at all? I'd check to see if they have the same part number as a 09-13 and if they don't then that means you don't have to think about the rod length because it would be compensated for in the piston. Like they do on a chevy 383 and 6 inch rods lol although I doubt Yamaha would make em like 383 pistons because they have to use a supporting ring for the oil ring because the wrist pin sits under the oil ring, which wouldn't be good at 10k rpm like yfz's run. I gotta carb bike this doesn't pertain to me at all but thought I'd give some input that might help ya
 

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I wouldn't try 2 layers of head gasket, when u peel a layer off there is a copper middle layer that I dont think would seal right...and idk if using both outsides would b smart either...personally I would do slhg and check squash.

I just did mine when I installed gytr head and cams, haven't gotten to ride it yet but she sounds mean!
 
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hi we drive Wössner 13,5: 1 pistons and silver bearings after 30 hours of the pistons and rings still looked very good.
A friend goes CP Project X Piston, he is satisfied
I want to ported my cylinder head YFZ450R
which is better Hotcams Stage 2 or 3 for Xc Racing ?
I've been driving the cam 06
notice the difference to Stage 2 or 3
We drive 100 Octane Shell or Aral 102 Octane
 
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