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If a YZ125 is modified for trail riding will it hurt it's overall performance?

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Hey guys, so i was just wondering, if you were to ad an FMF Gnarly pipe, a Fly Wheel weight and change the gearing and the reeds in it, would this hurt the bikes performance out side of the forest? Would it be falling behind/not very good around an MX course?
~Elias

Edited by melias24

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Hey guys, so i was just wondering, if you were to ad an FMF Gnarly pipe, a Fly Wheel weight and change the gearing and the reeds in it, would this hurt the bikes performance out side of the forest? Would it be falling behind/not very good around an MX course?

~Elias

You don't need to do any of those things to ride and race that bike very competitively in the woods. I use mine mainly for that purpose. I have only added hand guards and re-valved the suspension.

If you want to do both, leave the bike completely stock including suspension. Get yourself a set of hand guards and maybe a glide plate. Put them on for the woods and take them off for the track. Adjust your suspension clickers for the riding conditions. Use the money you save for fresh tires.

Edited by rpt50
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Short answer is yes. Changing any bike for another purpose diminishes it's original intended use.

 

I don't race so I would say the changes on my bike make it more fun on the mx track but absolutely slower.

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Depends on your skill level. If you are skimming the whoops, holding the throttle wide open all the way around the track and jumping all the tripples, then yes, you will slow down with the woods mods. 

 

If you are riding the track at a slower pace, mellowing the bike a bit might even help.

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Just an observation,

an FMF 'Gnarly' type pipe is not available for a YZ125, just the Fatty and *SST models (*some years)

 

If it's a 2005+ YZ125, keep the stock pipe as it's actually pretty good for overall trail/track use.

Edited by mlatour
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Just an observation,

an FMF 'Gnarly' type pipe is not available for a YZ125, just the Fatty and *SST models (*some years)

 

If it's a 2005+ YZ125, keep the stock pipe as it's actually pretty good for overall trail/track use.

+1 for staying with the stock pipe!

Never used a FWW on our YZ125 in the woods.

Edited by Treesmacker
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+1 for staying with the stock pipe!

Never used a FWW on our YZ125 in the woods.

 

 

Just an observation,

an FMF 'Gnarly' type pipe is not available for a YZ125, just the Fatty and *SST models (*some years)

 

If it's a 2005+ YZ125, keep the stock pipe as it's actually pretty good for overall trail/track use.

Thanks, any pipe's that'd make it a bit quieter so i can ride into the evening without upsetting the neighbors?

Any advice on how many hours it should be when a rebuild happens?

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Unlike racing, for a recreational 2-stroke engine rebuilds should be based on compression loss instead of hours of use.

 

Example, lets say your freshly rebuilt top-end gets 180psi,

when it drop 10% to 15% of that value, it should be rebuilt.

Meaning that by 155-160psi it due for a piston and ring.

 

It will depend on your riding frequency, in my case (YZ125)

I get about 30-40 hours of recreational motocross track use before a rebuild is due. (not racing)

 

Someone that mostly trail rides will get more hours,

a pro motocross racer will want a more frequent engine refresh to have peak performance (5-10 hours, perhaps less)

 

Avoid any 'shorty' type silencer if noise level is a concern.

An 'FMF' Q silencer is a bit longer and a bit quieter but in reality

whatever silencer you have on a 2-stroke YZ125, it will never go un-noticed when neighbors are around.

Edited by mlatour

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