YZ 125 GYTR kit?

A good tuner can make it faster for less money. Bring you're bike to ehr tuning in the netherlands and he make's a rocket of it.

Hi fellow frenchman !

The comment above, to tune it, is good and indeed really add something. About the Athena, I didn't hear it brought top power at all, just bottom and a bit more mid, so it was not satisfying for someone relatively fast and could not be on par with a ktm/husky 150. About the Rinaldi, I didn't get the oppportunity to test it but I am a fan of the brand in general, so I did a quick search to help.

2500 euros is indeed steep, so on leboncoin maybe you will find something you like; especially if you already have some parts like a pipe and a Vforce, then just an ignition + a tuner (bottom/top/carb/set up) can make a great result (especially if you are ready to change pistons more often, below 20 hours):

https://www.leboncoin.fr/equipement_moto/1349203468.htm?ca=12_s

https://www.leboncoin.fr/equipement_moto/1354398924.htm?ca=12_s
https://www.leboncoin.fr/equipement_moto/1327827850.htm?ca=12_s

https://www.leboncoin.fr/equipement_moto/1354911434.htm?ca=12_s
https://www.leboncoin.fr/equipement_moto/1353483196.htm?ca=12_s

Enjoy !

I had a couple of Rinaldi (now GYTR) kits on my '99 and '00 Yamaha 125 and they where flying!
Basically the same thing as this kit, It was more expensive i I can recall.

Cannot compare or say anything towards the others apart from seeing that kit again gave me a nice warm feeling..

Thanks for the links mate, the first one makes the most sense I guess.

Tuning would be an option but I'm not very confident in sending my motor all accross Europe.
In addition to that I don't know any good tuner where I live.

I read the 144 athena makes 2 HP more all accross the power curve which means it doesn't even come close to a last generation KTM 125... I'm curious to see what the 125 GYTR power output looks like.

With a whole new cylinder, head, and everything I'd hope that it at least matches stock Husky 125 power.... And keep in mind a stock Husky still has room to grow. The 39-40hp stock can become 43-44 after upgrading all the same components pictured in that GYTR kit. The Yamaha is still a good bike it's just way behind. I would also be curious to see a dyno graph with this kit.

GYTR parts are quality and reliable kit

My understanding is that kit is not available to us here in the U.S. so its not likely many people here have gotten their hands on it. Looks like an awesome complete kit with the ignition and everything, I would definitely like to try it and prefer it over a 144 big bore setup.

I'm definitely thinking about getting one of these kits, costs around £2000 over here in the UK.

What's reason for not being available in US?

305FC250 wrote:

With a whole new cylinder, head, and everything I'd hope that it at least matches stock Husky 125 power.... And keep in mind a stock Husky still has room to grow. The 39-40hp stock can become 43-44 after upgrading all the same components pictured in that GYTR kit. The Yamaha is still a good bike it's just way behind. I would also be curious to see a dyno graph with this kit.

125 SX/TC 2016/18 are 37HP (not 39/40) it's 3HP more than the YZ...
The GYTR is made for serious racer, the reliability is not the same as the stock YZ,
you'll have to change often the piston etc

The best way to upgrade the YZ is to put a good pipe (HGS; Messico ;Damon's pipe, Scalvini etc)
+ vforce 4
+ Rinaldi rotor
+ VHM Dome AE32100-B

My opinion is that You don't need the GYTR unless you're a pro (french junior class).
EHR tuning is also pricey!
Tuning the whole engine is for PRO too, as you'll need to change the parts all the time!
In case that you don't mind that point,
you can send your motor to many people like Bud Racing, SR, Reptil, Dragontek etc

The 144 athena kit is good but you have to tune it and to modify the crank case...

nc_mx_kid wrote:

GYTR parts are quality and reliable kit

Not so sure about that? ? .... if you need a faster bike going forward.....you would prolly be better off putting the 2500 euros towards a nice two fiddy imo

I'm not a pro rider by any means just a 31 years old practice rider with 10 years riding experience.
Engine failure can happen on any engine... how many hours of abuse on this GYTR cylinder?
I'm a little sceptic on the 250 2 stroke it might be too much considering the type of tracks I ride here in France.

Big bore is the least probable option I'll go for, I simply don't trust the quality of these kits.

So vforce reed cage + VHM dome the best option to go? Will the power increase be really noticeable ?

Sach157 wrote:

I'm not a pro rider by any means just a 31 years old practice rider with 10 years riding experience.
Engine failure can happen on any engine... how many hours of abuse on this GYTR cylinder?
I'm a little sceptic on the 250 2 stroke it might be too much considering the type of tracks I ride here in France.

Big bore is the least probable option I'll go for, I simply don't trust the quality of these kits.

So vforce reed cage + VHM dome the best option to go? Will the power increase be really noticeable ?

134 kits are probably your best bet. The biggest issue is modifying your crankcases. Also the jetting can take a bit, but they are awesome when jetted.

Hi French man !

My best friend have a MJC race bike and I rode it, then I can tell you : YES the GYTR kit improves the power but NO (imo), it doesn't change that much the bike.
Moreover, after only a few hours (something like 5 to 8 hours, I don't know exactly), the piston broke. So he had to change the whole cylinder, piston, crank bearings, head, ...

So once again in my opinion, it doesn't worth the 2500€ they're asking for ! I was faster than him with a full stock YZ 125...

In the states, I'd say make it a 134 or 144 but also get the motor modded to redistribute the power. Porting, head mods, powervalve mods, etc. Eric Gorr or Tom Morgan would be a few top builders. Maybe shipping isn't so crazy that it could be done from overseas?

$450-500 USD is listed on Eric Gorr's website. Run race gas and let them build a rocket.

The Athena kit doesn't generally get very good reviews. Just putting the piston in makes it like a tractor, so if you're fast, you'll hate it since it won't feel like a 125 anymore. It won't rev out. That's why the displacement and motor mods need to go hand-in-hand if you keep it on the pipe.

Derek Harris is on here a lot. I don't know him but he seems legit from the outside. Check out some of his YZ125 work too.

http://www.hpracedevelopment.com/news

He says his mod 2 package has hit 45 hp on the dyno for some builds: it's $900.

I'd do this way before spending $2500 on a GYTR kit myself.

305FC250 wrote:

With a whole new cylinder, head, and everything I'd hope that it at least matches stock Husky 125 power.... And keep in mind a stock Husky still has room to grow. The 39-40hp stock can become 43-44 after upgrading all the same components pictured in that GYTR kit. The Yamaha is still a good bike it's just way behind. I would also be curious to see a dyno graph with this kit.

suzukifa2014 wrote:

125 SX/TC 2016/18 are 37HP (not 39/40) it's 3HP more than the YZ...
The GYTR is made for serious racer, the reliability is not the same as the stock YZ,
you'll have to change often the piston etc

The best way to upgrade the YZ is to put a good pipe (HGS; Messico ;Damon's pipe, Scalvini etc)
+ vforce 4
+ Rinaldi rotor
+ VHM Dome AE32100-B

My opinion is that You don't need the GYTR unless you're a pro (french junior class).
EHR tuning is also pricey!
Tuning the whole engine is for PRO too, as you'll need to change the parts all the time!
In case that you don't mind that point,
you can send your motor to many people like Bud Racing, SR, Reptil, Dragontek etc

The 144 athena kit is good but you have to tune it and to modify the crank case...

Ive seen several dyno graphs showing 39-40 at the rear wheel so I stopped reading your post after the first sentence...

For 2500 euros damn! Seriously get a yz 250 with a gytr flywheel on it bam problem solved. I've had both my 06 Eric Gorr yz 144 and 06 yz 250 for 10 years once I got used to the 250 the 144 collects dust most of the time now days.

Doesn't matter if I'm riding tight indoor arenacross track to big wide open out door tracks the 250 is the weapon of choice.

Crisp BRAAAP! wrote:

Derek Harris is on here a lot. I don't know him but he seems legit from the outside. Check out some of his YZ125 work too.

http://www.hpracedevelopment.com/news

He says his mod 2 package has hit 45 hp on the dyno for some builds: it's $900.

I'd do this way before spending $2500 on a GYTR kit myself.

With just our porting, head work and some other tricks we share with purchase of this - you can go up 4 hp. if you are ok with 50/50 fuel.
For 2500 with us, you can get 6 125 cc legal

With the 134 or 144 you can get 6 with massive front side gains that will run as reliably as stock on pump gas.

The ktm and TM are both leaps better stock now days, and just bolt ons wont get you there...yamaha is finally long in the tooth.

We had a fully mod EBR 16 KTM 125. It was making 40hp. Long story short we sold it and built a 17 yz125. After modding the YZ makes 39hp. The KTM motor is better off the showroom floor but is also pushed farther engine wise. The YZ has 4-5hp that any good tuner can find. Ours was built by Terry Varner and we are very pleased. The same motor setup had the fastest lap time at Mammoth.

If it were me I would build a 134 and have cylinder and head work done.

Good Luck!

Sometimes you can go faster for free. Just working on your own body, diet and riding skills can do miracles. I have seen riders in good physical shape and good riding skills win on stock bikes and not even be tired at the end of the race. I have also seen stock bikes pull hole shots many times. The other riders with all the expensive trick go fast stuff, and the cool custom graphics on their bikes were very tired, making mistakes, and their lap times fell off after a few laps. The race is to the checkered flag. the goal is to get their first, it can be achieved in many ways.

Crisp BRAAAP! wrote:

Derek Harris is on here a lot. I don't know him but he seems legit from the outside. Check out some of his YZ125 work too.

http://www.hpracedevelopment.com/news

He says his mod 2 package has hit 45 hp on the dyno for some builds: it's $900.

I'd do this way before spending $2500 on a GYTR kit myself.

Derek Harris wrote:

With just our porting, head work and some other tricks we share with purchase of this - you can go up 4 hp. if you are ok with 50/50 fuel.
For 2500 with us, you can get 6 125 cc legal

With the 134 or 144 you can get 6 with massive front side gains that will run as reliably as stock on pump gas.

The ktm and TM are both leaps better stock now days, and just bolt ons wont get you there...yamaha is finally long in the tooth.

Could 4 HP be gained without running race gas?

Crisp BRAAAP! wrote:

Derek Harris is on here a lot. I don't know him but he seems legit from the outside. Check out some of his YZ125 work too.

http://www.hpracedevelopment.com/news

He says his mod 2 package has hit 45 hp on the dyno for some builds: it's $900.

I'd do this way before spending $2500 on a GYTR kit myself.

Derek Harris wrote:

With just our porting, head work and some other tricks we share with purchase of this - you can go up 4 hp. if you are ok with 50/50 fuel.
For 2500 with us, you can get 6 125 cc legal

With the 134 or 144 you can get 6 with massive front side gains that will run as reliably as stock on pump gas.

The ktm and TM are both leaps better stock now days, and just bolt ons wont get you there...yamaha is finally long in the tooth.

ratonmacias wrote:

Could 4 HP be gained without running race gas?

If you had deep enough pockets to pay for a cone pipe, custom ignition map and the necessary durability testing time to ensure it would hold up in worst case scenarios.
You’d be asking for oem level work... which is better and more involved than most people ever appreciate.

I finally ordered a vforce 4 reed cage and a VHM head.
It should run pretty good in addition to the fmf factory pipe and shorty silencer.

If it is not enough I will consider sending my cylinder for some mods!

Don't use a short muffler if you want to improve the topend.

Crisp BRAAAP! wrote:

Derek Harris is on here a lot. I don't know him but he seems legit from the outside. Check out some of his YZ125 work too.

http://www.hpracedevelopment.com/news

He says his mod 2 package has hit 45 hp on the dyno for some builds: it's $900.

I'd do this way before spending $2500 on a GYTR kit myself.

I bought one of the yz125s he did and it flat out ripped

Muscle-Milk-KTM wrote:

I'm definitely thinking about getting one of these kits, costs around £2000 over here in the UK.

Before spending the money on a gytr kit speak with Roland Shaw at Hardcore Racing. He could make you a hell of a bike for that kind of money.

I would not consider a KTM 150 because the engine is much harder to ride. It has a lot of top end power but lacks the smoothness of the YZ.