First 125 Since 1989

Tim507
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Tim507
Edited Date/Time 9/22/2022 3:02pm
Looking for input in making it more Vet friendly - I'm 70, fit and in the kings clothes weight a buck fifty.
Really looking forward to riding a light bike.
Big Bore?
What size if?
I've heard about engine coatings and know very little, advantages - durability - disadvantage
ECU


Tim




38
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mtl
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mtl 9/19/2022 9:16am
9/19/2022 9:16am
I would just ride it and change the oil after the first 2hrs on the motor.
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Tim507
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Tim507 9/19/2022 9:17am
9/19/2022 9:17am
I have a 22 YZ 250 and will be keeping it as it is an awesome bike.
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Tim507
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Tim507 9/19/2022 9:18am
9/19/2022 9:18am
mtl wrote:
I would just ride it and change the oil after the first 2hrs on the motor.
that is the initial plan.....

The Shop

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Mouse153
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Mouse153 9/19/2022 9:26am
9/19/2022 9:26am
I'm in my 50s and I just went to a KTM150SX. Light, good torque and fun to run! Enjoy!
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dedi684
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dedi684 9/19/2022 10:14am
9/19/2022 10:14am
I've got a yz 250 myself can't decide between yz 125 or austria
dan45mt
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dan45mt 9/19/2022 10:39am
9/19/2022 10:39am
Got my 22 YZ125 a couple months ago. I finally have it jetted and it runs great. Went w/Jd kit. I am an old guy too and hope this lightweight bike puts the fun back in MX!
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suspensionguy
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suspensionguy 9/19/2022 10:54am
9/19/2022 10:54am
One of the most fun and memorable bikes I ever had was a 2006 yz144. Was a simple Athena bolt on 144 kit. Such a fun bike. The yz’s are workhorses. Always wanted to try a rpm 167 motor, I bet it’s a hoot.
1
SmokinJoe439 9/19/2022 12:03pm
9/19/2022 12:03pm
I would jet it first the newer 125's the jetting is way off fat on the bottom lean up top. Yamaha really missed with the jetting on this one.
They were trying to go for ultimate power and it didn't work.

Jet it more like the yz250 and how you'd typically jet a pwk and it will make it much easier to ride. Not as boggy of the bottom less like a light switch.

Second other than bars grips maybe tires you like practice 125 skills. Lots of aggressive riding is needed lots of revving it out. Carrying momentum.

Not sure if anyone has really done a big bore kit yet with this new engine.

I had for 15 years a 06 yz125 that within 6 months of new was made into a 144. I had Eric gorr do it. Was a fun bike really enjoyed it definitely liked it over stock. But it was a proper 144 with porting and head mods.

Negative to over boring the yz125 is the thin exhaust bridge. Since I had my 144 ported for more mid n top. It made it even thinner.

This trade off unfortunately causes the exhaust port bridge to hammer on the ring. Wears it out faster. So I had to stay on top of the top ends.

Ultimate reliability is to leave it stock and spend your upgrades on billet clutch parts and gas n premix.
6
MELROSEMAFIA
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MELROSEMAFIA 9/19/2022 12:46pm
9/19/2022 12:46pm
I have been on the fence myself regarding a new 125 dirtbike purchase...Prefer the X version trail bike, but not sure the seat height is low enough for me...I will probably talk myself into the Zuk 125...Half the price and a 6 inch lower seat height...
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Tim507
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Tim507 9/19/2022 2:34pm
9/19/2022 2:34pm
SmokinJoe439 wrote:
I would jet it first the newer 125's the jetting is way off fat on the bottom lean up top. Yamaha really missed with the jetting...
I would jet it first the newer 125's the jetting is way off fat on the bottom lean up top. Yamaha really missed with the jetting on this one.
They were trying to go for ultimate power and it didn't work.

Jet it more like the yz250 and how you'd typically jet a pwk and it will make it much easier to ride. Not as boggy of the bottom less like a light switch.

Second other than bars grips maybe tires you like practice 125 skills. Lots of aggressive riding is needed lots of revving it out. Carrying momentum.

Not sure if anyone has really done a big bore kit yet with this new engine.

I had for 15 years a 06 yz125 that within 6 months of new was made into a 144. I had Eric gorr do it. Was a fun bike really enjoyed it definitely liked it over stock. But it was a proper 144 with porting and head mods.

Negative to over boring the yz125 is the thin exhaust bridge. Since I had my 144 ported for more mid n top. It made it even thinner.

This trade off unfortunately causes the exhaust port bridge to hammer on the ring. Wears it out faster. So I had to stay on top of the top ends.

Ultimate reliability is to leave it stock and spend your upgrades on billet clutch parts and gas n premix.
My YZ 250 has an Electron and I have ordered one for the 125.

My son says not to get the big boreLaughing Perhaps he is right........

Hadn't thought about billet clutch parts - makes sense with a 125.

I work hard at being fit and that may prove to the best investment.

Tim
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Rocket164
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Rocket164 9/19/2022 4:37pm
9/19/2022 4:37pm
I have quite a bit of YZ125 experience and my thoughts are keep it simple with basic mods.…….Dial in the jetting, adjust gearing for your tracks, have suspension setup for your weight and ability, add your favorite bars/grips, works connection elite clutch perch, and install an exhaust system if you don’t like the looks of the stock pipe. If cost is not an issue I would suggest using some oxygenated fuel as this makes a noticeable improvement.

I would stay away from the big bores. JMO.
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Homey513
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Homey513 9/20/2022 12:31am
9/20/2022 12:31am
I had a 2 mil mod done by JM Racing. They talked me out of 144, said the 134 would keep the same characteristics that make a 125 fun. They still rev out like a 125, but has more power everywhere.

Hands done the best money I have ever spent on a bike part or mod.....
3
fanger
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fanger 9/20/2022 1:31am
9/20/2022 1:31am
I dunno, I feel like hunting hp on a 125 defeats the purpose of having one
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slowoldman
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slowoldman 9/20/2022 3:18am
9/20/2022 3:18am
Didn’t buy it new as I planned to just ride it initially, but being in my 50’s and can’t leave well enough alone, bare framed it, has a 144 kit along with all the other bolt on stuff we all love. I also went with the Lectron carb which is amazing IMO. I do know the stock carb is awesome too, just jetting initially and it rips! Anyway, love reading other old timers like ourselves getting back to our roots. Enjoy your new bike. 👍.
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wiedeman
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wiedeman 9/20/2022 4:28am
9/20/2022 4:28am
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on the 23, but I went to a 50 pilot, 168 main for trail riding, and a 55p 172m for sand. Awesome bike, but the suspension is set up a little bit stiff for a 150lb rider. Back your clickers pretty far out, and keep adjusting until the suspension breaks in (mine took ~10 hours to really start to feel plush) If you sit down a lot, the stock seat is pretty damn firm and you might want to look into changing that. Do your first top end at 20 hours no matter what kind of riding you do, the stock piston has been breaking on some bikes. Also, expect most of the paint to be worn off your pipe by 40 hours.
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dedi684
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dedi684 9/20/2022 4:34am
9/20/2022 4:34am
wiedeman wrote:
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on...
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on the 23, but I went to a 50 pilot, 168 main for trail riding, and a 55p 172m for sand. Awesome bike, but the suspension is set up a little bit stiff for a 150lb rider. Back your clickers pretty far out, and keep adjusting until the suspension breaks in (mine took ~10 hours to really start to feel plush) If you sit down a lot, the stock seat is pretty damn firm and you might want to look into changing that. Do your first top end at 20 hours no matter what kind of riding you do, the stock piston has been breaking on some bikes. Also, expect most of the paint to be worn off your pipe by 40 hours.
We're you able to keep stock springs I'm about 145 these days?
Tim507
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Tim507 9/20/2022 6:23am
9/20/2022 6:23am
wiedeman wrote:
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on...
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on the 23, but I went to a 50 pilot, 168 main for trail riding, and a 55p 172m for sand. Awesome bike, but the suspension is set up a little bit stiff for a 150lb rider. Back your clickers pretty far out, and keep adjusting until the suspension breaks in (mine took ~10 hours to really start to feel plush) If you sit down a lot, the stock seat is pretty damn firm and you might want to look into changing that. Do your first top end at 20 hours no matter what kind of riding you do, the stock piston has been breaking on some bikes. Also, expect most of the paint to be worn off your pipe by 40 hours.
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not available. Spoke to another BB company and they felt the 140 was as big as the 125 should go. So that is in line with what Homey510 says.

Since I'm also light, the suspension will need some attention.

For now I'm just going to ride it and get it broke inWoohoo
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SmokinJoe439 9/20/2022 7:33am
9/20/2022 7:33am
wiedeman wrote:
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on...
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on the 23, but I went to a 50 pilot, 168 main for trail riding, and a 55p 172m for sand. Awesome bike, but the suspension is set up a little bit stiff for a 150lb rider. Back your clickers pretty far out, and keep adjusting until the suspension breaks in (mine took ~10 hours to really start to feel plush) If you sit down a lot, the stock seat is pretty damn firm and you might want to look into changing that. Do your first top end at 20 hours no matter what kind of riding you do, the stock piston has been breaking on some bikes. Also, expect most of the paint to be worn off your pipe by 40 hours.
Tim507 wrote:
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not...
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not available. Spoke to another BB company and they felt the 140 was as big as the 125 should go. So that is in line with what Homey510 says.

Since I'm also light, the suspension will need some attention.

For now I'm just going to ride it and get it broke inWoohoo
I would ask the company that suggested the 140 kit. What piston do they use. Last time I looked wiseco discontinued the 57mm piston used in the 139/140 kits. They were only offering for the 05+ yz125 stock 56mm (133/134) and the 58mm 144 pistons.

The 57mm is probably the least popular size I don't think I'd go with that one. Getting a piston could be troublesome
1
Tim507
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Tim507 9/20/2022 7:41am
9/20/2022 7:41am
wiedeman wrote:
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on...
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on the 23, but I went to a 50 pilot, 168 main for trail riding, and a 55p 172m for sand. Awesome bike, but the suspension is set up a little bit stiff for a 150lb rider. Back your clickers pretty far out, and keep adjusting until the suspension breaks in (mine took ~10 hours to really start to feel plush) If you sit down a lot, the stock seat is pretty damn firm and you might want to look into changing that. Do your first top end at 20 hours no matter what kind of riding you do, the stock piston has been breaking on some bikes. Also, expect most of the paint to be worn off your pipe by 40 hours.
Tim507 wrote:
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not...
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not available. Spoke to another BB company and they felt the 140 was as big as the 125 should go. So that is in line with what Homey510 says.

Since I'm also light, the suspension will need some attention.

For now I'm just going to ride it and get it broke inWoohoo
SmokinJoe439 wrote:
I would ask the company that suggested the 140 kit. What piston do they use. Last time I looked wiseco discontinued the 57mm piston used in...
I would ask the company that suggested the 140 kit. What piston do they use. Last time I looked wiseco discontinued the 57mm piston used in the 139/140 kits. They were only offering for the 05+ yz125 stock 56mm (133/134) and the 58mm 144 pistons.

The 57mm is probably the least popular size I don't think I'd go with that one. Getting a piston could be troublesome
Joe, I'm a RHS graduate - 1970! Grew up in the Skyway area.

Lots if riding at the Tank Tracks and the surrounding woods before all the homes in the late 60's. Lake Desire area, again before homes were built. The Newcastle area and countless other areas. Cle Elum........many more. Poached Seward Park on late afternoon about 1971WhistlingWoohoo

Tim
Johnny Ringo
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Johnny Ringo 9/20/2022 7:49am
9/20/2022 7:49am
JD Jet kit, up a tooth in the rear and FMF system and you are dialed in bro
Falcon
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Falcon 9/20/2022 8:54am
9/20/2022 8:54am
Johnny Ringo wrote:
JD Jet kit, up a tooth in the rear and FMF system and you are dialed in bro
I was going to say, "and add a V-Force reed system," but I think they come with those now. In any case, the new air intake makes that bike faster than any of my old YZ125s. Get that thing running right and you'll forget all about a big bore. Wink
SmokinJoe439 9/20/2022 8:55am
9/20/2022 8:55am
Tim507 wrote:
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not...
Thanks for the information wiedeman! The lectron should solve the jetting issues. As far as the BB goes, the 167 kit from maxrpm is currently not available. Spoke to another BB company and they felt the 140 was as big as the 125 should go. So that is in line with what Homey510 says.

Since I'm also light, the suspension will need some attention.

For now I'm just going to ride it and get it broke inWoohoo
SmokinJoe439 wrote:
I would ask the company that suggested the 140 kit. What piston do they use. Last time I looked wiseco discontinued the 57mm piston used in...
I would ask the company that suggested the 140 kit. What piston do they use. Last time I looked wiseco discontinued the 57mm piston used in the 139/140 kits. They were only offering for the 05+ yz125 stock 56mm (133/134) and the 58mm 144 pistons.

The 57mm is probably the least popular size I don't think I'd go with that one. Getting a piston could be troublesome
Tim507 wrote:
Joe, I'm a RHS graduate - 1970! Grew up in the Skyway area. Lots if riding at the Tank Tracks and the surrounding woods before all...
Joe, I'm a RHS graduate - 1970! Grew up in the Skyway area.

Lots if riding at the Tank Tracks and the surrounding woods before all the homes in the late 60's. Lake Desire area, again before homes were built. The Newcastle area and countless other areas. Cle Elum........many more. Poached Seward Park on late afternoon about 1971WhistlingWoohoo

Tim
Haha awesome I'm lil younger than you though but from the area. I lived out in Snohomish just north of Woodinville. Wouldn't you kill to have all the old spots to go ride again. I do miss cle elum not so much the coal pile. I could get up it on an xr75 on some of them.

Buddy scared himself on them. First time there he knew how to ride. But he thought it was flat for some reason at the top not peaked. Went up it on his maico 250 and jumped off the top. Landed about a quarter past the top. Crashed luckily only just some scratches. I didn't see it. He was like mad at us and we were like we didn't know you was gonna jump off it. That coal pile sure drew the squids I loved the trails that place had. Some of the crazy night riding in the summer.

Things have sure changed I still ride but mostly just a professional practice rider. Only races we do old timers mx and 125 dream race.
No longer on yz's on a pair of 21 ktm's 150 n 250sx.


joemez
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joemez 9/20/2022 2:24pm
9/20/2022 2:24pm
Mouse153 wrote:
I'm in my 50s and I just went to a KTM150SX. Light, good torque and fun to run! Enjoy!
I turn 50 next month and i still ride my 1990 honda cr 125 and i have a 1988 cr 125 . Its enough to get my heart pumping.
6
Rabbit Run 41 9/20/2022 3:26pm
9/20/2022 3:26pm
slowoldman wrote:
Didn’t buy it new as I planned to just ride it initially, but being in my 50’s and can’t leave well enough alone, bare framed it...
Didn’t buy it new as I planned to just ride it initially, but being in my 50’s and can’t leave well enough alone, bare framed it, has a 144 kit along with all the other bolt on stuff we all love. I also went with the Lectron carb which is amazing IMO. I do know the stock carb is awesome too, just jetting initially and it rips! Anyway, love reading other old timers like ourselves getting back to our roots. Enjoy your new bike. 👍.
Very nice build. Didn't mention the WP forks?? I rode my fairly stock '03 RM125 this weekend. 1st time in 6 years on that bike. My race bike is a 350SFX.
You nailed it with remembering why we got into this sport. At 60, I had a blast going slower and just playing with the track.

slowoldman
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slowoldman 9/20/2022 4:55pm
9/20/2022 4:55pm Edited Date/Time 9/20/2022 5:35pm
slowoldman wrote:
Didn’t buy it new as I planned to just ride it initially, but being in my 50’s and can’t leave well enough alone, bare framed it...
Didn’t buy it new as I planned to just ride it initially, but being in my 50’s and can’t leave well enough alone, bare framed it, has a 144 kit along with all the other bolt on stuff we all love. I also went with the Lectron carb which is amazing IMO. I do know the stock carb is awesome too, just jetting initially and it rips! Anyway, love reading other old timers like ourselves getting back to our roots. Enjoy your new bike. 👍.
Rabbit Run 41 wrote:
Very nice build. Didn't mention the WP forks?? I rode my fairly stock '03 RM125 this weekend. 1st time in 6 years on that bike. My...
Very nice build. Didn't mention the WP forks?? I rode my fairly stock '03 RM125 this weekend. 1st time in 6 years on that bike. My race bike is a 350SFX.
You nailed it with remembering why we got into this sport. At 60, I had a blast going slower and just playing with the track.

WP suspension is awesome. I didn’t mention it or all the other things I did either, because people think your bragging. I am too old to brag on anything but my now full grown kids which the Good Lord Blessed me with. This 2008 has every nut, bolt and even hard parts replaced with New. Yes, I surely would have saved some money going new, but as we age we save money and can still feel good about our decisions. 👍
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wiedeman
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wiedeman 9/20/2022 5:04pm
9/20/2022 5:04pm
wiedeman wrote:
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on...
I have a 22 and its a great bike in stock form, apart from the jetting. I don't know if they sorted the jetting out on the 23, but I went to a 50 pilot, 168 main for trail riding, and a 55p 172m for sand. Awesome bike, but the suspension is set up a little bit stiff for a 150lb rider. Back your clickers pretty far out, and keep adjusting until the suspension breaks in (mine took ~10 hours to really start to feel plush) If you sit down a lot, the stock seat is pretty damn firm and you might want to look into changing that. Do your first top end at 20 hours no matter what kind of riding you do, the stock piston has been breaking on some bikes. Also, expect most of the paint to be worn off your pipe by 40 hours.
dedi684 wrote:
We're you able to keep stock springs I'm about 145 these days?
Stock springs work for me at ~145. 100mm sag with ~34mm static. Slightly stiff but works really good when riding at a moderate pace. Works amazing at full tilt.

I really like the motor on the 22. Not as much 'off idle' power as the previous gen in my opinion, but once you twist that throttle just a little bit, it lights up very quick and pulls hard!! Feels like it has a lot more power in the mid, and plenty up top. I've spent about 1/4 of the time on the bike riding tight single track, and I can easily chug around in 3rd. Its not a 250, but has great power as long as you keep it above 3000 rpms.

I'm sure you know this, but if you put a lectron on the bike, do not expect it to be perfect out of the box!! Some can come very lean, so take your time!
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Tim507
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Tim507 9/21/2022 11:36am
9/21/2022 11:36am
Rode the bike yesterday afternoon at Parc Moto in Canby OR. PM is a relative tight track.

The carb is (as previously noted) way to rich, Lectron will be here this weekend
The tank came nearly full with the dealers mix - I run T2, so the next ride the fuel will be T2
At this track an added tooth in the rear would help - we'll see on Sunday at a more open and faster track
Grips suck for sure - have some Renthal Grips that go on tomorrow
Suspension worked for me - I'm sure even better after they break in
Very easy to ride and loads of fun





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slowoldman
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slowoldman 9/22/2022 1:19pm
9/22/2022 1:19pm
Tim507 wrote:
Rode the bike yesterday afternoon at Parc Moto in Canby OR. PM is a relative tight track. The carb is (as previously noted) way to rich...
Rode the bike yesterday afternoon at Parc Moto in Canby OR. PM is a relative tight track.

The carb is (as previously noted) way to rich, Lectron will be here this weekend
The tank came nearly full with the dealers mix - I run T2, so the next ride the fuel will be T2
At this track an added tooth in the rear would help - we'll see on Sunday at a more open and faster track
Grips suck for sure - have some Renthal Grips that go on tomorrow
Suspension worked for me - I'm sure even better after they break in
Very easy to ride and loads of fun





Looks like the track was not a muddier, so Easy clean up too! 👍. I have the Lectron on my YZ125 and it rocks! The stock carb is also super awesome once dialed in, just so I’dont get hated on too bad. 😳. The suspension on your bike is by far the best stock suspension from my experience and others reviews. I believe it is called the triple S? Anyway, I only wish you lived closer to NC, we would be riding together as often as you wanted. Enjoy the new steed! Keep us updated on your experience with the 125. 👍
Gator 4
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Gator 4 9/22/2022 3:02pm
9/22/2022 3:02pm
I leave mine stock. Plenty of zip, you will pass plenty of 450's. Any mod you do will compromise your reliability. I have a CR 125 and have a blast completely stock. 63 yo.

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