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2020 YZ125X first impressions and review

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Interesting development. So when I went to start the girl up after installing the vforce, apex, and race fuel, I pulled the choke on and she fired instantly but was seriously high in rpm's! Immediately turned choke off and the rpm's came down to normal. That was so incredibly odd, that I lifted the choke again and again, high rpm's!

I'm thinking that the starter jet might have unscrewed itself and is sitting in the bottom of the carb, causing a lean mixture with choke on???

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2 minutes ago, MANIAC998 said:

Interesting development. So when I went to start the girl up after installing the vforce, apex, and race fuel, I pulled the choke on and she fired instantly but was seriously high in rpm's! Immediately turned choke off and the rpm's came down to normal. That was so incredibly odd, that I lifted the choke again and again, high rpm's!

I'm thinking that the starter jet might have unscrewed itself and is sitting in the bottom of the carb, causing a lean mixture with choke on???

My bike does the same thing. Always wondered why, been too lazy to look into it. I have vforce I doubt there's a relationship.

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19 hours ago, shrubitup said:

Depends on oil. High viscosity can do 40/1 but I just use 32/1 always in a small bore. 
 

when son had a kx100, I mixed 32/1 for it and then just fed the 300 that too. Creating no harm from this, I’m now a 32/1 guy except if it’s 927 where you can use less due to high viscosity. 
 

just keep amsoil away from any 125 and you’ll be ok. 

I’ve allways used motorex 

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Well fellas- here she is. 2017 yz125. Factory Connection Suspension set up for woods and spung for my weight, FMF fatty, 18inch rear, Vforce reeds, JD jet kit. I got the bash plate and hand guards in a box - going on today.  All for about $$1/2 the price I could get an X for OTD.   This thread was 99% influence on this buy.  I’m putting the 3.2 tank on and racing it as is. Over time I will slowly do The full X conversion.   Thanks guys for all the advise -  best thread around.  

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Posted (edited)
9 hours ago, MANIAC998 said:

Interesting development. So when I went to start the girl up after installing the vforce, apex, and race fuel, I pulled the choke on and she fired instantly but was seriously high in rpm's! Immediately turned choke off and the rpm's came down to normal. That was so incredibly odd, that I lifted the choke again and again, high rpm's!

I'm thinking that the starter jet might have unscrewed itself and is sitting in the bottom of the carb, causing a lean mixture with choke on???

Every 2T I’ve owned does that.

Edit:  Maybe not “seriously high”.  Just checked: ~4500rpm cold start with choke on my 125x.  Choke off it drops to 1200 rpm cold. Idles about 950 when warm.  

Edited by mgw929
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Ok, I’m gonna sidetrack this one a little. I’ve been scrolling through reading for the past couple days off and on. I’ve not been on a 125 in over 20 years, and we don’t have any decent dealers within 100 miles. I’m 6’1”, average 230lbs. A small bore 2T is really drawing me. 
Does the 125X have enough Oomph to pull my big arse around, or would it need to be WOT all the time to enjoy it? The feel of something lightweight and zippy sounds fun for a change. Big bore four strokes aren’t as fun as they used to be.

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36 minutes ago, PopWill said:

Ok, I’m gonna sidetrack this one a little. I’ve been scrolling through reading for the past couple days off and on. I’ve not been on a 125 in over 20 years, and we don’t have any decent dealers within 100 miles. I’m 6’1”, average 230lbs. A small bore 2T is really drawing me. 
Does the 125X have enough Oomph to pull my big arse around, or would it need to be WOT all the time to enjoy it? The feel of something lightweight and zippy sounds fun for a change. Big bore four strokes aren’t as fun as they used to be.

I’m 6’1, and about 230 with gear on.  I ride Idaho single track mostly-  usually 2.5k to 6k elevation.   I have no issues getting around, and I was surprised by how much grunt the 125x does have.  Rocky and rooty steep climbs are much easier on this bike than either my kx250/310 ever was and I’m not tired at the end of the day.  I’m on the pipe less than 30% of the time I’d guess.

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17 minutes ago, mgw929 said:

I’m 6’1, and about 230 with gear on.  I ride Idaho single track mostly-  usually 2.5k to 6k elevation.   I have no issues getting around, and I was surprised by how much grunt the 125x does have.  Rocky and rooty steep climbs are much easier on this bike than either my kx250/310 ever was and I’m not tired at the end of the day.  I’m on the pipe less than 30% of the time I’d guess.

Awesome! That’s great to hear. It’ll definitely go on the list to test ride then. 

I actually haven’t ridden much in a long time. My trusty old XR400 hydrolocked a few years ago, and life went elsewhere. My son is riding now though, and the fever has really hit me again. The XR will definitely live again, but a lighter, zippier ride is a must. It’ll probably be several months away, but I’m like a kid on Christmas Eve!

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58 minutes ago, PopWill said:

Awesome! That’s great to hear. It’ll definitely go on the list to test ride then. 

I actually haven’t ridden much in a long time. My trusty old XR400 hydrolocked a few years ago, and life went elsewhere. My son is riding now though, and the fever has really hit me again. The XR will definitely live again, but a lighter, zippier ride is a must. It’ll probably be several months away, but I’m like a kid on Christmas Eve!

I think you’d like it..  After I sold my KX I worked over a 230F and rode it for a season.  One extreme to another-  but for a single track bike, the 230 was actually really decent and I had to learn a bunch about keeping momentum, line choice and clutch control to keep up (vs KX310 point, twist and hold on).  The 125x is an absolute joy to ride in wooded singletrack compared to the other 2.  It is so forgiving in my opinion, yet fast. Smiles for miles.

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12 hours ago, monkeyboy57 said:

Is that the 125 karts? How many rpm. What brand / type oil and fuel was used at 40:1. 

Pretty different sort of conditions to single track though I would have thought. 

I assume you have nikasil bores?

Many Karts rev over 19K + rpm's. I raced a Rotax 125, and a Leopard 125, Yamaha KT100S. But, the open class engines rev even higher

Maxima K-2000. BP Ultimate, 40/1 Controlled fuel at open race meets, everyone had to get their fuel from the same pump, at the same servo.

We tested the different fuels on the Dyno, but yrs ago now. We tested spark plugs, all sorts of things. Well, actually, I only watched.

One of my top ends was done by Millennium, other was done in Aus, Can't remember the name atm, They're in Port Melbourne I think, been there for many yrs. They do coating as well, anno, hard anno, etc etc etc "Nikasoul", something like that.

My 144cc top end originally came from Eric Gore, but Dave at TSP did a new head, not sure if he changed anything else. The entire tranny was brand new, and Isotropic Super Finished, New crank, Micro Blue ceramic bearings throughout (1K for the bearings, when our $ was worth more than the USD), HPC internal coatings. Can't remember the name of the Ignition atm.

I put 7K into the 144 engine, back in 2013. 7K Including the pipe, carby, and Ignition.

Edited by Drop-Bear
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3 hours ago, PopWill said:

Awesome! That’s great to hear. It’ll definitely go on the list to test ride then. 

I actually haven’t ridden much in a long time. My trusty old XR400 hydrolocked a few years ago, and life went elsewhere. My son is riding now though, and the fever has really hit me again. The XR will definitely live again, but a lighter, zippier ride is a must. It’ll probably be several months away, but I’m like a kid on Christmas Eve!

If you haven't ridden one before, as in, a proper ride, give it some time. They require a different riding style than larger CC bikes.

I hadn't ridden a 125 in yrs, got on one, and was riding like a dog. I stopped, thought to myself "Ride it like a 125, remember how to do that". Then the fun began.

I'm getting slower these days, too unfit, but I always try to ride on the pipe as much as possible. That's how they're supposed to be ridden. Lots of revs, with lots of clutch.
If you're not "thrashing". or at least trying to thrash the ass out of it, you're not riding it properly. IMO.

A 300cc 2T is really easy to ride. A 125cc 2T requires actual skills to ride. Properly.

If you're a heavier rider, work on your cardio, you'll lose weight and slim down a bit. 125 riding is mostly cardio IMO. 
Free Tip: The best cardio workout on the planet, is sex. I'm not even kidding.

Edited by Drop-Bear
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3 hours ago, mgw929 said:

I think you’d like it..  After I sold my KX I worked over a 230F and rode it for a season.  One extreme to another-  but for a single track bike, the 230 was actually really decent and I had to learn a bunch about keeping momentum, line choice and clutch control to keep up (vs KX310 point, twist and hold on).  The 125x is an absolute joy to ride in wooded singletrack compared to the other 2.  It is so forgiving in my opinion, yet fast. Smiles for miles.

Yeah, that’s more what I’m looking for. I actually enjoy a lighter bike that doesn’t wear you out as much, and that thrilling zip is nice too.

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15 minutes ago, crujones7 said:

Please be gentle, newbie onboard.

https://youtu.be/XML0UXaOsh8

Keep doing what you're doing, until you're comfortable, but more importantly, confident on the bike. Once you feel confident, and comfortable, then you can start working on technique.

Confidence. IMO. Will improve your riding more than anything else.

I assume that vid is with the lectron? If so "Don't fix what isn't broke". IMO, the jetting/tune, sounds good for your style of riding atm.

Just ride mate, put your $$ into fuel and seat time, maybe a gym membership as well. The bike IMO, sounds great, I know it looks great as well. Your bike is awesome.

Knowing I'm fit, and strong, gives me more confidence than anything else. I'm not fit and strong atm, just sayin.

Edited by Drop-Bear
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Posted (edited)

40yrs old, 2 kids, 1st Dirtbike ever & I believe got around Mid-Jan, let alone a 2T. Pretty fit for a dad. Just having fun and enjoying a Sunday.

Edited by crujones7
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1 minute ago, crujones7 said:

40yrs old, 2 kids, 1st Dirtbike ever & I believe got around Mid-Jan, let alone a 2T. Pretty fit for a dad. Just having fun and enjoying a Sunday.

For some reason, I was thinking you were early 20's at most, and single :D

Same advice from me anyway. And, at our age, fun is the only goal you should have.

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Posted (edited)

Thanks, man.  I started kinda late, but I love it. I’ll be 41 this year, smh...

Edited by crujones7
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