Yz125 as a trail bike

[Vova]

Hello everyone
I’m new to dirt bikes. Just bought a new yz125, and planning to use it on trails.
I know it is not a very good choice bike for trails, but that’s pretty much the only thing I could find with this COVID madness. Not sure where I’m going to use it yet, most like in Ganaraska a lot. I was wondering what any of you with experience can recommend to do to it, to have it more suitable for trails and more technical slower stuff. Any kind of advise would be appreciated. Thank you.

 

[GreyGhost]

My guess would be steeper gearing but since you already have it, I would head out and enjoy it. As you find things that you don't like, work on those. Try to learn something new every ride. One day try to take really tight and twisty single-track and see how it does (maybe first is too tall, maybe it is too jumpy wound out and you need to be feathering the clutch all the time anyway). The next day try faster trails and see how it behaves there. After a few weeks you should have a good idea of the strengths and weaknesses (of the bike and you) and can then start to make changes. As with most bikes, changing you will provide a lot bigger improvement than modifying the bike. Booking something like trail tours can help up your skills quickly.

 

[Delboy]

Nice bike.

I have a 2004 KX125 with a 144 big bore. I don't race it, I use it more as an all round off road bike and its fine for that. The 144 does have a bit more torque than my old 125 cylinder, but in general a 125 2T compared to a 4 stroke is lighter and more agile and holds its line better on tight stuff, and there is no hard deceleration when you shut off the gas so quite good for tight technical stuff.

I think you will be just fine. If you are riding a lot of tight stuff and feathering the clutch a lot you could maybe try going down a front sprocket size to see if it makes any difference

 

[blackcamaro]

I love my YZ125. Most fun I’ve ever had on two wheels.

Anyways I ride mine both mx and in the woods. I ride it pretty much stock. You will need to find a silencer that has a spark arrestor to be legal but that’s really the only must have in terms of mods.

A skid plate and hand guards is a good idea. I just run mx suspension, soften it up with the clickers a little for a bit of comfort. If you find it harsh a woods revalve would be helpful. Ride it for a while before you decide to do that though.

Gearing and power delivery is fine the way it is.

Do you have insurance for it yet? Tough to find insurance for bikes under 150cc these days.

 

[Ash]

A heavier flywheel is a common mod for MX bikes in the woods

 

[Vova]

My guess would be steeper gearing but since you already have it, I would head out and enjoy it. As you find things that you don't like, work on those. Try to learn something new every ride. One day try to take really tight and twisty single-track and see how it does (maybe first is too tall, maybe it is too jumpy wound out and you need to be feathering the clutch all the time anyway). The next day try faster trails and see how it behaves there. After a few weeks you should have a good idea of the strengths and weaknesses (of the bike and you) and can then start to make changes. As with most bikes, changing you will provide a lot bigger improvement than modifying the bike. Booking something like trail tours can help up your skills quickly.

 

[Vova]

Thank you
Never thought of it that way, it makes a lot of sense skill up first and then decide on the mods
Sounds like you know what you’re talking about thanks again

 

[Vova]

I love my YZ125. Most fun I’ve ever had on two wheels.

Anyways I ride mine both mx and in the woods. I ride it pretty much stock. You will need to find a silencer that has a spark arrestor to be legal but that’s really the only must have in terms of mods.

A skid plate and hand guards is a good idea. I just run mx suspension, soften it up with the clickers a little for a bit of comfort. If you find it harsh a woods revalve would be helpful. Ride it for a while before you decide to do that though.

Gearing and power delivery is fine the way it is.

Do you have insurance for it yet? Tough to find insurance for bikes under 150cc these days.

Thank you very useful info about skid plate and hand guards, I can’t really find a good skid plate for a decent price. Where do you shop?
also, insurance?
do I need it on trails? I hope it’s just liability like I have on my ATV

 

[GreyGhost]

Thank you very useful info about skid plate and hand guards, I can’t really find a good skid plate for a decent price. Where do you shop?
also, insurance?
do I need it on trails? I hope it’s just liability like I have on my ATV

You need liability if you ride on private property you don't own or on trails. The exception is competition where they carry the insurance.

 

[Vova]

Nice bike.

I have a 2004 KX125 with a 144 big bore. I don't race it, I use it more as an all round off road bike and its fine for that. The 144 does have a bit more torque than my old 125 cylinder, but in general a 125 2T compared to a 4 stroke is lighter and more agile and holds its line better on tight stuff, and there is no hard deceleration when you shut off the gas so quite good for tight technical stuff.

I think you will be just fine. If you are riding a lot of tight stuff and feathering the clutch a lot you could maybe try going down a front sprocket size to see if it makes any difference

Thank you
About the tight technical stuff, the mechanic at the dealer told me I’ll be going thru spark plugs if I don’t race it like it was meant to. He said it should be treated like a chainsaw, high rpm and don’t let it idle for too long

 

[GreyGhost]

Thank you
About the tight technical stuff, the mechanic at the dealer told me I’ll be going thru spark plugs if I don’t race it like it was meant to. He said it should be treated like a chainsaw, high rpm and don’t let it idle for too long

Spark plugs are cheap. Carry a spare and have fun.

 

[Vova]

Also, does anyone know a good suspension place around GTA
I do need to lower it I’m like 5’5” and struggle quite a bit, specially kick starting it

 

[Ash]

And rejetting the carbs to reduce low-throttle richness is fairly easy, although somewhat annoying depending on how hard it is to get the carbs out. I have no experience with that bike, but it's very unlikely that you will ever spend more than 5% of your time at full throttle on single track, so a rejet could be worth the effort if you find that it does foul up too often.

 

[Vova]

And rejetting the carbs to reduce low-throttle richness is fairly easy, although somewhat annoying depending on how hard it is to get the carbs out. I have no experience with that bike, but it's very unlikely that you will ever spend more than 5% of your time at full throttle on single track, so a rejet could be worth the effort if you find that it does foul up too often.

thank you and yes
I was playing around with it at my in-laws property at slow speeds and that is exactly what’s happening, like you said the spark plug is wet. So I too think it needs to be done, simply because I don’t see myself opening it up to it’s full potential very often

 

[blackcamaro]

Thank you very useful info about skid plate and hand guards, I can’t really find a good skid plate for a decent price. Where do you shop?
also, insurance?
do I need it on trails? I hope it’s just liability like I have on my ATV

I usually order stuff from Rocky Mountain Atv in the U.S. ships fast and good selection. Fortnine is Canadian but the selection isn’t great and the website is often out of date so I can’t be bothered. Btw the YZ’s are pretty much the exact same bike since 2006 other then the plastics were updated in 2015 so you can find used stuff. 2005 is the same frame and engine but different suspension.

@GreyGhost covered the insurance.

So I actually have two YZ125’s. First one I got was for my gf and after a few years I had to have one for myself. We almost never foul plugs. The only time I will foul a plug is if I start the bike before I’m ready to ride and turn it off after it’s been idling for a few minutes. You should carry a spare like greyghost mentioned though. I haven’t touched the jetting, sure it could probably be a little better but it’s pretty dang good the way they come. I run 91 non ethanol and Amsoil dominator (easy to find) mixed at 40-1.

Suspension shops. Accelerated technologies, MP1 suspension, Mission cycle is a race tech dealer, Two Wheel Motorsport (pro-action). There’s more but those come to mind. Two Wheel lowered my gf’s 1.5” when I bought it new and I’ve used MP1 for revalves on past bikes. MP1 will send you boxes you can send your suspension back in. I would try to get some ride time on the bike first and let it break in before lowering.

 

[Ash]

thank you and yes
I was playing around with it at my in-laws property at slow speeds and that is exactly what’s happening, like you said the spark plug is wet. So I too think it needs to be done, simply because I don’t see myself opening it up to it’s full potential very often

If you are handy, you can rejet it yourself. And you might want to do this yourself anyway, because if a shop does it for you they're just going to have to guess at how you'll be riding it. Grab a box of nitrile gloves to keep your hands from stinking of gas, and a selection of proper Mikuni jets from Snowmobile, Motorcycle, ATV and Watercraft - winnerscirclecanada.com. Get two of each jet (one size smaller and two sizes smaller than stock) as a starting point.

edit: and don't chase jetting issues by changing the premix oil ratio. Stick with whatever premix ratio that you want to use, and jet around that

 

[Vova]

If you are handy, you can rejet it yourself. And you might want to do this yourself anyway, because if a shop does it for you they're just going to have to guess at how you'll be riding it. Grab a box of nitrile gloves to keep your hands from stinking of gas, and a selection of proper Mikuni jets from Snowmobile, Motorcycle, ATV and Watercraft - winnerscirclecanada.com. Get two of each jet (one size smaller and two sizes smaller than stock) as a starting point.

edit: and don't chase jetting issues by changing the premix oil ratio. Stick with whatever premix ratio that you want to use, and jet around that

Thank you

 

[Vova]

I usually order stuff from Rocky Mountain Atv in the U.S. ships fast and good selection. Fortnine is Canadian but the selection isn’t great and the website is often out of date so I can’t be bothered. Btw the YZ’s are pretty much the exact same bike since 2006 other then the plastics were updated in 2015 so you can find used stuff. 2005 is the same frame and engine but different suspension.

@GreyGhost covered the insurance.

So I actually have two YZ125’s. First one I got was for my gf and after a few years I had to have one for myself. We almost never foul plugs. The only time I will foul a plug is if I start the bike before I’m ready to ride and turn it off after it’s been idling for a few minutes. You should carry a spare like greyghost mentioned though. I haven’t touched the jetting, sure it could probably be a little better but it’s pretty dang good the way they come. I run 91 non ethanol and Amsoil dominator (easy to find) mixed at 40-1.

Suspension shops. Accelerated technologies, MP1 suspension, Mission cycle is a race tech dealer, Two Wheel Motorsport (pro-action). There’s more but those come to mind. Two Wheel lowered my gf’s 1.5” when I bought it new and I’ve used MP1 for revalves on past bikes. MP1 will send you boxes you can send your suspension back in. I would try to get some ride time on the bike first and let it break in before lowering.

Thanks a bunch
I honestly didn’t think I would get so much help so quickly. This is great
Now I just want to ride, and I wish I didn’t have to work so I could ride more

 

[Jayv]

Also, does anyone know a good suspension place around GTA
I do need to lower it I’m like 5’5” and struggle quite a bit, specially kick starting it

John is probably your best bet for this-although I would probably do this as a last resort.

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[Vova]

John is probably your best bet for this-although I would probably do this as a last resort.

Home - Accelerated Technologies

Services Lowering SAG & Set Up Track Preparation Fork Service & Tuning General Service Shock Service & Tuning Products Accelerated Technologies Welcome to Accelerated Technologies. As Motorsports Suspension specialists we specialize in suspension of all kinds including street bikes, road racing...

acceleratedtechnologies.ca

thank you