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New used YZ125..

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I just traded my xr100 for a yz125 and have a couple questions

Whats the deal with this top end rebuilding, how often does it need to be done, what parts do i need, and how much?

What oil does this take? I read around and some say 10w30 with no friction modifiers or additives..

I cleaned the air filter, fixed the front brake, and the throttle, and also cleaned the air filter, is there any other maintenance or check-ups I should do on this beat up on bike? I was thinking to clean the carburetor but it runs fine and I didn't really want to...

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Hello

top ends according to manual are about every 10 hours, I think it depends on your riding style. Riding agressively you need to do the top end every 20 hours, tugging along taking it easy you get away with more maybe even double. Gear oil is up what you like and what you get. Oilchanges also every 5 hours.

Carb cleaning is important too. Runing the bike too lean and you could get a piston melt down.

Have fun

Arnego2

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Hey there

I would first throw a top end in the bike for the insurance of the bike. You never know what the bike has gone through.

As for top end life i would go about every 10 to 30 hours. On the way you ride, like arnego said if your going to beat the crap out of the bike then i would do every 10-15 hours. If you putting maybe like 30 and above.

Gear oil you can use gear saver, amsoil, etc etc:blah:

As long as you use the correct weight. I personally used gear saver and never had a problem.

I would check the wheel bearings on the bike and clean and regrease, check the suspension for any leaks, check the spokes, check the brake pad life, also check the caliper for any leaking of brake fluid.

There is a ton of stuff you can check. But start with that but take your time checking all this, trust me just do it right the first time, never do anything half way.

thanks man and god bless

Alex

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I just traded my xr100 for a yz125 and have a couple questions

Whats the deal with this top end rebuilding, how often does it need to be done, what parts do i need, and how much?

What oil does this take? I read around and some say 10w30 with no friction modifiers or additives..

I cleaned the air filter, fixed the front brake, and the throttle, and also cleaned the air filter, is there any other maintenance or check-ups I should do on this beat up on bike? I was thinking to clean the carburetor but it runs fine and I didn't really want to...

You will also want to grease the entire bike. Steering bearings, wheel bearings, linkage bearings, swingarm bearings. Basically anywhere that there is a bearing on your bike, you'll want to grease it. Most people do not take care of this, and it WILL cause a huge problem down the road.

Change your suspension fluid frequently (according to your manual.) This fluid gets very hot when riding. Hot oil breaks down fast. Broken down oil is not good. Change it.

Also, clean and oil your air filter at least every other ride. You'll thank yourself later.

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I got some castrol 4t oil for it and put in approximately 650cc's. I also cleaned the carburetor tonight, It started right up almost the first kick. (yay)

I still need this bit of information.

"Whats the deal with this top end rebuilding, how often does it need to be done, what parts do i need, and how much?"

Oh and how do i go about doing it most importantly, how do i clean reeds/powervalve too?

Do i need to actually take the engine out? take off the gas tank? - for the top end.

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I got some castrol 4t oil for it and put in approximately 650cc's. I also cleaned the carburetor tonight, It started right up almost the first kick. (yay)

I still need this bit of information.

"Whats the deal with this top end rebuilding, how often does it need to be done, what parts do i need, and how much?"

Oh and how do i go about doing it most importantly, how do i clean reeds/powervalve too?

Do i need to actually take the engine out? take off the gas tank? - for the top end.

You will need this:

http://www.motosport.com/dirtbike/product/WISECO-PROLITE-PISTON-KIT-2STROKE/?id=108625

Comes with everything you need except the needle bearing i think.

Yes you will need to take the gas tank off. Piece of cake, take the seat off, then there will be 2 bolts that bolt to your radiatiors, then pull that little rubber holder thing at the bottom of the tank. Should take like 2 minutes to take the tank off.

Heres how to do the top end :

Also for the powervalve you have to pull the cylinder off, and you'll see in the video, you powervalve linkage, that needs to be take off and then once you get the cylinder off, you take that little cover at the top off.

As for the reeds, pull the reed block out of the cylinder and inspect, if there is any chipped edges replace them. If they look like they arent getting a a good seal against the surface then replace them.

thanks i hope this helped

Alex

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so its just a piston, rings, piston pin, and some gaskets then...? thats what makes up a top end rebuild?

And thats all i need for it?

Pretty much man, also i would get the OEM needle bearing too.

Also do you have a manual? Because you can download one here:

http://www.yamahaownershandbook.com.au/?r=0

Because its good to know torque settings. But dont get yourself worked up over a top end. Its very easy to do. Just take your time and be very carefuly not to loose anything or drop anything down in the motor.

thanks man

Alex

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I'm really just worried about cost, i don't even have enough to register the bike for the trails :thumbsup:

and yamaha apparently doesnt have my model year... (1994)

also where would i find an OEM needle bearing?

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I'm surprised people change their top ends every 10-30 hours. I make mine last a little longer, closer to the 40hr mark at least. If you feel like your losing power or just want to reassure yourself then pull the plug and do a compression test.

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yes I have a few in the area, heinens (www.heinenmotorsports.com/), and hitching post stick out.(www.hponline.com)

what are the online stores you know of?

also on a side note, i just got up to 60 on it around the block.

Theres all kinds. bike bandit, motorcycle superstore, motosport, rocky mountain ATV. But see if your local dealer can help you out with finding some of the OEM stuff.

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I'm surprised people change their top ends every 10-30 hours. I make mine last a little longer, closer to the 40hr mark at least.

Riding style could be an explanation:) :thumbsup:

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