How often do you have to replace cylinders, and also piston, rings, etc on a yz250?


23 replies to this topic
  • rcdude33

Posted December 21, 2009 - 07:32 PM

#1

Im looking into a yz250 2 stroke. I am currently coming off of a ttr125, but i know the yz250 is a lot of bike, but do you guys think that i will get used to it. I have ridden one and it was a blast to ride, except the forks had no oil in them. but it was sick!


But my main fear is top ends, and rebuilds, but i was looking at 4 strokes but im mainly worried about valves, top end rebuilds, and all that other stuff. I like how easy a 2 stroke is to work on.

but my main question is, how often doyou normally change the pitson, rings, ect. Also, what about the cylinder head?

Im not gona ride hard for like the first month or 2, but i do ike the keep the bike in the powerband.

thanks guys! Sorry for the other post too. But i thought making a completely different post would be better for me.

Also just to throw this out there if i get this bike, will i be able to keep up with my buddy on his 2008 yz250f?

  • brentn

Posted December 21, 2009 - 07:51 PM

#2

A top end is nothing on these bikes if you have some basic mechanical experience.

The manual makes things pretty clear, combine that with posts here about top ends and the youtube vids out there on top ends and your laughing. At least that's how I feel about it.

The manual, believe it or not, calls for piston and ring inspection after EVERY RACE. They also call for piston replacement after either every 3rd or 5th race, I cannot remember which.
There are people here who have had hundreds of hours on a top end, I don't think mine has ever been done and it's a 2005. Depends how aggressively you ride, how often you ride, and most importantly how often you change and clean your air filter and how well you premix your oil.
Jetting has a huge impact as well, a lean running engine is going to require a top end much quicker.

If you have a well tuned bike, run 30:1 premix, use a decent premix, do regular air filter changes, then you should have a top end that lasts years and years.
There's a guy on this forum with like 500 hours on his top end, he's just rebuilding it now and it's showing no signs of problems

  • RCannon

Posted December 21, 2009 - 07:54 PM

#3

You'll keep up just fine! LOL

Top ends??? Thats a lot like asking how long a tire will last. Much of that depends on you. If you keep your air filter clean, top end life will be 40-80 hours of running time..some have reported more. You could also get much less if you try to build your own airfilter from a sponge. I had a friend try to do just that.


Cylinders can also last a LONG time if the piston is kept in reasonable condition.

  • kotaro

Posted December 22, 2009 - 07:54 AM

#4

Im looking into a yz250 2 stroke. I am currently coming off of a ttr125, but i know the yz250 is a lot of bike, but do you guys think that i will get used to it. I have ridden one and it was a blast to ride, except the forks had no oil in them. but it was sick!


But my main fear is top ends, and rebuilds, but i was looking at 4 strokes but im mainly worried about valves, top end rebuilds, and all that other stuff. I like how easy a 2 stroke is to work on.

but my main question is, how often doyou normally change the pitson, rings, ect. Also, what about the cylinder head?

Im not gona ride hard for like the first month or 2, but i do ike the keep the bike in the powerband.

thanks guys! Sorry for the other post too. But i thought making a completely different post would be better for me.

Also just to throw this out there if i get this bike, will i be able to keep up with my buddy on his 2008 yz250f?


Changed my OEM top-end after 2 years of trail-riding....
....Yet, my piston still looks oh so goody! ---- actually i kept my OEM for spare :moon:

Premix 32 : 1 guy here :cheers:

  • adam728

Posted December 22, 2009 - 08:13 AM

#5

Im looking into a yz250 2 stroke. I am currently coming off of a ttr125, but i know the yz250 is a lot of bike, but do you guys think that i will get used to it. I have ridden one and it was a blast to ride, except the forks had no oil in them. but it was sick!


But my main fear is top ends, and rebuilds, but i was looking at 4 strokes but im mainly worried about valves, top end rebuilds, and all that other stuff. I like how easy a 2 stroke is to work on.

but my main question is, how often doyou normally change the pitson, rings, ect. Also, what about the cylinder head?

The cylinder head requires no maintance. There's zero moving parts, unlike a 4 stroke head which contains the valves, guides, cam(s), etc etc. A 2 stroke head is just a chunk of aluminum with nothing to wear out. Only if you have a big engine failure will the head possibly need to be cleaned up (munching a bearing, breaking a piston, etc will often embed debris into the head as they get smashed between the piston and head).

Cylinder is sort of the same. For the most part all it will need is a replate if damaged. Usually damage comes from maintanance neglect, air filter letting dirt in, running a piston WAY too long and breaking a skirt, etc. For the most part the cylinder will not need anything done to it unless damaged.

For piston and rings you'll get 100 answers. One guy will claim you need to change them every 25 hours. Someone else will chime in that they have over 200 hours with no problems. It depends greatly on how you ride, and how picky you are with your bikes maintanance. Personally, I change piston and rings around 50 hours of trail riding. I could probably just do rings and change the piston at 100 hours, but I like the peace of mind of doing it all at once.

Or you can ride it 5 years on one top end until a piston skirt breaks, it locks up, the rod breaks and gouges out the cylinder while bending the crank and then punches a hole through the crankcases. Suddenly that couple of hundred bucks you saved by not doing top ends becomes $1000+.


Im not gona ride hard for like the first month or 2, but i do ike the keep the bike in the powerband.

Don't take offence, but if you are trail riding and coming from a TTR125 you are going to keep the bike in the powerband about 2% of the time. I'm no slow-poke, and even for me it's hard to stay "on pipe" at all times. In many situations it's better to lug a bit for control. No use riding at 7500 rpm when the root covers sidehill you are on only needs 6 hp to navigate at speed.


Also just to throw this out there if i get this bike, will i be able to keep up with my buddy on his 2008 yz250f?

Totally depends on the rider. The bike will be more than capable. This is where I need the link to the video of a kid on a KX80 passing a CR500 and then absolutely running away from him in a harescramble. It's all rider.

  • bergermeister

Posted December 22, 2009 - 08:24 AM

#6

Some good posts in here!

Don't stress about the top ends mate, their easy to do. You'll easily get 50 hours on a top end (probably a lot more especially if your coming off a TTR125 :cheers:). By running a forged piston like the Wiseco or Wossner you can afford to let your piston go longer than a cast OEM (Yamaha) piston.

KEEP YOUR AIR FILTER CLEAN!!!!

... and your piston, rings and bore will reward you.

My bike has got about 300 hours on the stock cylinder. It still looks great, because I clean my filter EVERY ride, no exceptions.

Run a good quality 2T oil, not the extra super expensive stuff, middle of the road is fine. Also, warm the bike up properly before riding it and you'll get hours of reliable service from you bike.

The worst thing about riding a YZ is figuring out how to wipe that dirty great big 2T grin off your dial after every ride. These bikes are intoxicating :moon:

Berg

  • shrubitup

Posted December 22, 2009 - 10:21 AM

#7

I went 76 hours on the last one. I usually go 60 hours. This is the second top end on this bike now aside from the original. I only have 140 hours on the bike so far but the cylinder looks like NEW! 32:1 here. Clean filter when dirty because there's no dust in the winter here. :moon:

  • xxxbranham

Posted December 22, 2009 - 05:49 PM

#8

When ZipTy sold my bike they said just put a new yamaha piston in once a year .... and ride the shap out of it.

  • rcdude33

Posted December 22, 2009 - 05:53 PM

#9

ya you are right but if i lug a 250, wont it foul plugs like crazy?

  • rusky

Posted December 22, 2009 - 05:56 PM

#10

ya you are right but if i lug a 250, wont it foul plugs like crazy?


not if you jet it properly. If you are lugging a bike around, you would tend to jet it leaner than a person who rides MX and Enduro.

  • rcdude33

Posted December 22, 2009 - 05:59 PM

#11

Oh, ok but my buddy says that 2 strokes are junk, but do you still think i will be able to keep up with him? He has a 08 yz250f

  • rusky

Posted December 22, 2009 - 06:16 PM

#12

Oh, ok but my buddy says that 2 strokes are junk, but do you still think i will be able to keep up with him? He has a 08 yz250f


I think your buddy wants you to get a 250f so you won't beat him! BTW two strokes are the dominant bike in harescrambles and trail riding.

  • harrperf

Posted December 22, 2009 - 06:29 PM

#13

the 250 two stroke, when running as intended from manufacturer...kill 250f's in the power department.

It's not even close...one drag race will set him straight.

  • MIKE ANIMAL

Posted December 22, 2009 - 06:50 PM

#14

Oh, ok but my buddy says that 2 strokes are junk, but do you still think i will be able to keep up with him? He has a 08 yz250f

he just dont want u to have a faster bike then him. a 250f is onley a 125 2stroke. that yz250 will eat his 250f alive.

  • Aido_DRZ

Posted December 22, 2009 - 07:57 PM

#15

32:1 here. Clean filter when dirty because there's no dust in the winter here. :cheers:


hey! i thought you were running 24:1 or something..shenanigans wat wat! :moon:

  • jimmy123456789

Posted December 22, 2009 - 08:39 PM

#16

Oh, ok but my buddy says that 2 strokes are junk, but do you still think i will be able to keep up with him? He has a 08 yz250f


I used to think like this, until I opened my eyes and realized what I was missing. I was at the dealer looking at 250f's and 450f's and overheard someone
saying something to the effect of "What if I told you I could find a bike that is 250cc's, has 10 more hp 250f, is more fun to ride, is cheaper to maintain, is lighter and is easier to work on, and that I could find this bike for 10% cheaper than a 250f almost anywhere? I am talking of a 2-stroke 250". That's when it hit me-this person was right. I started researching and decided that I couldn't go wrong with a yz250: Light, reliable, nimble, powerful, cheap to maintain.....the list goes on. Get a yz and leave your 4stroker buddy in the dust. :moon:

  • hondamx32x

Posted December 22, 2009 - 08:51 PM

#17

[/QUOTE]Totally depends on the rider. The bike will be more than capable. This is where I need the link to the video of a kid on a KX80 passing a CR500 and then absolutely running away from him in a harescramble. It's all rider.[/QUOTE]



here ya go! i agree, its all the rider, like they say, 90% rider 10% bike.

  • shrubitup

Posted December 22, 2009 - 09:26 PM

#18

hey! i thought you were running 24:1 or something..shenanigans wat wat! :moon:

That's too much oil for what/how/where I ride. :smirk: One can evolve if they see the light. :cheers:

Edited by shrubitup, December 23, 2009 - 10:43 AM.
horrile punctuation and spelling!


  • kotaro

Posted December 23, 2009 - 03:08 AM

#19

Oh, ok but my buddy says that 2 strokes are junk, but do you still think i will be able to keep up with him? He has a 08 yz250f


He's absolutely 100% right :moon: ....if he's that type
1. Who has had NO prior solid 2-stroke experience;
2. Who didn't learn how to use them;
3. Who's afraid of 2-stroke hit and can't come to terms with it; or
4. Who just parachutes to believing that 4-broke are superior than 2-stroke, as most young people now have been brainwashed to believing, without even having to ride one.

Tell him that J-Law (who's a former '04 RM250 2-stroke rider before he boarded the 250F bandwagon) wasn't actually 2 to 4 seconds faster per lap on the YZ250 than on his (former) race bike YZ250F, in the tracks! :cheers:

....Read about it in Transworld Motocross :smirk:.... and realize that those who really have had solid 2T experience are way faster on 250 2T's than 250F's.... meaning when you push these two different bikes to the limits, as faster experienced riders do, the 2-stroke far outshines the 4-broke :smirk:

  • kotaro

Posted December 23, 2009 - 03:17 AM

#20

That:s too much oil for what/how/where I ride. :cheers: Once can evolve if they see the light. :moon:


You're back to your senses now, finally haha! :smirk:





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