Jump to content

Yz250 top end kit.

Recommended Posts

Hey just bought a clean tidy older yz 250 2003 and am starting to rebuild it to a standard where I can ride it when ever and not have to worry to much if I ride it hard it’s going to break down on me . I’m going for advice on what’s the best  top end kit to get ? Cheers 

  • Sad 1

Share this post


Link to post
Share on other sites

I highly recommend taking a forged piston and sawing in half, then a cast and weld together and you'll have a piston that is so good that there's zero chance of ever losing a race or breaking down:applause: or just put in either(Wiseco, vertex, pro-x) and replace it on a reasonable schedule:ride:

Share this post


Link to post
Share on other sites

I use the Wiseco like this :  image.png.2e6138c12d4b35c380525a304b163db5.png  make sure you get a small end bearing as well  (not incl in the kit) 

If you want to go all out, get a VHM Machined-from Billet piston ....I have one in my YZ125,  i'm pretty sure they make them for the YZ250 

  • Like 1

Share this post


Link to post
Share on other sites
Posted (edited)

Prox cast #1 ??? and cheaper than the rest 

Edited by Motox367
  • Like 2

Share this post


Link to post
Share on other sites

My son races MX, started on yz85, yz125 now on his second yz250, always used Yamaha rebuild kits and pistons, never had a problem. Buddy of his keeps using after market pistons and keeps blowing them up.

  • Like 2

Share this post


Link to post
Share on other sites

To save you searching:

 

Oem gaskets - there is a genuine kit.

 

Piston either oem or prox for cast or wiseco for forged. Prox was $50 cheaper for me over oem.

 

I just did mine with prox as most in here prefer cast...had I not been on here, I would have gone wiseco... I don't think it matters if you build it with correct tolerances and warm up properly...main reason I went cast is my brother is half owner and I wasn't sure if he'd follow warm up process, so one less risk.

 

Share this post


Link to post
Share on other sites

And have a read through my thread, and also "spencerr" (with two r's) thread as a few on here helped us two numpties through the builds :-)

  • Like 2

Share this post


Link to post
Share on other sites

I bought a 2001 yz250 super clean with a blown top end. After making several calls I went with www.lukesraceing.com I decided to go with a 293 big bore kit. 750$ shipped to my front door in 3 days. It came with everything you need. Excellent cs if you get a chance check them out.

  • Like 1

Share this post


Link to post
Share on other sites
Posted (edited)
58 minutes ago, Curtisy said:

I bought a 2001 yz250 super clean with a blown top end. After making several calls I went with www.lukesraceing.com I decided to go with a 293 big bore kit. 750$ shipped to my front door in 3 days. It came with everything you need. Excellent cs if you get a chance check them out.

Something ESR has no clue how to be. I would be interested in who their R&D is. That search doesn't work.

On 4/19/2019 at 10:39 PM, Chris555 said:

Hey just bought a clean tidy older yz 250 2003 and am starting to rebuild it to a standard where I can ride it when ever and not have to worry to much if I ride it hard it’s going to break down on me . I’m going for advice on what’s the best  top end kit to get ? Cheers 

OEM (kits are only in B size)/Vertex/ProX/Wiseco/Wossner, heck even a MSR or Moose as long as they are ART you'll be fine. Just never a Namura as they are junk. 

Edited by 2 STROKE YZ DOC

Share this post


Link to post
Share on other sites
Hey just bought a clean tidy older yz 250 2003 and am starting to rebuild it to a standard where I can ride it when ever and not have to worry to much if I ride it hard it’s going to break down on me . I’m going for advice on what’s the best  top end kit to get ? Cheers 

Keep us updated on the top end. Something I didn't do was check the squish so after I spent another 300$ to make sure I did the install, come to find out my top end psi is 213 so I can either send my head in so they can machine it down so I can run pump gas or leave it alone and run straight vp and in Las Vegas it's 90$ for five gallons so that's what I've been doing. I was also told I could stack my head gaskets to drop the psi but I'm not sure if that's a good idea so I just run the VP for now

Share this post


Link to post
Share on other sites
Oh no Chinese made lol let us know how it works

Omg ya I see what you mean. That is not what mine is. I still have the OG box and paper work I will look later when I get home. What I thought I was getting is a stock cylinder bored out to a 293. I do no that it dose not have that Chinese brand on it. It is identical to my stock cylinder but like I said I will inspect later when I get home.

Share this post


Link to post
Share on other sites
Namura? Oh crap!!!

Ok well I sent doc a few pic of my cylinder in his msg. It has no stamps on it what so ever. I'm guessing that's bad news. Sry for changing your topic. I guess if this big bore is a Chinese atleast I learned something.

Share this post


Link to post
Share on other sites
Posted (edited)

IMO not going to be top quality. A couple extra huntit, and you would have a Athena GYTR approved, or even an EG kit.

Edited by 2 STROKE YZ DOC
  • Like 1

Share this post


Link to post
Share on other sites
8 minutes ago, Leftdagrid said:

Just rebuilt my 17 X,

Vertex kit

Needle bearing

Tusk gasket kit (crap)

$148.00

 

Best gasket set to oem is Comedic. They are same metal type gaskets as oem

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×
×
  • Create New...