Best Top-End for an 04 YZ250?

KBOLTZ
Profile picture for user KBOLTZ
Posts
381
Joined
4/24/2016
Location
Tarzana, CA US
KBOLTZ
Edited Date/Time 4/26/2016 12:33pm
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up an 04 YZ250. It's a good bike doesn't seem "too" beat for a So-Cal bike but to be safe I'll be replacing the top end and checking the bottom end as well.

My question is... Which brand is most reliable for top end replacements? I've used weiseco for my 94 KX250 back in 2000 but blew the skirt off after a month or so. What is a wise choice for a guy like me who would mostly be riding trails and tracks occasionally?

Stoked to be on here with you all!



|
DrSweden
Profile picture for user DrSweden
Posts
6767
Joined
8/30/2008
Location
Stockholm SE
DrSweden 4/25/2016 3:43pm
4/25/2016 3:43pm
You will get many suggestions, mine is just one of them...

1. Stock
2. Wössner

Japan or Germany. I made quite a lot of research before buying to my YZ250. If you by accident by a Wössner, ze german before stock, don't cry over it. Smile
zehn
Profile picture for user zehn
Posts
7272
Joined
1/15/2013
Location
Anchorage, AK US
zehn 4/25/2016 3:53pm
4/25/2016 3:53pm Edited Date/Time 4/25/2016 3:54pm
I'm all for OEM replacement parts in both the top and bottom end. They're a little more expensive but worth it IMO
scooter5002
Profile picture for user scooter5002
Posts
4761
Joined
6/6/2010
Location
Nanton Alberta CA
scooter5002 4/25/2016 4:19pm
4/25/2016 4:19pm
Friend of mine owns a machine shop, heavy into the automotive end of things, CR500's are his specialty, personal sideline. He will bore a cylinder to what ever the next oversize is, without the piston to measure first, as long as you have a Vertex. Their sizes and quality control are THAT exact on their pistons, every one is the same size. Period. Do with that advice what you will.
Cygnus
Profile picture for user Cygnus
Posts
14849
Joined
8/15/2006
Location
Hanover, CO US
Cygnus 4/25/2016 4:24pm
4/25/2016 4:24pm
Stock is good. Wiseco are great. If you do go with a forged piston make sure to warm up the engine to operating temp before riding to prevent a cold seizure.

The Shop

See All »
KBOLTZ
Profile picture for user KBOLTZ
Posts
381
Joined
4/24/2016
Location
Tarzana, CA US
KBOLTZ 4/25/2016 4:59pm
4/25/2016 4:59pm
Thanks for the info guys. Seems like a safe plan is to go with an OEM setup. I don't mind spending the extra $$ to have a more reliable motor.
BobPA
Profile picture for user BobPA
Posts
8029
Joined
10/31/2013
Location
PA US
BobPA 4/25/2016 5:11pm
4/25/2016 5:11pm
KBOLTZ wrote:
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up...
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up an 04 YZ250. It's a good bike doesn't seem "too" beat for a So-Cal bike but to be safe I'll be replacing the top end and checking the bottom end as well.

My question is... Which brand is most reliable for top end replacements? I've used weiseco for my 94 KX250 back in 2000 but blew the skirt off after a month or so. What is a wise choice for a guy like me who would mostly be riding trails and tracks occasionally?

Stoked to be on here with you all!



Blew the skirt off a Wiseco? That is basically unheard of....forged Pistons usually never break unless the cylinder is wore, or dirt was injested. Stock cast pistons are ok....but there is a reason that all high horsepower race engine use forged...
zehn
Profile picture for user zehn
Posts
7272
Joined
1/15/2013
Location
Anchorage, AK US
zehn 4/25/2016 5:24pm
4/25/2016 5:24pm
KBOLTZ wrote:
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up...
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up an 04 YZ250. It's a good bike doesn't seem "too" beat for a So-Cal bike but to be safe I'll be replacing the top end and checking the bottom end as well.

My question is... Which brand is most reliable for top end replacements? I've used weiseco for my 94 KX250 back in 2000 but blew the skirt off after a month or so. What is a wise choice for a guy like me who would mostly be riding trails and tracks occasionally?

Stoked to be on here with you all!



BobPA wrote:
Blew the skirt off a Wiseco? That is basically unheard of....forged Pistons usually never break unless the cylinder is wore, or dirt was injested. Stock cast...
Blew the skirt off a Wiseco? That is basically unheard of....forged Pistons usually never break unless the cylinder is wore, or dirt was injested. Stock cast pistons are ok....but there is a reason that all high horsepower race engine use forged...
That's true and we use forged pistons in all of our vintage road race bikes but for a trail and occasional track bike, I'm not sure it's all that necessary IMO.
Underground 4/25/2016 6:00pm
4/25/2016 6:00pm
Never had an issue with Vertex and I've fitted plenty. They are also KTM OEM piston manufacturers. Never had ann issue with stock also, other than price.
ledger
Profile picture for user ledger
Posts
3673
Joined
1/17/2013
Location
TN US
ledger 4/25/2016 8:49pm
4/25/2016 8:49pm
All suggestions are spot on, just get the jetting right and ride her. The 04 is getting a lot of attention these day's so you got yourself one helluva good bike. Off topic, I put a 9oz.FWW on my 07, it tamed the hit a bit, gained better traction and made me want to ride more, thought I would throw that on the table since you mention trail riding. If you don't mind, what clamps are on the bike ? and welcome to V.
SmoothOperator 4/25/2016 9:18pm
4/25/2016 9:18pm
if going oversized, the machinist is more important than the piston. No piston lasts in a shitty out of tolerance bore.
gsxr6
Profile picture for user gsxr6
Posts
1956
Joined
9/3/2011
Location
Anderson, CA US
gsxr6 4/25/2016 9:34pm
4/25/2016 9:34pm
Anything but vertex by my experience.
Matt Fisher
Profile picture for user Matt Fisher
Posts
3948
Joined
4/1/2008
Location
Visalia, CA US
Fantasy
1177th
Matt Fisher 4/25/2016 10:24pm
4/25/2016 10:24pm
I've used pretty much all of them and only Namura makes the list of "never again". Garbage product, even worse customer (dis)service.

As mentioned, if you run a Wiseco just make sure to fully warm the bike up before putting a load on it.
adam8781
Profile picture for user adam8781
Posts
670
Joined
12/22/2015
Location
CA
adam8781 4/26/2016 12:40am
4/26/2016 12:40am
oem
pro x
vertex
wossner

wiseco would be my last choice.
C-Rock
Profile picture for user C-Rock
Posts
353
Joined
4/19/2016
Location
FR
C-Rock 4/26/2016 3:28am
4/26/2016 3:28am
gsxr6 wrote:
Anything but vertex by my experience.
Anything but Wiseco in my experience.
C-Rock
Profile picture for user C-Rock
Posts
353
Joined
4/19/2016
Location
FR
C-Rock 4/26/2016 3:29am
4/26/2016 3:29am
Underground wrote:
Never had an issue with Vertex and I've fitted plenty. They are also KTM OEM piston manufacturers. Never had ann issue with stock also, other than...
Never had an issue with Vertex and I've fitted plenty. They are also KTM OEM piston manufacturers. Never had ann issue with stock also, other than price.
Just the same for me.
mb
Profile picture for user mb
Posts
769
Joined
7/22/2014
Location
Columbia, SC US
mb 4/26/2016 6:52am
4/26/2016 6:52am
Pistons are just like oil, everybody has their own opinion. You have to form your own.
mxrose3
Profile picture for user mxrose3
Posts
2171
Joined
8/17/2006
Location
Delmar, DE US
Fantasy
1116th
mxrose3 4/26/2016 7:07am
4/26/2016 7:07am Edited Date/Time 4/26/2016 7:08am
Matt Fisher wrote:
I've used pretty much all of them and only Namura makes the list of "never again". Garbage product, even worse customer (dis)service. As mentioned, if you...
I've used pretty much all of them and only Namura makes the list of "never again". Garbage product, even worse customer (dis)service.

As mentioned, if you run a Wiseco just make sure to fully warm the bike up before putting a load on it.
x2
Namura is junk. They must be made out of cheap chinese metal. I tried them because they were cheap. I had two of them break a piece of the top of the piston off above the top ring. On sepearate bikes. One was in a brand new cylinder. Never again.

Pit Row

See All »
Andrew337
Profile picture for user Andrew337
Posts
128
Joined
6/24/2015
Location
Grand Prairie, TX US
Andrew337 4/26/2016 8:22am
4/26/2016 8:22am
I have 30 hours so far on the Vertex in my '02 YZ250. I just tore it down last week to inspect and everything looks great, I'll throw some new rings on it and run it another 30.
KBOLTZ
Profile picture for user KBOLTZ
Posts
381
Joined
4/24/2016
Location
Tarzana, CA US
KBOLTZ 4/26/2016 8:45am
4/26/2016 8:45am
ledger wrote:
All suggestions are spot on, just get the jetting right and ride her. The 04 is getting a lot of attention these day's so you got...
All suggestions are spot on, just get the jetting right and ride her. The 04 is getting a lot of attention these day's so you got yourself one helluva good bike. Off topic, I put a 9oz.FWW on my 07, it tamed the hit a bit, gained better traction and made me want to ride more, thought I would throw that on the table since you mention trail riding. If you don't mind, what clamps are on the bike ? and welcome to V.
Ledger- thanks for the info man. I'll definitely look into a heavier flywheel for more bottom on trails. The triple clamps are older pro-tapers.
KBOLTZ
Profile picture for user KBOLTZ
Posts
381
Joined
4/24/2016
Location
Tarzana, CA US
KBOLTZ 4/26/2016 8:48am
4/26/2016 8:48am Edited Date/Time 4/26/2016 8:49am
KBOLTZ wrote:
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up...
First off I'm a long time reader of the forum and just now signed up. After a few years without a bike, I've finally picked up an 04 YZ250. It's a good bike doesn't seem "too" beat for a So-Cal bike but to be safe I'll be replacing the top end and checking the bottom end as well.

My question is... Which brand is most reliable for top end replacements? I've used weiseco for my 94 KX250 back in 2000 but blew the skirt off after a month or so. What is a wise choice for a guy like me who would mostly be riding trails and tracks occasionally?

Stoked to be on here with you all!



BobPA wrote:
Blew the skirt off a Wiseco? That is basically unheard of....forged Pistons usually never break unless the cylinder is wore, or dirt was injested. Stock cast...
Blew the skirt off a Wiseco? That is basically unheard of....forged Pistons usually never break unless the cylinder is wore, or dirt was injested. Stock cast pistons are ok....but there is a reason that all high horsepower race engine use forged...
zehn wrote:
That's true and we use forged pistons in all of our vintage road race bikes but for a trail and occasional track bike, I'm not sure...
That's true and we use forged pistons in all of our vintage road race bikes but for a trail and occasional track bike, I'm not sure it's all that necessary IMO.
I'm sure that 94 cylinder wasn't in the greatest shape so that could have been a possibility.
KBOLTZ
Profile picture for user KBOLTZ
Posts
381
Joined
4/24/2016
Location
Tarzana, CA US
KBOLTZ 4/26/2016 9:03am
4/26/2016 9:03am
mb wrote:
Pistons are just like oil, everybody has their own opinion. You have to form your own.
Definitely seems that way haha. Lots of opinions in here but one is certain... Stay away from Namura.
DrSweden
Profile picture for user DrSweden
Posts
6767
Joined
8/30/2008
Location
Stockholm SE
DrSweden 4/26/2016 9:19am
4/26/2016 9:19am
scooter5002 wrote:
Friend of mine owns a machine shop, heavy into the automotive end of things, CR500's are his specialty, personal sideline. He will bore a cylinder to...
Friend of mine owns a machine shop, heavy into the automotive end of things, CR500's are his specialty, personal sideline. He will bore a cylinder to what ever the next oversize is, without the piston to measure first, as long as you have a Vertex. Their sizes and quality control are THAT exact on their pistons, every one is the same size. Period. Do with that advice what you will.
Oh snap, I think I bought a Vertex just like you suggested, not Wössner? I'm pretty sure the above info was the decider when you told me last year...

Post a reply to: Best Top-End for an 04 YZ250?