Vertex 2-Stroke Piston Kit - Stock Bore

Vertex 2-Stroke Piston Kit - Stock Bore
Vertex 2-Stroke Piston Kit - Stock Bore

$84.98 - $194.98
17% Off - Save up to $16.95

Description See Also: 43 Reviews 31 Questions Fitment
Item #VER0008

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43 Reviews
4.5 out of 5 stars
5 Star   37 4 Star   9 3 Star   0 2 Star   1 1 Star   3
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All Reviews
Duck5 Verified Purchaser
Weatherford, ok
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
KTM 65sx

Quality is outstanding, the install went perfectly and the bike runs much better. Ktm uses vertex from the factory, the durability has been outstanding. I highly recommend using this product, the gaskets are very good as well.

Pittcrew Top 500 Contributor Verified Purchaser
Pittsburgh
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Great kit.

Used this in a 2011 kx85. It's been through 2 woods series races and is holding up just fine. Every bit as good as any other brands I've used.

Phil
Dayton, OH, USA
Ease of Installation 4/5
Good kit

Parts seems of good quality. I like that the needle bearing it comes with us hot rod. Haven't ridden with it yet so I can't speak on power or reliability. My only complaint is it didn't come with the copper crush washers for the head bolts that my YZ 250 has. I didn't notice untill reassembly. Had to order them separately. Would rather pay more for the kit and have them included. Other than that it went together great.

Loaner Verified Purchaser
San Diego, CA, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Easy Top End Package

This gave me everything i needed to swap out the top end on my KTM. What a dream, no running back to the shop for a gasket, or needle bearing. I highly recommend this kit, and the Vertex pistons have lasted for me with no issues.

pmdparts Verified Purchaser
Abbeville, SC 29620, USA
Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Nice product--but beware of "A" ,"B", or "C"sizes

Ordered this kit for 2013 KTM 85 sx. Description says "standard bore'" but apparently, KTM produces engines with "A", "B", and "C" bores from the factory. These are just three different size pistons that vary by a fraction of a millimeter and are fit to each motor individually to help account for variance in machining and plating of the bores. The piston I received was a "B" unit and it turns out that our bike was fitted with a "C" piston from the factory. I wish that the item description had spelled this out so that I could have gotten the "c" piston instead, but there was no mention of this in Motosport's description. I installed the "b" unit and I'm sure it will be fine since I will replace it in about 20 hours anyway.

Rider13 Verified Purchaser
Modesto, CA, USA
Durability 1/5 Ease of Installation 4/5 Performance 1/5 Power 4/5 Style 3/5
Faulty product

Shortly after installation of this piston and break in my engine seized. A large chunk of the top of the piston broke off wedging itself between the head and the remaining piston, destroying not only my new piston, but also my cylinder and head.

DirtLife Verified Purchaser
DTown Racer
Durability 4/5 Ease of Installation 4/5 Performance 5/5 Power 5/5 Style 4/5
First Top end rebuild on 85r Honda

Researched rebuild days before part showed up. Made job easy.

1Racing Verified Purchaser
Texas, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5

Great replacement for stock.

Pickle Verified Purchaser
Atlant Ga
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Great top end

Never have a problem with this top end in my sons yz-85

speedy Verified Purchaser
Montana, USA
Durability 4/5 Ease of Installation 4/5 Performance 4/5 Power 4/5 Style 3/5
Good kit

everything you need

DirtWarrior
Western PA
Durability 5/5 Ease of Installation 4/5 Performance 5/5 Power 5/5 Style 5/5
2 Stroke Power!

This is a great rebuild kit. Very high quality parts. The only improvement that I think could be made is if Cometic decided to put a paper in their gasket kit that labeled each individual gasket and O-ring. Other than that, fantastic product. Just as good, if not better than Wiseco.

brokendad Verified Purchaser
Edmond, OK
Durability 4/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 3/5
Top End Kit

Restore the power in your bike byu using quality parts!

shnedy Verified Purchaser
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Great product vertex piston

Got the piston kit for my cr 125 it had no compression.
After i replaced the piston and ring wow what a difference. Before i changed it i was able to start the bike with my hand. Those days are over .
Great product.

Roosty Verified Purchaser
Salt Lake City, UT, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
As usual motosport delivers

Love these guys! The vertex piston fit perfectly and the cometic gaskets are working as advertised. In fact, the expansion chamber o-rings fit much tighter than OEM so no more oil spooge from exhaust! Thanks motosport!

Tony Verified Purchaser
Durability 4/5 Ease of Installation 5/5 Performance 4/5 Power 5/5 Style 4/5
Great buy!

I will buy again! Installed on a 97 cr 125 that had a dime size hole in the Piston marked clearly fits factory specifications. Gaskets that come with the kit are way better then the oem paper gasket

yzrippa
Louisiana, USA
Durability 1/5 Ease of Installation 5/5 Performance 2/5 Power 2/5 Style 5/5
DO NOT BUY!!!!

because this piston is not forged its cast which causes weak spots in the piston and after about 8 hours of run time always on a track with races the skirt of the piston blew off and ruined my cylinder and crank.

Zach
Binghamton, NY
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Great piston

I decided to do a top end on my cr125 this winter and change it up from my usual Wiseco piston. Now that the snow is melting I can finally get back out and ride and this piston is great in my bike. Would definitely recommend this kit!

Deema00 Verified Purchaser
Napa, CA, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
03 CR250 Top End Build

Super Stoked on the Vertex Top End Kit. The power is back! It came with everything needed for the rebuild. Installation was easy and a breeze. I recommend this set-up for any CR owner. Quality, Super Quick and Great service. From Motosport to my House to My Bike. couldnt be happier to be back riding.

Deema00
Napa, CA, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 4/5
03 CR250 Top End

Super stoked on the vertex top end kit, the power is back in my 2stroke. The kit came with everything needed to re-do the top end. Straight from Motosport to my house to my bike! Recommend this set-up to any CR owner. Quick, Convenient, and Quality. Everytime.

John Verified Purchaser
Phoenix, AZ, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
Great Purchase

I have ordered numerous parts from Motosport for my son's dirt bike. It is easy to order, it always ships on time, and I have never had any issues with the quality of the parts I ordered. I recently ordered a piston kit for his dirt bike. It contained everything I needed to rebuild the top end of his bike. Thank you so much for your service!

See 20 More Reviews
31 Questions
Answered:   31
Not Yet:   0
Kurt820
Location: Oklahoma, USA
Q: Is this a single ring piston and what will fit a 2014 kx85 85?
2 months 10 days ago
MotoSportExpert
MotoSport Staff Expert
2 months 8 days ago
A: Yes. Just be sure to correctly select the Year/Make/Model of your bike before ordering so we can be sure to send you the correct kit for your bike. Also, feel free to give us a call at 888-676-8853 and we would be happy to help you out with your order.
Jesse
Location: Nanticoke, PA
Q: 99 YZ250?
2 months 27 days ago
I am currently rebuilding a YZ250 from the ground up, the cylinder has just been re-plated to stock bore of 66.4mm. It's telling me that this is an exact fit for my bike, but I see the piston is listed as 66.35mm. Will this work?
MotoSportExpert
Expert MotoSport Staff
1 month 28 days ago
A: Yes the 66.35mm would be correct.
Kelson
Q: Is this the exact stock piston that comes in the bike 2014 ktm 250 sx?
Over 6 months ago
Loaner
Over 6 months ago
A: It exactly matched my 11 300xc & 12 250xc, so i bet it is.
Deland
Location: Orangeburg, SC, USA
Q: May I use this piston kit with the Athena cylinder?
Over 6 months ago
MotoSportExpert
MotoSport Staff Expert
Over 6 months ago
A: Yes this Vertex 2-Stroke Piston Kit - Stock Bore would work with a stock bore Athena Cylinder.
Dylan22
Location: Georgia, USA
Q: Will a size c fit a 2004 KTM 125sx that has had a stock piston in it?
Over 10 months ago
I have a 2004 KTM 125sx and I would like to know if there Is a real big difference in piston sizes for this bike. The piston hasn't been changed before I don't think.
MotoSportExpert
Expert MotoSport Staff
Over 10 months ago
A: Vertex offers A, B, C, D, sizes so that the customer can properly fit each piston to the cylinder. The difference in the sizes is 0.01mm (0.0004") increments with A being the smallest and D the biggest. When a cylinder wears, the customer can choose the next larger piston size to regain the proper factory fitment. If you are just replacing the piston, then you need to first know the bore of the cylinder. This can be done by using a bore gauge to find the diameter or by reading the owner’s manual to find the bore specifications. Ultimately, the bore should be measured for the best possible results. After the diameter is known, then you can pick which size piston will work best in your cylinder. Remember to maintain about a 0.05mm (0.002”) piston to cylinder clearance, depending on application. If you are having a cylinder re-plated, then you will want to choose a piston of the OE bore size (an A or B size is probably best). When you send the piston and cylinder away to get re-plated, the plating facility will match the cylinder bore to piston diameter. If you have a cast iron bore cylinder and you are sending the piston and cylinder off to a machinist to be bored out, then you will want a piston that is oversized from the current diameter. For example: If your current bore is 64.00mm, then you will want to choose a 64.50mm or similar oversized piston. The machinist boring the cylinder will bore and hone the cylinder to match the piston size.
Also, feel free to give us a call at 888-676-8853 and we would be happy to help you out with your order.
Moe987
Location: Reno
Q: Piston size.?
Over 11 months ago
I just returned a kit that came with a piston that was 66.40. Will this fit mine which needs a max of 66.35?
MotoSportExpert
MotoSport Staff Expert
Over 11 months ago
A: The stock bore Vertex 2-Stroke Piston Kit (22584B) for your 2004 Yamaha YZ250 would be 66.35mm. Also, feel free to give us a call at 888-676-8853 and we would be happy to help you out with your order.
cartwright
Q: What size bore is a 99 yz125?
Over 11 months ago
Im trying to bore over my 99 yz 125 but I don't know if I need a big bore kit or can I just get a bigger piston and resize my own cylinder. I need to know what size is my stock cylinder.
MotoSportExpert
Expert MotoSport Staff
Over 11 months ago
A: Stock bore on the 1999 Yamaha YZ125 would be 54.00mm. Feel free to give us a call at 888-676-8853 and we would be happy to help you out with your order.
edd653
Location: London, UK
Q: Oversized pistons?
1 year ago
Are you able to get 0.5/1.0mm oversized pistons for yz 125 (05)
MotoSportExpert
MotoSport Staff Expert
1 year ago
A: If the part is available through one of our suppliers, we would be happy to order it for you. Please contact one of our sales professionals to inquire about special orders and availability.
Dirt Bike / ATV: 1-888-676-8853
Kawasaki
Q: What is the stock size for a 2004 kx 125?
1 year 1 month ago
I ordered a vertex piston and just rid the cylinder and got it re-sized and the piston wiggles side to side is that ok?
MotoSportExpert
MotoSport Staff Expert
1 year 1 month ago
A: This stock bore Vertex Piston would be 53.96mm. You need to first know the bore of the cylinder. This can be done by using a bore gauge to find the diameter or by asking the machine shop who did the work. If you had the cylinder bored and replated you would need to go to the next size up.
Remember you want to maintain about a 0.05mm (0.002”) piston to cylinder clearance.
Javon
Location: Jamaica
Q: Can this fit my 03 Yamaha yz 125 2 stroke ? My piston only has 1 ring?
1 year 1 month ago
MotoSportExpert
Expert MotoSport Staff
1 year 1 month ago
A: Yes this Vertex 2-Stroke Piston Kit will fit your 2003 Yamaha YZ125. Just be sure to correctly select the Year/Make/Model of your bike before ordering so we can be sure to send you the correct kit for your bike. Also, feel free to give us a call at 888-676-8853 and we would be happy to help you out with your order.
*The image is a generic image supplied by the manufacturer for reference only. It may not be displaying the exact part for your bike.
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