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Athena Factory Cylinder Kit
Athena Factory Cylinder Kit

$602.99 - $689.99
15% Off - Save up to $121.96

Description See Also: 8 Reviews 25 Questions Fitment Part Numbers
Item #ATH0008

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8 Reviews
4.5 out of 5 stars
5 Star   7 4 Star   0 3 Star   0 2 Star   0 1 Star   1
All Reviews
Ktm40 Verified Purchaser
3 months 15 days ago Long Island New York
Durability4/5Ease of Installation5/5Performance5/5Power5/5Style4/5
Great product

Bolted right on without any modifications and the bike is finally running to its full potential

3 months 19 days ago Arvada, CO
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
Easy to Build and Install

I bought this kit so I could be running a 125 piston instead of the 144 and the bike runs great it is super crisp and the motor feels awesome. Also it gives good instructions on how to build the head and everything.

Hitty216 Verified Purchaser
Over 5 months ago Walton New York
Durability5/5Ease of Installation4/5Performance5/5Power5/5Style5/5
Excellent Product

I bought this for a 2003 kx125 and man did it bring it back to life plus some. My 2003 can keep up with modern 125’s with this kit.

RangerDrew Verified Purchaser
1 year 10 months ago
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
Excellent Head

Easy to install and give tons of power.

2 years 5 months ago
Durability1/5Ease of Installation1/5Performance1/5Power1/5Style1/5
Stock Cylinder bore

Purchased a stock bore Athena replacement cylinder. Would've been nice to know they intentionally spin the stud bold holes 180 degrees so you have to buy their cylinder head. Next time I'll just spend the extra money and buy an OEM jug. Not worth the hassle of going aftermarket.

Boomer Verified Purchaser
Over 3 years ago Arlington, WA, USA
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
Very complete kit

With v force reeds this thing runs super clean and crisp. Good power.

Over 8 years ago Winter Garden, FL
Durability5/5Ease of Installation5/5Performance5/5Power4/5Style5/5
Good Buy

My stock cylinder was trashed. Picked up the Athena kit and after the simple install there was noticeable performance gains.

Over 8 years ago Mill Creek WV
Durability5/5Ease of Installation4/5Performance5/5Power4/5Style5/5
Top End Kit

Bought this kit for my YZ125 that I had blown up. It was super easy to install and got me back into the season without missing a race and the bike seemed to have a little more power also.

25 Questions
Answered:   22
Not Yet:   3
Q: On a 99 yz125 what does it bring the compression ip to
4 months 25 days ago
Top 25
4 months 25 days ago
A: For this kit, the technical data for this item shows the compression ratio to be 14,8:1.
more details can be found here:
Q: Can you still use pump gas with this kit?
Over 5 months ago
Top 25
Over 5 months ago
A: Yes you can, I would advise using Premium Ethanol free gas.
Q: Does it come with the power valve?
Over 10 months ago
Top 1
Over 10 months ago
A: Uses specially designed high-performance, high anodized power valves.
2 tokes
Q: Will Wiseco pistons work in these Athena cylinders or only the Athena piston?
Over 10 months ago
Trevor Gearhead
Top 10
Over 10 months ago
A: A Wiseco piston would work. The cylinder isn't piston specific.
Q: My 05 yz125 have the athena standard bore kit with the copper head I run it with a br9eg spark plug. I tried loctite on treads but it keeps comming out anyway, is there a specific spark plug for this head?
1 year 1 month ago
Top 1
1 year 1 month ago
A: You are running the correct plug for that application. I would suggest contacting Athena to discuss a possible manufacturer's warranty issue.
Q: My exhaust off my 98 yz 125 won’t fit I bought this kit what pipe would I have to buy for it ?
1 year 1 month ago
Top 1
1 year 1 month ago
A: We would need to know more about which exhaust you are running. Please give us a call so that we can help you solve your issue.
Q: My 02 yz125 has this cylinder kit on it. The head gasket has blown. Where can i find the right size o-rings for this cylinder?
1 year 2 months ago
Trevor Gearhead
Top 10
1 year 2 months ago
A: Athena Cylinder Head O-ring Kit - Manufacturer Part # P400485999003 I would recommend ordering from Athena directly
Q: I installed kit the piston seams to be hitting head . Does the kit need to use the Athena gasket set ? It kits over but stops at dead top and wont move.
1 year 3 months ago
Top 10
1 year 3 months ago
A: No, the Athena head gasket is not necessary when installing the Athena piston however it is recommended.
Q: Do you have to use the Athena power valves? Or can I use stock ones for the factory cylinder?
2 years 7 months ago
Will help me a lot thanks!!!
Top 25
2 years 7 months ago
A: The Athena Factory Cylinder kit will be sold with Power Valves.
Q: 144 kit?
2 years 7 months ago
Is this considered a 144 kit or completely different?
1 - 10 of 25

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See Fitments
# Part Numbers
Product Variant Manufacturer Part #
Athena Factory Cylinder Kit P400250100001
Athena Factory Cylinder Kit P400485100003
Athena Factory Cylinder Kit P400485100017
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