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Cylinder Works Big Bore Cylinder Kit
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Cylinder Works Big Bore Cylinder Kit 434cc

Fits: 2003 KAWASAKI KLX400SR
Part# 1296750014

Our price: $430.34

MSRP: $649.95 - You save $219.61 (34% off)

Get $21.52 in Quick Cash

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5+ In-Stock

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    -Dan Thomas, CEO and Founder

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Additional Videos

How to - rebuild the top end on a motorcycle or atv (Part 2)

Cylinder Works

How to - rebuild the top end on a motorcycle or atv (Part 1)

RM YouTube Channel


    Cylinder Works Big Bore Cylinder Kits set the standard when you want to increase the displacement of your motorcycle, UTV, or ATV. With this kit you get top quality parts rolled into one package so you’ll be able to directly fit every component, torque everything down, and get back to riding. The cylinder itself is made from an OEM grade aluminum casting with a nickel silicon carbide cylinder sleeve that comes precisely sized and honed, giving your engine great ring sealing and cylinder wall longevity. The dimensions of the big bore cylinder are sized to fit your stock engine without any machine work or modification. And to make things easier for you, the kit also includes the correctly sized piston, rings, wristpin, and gaskets to fit your new larger displacement bore perfectly.

    If you want to get more from your machine, pick up Cylinder Works’ Big Bore Cylinder Kit to give your ride with a whole new attitude.

  • Nickel Silicon Carbide plated cylinder
  • Bore comes properly sized and honed
  • Easy bolt-on installation
  • No machining or alteration of your engine or cases needed
  • Kit comes complete with cylinder, gaskets, and piston kit
  • Replacement piston kits and gaskets available

Cylinder Works Big Bore Cylinder Kit Reviews

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0 of 0 people found this review helpful.

AWESOME Product!!

Comments On Apr 24, 2016:Smooth and easy install and could tell that the larger piston produced a HUGE power increase! Solid performance and the break in went well.

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0 of 0 people found this review helpful.


Comments On Mar 14, 2016:This definitely woke my KTM up! She absolutely loved the big bore kit! Dialing the carb in was difficult though....I definitely suggest a JD Jet kit!

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0 of 0 people found this review helpful.


Comments On Dec 29, 2015:Great product. Complete with all you need to assembly your engine

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0 of 0 people found this review helpful.

Big bore kit

Comments On Dec 22, 2015:I bought this kit for kawasaki kx250f but ive noticed that the year of the kit if for a 2009 i just want to male sure that this will fit for my 2010 cus there no kit for the 2010 models pls help me! Thx

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0 of 0 people found this review helpful.

The vertex piston oil ring was pretty cheesy

Comments On Nov 02, 2015:Not to sure how long this thing will last . Over all every thing was allright but the oil ring was pretty cheap . You would think they would give a better oil ring thats the only thing i could see going wrong .the stock pistons oil ring was 3 times stronger. Will let u know how it holds up thanks

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1 of 1 people found this review helpful.

Good for a little extra power

Comments On Oct 23, 2015:I installed this kit on my 350 because I was having some issues with the lack of low to mid range. I'm not a guy who likes to rev his bike to the moon. I like to ride in the mid range. I didn't have a problem with the power of the 350 until I switched from racing hare scrambles to racing motocross. I was going to buy a new 450 but I talked myself out of it. Instead I bought the 365 kit to see if would help the bike enough to keep it. I was right. The 365 will not make it as fast as a 450 but it did help out a lot. I have about every bolt on performance part you can put on a 350 (yoshimura exhaust, velocity stack, 2012 350 mapping, high flow water pump and the list goes on). The extra power that the engine gained allowed me to be more comfortable on the bike. If you are looking at this kit thinking it will turn your 350 into a 450 you are wrong. But if your looking for a few more ponies out of your 350 this a great option. Hopefully this has helped with your decision.

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0 of 0 people found this review helpful.

Bolt on power

Comments On Jul 09, 2015:Swapping out the old cylinder for the new was very strait forward and conversion fitted well with all mated factory parts. It was an easy bolt-on 8% extra power.

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4 of 7 people found this review helpful.

Catastrophic Failure

Comments On May 12, 2015:Bought this kit, install went great! Installed this and hotcams at same time. Broke in cams and cylinder as per specs. Took out for first ride and changed oil after, FOUND BROKEN WRISTPIN CIRCLIP IN OIL. Called company, they overnighted part without hesitation. Found other half in engine, removed it with magnet. Installed new ones, bike ran like a dream. 2 months in, let clutch out of a turn and the bike died on the spot with a small pop noise. Broke down engine AGAIN and found the wristpin slide out of place due to another failed circlip, the connecting rod threw the piston up into the head bending my valves and bent the connecting rod while scoring my cylinder wall at the same time. 2,000 in damage thank you

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1 of 2 people found this review helpful.

365cc for KTM 350sxf...buyer beware

Comments On Nov 03, 2014:Cylinder kit goes together nicely, but Cylinder Works gave no support after the installation of this kit. The kit obviously changes the fuel needed, which will require a ECU software change, they offer zero support except a jpeg of suggested settings.

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4 of 4 people found this review helpful.

Awesome kit

Comments On Mar 27, 2013:The cylinder works kit is a very reliable upgrade over stock. Comes with everything necessary to install it. There's no replacement for displacement!

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