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Cylinder Works Big Bore Kit
Cylinder Works Big Bore Kit

$445.46 - $1052.96
10% Off - Save up to $116.99

Select your bike to see if this big bore kit fits
Item #CYW0003

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7 Reviews
4.9 out of 5 stars
5 Star   6 4 Star   1 3 Star   0 2 Star   0 1 Star   0
All Reviews
2010 kx250f guy Verified Purchaser
Over 7 months ago Pa bloomsburg
Durability5/5Ease of Installation4/5Performance5/5Power5/5Style5/5
Perfect Fit Simple install

Purchased one of these kits after the previous owner hot siezed the piston to the cylinder. Install was cake, nothing different then a standard cylinder and piston, bottom end picked up a little bit for sure, I really recommend adding a few drops of oil to the piston rings and adding a little bit to the top of the piston after it’s in the cylinder to keep it from binding really hard during the install, getting the piston initially in the cylinder is difficult but afterwords it’s a clean install, I run engine Ice with a super cooler kit and I have zero issues with over heating. You will likely require a re-jet kit, a 269 with stage one cams a loudmouth intake and a fmf exhaust caused a very lean run in my bike to the point where starting and idling the bike was almost impossible. I recommend sigma six they’re very helpful. This is on a kx250f 2010

Buddy D Verified Purchaser
Over 7 months ago Duncan SC
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
Works Big Bore Kit

I just installed this Big Bore Kit with a set of Hot cams stage 2 on my RMZ250. Everything went on perfect with no issues. Starts and runs great only problem is I haven’t got to take it to the track yet.
Thanks you Motorsport for your great customer service.

Shawnzzy Verified Purchaser
1 year 3 months ago Fargo nd
Durability4/5Ease of Installation5/5Performance4/5Power5/5Style4/5
Simple to install

Am vary happy with this product simple to install and definitely can tell the increase in torc on the bottom end! Do recommend sending in your computer to be reprogramd for full power gain!

WideOpenMotorsports Verified Purchaser
1 year 4 months ago Tn
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
Good Product

I have never liked the gaskets that come with big bore kits but these actually come with oem style and fit gaskets. Theres no replacement for displacement!

Kevindbike16 Verified Purchaser
1 year 6 months ago
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
Bad to the bone

Power difference is great and perfect. Excellent buy

2 years 5 months ago Riverview, FL, USA
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5
I will buy again. Greak kit

At first I was skeptical buying this. But after reason all the positive reviews. I decided to buy this kit and a crank kit due to a engine seize I had with oem parts. I put the bike back together and it roared. Sounded meaner. After the break in period,it was hammer down with no issues at all at 15 hours in so far. Bike is running strong and great. I recommend this kit to every one who is looking for a big bore. Installation was a ease with no issue. Also have had zero over heating issues even when running in a Sugar sand feild with the Florida sun bearing down at 89 degrees out

woodsguy Verified Purchaser
2 years 5 months ago
Durability5/5Ease of Installation5/5Performance5/5Power5/5Style5/5

Improves power where you need it without sacrificing anything. It;s no 450 but it does help narrow the playing field.

31 Questions
Answered:   28
Not Yet:   3
Q: 2004 Suzuki Rmz250, will this work with no case machining?
4 months 8 days ago
Top 25
4 months 8 days ago
A: According to Cylinder works you would not need to get your case machined. It would be an install and play kit. If you have any questions give us a call at 1-888-676-8853.
Q: Hi I was curious what the Hot Rods #4259 was. I wasn't able to find it. I did find a 4059.
4 months 16 days ago
Top 10
4 months 16 days ago
A: Hot Rods part #4259 is the Heavy Duty (+4mm stroker) makes 424cc with the stock piston. We do offer the item.
Q: I have a 2017 ssr sr250s will this work for that? and what else would i have to buy to compleat the project?
Over 5 months ago
Top 25
Over 5 months ago
A: The Cylinder Works Big Bore Kit will not fit your SR250S.
Q: I have a 08 yz250f would I have to machine the cases for this kit
Over 7 months ago
Top 10
Over 7 months ago
A: No you do not for your model.
Q: Will this 468cc kit bolt right up to my 09 yz450f without any other modifications?
Over 7 months ago
Top 10
Over 7 months ago
A: This will be everything needed beside re-jetting or fuel programming on the bike.
Q: I have a 2017 crf250r would I need any other other upgrades to use this? Or would you recommend anything else to go along with this kit?
Over 7 months ago
Trevor Gearhead
Top 10
Over 7 months ago
A: To achieve optimum performance, re-jet the carburetor but other than that yo should be good!
Q: I have a 2017 kx 250f and was wondering if this kit would be a good fit for my bike. Could you help me out?
Over 8 months ago
Top 10
Over 8 months ago
A: Yes, this kit will work with your bike and increase displacement +3mm. Just be sure to profile your Kawasaki into the website before ordering to ensure that you are getting the right fitment.
Q: So i have a 2004 ktm sx 125 how many more cc's would this make my bike push?
Over 8 months ago
Trevor Gearhead
Top 10
Over 8 months ago
A: This kit will not work for your 04 125SX
Q: Hey, are there bigger bore kits for the 17 yet? Or is stroking it the only option to get more displacement?
Over 9 months ago
Trevor Gearhead
Top 10
Over 9 months ago
A: I need the year, make and model of the machine in which you're referring to answer your question.
Q: I have a 2004 Honda CRF250R. Is this kit a bolt on option with the 269cc kit? Or does it require case machining?
Over 9 months ago
Top 1
Over 9 months ago
A: Requires case machining.
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See Fitments
# Part Numbers
Product Variant Manufacturer Part #
479cc 11003-K01
477cc 11005-K01
159cc 11004-K01
269cc 11001-K01
270cc 11007-K01
488cc 11002-K01
478cc 11006-K01
434cc 41001-K01
269cc 31001-K01
269cc 31004-K01
474cc 41002-K01
+3mm/478cc 23001-K01
269cc 21002-K01
478cc 21003-K01
269cc 31006-K01
269cc 31006-K02
159cc 11004-K02
256cc 12001-K01
478cc 11006-K02
478cc 11008-K01
270cc 51004-K01
269cc 31005-K01
469cc 31011-K01
276cc 51002-K01
365cc 51001-K01
365cc 51003-K01
269cc 41003-K01
269cc 41004-K01
269cc 41004-K02
269cc 21010-K01
478cc 23001-K02
468cc 21005-K01
468cc 21005-K02
103.5cc 21007-K01
727cc 11009-K01
478cc 21003-K02
727cc 21004-K01
727cc 21004-K02
727cc 21104-K01
727cc 21104-K02
107.8cc 21107-K01
860cc 31007-K01
859cc 31007-K02
975cc 61001-K01
808cc 61002-K01
808cc 61002-K02
1110cc 61003-K01
+3mm 11010-K01
+3mm 31012-K01
+3mm 51006-K01
+2mm 51007-K01
+5mm 61004-K01
270cc CW11011K01
468cc CW21012K01
California Proposition 65

WARNING: This product contains chemicals known to the State of California to cause cancer, and birth defects or other reproductive harm. Wash hands after handling. For more information, go to

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