Eric Gorr Racing LLC W4550 Lakepark Drv #7, Fond du Lac, WI, 54935-2708 USA Text (630) 825-5645
Email or Paypal: mxericgorr@gmail.com
NEW PRODUCTS IN THE PIPELINE
YZ? WHY ME? If you have a Yamaha YZ125 we have replacement parts like 125,134,144,250, & 295cc cylinders, cylinder heads, and powervalves for the 250,295.
YZ125 2022 and newer cylinders are unreliable and expensive to replace. Plating companies won't even try to fix a YZ125 cylinder with cracked exhaust bridges because it’s a bad design. Athena and Cylinder Works DO NOT MAKE 144s.
MAGNUM will be the first company to offer a reliable 144 off-road top end assembly with my original porting design. This kit features a special cylinder with strong bridges to reduce wear and seizures. The cylinder uses the new Wossner 2-ring 12-degree race piston for maximum engine hours. The porting and head mods are designed to work with the custom powervalves for a smooth broad powerband that is dominant over the standard KTM150. Available Christmas 2024
2024 YZ125 144 SERVICE NOW
If you need a 2022-24 cylinder repaired to a 134 or 144 with the new style mods and porting, we can handle that until the new cylinders are available. The service and parts run $600
Text or email for an appointment. (630) 825-5645 mxericgorr@gmail.com
NSR HONDA IS BACK!
All throughout the 1980s I worked for a Honda motorcycle dealer in Chicago and built a custom Honda CR business. Our Honda CRs raced in outdoor nationals and the Moto GPs of Europe competing head-to-head with our rivals the HRC Hondas. Now I'm bringing it back with some special new products for Honda CR 2-strokes.
The CR144 prototype, far left and right, compared to the 1990-2002 cylinders
Universal 144 is a top end kit that converts a 125 to a 144 with an all-inclusive top end assembly that fits a wide range of model years including 1987-2002 CR125. This modern plated 144 includes the cylinder, head, exhaust manifold, piston and gasket kits, and the best part is I eliminated the powervalves so its maintenance free. These cylinders have the proper porting so they don't need unreliable powervalves.
The CR144 prototype is a hybrid of a 1989 CR125 with a 2002 CR125 exhaust port and a 2007 CR125 porting using an Advanced Sleeve with Millennium plating. The head is from a 1999 CR125 and the piston kit is from a 2025 YZ144. The best aspects of 5 decades of 125s! Available late 2025
CR550 HONDA MX BIKE OR DIRT KART
I NEED MORE! That's what guys riding CR500s say. So, I made a cylinder with my Mo-Betta porting, with a cast aluminum cylinder and plating from Millennium. The whole deal is made by us Cheeseheads in Wisconsin USA. I designed a cylinder that ranges from the stock 89mm (490cc) to 93mm (516cc) so a 26cc range. The ports are designed to allow modification so it can be tuned for technical mountain climbing to WFO dunes or even a winged dirt kart, and it’s designed to accept the new 2-4mm stroker crankshafts available from BUILT 500.
The cylinder head is a smooth hemi design with a KPM button decompressor made in California, the cylinder heads can be customized in almost any configuration. This big bore kit will include a cylinder, head, piston, gaskets, bearing, head-studs and alignment pins $1,295 Available Christmas 2024
The new kit for the CR500 will include an all-aluminum plated cylinder with a decompressor- head, piston kit and gaskets. Available in 3 different bore sizes and 3 different stroke lengths.
NEW SERVICE CR500
If you have a CR500 that needs the iron sleeve repaired, we can repair it with an Advanced Sleeve forged aluminum sleeve, that how we built our prototype for the new cast cylinder. Eric can customize it for whatever bore and stroke combo that you want. That Product-Service costs $995 work to parts that you supply: cylinder and head. This service includes your choice of piston brands from 89 to 93mm for stock to +4 stroke, an Advanced Sleeve, and all the machine work and porting and plating from Millennium. KPM decomp button in the modified head too!
This is Advanced Sleeve 4042 forged aluminum sleeve for all CR500s. Custom ported and plated for all types of motorcycle and kart racing. $995 parts and service when using your old top end assembly.
SUPERMINI KX80,85,100,112 KAWIE-UNIVERSAL TOP END KIT 1991-2025 KX Minis
I designed a non-KIPS cylinder and head assembly with the standard 52.50mm bore that fits 1991-2025 KX 80, KX85, KX100 Kawasaki minicycles. The critical bolt holes are all similar so there’s just one top end kit that fits all those bikes! The best part is that the porting is modernized similar to a Honda CR intake port, more reliable and easier on piston skirts. The kit makes more top power because it doesn't have KIPS powervalve governor drag and friction!
KX mini cylinders L to R 1991-97, 1998-2013, 2014-2025. The universal 100 prototype is based on a the 1997 KX80 but with miniaturized porting from a 1988 Honda CR250.
The KX prototype has a different intake port for more power and durability. This new design enables the use of stroker crankshafts up to 4mm and oversized pistons up to 54.5mm, a 121cc potentially 34hp. The cylinder on the right is a stock KX with the vertical bridges in the intake port that wear the stock pistons.
BUY NOW REPLACEMENT PARTS IN STOCK!
YZ295 2-STROKE BIG BORE KIT $795
Originally designed by Eric Gorr for Magnum distributing under the brand name MAGNUM MX-COMPONENTS. This kit fits Yamaha YZ250 dirt bikes made from 1999 through 2024. If you want a customized build, Eric offers the kit for $795
Eric offers 3 choices of porting powerbands to suit your riding needs and 2 fuel choices. The porting powerbands are: #1 Low to mid for single trail trail riding #2 Mid top top end revs 1,000 higher than stock #3 Wider powerband for a mix of riding from mx to off-road.
The fuel choices are up to you and the choices are pump gas 10% Ethanol 89 RON and race gas of 98 RON or greater. Eric also offers high altitude head mods for no extra charge.
Eric Gorr ports every cylinder by hand then signs and dates his work.
YZ295 kits are shipped by USPS Priority Mail for $25
YZ295 KIT $820 North America: 50 States USA and Canada
Kit includes an Eric Gorr ported, plated cylinder, cylinder head, all 3 powervalves and center retaining clip, new Yamaha studs, forged and coated piston kit with bearing, and top end gaskets and washers.
SPARE PARTS
CYLINDER $450 New plated and honed YZ295 cylinder
The Cylinder Works YZ295 is on the left and Magnum MX Components cylinder on the right
CYLINDER HEAD $175
CYLINDER HEAD WITH BUTTON DECOMPRESSOR $295
New aftermarket cylinder head modified for compression and powerband and fitted with a KPM decompressor button for easier kick starting.
POWERVALVES $185
Includes all 3 powervalves manufactured for the YZ295. Fits all big bore YZs modified for the past 25 years by Eric Gorr, Millennium, TMR, Max Power, RPM, & Athena.
TOP END REBUILD KIT $250
Includes piston assembly with bearing and gasket kit for YZ295
HEAD GASKETS $20
Includes 1 MLS head gasket and 6 copper washers
PISTON KIT $165
Includes a forged and coated Wiseco piston kit with rings, clips, and pin.
AFTERMARKET CYLINDERS FOR YZ125, 134, & 144 2005-2021
These aftermarket cylinders are designed by Eric Gorr for better reliability over original Yamaha cylinders. Eric ports every cylinder by hand. The 125 and 134 cylinders are ported for a stronger mid-range to top end powerband. The 144 is ideal for off-road with a wider and stronger powerband and a great replacement for any YZ144 cylinder converted by other tuners or purchased as a kit from Athena, and their parts should bolt on our cylinders.
YZ125 $350
124cc Ported for more mid to top in comparison to stock Yamaha and the exhaust bridge is strengthened for better reliability. The exhaust port height is 28mm and the transfer port height is 42, advanced 1mm over stock. All Yamaha parts will fit in this cylinder. No head mods needed but it helps and we sell matching spare heads. Cylinder porting is a stronger mid-range and top end, by Eric Gorr in Wisconsin.
SPARE PARTS
CYLINDER HEAD $150
Includes a modified original Yamaha head.
TOP END REBUILD KIT $150
Includes cast PRO-X piston, ring, pin, bearing, circlips, and all top end gaskets
YZ134 $550
134cc Ported for mid to top end. This cylinder is a replacement for top ends previously converted to a 134cc. This assumes that the powervalves and cylinder head have been modified for the larger bore size. The stock Yamaha head will work but the powervalves need trimming by 1mm in order to clear the piston. No mods needed to the crankcase or crankshaft. Cylinder porting by Eric Gorr for more mid-range to top end, cylinder plating by Millennium. Made in Wisconsin USA.
SPARE PARTS
CYLINDER HEAD $150
Includes a modified original Yamaha head.
TOP END REBUILD KIT $175
Includes forged piston (Wiseco or Wossner), ring, pin, bearing, circlips, and all top end gaskets.
YZ144 $550
144cc Ported for a wider powerband, motocross and off-road riding. This cylinder is a replacement for engines previously converted to a 144cc. Cylinder porting by Eric Gorr, cylinder platin
SPARE PARTS
CYLINDER HEAD $150
Includes a modified original Yamaha head.
TOP END REBUILD KIT $175
Includes forged piston (Wiseco or Wossner), ring, pin, bearing, circlips, and all top end gaskets. Top end rebuild kits include a forged piston, rings, pin, bearing, circlips and the gaskets, o-rings, and washers for the cylinder assembly. All top end kits shipped by USPS Priority Mail for $18
144cc $150 and $168 shipped by USPS
Model years: Honda 1988-2007, Husky 1998-2013, Kaw 1994-2008, KTM 2002-2015, Suzuki 1990-2008, Yamaha 1994-2024
1-Ring piston Wiseco racing with spare ring or 2-Ring piston Wossner durable
ENTER the brand and model year for your dirt bike___________
295cc $250
Model years: Kawasaki 1993-2004, Suzuki 2003-2008, Yamaha 1999-2024
KX295TOP
RM295TOP
YZ295TOP
330cc $275
KTM330TOP
Fits KTM300 SX,EXC,MXC 2006-2024
PISTON KITS
A piston kit includes the rings, pin, and circlips.
All piston kits shipped by USPS Priority Mail for $10
134cc $150
Model years: Honda 1988-2007, Yamaha 2005-2021
ENTER the brand and model year for 144 dirt bike___________
144cc $144
Model years: Honda 1989-2007, Husky 1998-2013, Kaw 1994-2008, KTM 2002-2015, Suzuki 1990-2008, Yamaha 1994-2024
ENTER the brand and model year for your dirt bike___________
265cc $175
Model years: Honda CR265 1986-2007, Kaw KX265 1993-2004, Suz RM265 2000-2008, Yam YZ250 1994-2024
ENTER the brand and model year for your dirt bike___________
295cc PISTON KITS $165-$285
Model years: Kawasaki 1993-2004, Suzuki 2003-2008, Yamaha 1999-2024
11320M07200 EGR-WISECO forged, coated, 2 rings $165 325 grams.
8216D560 WOSSNER forged with intake boost port $195 323 grams.
24079A,B VERTEX cast piston $285 317 grams.
KTM 330cc $195
Model years: KTM300 1996-2024
12331M07600 EGR-WISECO forged, coated, 2 rings, fits 2006-2024
12192M07600 EGR-WISECO forged, coated, 2 rings, fits 1996-2005
STEEL HEAD GASKET BIG BORES
Big bore cylinders require big bore head gaskets. COMETIC makes the best MLS steel gaskets.
Head gaskets are shipped by USPS Priority Mail for $10
144cc $15 each
Honda CR 1989-1999
Honda CR144 2005-2007
Kaw KX 1992-2002
295cc $20 each
Kaw KX295 1993-2008
Suz RM295 2003-2008
Yam YZ295 1999-2024