1988 KX500 ENGINE SHOED INTO 2003 KX250 CHASSIS

By Robert Reed

A few years ago, I decided to take a welding class and needed a project to work on in class. I assist a buddy as an admin on KXRiders.com, and the guys on that site have a deep love affair for the KX500. I decided to take the plunge and bought a 1988 KX 500 engine on eBay and a fairly clean 2003 KX250 on Craigslist and made it my welding class project. After a few years of riding it, I finally was able to put together the will power to stop riding it long enough to tear it down for final detailing. Around that time, TX Race released their kit that allows you to put 2017-19 KX250F plastic on your 2003-07 KX250 or 125, so I decided to update the look as well.

The 500cc conversion to a later steel frame is fairly straightforward, and the results are well worth it. The big two strokes have a ton of torque and are easier to ride than you think. You won’t regret buying one.

Build Specifics:

• 2003 KX 250 chassis, modified by owner
• TX Race 2017-19 KX250F plastic conversion kit and seat, Decal Works custom OEM graphics
• Clarke 3.0-gallon tank, Tusk gas cap
• 1988 KX500 motor, re-sleeved by Millennium Technologies and bored to 88 mm (525 cc), Wossner piston, cylinder head modified to 88 mm and compression release added by Larry Wiechman, 1986 KX500 steel KIPS valves, TSR aluminum KIPS cover
• Service Honda FMF Gnarly pipe, FMF CR 500 Q Stealth Silencer
• V Force 2 reed block, 44 mm Lectron Carb with billet float bowl from Packard Racing, Uni KX500 air filter
• EFM Full Auto Clutch (still retains clutch lever use), KX Guru Racing two-piece clutch cover conversion, clutch cover spacer for the EFM clutch fabricated by Jon Pickel
• Boyesen Racing ignition and clutch covers
• 2009 KX250F forks with Stillwell Performance A Kit upgrade, Fox Racing fork caps, Applied Racing 25mm offset clamps
• Pro Circuit Kayaba Kit Shock (similar to their works Splitfire bikes’ shock)
• Tusk Impact wheels, Dunlop MX 32 tires
• Tusk Typhoon oversized front brake rotor, Tusk Typhoon rear brake rotor, Galfer Racing front and rear brake lines
• Mika Metal bars, ASV F3 levers, Works Connection clutch perch, ODI lock on grips, Faast Racing anti-vibration bar ends
• Trail Tech Vapor Speedometer/Tachometer
• Trail Tech side stand
• Tusk shifter
• IMS foot pegs
• Tusk KX250F rear brake pedal, Tusk rear brake clevis, Fasst Racing rear brake spring delete
• TM Designworks rear disc and caliper guard kit, 2009 KX250F caliper, Tusk rear axle blocks, Tusk Nylock axle nut
• Primary Drive sprockets and gold chain, Topar Racing case protector, Acerbis chain slider, TM Designworks Factory Edition rear chain guard

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