Thumper Racing 662 Big Bore

Thumper Racing is known for their unstoppable big bore kits and they are no stranger to the podium, endurance racing or just regular riding - so when we got a call to test their stroked out 662 big bore engine on one of our KTM 500’s we jumped at the opportunity.

[@sampep]

Sick engine! Did it survive a full season of snowbike? I keep hearing the rod just grenade.

[@brianparshall8231]

660 what awesome

[@purebloodheretic4682]

Bigger Bore & Piston= Slower RPM & more Vibration! The 500 has good power - just uncork - map & port & pipe if necessary I have the ol' school 525 & it still goes strong! 💪

[@Shawn-in-da-Canyon]

What happened to Thumper Racing?

[@Natehustlin4232]

They close their business.

[@a64738]

How does it run? It sounds for some reason slower then a normal 500 but way louder lol :)

[@GyroPyro121212]

It’s surely faster, otherwise there would be little point in building it. It might not make a ton more peak hp, but I’m sure it makes quite a bit more torque with the extra displacement. It sounds slower probably because it doesn’t rev as freely given a heavier rotating mass, lessened balance, etc...

[@simonespiga4374]

Top speed? Nice video.

[@marquisewatts9650]

Where did you get that muffler from

[@streamsniperontheshitter8232]

My 525 would climb that hill just as good?

[@brian5606]

What's the Bore & Stroke I'm looking into replacing my YZ450f engine with this parts kit you've assembled. I was just curious what bore & stroke you've conjured up to make 662cc. The 588 would probably be enough for me, thanks . . . Brian

[@jaysmith9892]

where was this video taken

[@Karlan_]

sound awful just throw on a regular end can! Otherwise awsome!

[@matthewchurch1320]

so what was it befor the big bore kit

[@Aspired329]

500

[@diamondmidnightgardener]

You should do a big bore kit for the Duke 390.... it needs it, or perhaps I should say "I need it"

[@onnikallioniemi]

just get a bigger duke

[@diamondmidnightgardener]

@@onnikallioniemi true, I will.... when I get off my restrictions

[@9MinuteMotos]

nice job speeding up the video. Not impressed.

[@kochj0713]

Verge of. Crashing the whole way

[@cschilli68]

How can I buy one?

[@matthewchurch1320]

go to the Thumper Racing site

[@deeellis9503]

You must build it