Big Bore piston weights?

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Jan 23, 2025 | 06:48 AM

#31

RaceGass

Senior Member

Joined: Jun 2008

Posts: 1,392

From: So Cal

1st Gear Member

Quote:

Originally Posted by 1994klr250

I put the Keng engine 402cc big bore kit on my latest klx project bike. Unfortunately I didn't have a scale to weigh the piston before I built the engine. As far as vibration goes there's no difference in the handlebars and seat between the 402 and 351 big bore engines vibration. The klx402 just has more power.

I seen the updated rod used, is the piston pin sized up as well? If only Keng could stroke the crank too

Jan 23, 2025 | 06:54 AM

#32

tsc

Senior Member

Joined: Sep 2023

Posts: 174

1st Gear Member

Quote:

Originally Posted by RaceGass

I seen the updated rod used, is the piston pin sized up as well? If only Keng could stroke the crank too

Keng's 402 kit comes with 63.2 stroker crank and 90mm piston

Jan 23, 2025 | 07:00 AM

#33

RaceGass

Senior Member

Joined: Jun 2008

Posts: 1,392

From: So Cal

1st Gear Member

Very well, thanks for the info

May 17, 2026 | 01:31 PM

#34

Bullfrog12

Junior Member

Joined: Jul 2024

Posts: 3

Compression Ratios

Is there any advantage to the Keng 355 kit vs the BB 351 kit other than cost?

What compression ratios do you end up with after installing the kits mentioned above? If anybody has the info for either kit, please post.

Thank You