Thumper Racing 430 kit

Has anybody tried the 430 big bore kit on their 400? I have been told by some local riders that boring the 400 creates problems and makes the engine unreliable. Any comments on this?

Randy

the thumper kit utilizes a cast iron sleeve instead of nicasil plating.

I believe you can make a 400 a 420 and a 426 a 444.

There is reduced headgasket sealing area but proper assembly will yield a reliable machine.

My experience has been with the eric gore 444 kit and it uses a replated nicasil bore, BTW.

i have a 97 suzuki DR350 that i put the thumper racing big bore kit in and made it a 435. about 2 weeks later it blew the bottom end. i wouldn't recommend getting any big bore kits cause it's gonna cost ya big time. just my 2 cents

Thanks for the info, I think that I will leave it a 400 and be happy it runs every weekend.

This is my favorite part about my big bore kit in my 426.

Before and after dyno runs.

http://209.197.247.209/Dyno_runs/baseline_yzf_+444.htm

The extra ten hp on top is really fun for fifth gear wheelies and 15/42 gearing...

I got 50+ dyno runs on the motor and 1400+ baja miles without a single wimper reliability wise.

I got my stuff from

http://ericgorr.com/

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