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Workshop => Engine and Bottom End => Topic started by: Quinnlt4 on May 29, 2014, 01:01:40 PM

Title: Big bore with a short rod crank
Post by: Quinnlt4 on May 29, 2014, 01:01:40 PM

I am looking at getting a 330 from ESR  but have an 86 motor with a short rod. Question is should I just stick with my short rod?  Anyone currently running a BB with a short rod?

Title: Big bore with a short rod crank
Post by: lonestar on May 29, 2014, 02:38:03 PM

if you have a short rod you don't need to use the spacer plate.all bb are set up for short rod motor's.it's cheaper to do it that way and just add the spacer for the lr motor's.

Title: Big bore with a short rod crank
Post by: christph on May 29, 2014, 08:59:46 PM

I have a Duncan big bore with a short rod and love it.  It's a 340cc PC2000 with a power valve.  I just recently figured out how to get the most out of it.  It has a ton of torque and revs to the moon.  Theoretically the short rod should rev out a bit quicker than the long rod, but the long rod should have a bit more torque.  I like a rev-happy engine so I went with the short rod.

Title: Big bore with a short rod crank
Post by: aberegg05 on May 29, 2014, 11:48:41 PM

My brother has  a 350 short rod with a rotax pv......screamer.

Title: Big bore with a short rod crank
Post by: Jerry Hall on May 30, 2014, 12:42:46 AM

I have built a lot of 330s with short rods.  The short rods are slightly beefier than the oem long rods. They work well and I am not afraid to build an engine with a pipe/port combination that will let it rev.    I have not been able to see any less piston life with the short rod nor power difference.  The shape of the power curve is primarily shaped by the pipe and porting and not the length of the rod.

Title: Big bore with a short rod crank
Post by: Quinnlt4 on June 02, 2014, 08:30:27 PM

Thanks for all the feedback.