TRX250R.ORG

Workshop => Engine and Bottom End => Topic started by: Greg Huntley on August 12, 2013, 05:05:07 PM

Title: crank for 310 sphynx
Post by: Greg Huntley on August 12, 2013, 05:05:07 PM

I was looking on cpi website,  Do sphynx 310 cylinders require the long rod crank?  Or is ok to run with short rod and no spacer.  Cylinder doesnt seem to be decked any different than other cylinders

Title: crank for 310 sphynx
Post by: Polonda on August 12, 2013, 08:31:32 PM

Rsss396 should be able to answer this.  Shoot him a pm.  I don't believe you will be able to do a short rod with no spacer though.  Unless cp has a special piston for it.

Title: crank for 310 sphynx
Post by: Dirt man on August 13, 2013, 12:02:08 AM

If you're spending the money on a sphinx cylinder it seems to me that you should also put a new crank in. And go with the long rod.

Title: crank for 310 sphynx
Post by: Greg Huntley on August 13, 2013, 04:01:23 PM

Its going to be all brand new.  My parts guy has a brand new short rod crank.  I prefer short rod motors.  Hopin it can be used

Title: crank for 310 sphynx
Post by: Dirt man on August 15, 2013, 09:48:07 AM

Short rods are harder on pistons, and now your piston will be about 5 mil over stock.

Title: crank for 310 sphynx
Post by: Tbone07 on August 15, 2013, 09:56:49 AM

As per an Arlan Lehman video...they don't work with the short rod cranks...lemme find the video

Title: crank for 310 sphynx
Post by: Tbone07 on August 15, 2013, 09:59:24 AM

[video=youtube;KZO4shPFWWg]http://www.youtube.com/watch?v=KZO4shPFWWg[/video]

Title: crank for 310 sphynx
Post by: rsss396 on August 15, 2013, 02:25:12 PM

I think it can be done with a certain model Cheetah piston and a slightly thicker base gasket, but the long rod is how CPI has set them up to be run and is the best way IMO

Title: crank for 310 sphynx
Post by: Polonda on August 15, 2013, 08:41:19 PM

I need a mandrel and sleeve setup like that!  Making the mandrel is cake.  No idea where to get the sleeve though.  Google here I come!

Title: crank for 310 sphynx
Post by: ledperformance on August 17, 2013, 11:28:17 AM

The Cp industries TRX cylinders are designed to use the long (130.3 mm) rod. Including Sphinx, Puma and Saber. I am pretty sure the piston skirt on the 300 piston would hit the flywheels with the short (125.3mm) rod. The cylinder would need to be ordered to a different length and the use the W845 PS piston. It would take a long time to get a special made. We are building Short rod CR and YZ 350 cylinders, and the 78 mm 1056 piston does clear the flywheel.