2007 GS500F Top End Rebuild

[Steve146]

I have an 07 and am looking to replace the pistons and cam with a slightly upgraded version.

I've searched here and at Wiseco and JE and I'm not finding much in the way of aftermarket HC pistons.
Arias pistons will custom make a set in any bore or compression ratio.  If we can get a group of 4 there is a price break.  I am looking for a size of 74.5 mm with a CR of about 10.25-1.  They need a sample piston and if possible a head.  With the price break the piston set including rings, pins and clips is around $150 each. 

Megacycle cam will build a 384-70 cam  .380" lift  261°duration (stock is .345" 243°) for $299 per set and $35 for springs on my cores.  Because of the higher CR we need to be sure the valve relief cutouts are adequate.

Currently it has 25K miles, K&N lunchbox, rejet and an exhaust from a 2005 GSXR750 (Titanium)
I'm sending the piston and  off Friday to get going.  Apparently it takes about 4 weeks.

[wera90ex]

 Hi Steve, this a street bike or track bike ?

[Steve146]

Street Bike

[wera90ex]

Message sent

[Steve146]

As an update to this thread, I elected to have Arias pistons make a set of 77 mm pistons with 11:1 compression rationand have the cam reground to the MegaCycle 384-70 with a lift of .380" and a duration of 261°.

Based on my reading of the threads in general, I take it that this is a generally bad idea, but I'll try it anyway.


In the mean time, I fell and tore my Achilles tendon and it was so bad I had to have a splice of tendon taken from an organ donor.  That's like taking a Honda suspension parts and putting them on a Suzuki.

So, it might be a while before I get it back together and ride.  I expect some jetting changes might be necessary.