What compresson piston should I get? I can gat a je 10.5 to 1 for 139.00$ or a CP 11.5 to 1 for 240.00$. I do alot of drag racing and race cams are next. I got beat by a 440ex I just bult and I can't have that......It is 11 to 1 ,hotcams stage 2, 1mm oversized valves and a little port work. Is it normal to get beat by this creation? I dont like it...

 

Well, I wouldn't mess around for anything under 11.5:1. After that, its how much you want to spend and knowing what works. Get a good cam and good valve springs to match. Consider the type of cams and springs for the type of riding you do. Shim under bucket valve springs are safer than the dual race springs, but if you dont think you will over rev by accident or on purpose, than there really isn't any point to having them. I think the 14:1 piston is the highest out there (actually its closer to 14.5:1) that works well. I was the test pilot on that and found some interesting things about it.

 

Such as??? Do tell..

Any problems w/ overheating, gasket retention, or starter/gear problems when running 14:1? How trailable is the 14:1?

 

i'd go 12.5 plus i don't think you get enough bang from the 11 and below

 

Overheating: No problems - in fact I run fanless with one of those in-line coolers. I did notice that it did run a little warmer, but still well within manageable levels.

Starting Problems?: No problems whatsoever with the Vortex ignition. I did have starting problems and idleing problems with the RWR ignition. The RWR ignition was purchased from them back in early 2000. I don't know if they have changed or modified the curves since.

Gasket retention: No problems, although we used new gaskets as well as a gasket sealer. No leaks inside or out. Two base gaskets were used however. The compression rating is still over 14:1 with two base gaskets.

Trailable? Very! Better than my old set up with the RWR ignition and the 11.5:1 piston. The power was steady and very usable at even the lowest RPM. I found myself not down-shifting like I would normally do with the old set up. I found that just stabbing the throttle would produce all the power I needed. When hill climbing, I went up the steepest hills I could find at Winchester Bay and found that third gear would suffice simply by (as mentioned above) simply stabbing the throttle - no down shifting was needed. This is going to be extremely helpfull when side-hilling dunes.

I dont know how the other 10 power curves will do with the 14:1 piston. I'll be trying that out this weekend at Sandlake.

 

Here is the latest, The RWR power curve has not changed since its inception.

 

ironrod this is something i'm starting to notice, it seems the low end bog of the 45 is less with the higher compression, my it isn't the compression but it seems it could be.

 

Sandman,

I like the pump.

Marky