How much for a CP piston made to 105 or 105.5 specs?

$60 Cometic gasket and $415 featherlite piston is included in the HPR 730 kit.

You also don't have to modify your stock cylinder with the 730. You can keep it or sell it to offset the cost of the new cylinder.

I don't necessarily buy the old school conventional wisdom that simply by going higher compression and higher rpms will shorten the life of your motor. There are many other factors that shorten engine life much more commonly like poor maintenence, or lean jetting or failing to use appropriate octane fuel. The biggest determining factor is how hard you run them.

Remember when you put your new piston and rings in you are installing a much higher quality part that will withstand heat much better. As I recall, the ring packages that come with the 730 kit have a nikasil coating on them to. Nikasil on nikasil will make for much longer ring endurance at acceptable compression range.

Most CDI's are going up to about 8750 rpm which is 1000 over stock. Most people are not cammed to rev this high in normal applications so the small amount of time spent at these rpms will probably not make much difference. Those that are cammed to run that high and make power up there have much stiffer valve springs to keep the valves from floating which can be a cause of immediate engine failure under the right circumstances..........especially on NOS.

I think if you run a stock bike all out all the time under race conditions, its life will be shortened much more than simply performing performance mods that increase internal stress will. When you install the lighter piston, you dramatically reduce internal stress. Also a good Cometic gasket will last longer at 12:1 than a stocker will last at 9:1 under similer riding conditions.

I would not factor engine life into the kinds of performance setups we are talking about here. The motor might last 5 minutes longer if you don't modify it after you look at all the factors.

 

NUT,

Ok, you sold me. I'm saving up for a 730 as I speak right now.

 

Sandman, thank you for mentioning "into it for a grand". That's about what I got in my home grown 730. I was reading this thread and was getting pi$$ed I spent so much. I think I'm alright now.

 

$300-400 for a piston, no!! $160 shipped and JE stocks them, no need to buy a set of 4.

I paid $375 shipped for my 720cc kit, plus gasket.

 

Ill be at $600 total for my 720 kit (Cylinder, Piston 13 to 1, Cometic gaskets), mine was more than scoobys I had a steel sleeve removed from my cylinder and replaced with a aluminum sleeve.

 

I never knew you already had a steel sleeve. Have you been running a 720 sleeved bore all this time?

 

Saw some Pami 108's run at the Clash, if your into the motor at any length, I would go with that set-up for sand-drags.

 

108mm dia? My goodness, that's a whopper.

Is this an AL cylinder and what does this kit cost?

 

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