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Just got it in yesterday, looks great and should do very well. The last pic is the 14:1 and 11:1 side by side:



^^^^^On the forfront to break these machines open!
The 450r does have 12:1 stock but as Bo mentioned the cam profile "bleeds" pressure off by closing the intake valve later and opening the exhaust valve earlier. This works both ways. You can do the opposite and actually raise cylinder pressure from a scavenging effect of the exhaust side. (Search effects of LSA).Do you know what the stock comp on the 700XX is?........11:1 seems awefully low for an aftermarket piston. I know US pump fuel is low octane but from what I know all of the 450's have higher comp than that in stock form.
Also.....You have said that the XR650 cam will fit (great info) but what will it do.......It's still stock Honda.
Linc
There will be some 12:1 made in this first order just not the majority. You will not lose any top end with higher compression. Higher compression is a magical power adder that has no ill side effects except if you go to high on improper octane. You gain torque and Hp bottom to top.i would like to see a 12:1 for the XX, i don't want to go to high cause of octane rating and i don't want to loose to much topend. im not sure about the hole loosing topend by going with a higher compression, does anybody know?
How are ya gonna loose topend?i would like to see a 12:1 for the XX, i don't want to go to high cause of octane rating and i don't want to loose to much topend.
Doesn't the scavenging help for low end power for the motor, i was always told that and also keep advance the timing.The 450r does have 12:1 stock but as Bo mentioned the cam profile "bleeds" pressure off by closing the intake valve later and opening the exhaust valve earlier. This works both ways. You can do the opposite and actually raise cylinder pressure from a scavenging effect of the exhaust side. (Search effects of LSA).
I didn't feel that many 12:1 or 14:1 would sell so the most of the first order will be for the non pro guys running 11:1 on pump gas. When there is more interest or I source another motor I will get some 14:1 and start my death clock countdown.
let me know when that order comes out i want that piston.There will be some 12:1 made in this first order just not the majority. You will not lose any top end with higher compression. Higher compression is a magical power adder that has no ill side effects except if you go to high on improper octane. You gain torque and Hp bottom to top.
one of my raptor buddys, i think he told me that to discourage me from putting a piston in it, i think thats cause he only got the big 3 and he can't stand to be out done by anybody else.How are ya gonna loose topend?
That will remain to be seen for now. Efficiency in what areas will be close really, to a point. The 700R is mechanicaly the same in alot of areas. You wanna compare stock to stock or mod for mod? I will say this, once you get into the very large builds(770 or larger) the ability in power production will go in the 700R's favor. The XX cylinder head cannot supply the airflow required as easily as the 700Rs cylinder head can. Just doesnt have the overall design that can be modified to the extent to properly supply a very large engine. It probably does an awesome job supplying a 686 but once you get a bigbore and stroker crank in it the cylinder head will be the limiting factor comparitively speaking. You can make the XX cylinder head into a pretty good cylinder head but in all out airflow for an all out engine the 700R cylinder head will be hard to beat. Once we start building +75rwhp stockbore/stockstroke XXs then we can shut the Raptor guys up and earn the respect Honda deserves in the bigbore ranks.700xx is not a Raptor and (IMO) is a far more efficient beast; no it's not a 450cc MX based engine but it's not an dark-ages V8 either.
Linc
Thanks for the edit, I was wondering what the intent of your words were.Thanks Smooth.........yes I do understand cam overlap and it's effect on Dynamic Compression..........I actually do know what I'm on about.......I know I carry on sometimes but it is the interweb thingy, you gotta have fun sometimes.
12:1 will be about 11.7~11.8 Dynamic and IMO will be good and safe with PULP fuel.
700xx is not a Raptor and (IMO) is a far more efficient beast; no it's not a 450cc MX based engine but it's not an dark-ages V8 either.
Linc