[VelociRaptor]

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:

 

[VelociRaptor]

Sorry to pull you chain lol. These are for a Raptor 700(the 11:1 is the Wiseco) but these are on the way for the XX! Just wanted to see what feedback these will get for smo0oth since hes having these made right now. On the forfront to break these power potential machines open!

 

[scuzz]

On the forfront to break these machines open!

^^^^^

This is what my brain read. :scared:

 

[VelociRaptor]

Man, I wont lie to ya. I definately want to see what one of these XXs will do setup 14:1/stage III cam/ported head/good exhaust/bored TB properly tuned!

 

[smo0oth1]

lol Dam Bo, While I was reading the first one my heart dropped! I was like MuthaF's!!! Its looking like after they CAD the piston I sent they'll have to mail it back so I can reinstall it to get the deck height at TDC. Hadn't had any luck finding the specs without actually measuring it in the hole. If anyone knows it would speed things up about 5 days r so.

 

[trailin'me]

im working on getting that for you. as soon as that piston is available its going in my machine. I dunno who has the cam though... guess ill worr about that later

 

[VelociRaptor]

The XR650R cams will interchange, just swap your decompression mechanism over and pop it in there.

 

[OzLinc]

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

 

[scuzz]

10:1

Also it is suggested that you run premium. (91 octane in the States)


....and a picture for you nerds like me:

 

[VelociRaptor]

Im talkin the aftermarket cams for the XR650R. The 450s cannot be compared to our(Raptor included) bigger engines. Our combustion chambers arent as good and the cam profiles arent setup to bleed off cylinder pressure like the 450s either. 12:1 in a 450 is like 11:1 in these 700s. The XX has 10:1 from the factory(so they say, probably more like 9.5:1 if ya measure it). The Raptor is said to be 9.2:1 but with a piston that has a 10cc dish and .050" in the hole @ TDC combined with a 60cc chamber it actually measures out at 8.8:1

 

[DblXX]

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?

 

[smo0oth1]

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

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.

 

[smo0oth1]

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?

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.

 

[VelociRaptor]

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.

How are ya gonna loose topend?

 

[DblXX]

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.

Doesn't the scavenging help for low end power for the motor, i was always told that and also keep advance the timing.

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.

let me know when that order comes out i want that piston.

How are ya gonna loose topend?

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.

 

[VelociRaptor]

Probably so, read up:
http://www.club700xx.com/vb/showthread.php?t=476

 

[smo0oth1]

No the scavenging effect is mostly found in Higher RPM cams that sacrifice cylinder pressure for High Rpm capabilites. (exhaust valve opens before TDC, Hence why aggressive cams lope at idle)
Stock cams and high torque 4x4 cams make the highest cylinder pressures and generally make best power down low. (Exhaust valve opens after TDC, making for a gentler idle)

Retarding timing will give you more top end power sacrificing low end. It goes the other way around when Advancing.

 

[OzLinc]

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

 

[VelociRaptor]

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

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.

 

[smo0oth1]

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

Thanks for the edit, I was wondering what the intent of your words were.