Page Mohler, on 23 May 2012 - 04:35 PM, said:

Page Mohler, on 23 May 2012 - 05:02 PM, said:

I don't have numbers for the 11.25:1 JE slug since it's pretty new and it won't do any good to throw numbers around without knowing what piston you want to get.

The thing with going high compression first is that your engine is going to be more octane sensitive until you at least get a cam. I don't know how high the compression can go on pump gas with aftermarket cams, but I do know that around 9.8:1 is where the stock cam draws a line in the sand. A "10.5:1" piston will produce about that much static compression. An 11.25:1, I don't know.

HeadTrauma, on 23 May 2012 - 08:49 PM, said:

I'm gonna have the stage 1 hotcam put in at the same time.

So you're saying that the 10.5 will actually be 9.8?

Page Mohler, on 23 May 2012 - 11:48 PM, said:

don't use a hotcam there's many other cams that are much better that you can tailor to your compression level.
get a custom cam built it's the same price or less...

for compression you want a slug that will bring the piston to zero deck ht. or a few thou in the hole and then match your custom cam to that, your motor will thank you for it.

11.1 is the number you should be looking at, then with the right cam you can still run pump fuels, after 11.1 comp you're going to have to run 98 octane levels,  with a super huge bumpstick you can squeeze out more comp on pump gas........remember this 4 strokes love compression...and big cams....

Remember this one fact, compression only counts when the valves stay in the closed position, anything after that is mute.
As soon as the valve starts to open there goes your compression so a big cam = more comp.

cyclewizard, on 24 May 2012 - 05:12 AM, said:

I didn't know that. I always thought "big" meant more meat on cam away from center with a longer open time.

HeadTrauma, on 23 May 2012 - 09:20 AM, said:

I second that. And my 8.7-1 Wiseco sits .100" low in the bore so I don't think the JE is any more appropriately advertised than the Wiseco 4562 if that's correct. My experince is that all the commonly avalable pistons with a hotcam work fine on pump gas as long as they're rejetted correctly. Still no compression height for the "new" Wiseco 10.5. Bueller.... Bueller....

Edited by valvesrule, 24 May 2012 - 09:12 PM.

here is an off question for the masses

cw Im getting your hrc cam, springs, keepers and rockers from you...

will that need a jetting change, being that the "powerband" is being moved "up" a bit?

thanks

christian

I used the 600R piston in my 650L and I believe the comp. ration is around 9.5:1.

Its perfect for the crap pump gasoline here and easy on the starter.

It's lower than 9.5:1.

See this:
http://www.thumperta...st__p__10055309

And then use your favorite online compression ratio calculator.

I think B meant his piston sits below deck ten thou...........not 100 thou.

elsalvadorklr, on 25 May 2012 - 05:51 AM, said:

The HRC628 cam works wonderfull but you need to add some comp to your motor to get it's full effect.

jets are 58 slow 160 main and .030 shim under the needle...
Steve is sending me a cam core and rocker arm core for you..
Steve's a good man..

That`s what i meant,,,,,,,,i put it in the calculator at 10 thou.........i wrote 100 thou in my message here...i thought i had that wrong...i edited my previous post to reflect my error..

B

Edited by brianhare, 25 May 2012 - 01:28 PM.

cyclewizard, on 25 May 2012 - 01:13 PM, said:

I

brianhare, on 25 May 2012 - 01:22 PM, said:

Good. The Wiseco 8.7 is .100" in the hole. Had me off balance thinking JE could be that far off for the comp ratio. Still doesn't live up to it's advertised ratio but much closer.

valvesrule, on 25 May 2012 - 07:06 PM, said:

Yup..not surprized though.........CW says 10.5:1........i get arround that.........with his cam it goes like hell,,,,,so who cares

B

cyclewizard, on 25 May 2012 - 01:17 PM, said:

THATS WHAT BEER MONEY DOES TO A MAN! jajajajaja

thanks

This is for an xr600r jetting, mine is an 88, not xrl

sorry for the hijack

cant wait though! jajajaja

elsalvadorklr, on 27 May 2012 - 08:40 AM, said:

Awh shoot.......you got me on that one..