XR650L 11:1 piston

Started by martinfan30, Jan 21 2008 11:17 AM
40 replies to this topic

  • martinfan30

Posted 21 January 2008 - 11:17 AM

#1


Trying to decide which piston to buy... Need more power w/o pinging.

So, who runs a 11:1 and who runs 10.5:1?

Does the 11:1 require race fue3l to keep quiet, or is 91 OK?\




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  • stepho

Posted 21 January 2008 - 01:25 PM

#2

we run an 12 to 1 piston made by AAR with 91 shell from california. But I can tune that ping out with a tap of the finger. Depending on which cam timing we are using we keep it around 24 to 25 at WOT.

  • martinfan30

Posted 21 January 2008 - 01:27 PM

#3

stepho said:

we run an 12 to 1 piston made by AAR with 91 shell from california. But I can tune that ping out with a tap of the finger. Depending on which cam timing we are using we keep it around 24 to 25 at WOT.

Is that a measurement of "PINGING"?

Is ceramic coating worth it?

  • Norge

Posted 21 January 2008 - 04:27 PM

#4

I run 10.5:1 piston. No problems with pump gas (88 to 93 octane) and big power increase.

  • martinfan30

Posted 21 January 2008 - 04:42 PM

#5

Norge said:

I run 10.5:1 piston. No problems with pump gas (88 to 93 octane) and big power increase.

Hey Norge, you run a hotcam also??

Which gained more power??

  • dldavis_66

Posted 21 January 2008 - 04:55 PM

#6

I didn't think you could fit one of them in an L. Or can they be modified a little?? The 11:1(100 x 8.6) is made for the R, by Wiseco, and they say it will not fit in the L model...not the same stroke. Maybe its just a taller piston. If the dimension from the center of the pin to the very bottom of the skirt, then I guess you could put it in an L. I dunno....

Anybody care to add to this???

Wouldn't mind putting a 11:1 in my L's

  • Norge

Posted 21 January 2008 - 05:13 PM

#7

martinfan30 said:

Hey Norge, you run a hotcam also??

Which gained more power??

Yes, Hotcam stage 1 installed at the same time. I can't say what provided more gain, but together its much better than the mechanically de-tuned stock configuration.

  • stepho

Posted 21 January 2008 - 07:05 PM

#8

the 24 or 25 is the timing btdc at wide open throttle where most of our pinging happens.

  • dldavis_66

Posted 21 January 2008 - 08:48 PM

#9

Hey...I appreciate the info in the PM.

Geeze....I've heard about XRSOnly.com before...never though of giving them a peek.

Yeah...and about the 11:1 piston...wow. I thought JE stopped making pistons for the 650L...let alone a 11:1

Hey MartinFan, if you decide to go with the 11:1, keep us posted. I'd like to find out if your starter has any problems kickin that piston. But then again, it might not if you put in a HotCam ....

  • cleonard

Posted 21 January 2008 - 09:11 PM

#10

dldavis_66 said:

I didn't think you could fit one of them in an L. Or can they be modified a little?? The 11:1(100 x 8.6) is made for the R, by Wiseco, and they say it will not fit in the L model...not the same stroke. Maybe its just a taller piston. If the dimension from the center of the pin to the very bottom of the skirt, then I guess you could put it in an L. I dunno....

Anybody care to add to this???

Wouldn't mind putting a 11:1 in my L's

I'm pretty sure that most if not all of the large RFVC motors from the original XR500, to the XL600, the XR600 and XR650L all are the same overall size. The piston height is kept the same by moving the location of the piston pin. That would make the piston pin location 1mm different between the XR600 and XR650L, with the 650L piston pin being 1mm closer to the top. If you tried a 600 piston in the 650 it would go 1mm too high. Would it hit the cylinder head or valves, I'm not sure. I do know it would screw up the squish. Same thing if you put a 650L piston in a 600. It would be 1mm too low, lowering the compression and screwing up the squish.

At least that is what I think. I've never held a 600 piston next to a 650L piston to see the difference.

  • Captain Midnight

Posted 22 January 2008 - 12:07 AM

#11

I used a J.E. 10.25to1. Needed to mix in in a little race gas when lugging in the woods. Mostly OK on the street. Cut the piston down to 10to1. I like it a little better now.

  • martinfan30

Posted 22 January 2008 - 08:26 AM

#12

dldavis_66 said:

I didn't think you could fit one of them in an L. Or can they be modified a little?? The 11:1(100 x 8.6) is made for the R, by Wiseco, and they say it will not fit in the L model...not the same stroke. Maybe its just a taller piston. If the dimension from the center of the pin to the very bottom of the skirt, then I guess you could put it in an L. I dunno....

Anybody care to add to this???

Wouldn't mind putting a 11:1 in my L's

Check this out... I called XR'S and they said you'd have to mix in race fuel...


http://www.xrsonly.c...emart&Itemid=77

  • martinfan30

Posted 22 January 2008 - 08:28 AM

#13

stepho said:

the 24 or 25 is the timing btdc at wide open throttle where most of our pinging happens.

I was thinking some sort of RPM count for measuring ping..

Maybe I shouldnt drink my breakfast!LOL!:cool:

  • martinfan30

Posted 24 January 2008 - 07:39 AM

#14

Any other thoughts on this piston? I am on the fence still...

  • creeky

Posted 24 January 2008 - 09:31 AM

#15

My HRC628 had an 11:1 piston, it needed at least a mixture of 50/50 93 and race gas in hot weather conditions and/or riding in sand. Otherwise, it would get VERY hot and exhibit the death rattle.

  • martinfan30

Posted 24 January 2008 - 12:50 PM

#16

Ok, maybe a 10.5:1 is what i need..

Thanks all.:cool:

  • husky123

Posted 24 January 2008 - 01:11 PM

#17

The 600 and 650 pistons are different diameters. Now the piston for the 628 kit and the 650l piston are the same bore with the 650L getting the additional cc's from a tad longer stroke. Don't know about the variances in the squish though between the two.


cleonard said:

I'm pretty sure that most if not all of the large RFVC motors from the original XR500, to the XL600, the XR600 and XR650L all are the same overall size. The piston height is kept the same by moving the location of the piston pin. That would make the piston pin location 1mm different between the XR600 and XR650L, with the 650L piston pin being 1mm closer to the top. If you tried a 600 piston in the 650 it would go 1mm too high. Would it hit the cylinder head or valves, I'm not sure. I do know it would screw up the squish. Same thing if you put a 650L piston in a 600. It would be 1mm too low, lowering the compression and screwing up the squish.

At least that is what I think. I've never held a 600 piston next to a 650L piston to see the difference.

  • martinfan30

Posted 24 January 2008 - 01:13 PM

#18

husky123 said:

The 600 and 650 pistons are different diameters. Now the piston for the 628 kit and the 650l piston are the same bore with the 650L getting the additional cc's from a tad longer stroke. Don't know about the variances in the squish though between the two.

I wonder if the pin location in the piston may be a factor in his 600 over heating and pinging? The six hundreds piston sits up higher than the L, right? that could make a difference. The squish definately would, any one know?

  • Denn10

Posted 24 January 2008 - 01:26 PM

#19

martinfan30 said:

Check this out... I called XR'S and they said you'd have to mix in race fuel...


http://www.xrsonly.c...emart&Itemid=77

If there selling it as 10.5-1 but saying its closer to 11-1 then you may wanna check specs vs some other pistons, see where you can see the difference or do all of em have the same just call it a 10.5-1 setup. Have you seen any specs anywhere for pistons? pin height, overall, anything? Either way im sure between the little comp ratio you wouldnt see that much difference to warrant it. if it were me id get the 10.5 setup, with your cam already and carb your gonna flip that damn thing or run from the cops again.

even if you have to mix 25% race fuel no big deal, just pay the $11 a gallon and buy a 5 gal jug LOL

  • martinfan30

Posted 24 January 2008 - 01:39 PM

#20

if it were me id get the 10.5 setup, with your cam already and carb your gonna flip that damn thing or run from the cops again.

even if you have to mix 25% race fuel no big deal, just pay the $11 a gallon and buy a 5 gal jug LOL[/QUOTE]





Where can that fuel be bought? I'm also concerned about the heat. An oil cooler would probably be necessary with the 11:1.

RUN from the cops again!!!LOL!!:cool:



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