M8 Head CC

[BigT]

I've thought I've read that the stock M8 and SE heads are typically around 89 cc. I use the 89 cc in the Big Boyz calculator along the listed -4cc of my new Cometic 117" pistons and I come up well short of the advertised 11:1 compression. Has anyone measured the volume of these heads to confirm the size?

[Ohio HD]

Search is your friend. Charlie did.

http://harleytechtalk.com/htt/index.php?topic=95599.msg1111896#msg1111896

[BigT]

I saw the SBC post but the numbers don't seem to add up for even a stock 107 listed as 10:1

[BigT]

Just did a cranking compression test on the new motor that has never run. With the stock cams still in there it cranked over at 245 front and 239 rear with a .030 head gasket. Heads seem to be closer to 85cc.

[mike jesse]

TB open while being cranked? Seems really high.

[1FSTRK]

TB open while being cranked? Seems really high.

Why would the TB being closed would make the CCP higher?

[sfmichael]

TB open while being cranked? Seems really high.

Why would the TB being closed would make the CCP higher?

it wouldn't - if anything it would make it lower

[Durwood]

Need to run the engine and re-check, and yes, be sure the TB is held open.

[Don D]

Lifters are not full yet and intake close is early.

[Durwood]

Lifters are not full yet and intake close is early.

[laserp]

Lifters are not full yet and intake close is early.

I guess that's another reason why you should warm the bike up before doing a CCP check. 

[Durwood]

Lifters are not full yet and intake close is early.

I guess that's another reason why you should warm the bike up before doing a CCP check. 

Exactly.

[BigT]

The stock cam and lifters are still in there for the test and took a long time to bleed down so I would think they would be opening up the valves. The Andrews cam site shows the stock cam intake closing at 01 ABDC and with 117" pistons at 11:1 and .030 head gasket the cranking compression seems about right for 85 cc heads.

[Don D]

Tom
The valves are opening but when the lifter is compressed and equalizes there is still air in them. The intake valve closes early, it's like having a much shorter cam. Start it up and let the motor run until they are quiet then recheck.

[BigT]

Make sense!  Will do.

[BigT]

Rechecked on a warm engine and the CCP did drop a little to 238 front and rear with the stock cam still in with 11:1 pistons.  Still need to pick a cam leaning towards the TTS 200. Anyone see the specs for that cam?

[sfmichael]

I haven't looked but TTS is known to hold the cam specs pretty close to the vest.

The stuff they produce seems to work, so based on that, they're probably a pretty safe choice.

Durwood has done extensive M8 testing and I have ridden his 'shop mule' and I can tell you it is very fast and very responsive.

That being said, some of that power and responsiveness come from it being tuned to a gnat's ass.

As you likely already know, the complete package along with a comprehensive tune will dictate the overall result.

Good luck with your build 

[Durwood]

I haven't tried the CR-460 in a 117, but a guy in New Zealand did and street tuned it with PV....His exact words were, "It will suck your eyeballs to the back of your skull".

To which, I can only imagine at this point.

[BigT]

I had talked to Wes at Cycle Rama and he didn't recommend running the 460 cam at 11:1.
I'm going to give it another month or so to see if any new cams are released with backup dyno runs.

[Durwood]

I had talked to Wes at Cycle Rama and he didn't recommend running the 460 cam at 11:1.
I'm going to give it another month or so to see if any new cams are released with backup dyno runs.

There are a couple more grinds in the works at Cycle Rama that are geared towards larger builds with increased compression.

[sfmichael]

I had talked to Wes at Cycle Rama and he didn't recommend running the 460 cam at 11:1.
I'm going to give it another month or so to see if any new cams are released with backup dyno runs.

There are a couple more grinds in the works at Cycle Rama that are geared towards larger builds with increased compression.

        

[HD/Wrench]

That sounds like a TTS 200 series cam . I know that he has been making some minor changes to his line up of cams .. I saw the new 150 sheet recently very nice in a 107  . You might want to drop him an email .. 

Andrews has a few new cams coming out as well My testing I thought was going to be done but more  new cams showed up..  I am testing one in a 120 with 10.8  is  more of a tq cam than HP . But be happy to post results for you if you want .