Topic: f2, 836cc wiseco pistons, cx-7, static compression 1:11.5, standard gas

[MessnerMoto]

After all the decking of head and cylinders I have something like 1:11.5 static compression. Is this to much for standard gas?
I am asking because cx-7 has long duration and it needs bigger static compression.

I can add bigger base gasket...

[PeWe]

Thicker head gasket as Plan B? MLS can be reused.
DP315 has long duration too and much nicer cam for street than CX-7, at least in my engine that has used both. DP315 has nice smooth power all the way,  no suddden power kick as CX-7 get around 7000 rpm. CX-7 will probably give more top power

DP315
  Lift: 9,33/9,33 mm @ 0 lash            35/62  68/33   Dur 277/281  @ 0.040"lift   LC 103,5/107,5   overlap 68
  Lift: 8,95/9 mm    @ 0,3mm running lash  28,5/56,5   60/26  Dur 265/266  @0.040"lift   LC 104/107   overlap 54,5

DP315 cam numbers are more understandable for me at recommended lash of 0.3mm

CX-7 I bought 2013. Maybe not best timing. IN might open earlier and EX follow
CX-7  Lift 0.393 (9.98mm)/0.365 (9.28mm) @ 0lash    Duration @0.04" (1mm)   IN: 28.5/60  268.5    EX: 57.5/27.5  265    Lobe center 105,75/105  Overlap 56

CX-7 lash was later set to IN 0.1/ EX 0.15mm
CR has been around 10:1, maybe 10.5:1   Shell V-power fuel 
CX-7 used  with 836 that had around 185-190 PSI  in a later compression test with another cam with less duration and lift. Action Fours SS-1 dur 254/256* Lift 9.18mm.

Some data to process! 
Other will hopefully chime in with their experiences and answer your direct question about your compression and std gas

[MessnerMoto]

Thicker head gasket as Plan B? MLS can be reused.
DP315 has long duration too and much nicer cam for street than CX-7, at least in my engine that has used both. DP315 has nice smooth power all the way,  no suddden power kick as CX-7 get around 7000 rpm. CX-7 will probably give more top power

  Lift: 9,33/9,33 mm @ 0 lash            35/62  68/33   Dur 277/281  @ 0.040"lift   LC 103,5/107,5   overlap 68
  Lift: 8,95/9 mm    @ 0,3mm running lash  28,5/56,5   60/26  Dur 265/266  @0.040"lift   LC 104/107   overlap 54,5

DP315 cam numbers are more understandable for me at recommended lash of 0.3mm

My timing with the CX-7 I bought 2013. Maybe not best timing. IN might open earlier
CX-7  Lift 0.393 (9.98mm)/0.365 (9.28mm) @ 0lash    Duration @0.04" (1mm)   IN: 28.5/60  268.5    EX: 57.5/27.5  265    Lobe center 105,75/105  Overlap 56

CR has been around 10:1, maybe 10.5:1   Shell V-power fuel

Other will hopefully chime in with their experiences. 

I have two base gaskets. And currently engine is dry assembled so I can add second one without no problem

I think for big duration and overlap like on cx-7 I would need to go even higher on static compression  to get everything from that cam and regular gas.
And probably also to build squish area(like turboguzzi recommends) but thats beyond my experience right now. I would need to mill another 1mm from head or cylinders to get 1mm clearance between head and pistons for squish.

[PeWe]

One more thing.. F2 with different valve angle and larger valves than K. Have valve to valve clearance in mind

[MessnerMoto]

I will check with clay. But with wiseco valve pockets for f2 head and more then 2mm of clearance between pistons and head I think I will have no problem

[turboguzzi]

when you get to these CR squish counts a lot.

make a check with plastiline and post the pics....

[Old Scrambler]

What octane?  Regular in the US is 87 or less..............Premium-grade is usually 91. Racing gas sold at stations near stock-car tracks is usually the same as Aviation at 98 to 101 octane, although it is labeled as 110-grade. I would be afraid to use anything less than 91 in your motor. Be sure to listen for detonation.........all it takes is a few seconds and those Wiseco pistons will be ruined. There is a strong tendency for the 2-3 pistons to suffer..........which explains why old-school tuners would go up one size on the 2-3 jets.   

[PeWe]

Can only agree about 2-3 pistons!
I was never really sure why MY 2-3 pistons gave up. Leaking boots was my first thought. Later ideas included the ignition, I might have missed to check 2-3 timing. I have noticed that 2-3 easy will become way too advanced when timing. Last time too, 2-3 could not be adjusted, since point groove was not enough.
Point gap was too much with a dwell of 26-28 degrees (8cyl setting) Changed to 23.2 on both, adj 1-4 and 2-3 could be set correct.

One more thing, last summer my engine was running lean, 2-3 were the leanest. This support Old Scramblers post.
Below the photo of the meltdown for many years ago. Wrist pins and rods were bluish too. I used the highest available Octane then 98 RON, US 93. Today using Shell V-power in my car and CB750. Both are tuned My car got a cheap program upgrade for higher boost.

EU ratings are 95/98, which are equivalent to US ratings of 91/93.
So, EU 95 octane = US 91 octane and EU 98 octane = US 93 octane.

Below 2 with a hole on inlet side, 3 has a heat bump, close to a  hole. It is easy to jet wrong when testing WOT only. When cruising around at normal speeds, only pilot circuit will work that can be way too lean and it will run hot. I need to check my 2-3 plugs today, check after slow cruisng, not WOT I know is OK.

[MessnerMoto]

I was thinking 95 octan eu standard(87us)...
From pewe post I see i should but one more gasket

I will be using Mikuni rs34

[PeWe]

95... I doubt my engine will work with that without retarding the ignition and loose all wild horses. I had pinging on low throttle lift when taking off, I retarded the ignition just a little. No pinging and NO power either. Engine became really dull and slow.
The problem was lean pilot, increased pilot jets. (maybe opened the fuel screws more too)
Adjusted ignition so F was correct at idle and full adv from 2600rpm. All power came back :-)

My old 836, pistons after the RC meltdown ran OK with lower octane as 95. Since my head was made for the old RC, the chambers were opened from 22.5 to 24.4 cc. Action Fours 836 10.5:1. With my head CR 9 something. That engine was really good for touring

My old RC pinged really easy despite the highest octane here (98). I guess we had wrong mind about the ignition back then, driving in 100-120kmh on 5:th gear and twist the throttle it was OK if hear pinging. I had to gear down.
I'm convinced that CR 10 something in a CB750 will not work with 95 octane (US87).  Strange that newer bikes and cars with plenty of HP can

98 might work with 11. Maybe need of octane booster. OR use much larger jets and use E85, I think 104 octane. But alcohol is not that good for engine or rubber

See Ilja's post with a good link about timing which can explain modern engines possibility to run lower octane and still power. He might have some experience or ideas?
http://forums.sohc4.net/index.php/topic,127179.msg1898685.html#msg1898685

The US guys might have more experience of running higher compression on 87 US fuel. Which max CR possible.
- 95 octane and CR 11.5:1 can really work with thicker gasket? 98 and thicker gaskets might be OK.

[MessnerMoto]

I will lower the compression to below 11. Probably around 10.5 with double base gasket. Or I will cut 1mm base gasket from some klingerit I have around me...

I have that optical ignition from cycle x