Jetting with high-comp pistons?

[mik_str]

A question for those of you running high-compression pistons: did you have to make any jetting changes related specifically to the installation of the new pistons? I realize that changing exhaust and cams,... will require a change in jetting but was wondering if keeping those airflow elements unchanged and simply installing JE pistons would require one to alter the jetting?

In my upcoming rebuild (which will include adding new JE pistons), I will be leaving the exhaust and other such things as they are presently and was wondering if I have to plan for possible jetting changes (am trying to assemble all necessary parts ahead of time so I don`t fall into a "backorder blackhole" once I get the process started).

thanks in advance

[benny hedges]

i would suggest a before and after dyno run to see where you are at present with fuelling, and get it set up properly after.
i just had alarming results after dynoing mine - what i thought was a boost at 6k ish was just whn it came out of a horrendous rich patch, now that is mostly gone the bike feels so much smoother to ride, but the kick in the butt power band is gone.
took it for a good ride last night and the way it gets to 140+ is alarming and it even sounds like it's working harder.

the cams and pistons will probably change the vacuum of the engine which will definately upset the carburation.
times like this you wish you had fi!

same question - i need to know the valve to piston clearance with your setup and the new pistons as i'm just a bit concerned about fitting the same 11.5 pistons to mine if i have to start machining the crowns to get the clearance right with +2mm lift on the cams

[tony.mon]

Carburation- dyno it after and all will be well.
I'll have mine done shortly and will post what needed doing.

Re clearances, if you reassemble the engine with an old head gasket but no valve springs, just the valves, you can check the clearances with a dial gauge.
Just set the piston to TDC, fit the buckets back on and see if you can place the cam on with the lobe facing downwards- don't worry about the chain being fitted.
If you can, then using a magnet pull the bucket up so that it is in contact with the cam gives you the no-shim clearance, then calculate what shims you need, it's the difference in the two readings less the clearance.

Easy, innit?