JTS max 22 valve

[thesandman]

My gun is leaking so I did a tear down and found the valve exit is a restriction.  Should I open it up to the TP Dia of .217?  Then the restriction would be at bolt probe, barrel intersect. 

[thesandman]

The TP is larger than the valve also.  I would need to go from .237 to .247 on valve bore to match TP.  Is anyone making aftermarket parts yet?  Thanks

[Motorhead]

Was doing R&D a couple years ago upon receiving a couple Pre-production demo guns.
In .22 caliber looking back on near 15 years of PCP tuning and modification, the ideal transfer size for an @ 30-35 fpe "Regulated" .22 caliber PCP is @ .160" to .170"
My own .22 MAX actually got the transfer path "REDUCED" to stated specification.  It made the same power with a slightly lower reg set point yielding more shots per fill.

The large .217 transfer path is fine for a .25 cal, tad much for a .22 IMO.

[thesandman]

Thanks Scott.  So my .157 valve exit is sufficient? I was thinking open valve to near .250 and exit to .2++ and adjusting hammer for power.  Should i reduce TP instead?  But I don't know what that would do.   I read your balanced valve article on max. Thanks

[Motorhead]

Valve throat exit at .157" is enough ... But it exiting into a passageway going to barrel at .217" is a serious mismatch and lousy for efficiency.
If unable to fabricate a choke tube taking transfer path down a bit ? .... matching up the valves exit to existing transfer size will gain some power if nothing else !!!

FWIW ... the .25 cal max has this exit size of valve body already at transfer diameter. 

[thesandman]

Thanks Scott;  Not sure I will do anything except fix leaks for now.  I really don't need more power.  Has anyone done any testing to find best place for restrictions.  I would think at barrel but I'm guessing.  Also the TP seems long on these.  Thanks again

[thesandman]

As to the TP length I really don't have much of any experience so yes it's longer than the guns I've had but not longer than needed.

[Motorhead]

The length is fine, as it is shorter than quite a few other PCP's that are high performers.
Issue with excessive size is it takes more discharge volume in keeping the pressure within transfer path and what actually launches pellet to be HIGHER than what would be required with a smaller path of less volume.