35mm pwk airstriker vs 34mm pj

[Ryder25]

I've got a 4mil 72mm Twister motor with hjr agressive dune port, 170psi compression, CPI BB oof pipes, stock electronics, VF3's.

 

I haven't ever gotten it jetted right with my 35mm airstrikers (always rich).  I'm down to a 42 pilot and 150 mains and it is still rich.  I've taken apart the carbs and completely cleaned them twice (never anything clogged that I could see).  Idle is okay, fuel screw 1.5 turn out.

 

When I threw my buddy's 34mm PJ's on, I had 52 pilots and 165 mains (can't remember needle off the top of my head but it is at bottom clip) and that is perfect, fuel screw 2 turns out.  This is why I'm unsure of how low to go on the airstrikers (started at 170 and went down to 150).

 

Will the airstrikers really be that much lower on mains/pilots, or do you think I have a problem with the carbs?  I looked this up and saw some people have smaller mains with airstrikers, but will they really be in the 130's-140's when a PJ is 165?

 

temp is 20 degrees, elevation 800ft.

[Sandking]

The 42 pilot is way too small to begin with. Put a 50-52 in it. The 150 main should be 155-160

 

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[Ryder25]

yeah I've been checking plugs, monitoring temps, and looking at piston wash alot lately.  I also hate the PJ design, but I was too nervous to run anything smaller than a 150 main so I swapped carbs to see and all my buddy had were the PJ's that he runs on his 421 (with 175 mains).

 

thanks for the input.  I'll swap carbs again and try 140's for mains next time.

[Ryder25]

yeah I won't drop to a 140 right away.  I was saying I will jet into the 140's.

 

I think my buddy has more of a drag port, and 190psi compression.  CPI sb inframe pipes too.  That's why I stole his carbs to check jetting on my motor because of the differences.  He also put his motor in my yfz hybrid frame, so he used the CPI bb OOF pipes and was at a 178 main jet with the 34mm pj's (also might have been a 10-20 degree difference in temp), so we figured the pipes weren't making that big of a difference in jetting, it must be mostly from porting and engine size.

 

I haven't tried the 35mm airstrikers on his motor yet, probably the next thing I'll do if I still can't get it working correctly on mine.

[Ryder25]

Ended up today with 165 mains (48 pilots, CG L needle bottom clip, 1.25 turns out air screw) on 34mm PJ's

145 mains (42 pilots, DE K needle 2nd clip from top, 1.5 turns out air screw) on 35mm PWK Airstrikers.

 

Changed nothing else except for the carbs on the motor listed above.  Used an A/F meter to jet.

[trickedcarbine]

Sounds about right to me. Pj's are easy to tune once you come to grips with how much attention they need. Hope you get it dialed in. That is a bitchin machine. Wish I could afford to give it a new home right now.

[Coupelx]

i <3 my vortex proof 34pjs

[possum]

I have never had a problem jetting pjs. matter of fact i have had pwks give me more problems before on certain motors. they both have a sweet spot.