Fw: Aeroslave pipe set-up <clipped>

[patterndude at comcast.net]

Thanks for the update. 20% nitro gets you into a dicey situation.  It can help as you suggested, but can also lead to a detonation crackle.  I have extra head shims that can be used to decrease compression for this case, but we are venturing outside the standard setup.  If you try this, just buy one gallon for experimentation.  You also might try another 1/8" turn on the pump.
--Lance


--
District 6 AVP 
www.aeroslave.com

-------------- Original message -------------- 

Just an update:

The pipe length is at 32.5" ( exhaust to end of pipe ) , I have come out with the pump 1/4 turn and switched to the fine needle - huge improvement. Still a little rich in the middle, but good down lines and flat power from midrange to top end. I may consider shortening the pipe 1/2 inch and/or switching to 20% to improve the midrange and add a little power at the top.

Colin Chariandy.

colin chariandy <cchariandy at yahoo.ca> wrote:
Lance

I'm in Toronto, Canada...maybe 100' above sea level. This should not be a factor.

The angled baffle is at 12.75" and the main at 15.25" from the pipe inlet. If this is OK, I will try coming out with the pump in 1/4 turn increments and keep you updated. I'm also going to switch to the "fine" needle valve.

Colin.

Lance Van Nostrand <patterndude at comcast.net> wrote:

Colin,
Well we're making progress, but your data does not match most OS140RXs.  A duel plug head will help a bit, but that's a step to refine a good setup, not make a good one from a touchy setup.  The touchiness you describe and the rich midrange on such a long pipe gives this problem away.

What elevation do you fly at?  You may be at a veyr high altitude, which is influencing the tuning and will require less pump pressure.  The other scenario is that your engine just came from the factory with a bit too much pump pressure.  Either case, the solution is the same.  You have too much pump pressure.

Depending on how meticulous you want to be there's the 80/20 rule or the 99% rule.  for 80/20, unscrew the pump screw 3/4 turn and richen the idle a little bit.  This will be close and you should find the pipe setting much less touchy. use the techniques earlier to find the right length.  Since length is directly related to port timing, the ideal length should not change theoretically, but I think you are longer than ideal because your bigger problem is too much pump and you are way off the ideal pipe length just to lean the midrange.  If you want to confirm that the baffles were put in correctly, insert a small dowel down the neck past the first angle to the main baffle.  Let me know the distance.  Also, the distance the front of the angle baffle.  The other setup option is to set it to 31" and reduce the pump pressure until you get a good midrange, then test fly and listen to see if it sags on uplines.  If so, increase pump until it runs consistent.  thi smight require a small access hole in your firewall to simplify adjustments.
--Lance


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