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Old 10-14-2008, 02:50 PM   #1
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Ok...so I am really an electric guy that is getting deeper and deeper into Nitro. Still haven't quite figured out the voodoo around properly tuning a .21 buggy motor. A buddy gave me a JP Mods Black Case Turbo .21 that still has great pinch after he ran it for a couple gallons. It sat for a while before I put it in. I cleaned it out, flushed, checked for rust, etc. and it all looks good. It fires up no problem on the box, idles ok, low end seems good now, high end is killing me. When I go all in with the trigger, it accelerates fine, gets up to about 3/4 speed, then drops rpm and I have to blip the throttle. Running a new RB turbo plug, Byron Gen 2 30%, slowed down the throttle servo speed. Not sure why this would happen. Currently, the high needle is at just below 2 turns up from full lean. Any suggestions? I pulled the fuel filter to see if that was the issue and it didnt change anything. Temps stay cool, under 220 at all times. Help?
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Old 10-14-2008, 02:59 PM   #2
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Without actually seeing it run and hearing it, I would guess that it's running lean on the top...
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Old 10-14-2008, 03:00 PM   #3
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What happens when you blip the throttle? Does it eventually get up to full rev and speed? It sounds to me like you may be too lean on top and you're getting a lean bog when it winds up. Have you tried richening the top to see what happens?
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Old 10-14-2008, 03:15 PM   #4
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Quote:
Originally Posted by t0adman View Post
What happens when you blip the throttle? Does it eventually get up to full rev and speed? It sounds to me like you may be too lean on top and you're getting a lean bog when it winds up. Have you tried richening the top to see what happens?
Yes thats exactly what happens. I'll start richening up an hour at a time to see what happens.
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Old 10-14-2008, 03:54 PM   #5
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overlean top end and check the head shims , you should add an extra .10 shim to raise the deck clearance with these jp mod black case engines . b5n or b8n ? engine should be fast but have seen a few duds .
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