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Old 04-07-2009, 05:18 AM   #1
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Questions?? engine lag on rev down

Hi I just posted this question on the losi thread, but maybe y'all can help me:

I just finished building my Losi 8ight 1.0, installed a Novarossi .21, and started the break-in.

My problem is that after I release the throttle trigger the engine starts to rev down in a quick & normal linear manner (just like any other nitro engine I've had), but then it holds the revs for a few seconds (when it reaches 15-20% left to idle speed) and then finally goes down to rest at idle speed. The carb is fully closed by the servo, no binding. So, I believe its something with the mixtures, or the clutch, or an air leak maybe. Why aren't the revs going down all the way to idle speed in a quick linear manner??

Other than that, the engine seems normal. I was running the stock setup of silver/gold springs but the car needed to be revved really high to start moving, so now I have the silver/carbon shoes & gold/green spring setup (haven't tried it yet to see if it engages sooner). About half a tank of heat cycling (about 9 mins runtime). Carb high needle at rich (3.5 turns), haven't touched the low needle yet.

Help please

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Old 04-07-2009, 06:33 AM   #2
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you say you have 9 minutes of run time on this motor. Is that all the run time you have done from brand new? If so then your going to need to get about a half a gallon through this motor before you will start to be able to try and make good power with this motor. You said you had to really get on the gas to make the car move so I'm ussuming that the motor is still really rich, so there for a wouldn't worry about your clutch setup till the motor is broke in. Will the car sit and idle for a really long time, or does it start to load up and die after about 5-10 seconds? If it will sit there and idle all day long and your getting the slight verence in rpm then you might be slightly lean on the ls needle. But I have also seen an overly rich hs needle cause this to so if there is only about 9 minutes on this motor then you need to run some more fuel through it nice and easy and just keep an eye on your temps and make sure your getting the motor up to at least 190-200 if the temps won't run that hot wrap the head in aluminum foil so you can run the motor rich but still get it into the operating temps. Run about 5 more tanks through it will letting it cool down each time with piston at bdc. After you get that done then you can start to slightly lean it out and try to make Tempe without the aluminum foil. Run a few more tanks smooth and easy then start to try anfld get a good tune. Not sure if that answered your question but if it's a brand new motor then they do tend to act funny alittle till you get around 1/2-1 gallon through them.
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Old 04-07-2009, 08:13 AM   #3
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Kinda sounds like a high idle speed and rich LSN. Good for break-in. You could lower the idle speed if you think you can still keep the engine running at a lower idle.
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Old 04-09-2009, 12:35 AM   #4
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thanks guys, i'll fiddle with the settings to see what's up.
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