Tuning Picco p3 help!

[khughes18]

Hi guys,

I know there is a sticky with lots of info but I just cant seem to get it right and was wondering if any of you can perhaps come up with a solution to my problem.

I have just run in my picco p3 but as before am having an absolute nightmare with getting to grips with this tuning lark.

I've tried everything, read the stickys and watched the hpi and traxxas vids but am still obviously missing something.

I just cant seem to work out which part is out of tune, the engine idles nice with the lsn more or less at the out of the box setting, as soon as I fractionally lean it, the engine starts making that high reving spluttery sound, as if its too lean with the slightest of turns in. is it normal that the out of the box setting should be at this point?

at idle, it smokes a little and spits some fuel, which i am led to believe is a good thing. when I rev it, it bogs then revs, as if too rich!

its the same story with the hsn, which I gave attention first, at the moment its at 3 turns out(out of box), produces a fair amount of smoke at high end revs but as soon as you let off the throttle, the revs hang high for a few seconds.as soon as I lean it, it cuts out after a few secs at full throttle. It also seems to rev up in two stages, as if its bogging down or something.

I just wish it was as straight forward as the vids make it look. does anyone know the base settings for the p3? it doesn't say in the manual, only says that their carbs are pre-adjusted and only require fine tuning.

any help or advice would be appreciated, thanks guys.

[fraggs]

try reading this and see if it makes things any easier (I cannot remember where I got it from but thanks to whoever wrote it) hope it helps, it seems to make more sense to me than other tuning guides (just the way my head works I guess)

There are two guides but on the same idea of how to tune , see what you think

TUNING GUIDE 1

To make any of these adjustments the engine has to be at normal running temps (or as close as possible) and have the idle set at standard, usually a 1mm gap for the carb slide opening.

High Speed Needle (HSN).

Make a wide open throttle pass a couple times and listen what the engine does when you let off the throttle. As long as the rpm drops straight to idle, the HSN is either good or on the rich side. At this point you can lean the HSN in 1/12 increments until the idle seems to hang a little after a wide open throttle pass, when it starts to idle high after a pass it is on the lean side of a perfect tune, turn the HSN out 1/12 of a turn at a time after a wide open throttle pass until the engine drops straight to idle after a pass. Now your HSN is set.

To explain what is happening is simple. If your HSN is too lean after a wide open throttle pass when you let off the throttle the engine is still lean causing the idle to hang and idle high until the LSN has a chance to take over and meter the right amount of fuel to bring the idle down to normal running speed (given the LSN is set correctly)

If the opposite happens after a wide open throttle pass when you let off the throttle,

I.e. it drops to a good idle straight away and then the idle rises back up too high; it is a sign that the LSN is too lean. If it comes off wide open throttle with a good tune and will drop rpm smoothly the HSN is metering the fuel properly but once it hits idle the LSN being too lean will quickly take over causing the rpm to go back up.

Low Speed Needle (LSN).

Most of this is explained above but there are a few tips you can use to make sure the LSN is adjusted perfectly. We all know that you don't tune for temps but a temp gun is very handy for this part. After some wide open throttle passes with the engine good and warm, bring it in and let it sit for about 10 seconds, at this point take your temp gauge and hold it steady on the head, what you want to see is the temp dropping a degree every 4-5 seconds. You want the temp to drop very slightly at idle because when your off the throttle the engine should be cooling down, if not the temperatures will keep climbing higher and higher and with on and off throttle running will cause high temperature problems.

TUNING GUIDE 2

To get it tuned, first get the engine fully warmed up!

Never tune a cold engine.

Start from factory settings on all needles.

(Maybe 1/8 to 1/4 in on the HSN from factory.)

Be sure to set the idle gap as well as needles to factory settings before retuning from scratch.

Get your HSN set first.

Keep leaning the HSN 1/8 turn in at a time and watch the performance increase.

Making a couple top speed passes each time to let the engine get used to the new setting.

When you see a decrease in performance turn the HSN back out 1/8 to 1/4 turn to richen it back into the safe zone. Keep an eye on temps as well.

Good top speed and good trail of smoke at all speeds is what you want.

Then set the LSN.

You can do the pinch or punch test, or both.

PUNCH TEST-

Once you have the HSN set, engine warmed up.

Make a couple top speed passes and bring it in and let idle for 10- 15 seconds.

Then give it 3/4 to full throttle.

If is slow to take off and smokes a lot you are too rich and need to start leaning the LSN.

If it takes off fast, rev's and dies, It is too lean and you need to richen the LSN.

If it smokes and is slow taking off, start turning the LSN in 1/12 to 1/8 turn and again make a few passes to get it used to the new setting in between adjustments.

PINCH TEST-

Make a couple top speed passes, bring it in and pinch off the fuel line near the carb.

Start counting 1...2...3...

It should run for about 3 seconds before it revs and dies.

If it runs longer you need to lean the LSN.

If less than 3 seconds you need to richen the LSN.

Once you have good acceleration and still have smoke at all speeds you are done.

You may need to reset the idle on the carb once you are done tuning.

Weather always plays into your tuning and you will need to adjust the HSN for day to day conditions.

I.E. - colder weather requires a more rich settings and vice versa.

Edited April 30, 2010 by fraggs

[khughes18]

cheers fraggs, all i need now is the factory settings to start again, they dont give them in the manual.

[fraggs]

post 17 in the factory needle settings at top of nitro section should help you with them mate (on page 2 )

[khughes18]

Fraggs, I've cracked it! spent some time on it the last two days using the advice u gave me and i've cracked it, runs awesome without a hiccup or stall. Nice one mate!

[fraggs]

Glad I could help mate and glad you finally got it sorted, you will be an expert tuner now then won't you ?

[Bennettironman]

Hi 

 

interesting post enjoyed the read,I am running at Picco and have got her running ok my question is the mid range factory setting I cannot find any information anywhere does anyone have the setting or where to find it 

thanks in advance 

[Bennettironman]

Hi brilliant read did you find out what the factory idle gap should be ?

 

I can’t find it anywhere 

[froggy8]

1 hour ago, Bennettironman said:

Hi brilliant read did you find out what the factory idle gap should be ?

 

I can’t find it anywhere 

the mid range needle should never be touched, if uyou have moved it by accident then move it back to flush.

 

the idle gap should be between 1-2mm.