is this a problem???

[redck1979]

yes it's another tuning question...haven't found anything anywhere or in the manual that describes whats happening w/my engine...i have a jato 3.3 of course...it has about 3/4 of a gallon thru it...and yes has been broken in correctly as per traxxas break-in-procedure...it is set up pretty much stock other than the stinger on the blue resonator being drilled out to 13/64"...i have reset all needles to factory about twice now...the leanest i have had it is 3 1/2 turns out...runs mint not sluggish or anything...plenty of blue smoke when running...after doing a wot pass the engine will race (rpms increase almost like it's leaning out) for a few seconds after releasing the throttle...any info/thoughts would be greatly appreciated...thanks

[jaaato]

yes my engine is the same way, it seems to lean out when it is warmed up, other than that when its cold, it seems kinda sluggish to me, i dont lean it out because i know that it is going to "lean itself out", or atleast thats what it seems like....

[superfly13_69]

Sounds like the LSN is 1/8 turn too lean, probably being affected by the drilled stinger. Stock stinger should keep constant pressure on the fuel intake, so without that extra little pressure it probably runs a bit lean. 1/8 out should keep the rpms even after a WOT.

You can always do the pinch test to make sure that's what it is, before you dork with the needles. After a WOT, come to a stop and pinch the intake tubing. It should increase RPMs for about 3secs, then die in a total about 5secs. Too soon, and the LSN is lean. Too long and the LSN is rich.

[imhungry114]

Do you mean when it runs out of fuel? Because my 2.5 revs high right before it runs out of fuel.

[superfly13_69]

Do you mean when it runs out of fuel? Because my 2.5 revs high right before it runs out of fuel.

That's normal. Running out of fuel is the same as leaning out, then dies.

[redck1979]

Do you mean when it runs out of fuel? Because my 2.5 revs high right before it runs out of fuel.

no what i meant is after i let go of the throttle after a wot pass the engine rpm increases quite a bit for a few seconds after releasing the throttle...after a few seconds it goes back to normal...and thats w/a full tank of gas and does the same at half tanks...other than that runs mint and idles nicely...when i do pinch tests after high speed runs it varies sometimes between 2-3 sec...

[imhungry114]

I think I know what you mean. Im pretty sure it happens when the transmission shifts down into first. This is hard to put into words but I guess I can compare it like this: when you change gears on your bike(if your bike can change gears) to a lower gear the is less resistance on your legs so you pedal faster. Its the same for your engine. Bottom line is, its completely fine.

[redck1979]

cool...just never really noticed it doing that before...makes sense tho...like engine braking in a car...something stupid i should have thought of being a former mechanic...just wanted to make sure it was ok for it to do...thanks for the incite guys

[imhungry114]

No problem thats why were here.

[J.A.T.O.3.3]

superfly13 69 is right , I bet your LSN is a little lean ....

[imhungry114]

Its not the LSN its the transmission downshifting. The LSN wouldnt have anything to do with the engine reving higher when the truck downshifts.

[J.A.T.O.3.3]

Its not the LSN its the transmission downshifting. The LSN wouldnt have anything to do with the engine reving higher when the truck downshifts.

When you let off the throttle the motor should fall right down to idle , its not connected to the trans because the motor is not spinning fast enough to engage the clutch .

Richen the LSN 1/8 and see if it goes away ....