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Thread: New 3.3 Erratic

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  1. #1
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    New 3.3 Erratic

    i put a new 3.3 in my revo last weekend, did the break in and ran a few tanks through it before i stripped spur gear. i replaced it, and then the clutch shoe spring snapped, i replace it. now the 3.3 is kind of erratic. i got the idle to an acceptable level. it's not totally perfect, but its a lot better than what it was. but when i run the truck, it will take off good sometimes, other times not. it doesn't always hit 2nd gear. i've leaned it out some, so it goes into 2nd more often now than before. i though it was too lean, but my temps are 190, which is low for me (i am for the 230 range), so i lean it out then it bogs.

    also after a wot and i start braking, it gives off a high pitched which and the rpm's go up and down until it comes to a complete stop. i've messed with the cb-spur mesh and i think it's ok. i've tighted and loosened the slipper clutch nut and i've gotten better running results with it tighter, but i still get the crazy rpm stuff when slowing down. it also creeps at idle after it's been running. when i start it, it wil sit and idle, but while running it tries to roll forward. any ideas???
    Revo 3.3

  2. #2
    RC Turnbuckle Jr. CarGuy7a's Avatar
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    When the RPM's hang after you let off the throttle your HSN and LSN are probably too lean. When the LSN is too lean it will raise the idle speed and could be giving you the creeping forward problem. What are the outside temps like you are running it in? Sometimes you can have it tuned perfect but if the outside temps are cold, the motor temps will be cold and you don't ever want to lean it out to raise the motor temps up but rather wrap the head with a sock or tin foil to raise temps to an acceptable level.

    I also wouldn't do many WOT passes if temps are only 190F. That's a good way to split the rod. I let mine idle up to at least 220ish before I even move the truck.

  3. #3
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    normally when i warm it up, i just run it around my yard or drive way for a few minutes. i guess it's my lsn that's probably lean. i have the hsn at 4 turns out. it's mid 70's here in texas
    Revo 3.3

  4. #4
    RC Turnbuckle Jr. CarGuy7a's Avatar
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    Yeah when you let off the throttle, the RPM should just about snap right back to idle.

  5. #5
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    i did some reading and instead of trying to make the lsn flush, i saw on the traxxas site that it can be flush, or about 1.5 - 1.75 turns out. so i did that, started the truck and just let it idle for a little while. it seems better, the wheels are turning like they were, but i didnt have time on my lunch break to run it. hopefully i will later. it started easy i guess. just a few pulls.
    Revo 3.3

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