Need some help with a TRX 2.5

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cbaker65

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Update: the pin that the clutch shoes ride on walked out and was wedged up against the bell. I peened the hole so it was a tight fit again. Then I started running it. Runs great with about half a tank now, pretty dialed. But now, the only issue seems to be the idle end. nailing the throttle it bogs until it hits the highspeed side. It seems tweaking the low speed is okay until the level drops a little more, then you richen it again and its fine. There is a really fine line between good and stalling. I have the idle gap set to .8mm, any lower it doesn't like it and any higher it idles too high. I'm guessing I need to get the bottom end a little more adjusted but I ran out of nitro. Tomorrow is another day but any tips are appreciated. (Yes I am going to re-read everything above again.) :cheers:

You are probably almost there if the engine is staying running!
Usually ,you are suppose to preset your idle gap to .5mm an adjust your Lsn to match it to idle an not
match the idle gap to the existing Lsn mixter!..👍
 

littleblazer

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You are probably almost there if the engine is staying running!
Usually ,you are suppose to preset your idle gap to .5mm an adjust your Lsn to match it to idle an not
match the idle gap to the existing Lsn mixter!..👍
Fair enough. The book I have says .7-1mm per traxxas but I can try lower. Time to break out the feelers again. :thumbs-up:
 

cbaker65

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Fair enough. The book I have says .7-1mm per traxxas but I can try lower. Time to break out the feelers again. :thumbs-up:

There is two things that can cause the bogging on take off ,either a lean bog or a too of a rich
setting on the Lsn ,you just need to figure it out ,if your idle gap is set at .8mm ,you can close
it a little more ,an lean the Lsn in a little more to raise the idle ,as this will cure the rich bog on
take off!..👍
But it does sound like you are close for your engine to be happy!..👍😎
 

littleblazer

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There is two things that can cause the bogging on take off ,either a lean bog or a too of a rich
setting on the Lsn ,you just need to figure it out ,if your idle gap is set at .8mm ,you can close
it a little more ,an lean the Lsn in a little more to raise the idle ,as this will cure the rich bog on
take off!..👍
But it does sound like you are close for your engine to be happy!..👍😎
I used a micrometer on a paper clip and it measured almost exactly .8mm so that was my feeler for that setting. I have the proper wire feelers its just the car is blocking that tool box right now. But it seems lean, no smoke until it comes into the HS side. then takes right off. Richening it seems to make it better but again... I ran out of fuel just as I was starting to hone it in.
 

cbaker65

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I used a micrometer on a paper clip and it measured almost exactly .8mm so that was my feeler for that setting. I have the proper wire feelers its just the car is blocking that tool box right now. But it seems lean, no smoke until it comes into the HS side. then takes right off. Richening it seems to make it better but again... I ran out of fuel just as I was starting to hone it in.

For this reason ,is why it is hard to give info out on tuning ,tuning requires hands on ,sight ,sound plays a
major role in tuning ,but yea if it is the lean bog ,then you are correct as it is a two way street on the tuning ,
you just have to figure out which one it is an monitor how many turns you made!..👍😎
 

littleblazer

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For this reason ,is why it is hard to give info out on tuning ,tuning requires hands on ,sight ,sound plays a
major role in tuning ,but yea if it is the lean bog ,then you are correct as it is a two way street on the tuning ,
you just have to figure out which one it is an monitor how many turns you made!..👍😎
YEah. Luckily it was only about a quarter or so from where it was originally overall so I think it'll be okay. Should have it dialed by the end of the week.
 

cbaker65

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YEah. Luckily it was only about a quarter or so from where it was originally overall so I think it'll be okay. Should have it dialed by the end of the week.

You can also do a pinch test after a full WOT run ,if the engine dies with in 2 seconds ,then its too lean ,if
it dies with in about 4 seconds ,then you are spot on ,on the Lsn tune ,should be pinched just right at the
carb nipple!
Pinch test is not a tuning guide ,it only let's you know how close you need to be!..👍😎
 

littleblazer

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You can also do a pinch test after a full WOT run ,if the engine dies with in 2 seconds ,then its too lean ,if
it dies with in about 4 seconds ,then you are spot on ,on the Lsn tune ,should be pinched just right at the
carb nipple!
Pinch test is not a tuning guide ,it only let's you know how close you need to be!..👍😎
That's actually how I got it close, around the 3 second mark it idles up then immediately cuts out. I do have to pinch about a quarter inch past the inlet though. No room to grab it closer.
 

littleblazer

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So today, my fuel was dropped off so I messed around a little. Truck runs just fine on the street... little bog off idle but otherwise good. But when on the grass... you nail it it just sputters until it grabs the high speed side then takes off. I've tried fatter on the bottom and leaner on the bottom with no success. Wide open is right where it should be... thin stream of smoke and maybe an eighth turn more in it starts cutting out. So I backed it off a little like a quarter and left it a little fat on top. I'm wondering if there is a carb issue or is it possible the engine is actually hurt/weak...
 

cbaker65

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So today, my fuel was dropped off so I messed around a little. Truck runs just fine on the street... little bog off idle but otherwise good. But when on the grass... you nail it it just sputters until it grabs the high speed side then takes off. I've tried fatter on the bottom and leaner on the bottom with no success. Wide open is right where it should be... thin stream of smoke and maybe an eighth turn more in it starts cutting out. So I backed it off a little like a quarter and left it a little fat on top. I'm wondering if there is a carb issue or is it possible the engine is actually hurt/weak...

How old or long has the engine been sitting?
Possible that the o-rings are worn ,try screwing the lsn all the way in ,an
counting the turns while you do ,then pull it out an rub some sticky grease
on the o-rings an put it back in then run the truck!

I will do a vid on a carb!..😎👍
 

littleblazer

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How old or long has the engine been sitting?
Possible that the o-rings are worn ,try screwing the lsn all the way in ,an
counting the turns while you do ,then pull it out an rub some sticky grease
on the o-rings an put it back in then run the truck!

I will do a vid on a carb!..😎👍
I have a pretty good o-ring conditioner, I'll try that tomorrow... But the carb was pulled from the engine before installing it and boxed, so literally new in box from traxxas. But it is still entirely possible they've "set". You'd think with all the double pumpers, quadrajets and efi systems I've messed with this would be cake... But no. lol.
 

cbaker65

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I have a pretty good o-ring conditioner, I'll try that tomorrow... But the carb was pulled from the engine before installing it and boxed, so literally new in box from traxxas. But it is still entirely possible they've "set". You'd think with all the double pumpers, quadrajets and efi systems I've messed with this would be cake... But no. lol.

My friend had bought a new Reds engine that had damaged & pinched carb o-rings ,it took him a long
time to figure it out ,he didn't think the factory would screw them up!..🤣😂
 

littleblazer

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My friend had bought a new Reds engine that had damaged & pinched carb o-rings ,it took him a long
time to figure it out ,he didn't think the factory would screw them up!..🤣😂
True. But this will also be the third carb on this engine... IDK what is what anymore lol, I'm trying o swing my schedule so I can do an overnight tomorrow-thursday and then go on days sunday so I am for sure not firing on all 8 at the moment.
 

cbaker65

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True. But this will also be the third carb on this engine... IDK what is what anymore lol, I'm trying o swing my schedule so I can do an overnight tomorrow-thursday and then go on days sunday so I am for sure not firing on all 8 at the moment.

I don't run Traxxas ,so i don't know what their little issues are like people have with them!
I've only heard about them ,some people say they don't have problems & some people
say its pure hell!..🤷‍♂️😂
 

littleblazer

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I don't run Traxxas ,so i don't know what their little issues are like people have with them!
I've only heard about them ,some people say they don't have problems & some people
say its pure hell!..🤷‍♂️😂
Can't complain about the pro .15... the 2.5/3.3 carb however... ugh. :hehe:
 

cbaker65

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Can't complain about the pro .15... the 2.5/3.3 carb however... ugh. :hehe:

Yea my friends old 4-Tec .15 never had tuning issues ,however ,i did tune a 2.5 & a 3.3 for people before
off a break-in before with out issues ,but really only neede a slight turn of the Hsn to wake them up ,
that was about 10 years ago though!..😎
 

littleblazer

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Just out of curiosity, would the slipper clutch being too tight also cause this?
 

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