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picco exhaust problems

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A

aligc

RCTalk Racer
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Birmingham, UK
RC Driving Style
  1. Bashing
after listening to people on here who told me that my dual rear exit exhaust will do nothing but ruin my engine by making it lean, i took it off and replaced it with the original stock one. after a few runs of it being extremely rich, i just couldnt get the mixture right, after a bit of searching on tinternet i found out the stock exhaust is restricting it! just reducing pressure and chucking way too much fuel through the carb!
after cutting my header off the rear exhaust for another truck i couldnt put it back on my t maxx so i raided my dads spare parts, luckily he had a savage 25 exhaust, so I've fitted that and its made one hell of a difference!
just need a little more help though, when I'm accelerating it will get near top revs and the start jurking, like there is a loss of fuel or something but then pick up again, like a car kangarooing in a way, does anyone know the cause of this??

will upload some pics of my t maxx in the next couple of days.
 
Sounds like it is loosing back pressure on the top end to me. I could be wrong here, but I am willing to bet a few others just might agree.
 
i dont understand why it only does it now and agian, it wont do it all the time i can get a good run out of it but it sometimes goes like that and shortly aftrewards will cut out!
 
My only guess is that something is loose. Jar it one way it is fine. Jar it the other way not so much? Again, it is all speculation on my part. I could be wrong.
 
About jarring it? Well, since it only does it sometimes something could be loose. All is well till you hit a bump just right then it starts do mess up. Make sense?
 
the only thing that is loose is the exhaust, but its not loose as such its held on by cable ties.
 
More than likely your a bit lean on the HSN. Try richening it up a bit.

What temps are you running at after the "jerking" happens?

The savage pipe may not be restrictive enough. HPI pipes are breath easy pipes that not all engines work well with. I know many engines I've put one on ran ok, but ran a bit hot with weird tuning issues. Only a few engines ran "well" with the HPI polished pipe and the HPI ribbed. OS21RG ran well with it as did a Losi M26SS. LRP28 and XTM24.7 didn't. They liked a bit more restrictive pipe.
 
RC Addict said:
That was my feeling--loosing back pressure on the top end.
Click to expand...

Yeah, I figured as much.

If you try to richen it to make it better, it may make it doggy on the low-mid, but run great at WOT. You can try to tune it as best as you can to keep from running lean at WOT but still get decent performance on the low end. A new pipe better suited for your engine will make your tuning window much more forgiving though.
 
ok does anybody have any tips on a pipe to get for it, or where to get a replacement header for a rear exhaust in the UK, I've got the picco .26 maxx engine.
 
Last edited:
Ofna or Dynamite 086 pipes will work the best for the picco (price wise), they are pretty much the same pipe and dyno results show that they are a very good match to the picco .21-.28
 

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