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2.5R tuning problems

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yz250rider

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cape cod, ma
RC Driving Style
  1. Bashing
After running my t-maxx for about 1/2 a tank it starts to have very suggish acceleration. When i lean the HSN it doesn't change. I have already turned the HSN in from 4 turns out about 1/2 a turn. It runs nice the first time i take it out usually. Whats the maxx lean setting when running 20% nitro?
 
Wow. First off I don't think leaning it out is going to help. IMHO you have an air leak, most likely in the tank or fuel pickup. You are leaning out on warm-up and that is causing the sluggish acceleration.
 
The best way is to remove the engine from the chassis and remove the airfilter plus the muffler ......... take bubbled soap off the top of sudsy soapy water with a brush and stick the bubbles around the carb base,mount screws,needles , fuel inlet and bearings,plug up the carb and exhaust ports,take a clean piece of fuelline and stick it on fuel inlet,stick tube in mouth and compress the engine with air pressure and look for the soap to bubble up.Its almost the same deal as finding one in a bike tire..If it does bubble;-thats the airleak ....No bubbles = no air leaks...On the Traxxas 2.5 and 3.3 with composite carbs the airleaks are usually around the fuel inlet banjo,,,slider or rotator boot and the carb needles.I seal my carb at the banjo fitting and slider boot with med or thick tire glue.I would also remove the carb needles,clean them up with denatured alchohol and replace the o-rings plus replace the carb mount o-rings;-theres 2..After doing a thorough check and repair if necessary try the LSN at 1 3/4 turns out and the HSN at 3 1/2 turns out with an OS8 glowplug......
 
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It could be running sluggish after half a tank due to overheating as well. Might be the low speed needle is too lean, which isnt allowing the engine to cool at idle. I would check for an air leak first, be sure to check the tank as well for any cracks, I do this by plugging the fuel line, hold the fuel filler cap down, and blow into the exhaust pressure tube. With the tank empty this will let you know if theres any leaks. After this I would take both needles back to factory settings and re-tune, adjusting the LSN last.

-AxialLST
 
in the manuel it sais that if it is accelerating sluggish then it is running too rich. ill have to look at it again, thats what it sais about the HSN at least, not sure about the LSN. Whats the factory setting for the LSN again?? the HSN is 4 turns out, correct? Dirtbikes are soooo much less complicated!!!:\
 
The 2.5 is a fussy engine. But it's a lot of fun and rewarding once you get 'er hittin' right. You'll get it. How's the compression. If you can move the flywheel all the way around without much effort, it might be time for a new engine. Check into the 3.3 or an OS .18 if that's the case. Good luck.
 
ok so i got it tuned perfect and ran a full tank through it with no problems.(besides it stalling at idol) After that i left it alone for about 20 mins and tried to start it again but it flooded. After clearing the flooded engine it started right up first pull. But now it cuts out at wide open thottle. It wasn't even warm yet and i didnt mess with the adjustments after it ran out of feul. I think maby the carbs clogged and it can't get enough fuel?
 

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