DBXL 2.0 No torque...Need Help

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Bryfly51

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I've been in RC for over 30 years. I have a G320 Zendoah engine that lacks in take off speed. It will not spin tires. Engine starts and runs well. Temps are good. I will reach top end but takes a flat surface to reach. I have zero get up power. Engine has probably 2 gallons thru it. Things I've done to fix this issue. New plug, Cleaned carb many times, installed tuned pipe, went 1 tooth smaller on pinion, high flow filter with velocity stack and tried various clutch set-ups. I have good compression. I've tried various fuels. Nothing seems to fix this issue. When it was new it was a beast and quick off the line. Now it just lags to reach speed and cannot climb any sort of hill or jumps. The one thing that stands out to me is...A few times I have sucked in clayish dust from being in the south...Hence why I've cleaned the carb so much...But if it starts and eventually reaches top speed...I feel something else is wrong...Any ideas?
 
I assume you know how to adjust the carburetor if you've been doing rc that long. If not, I'd start there. Otherwise have you looked at the piston through the exhaust port? Any visible damage? Are you using a castor oil like Maxima 927 or Klots benol and the ring is stuck from the varnish it creates? Have you checked the compression with a small engine compression gauge? My healthy, broken in G320 has a bit over 200 psi compression using my Echo gauge. IMG_20240415_131045454~2.webp
 
Thank you I'll head down that road...I am only reading 50psi...but with the plug in it feels like more...But i'll check for ring fitment and or wear...thx again
 
Bryfly51 said:
Thank you I'll head down that road...I am only reading 50psi...but with the plug in it feels like more...But i'll check for ring fitment and or wear...thx again
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If you aren't using a small engine specific gauge it will read way low. There needs to be a schrader valve in the end you thread into the plug hole. Even the 10mm adapter needs this. Otherwise you are trying to fill the hose each time yiu pull.
 
If you sucked in a bunch of fine dust it will ruin an engine pretty quickly. I suggest getting a quality 2 or 3 stage foam filter, oil it with belray filter oil and grease the mating surface between the filter neck and your velocity stack. I run an outwears on mine as well. I have spotless carb throats / intake and we have black silty dust here. Like black talcum powder.
 
I'm using a automotive compression test using short lead to rubber boot and yes I do use outwears(now)...maybe the damage is done...maybe I'll be lucky and a new ring my restore it...
 
I reckon I found where the dirt deposited and some minor scoring…funny how it still started so well and reached top speed…
 
Cylinder has a scratch line that I can feel and the piston exhaust side has scrapping marks...At least I know what it is...90 bucks...not a big price to pay to learn what not to do...opps
 
Bryfly51 said:
Cylinder has a scratch line that I can feel and the piston exhaust side has scrapping marks...At least I know what it is...90 bucks...not a big price to pay to learn what not to do...opps
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Exhaust side scoring is most likely a lean condition. The factory carburetor isolator / intake is known for warping and sucking air. I caught mine in time. My tune changed in the middle of a run and went lean. I immediately adjusted the tune and it happened again. Thats when I shut it off and ordered a recommended aluminum intake after some recommendations from people here. If you don't change yours from original, it will cook a new top end.
 
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