Too rich on top, too lean on bottom G320RC WT-1107
- Thread starter biskazz
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Best I can tell from the pics they look ok.
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- Nj
Just to recap here. How much fuel have you ran through the engine to this point? How much slop do you have in the throttle shaft and the carb body, have you tried to rebuild the carb with an overhaul kit? Something somewhere has changed within the carb foe it to behave that way because a pipe wouldn't cause the engine to run like crap. Hows the cylinder look? Any scoring etc?
biskazz
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- #24
I've run no more than 4-5 liters or ~1.5 gal.
Looking through the exhaust and intake ports, no scratches of any kind. Compression is good enough to almost lift the car by the pull start. I haven't put a rebuild kit on the carb, though I've replaced the insulator gaskets. The throttle lever has some slop but I don't think nearly enough to mess stuff up that bad.
Even if there was some mystery air leak or a torn diaphragm, wouldn't all this cause a lean condition... I have a brand new G320 with the same carb in a box but really do not want to start throwing parts at it... Cannot wait for the weekend to see what going back to the stock exhaust at the known good needle settings from back then does.
To me it seems like an air restriction, but it runs so good when you are at full throttle after closing the HSN a bunch. Throttle servo opens fully, air filter is clean, gas is fresh 100 octane running Motul 800 25:1
Looking through the exhaust and intake ports, no scratches of any kind. Compression is good enough to almost lift the car by the pull start. I haven't put a rebuild kit on the carb, though I've replaced the insulator gaskets. The throttle lever has some slop but I don't think nearly enough to mess stuff up that bad.
Even if there was some mystery air leak or a torn diaphragm, wouldn't all this cause a lean condition... I have a brand new G320 with the same carb in a box but really do not want to start throwing parts at it... Cannot wait for the weekend to see what going back to the stock exhaust at the known good needle settings from back then does.
To me it seems like an air restriction, but it runs so good when you are at full throttle after closing the HSN a bunch. Throttle servo opens fully, air filter is clean, gas is fresh 100 octane running Motul 800 25:1
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- Nj
You didn't use rtv or silicone for the insulator gaskets right? Just making sure the carbs pulse port isn't blocked
biskazz
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I specifically poked the hole between the insulator and head with a thin screwdriver after I installed it to make sure it isn't blocked. But also didn't use RTV.
Regardless, even if it was fully or partially blocked, wouldn't that be too lean, especially at high RPM?
Regardless, even if it was fully or partially blocked, wouldn't that be too lean, especially at high RPM?
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All the afore mentioned issues would cause a lean run condition. Running too rich needle issue, main check issue (unlikely) diaphragm issue. Fuel inlet needle issue. Pop pressure (unlikely as it seems to be a variable issue) needle lever height. (Again unlikely imo).
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- Nj
Forgot to mention and a possibility, the plastic insulator can be warped. I'm just throwing random possibilities out there now.
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- Queens
atp just change the carb
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- Manitoba
Put another carb in it.
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- Nj
Throw the kitchen sink at it.
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I doubt this too, but tank over pressuring the inlet needle?
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It’s not a nitro. Nothing pressurizing the tank.
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- Nj
The gas tank can pressurize if the vent is clogged, same principle with gas cans left in the heat.
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buy a 88 diablo engine by Taylor RC. i have never heard of them having this problem.
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Thats because it's just as unkiley as most of the other stuff we mentioned being wrong. Intermittent rich running isn't from a dirty air filter. It would be rich all the time.
biskazz
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- #39
So it's been some time but finally got it together and had the chance to run it. With the small caveat that I took a bit of a detour through the engine and carb when assembling.
Modified exhaust and intake timing, as well as lightened the piston and flywheel. Also ground down the transfer plate covers. Tightened squish up to ~16-17 thou(which is too tight for my liking, I'll bring it up to .020). Advanced timing via grinding the woodruff key about 1 degree. Carb-wise cut down the pop-off spring to 23-24psi.
Now with all those changes, I don't have no clue what was wrong with it previously but now it runs like a MOFO. It has insane power which I'm sure will destroy the driveline in no time, and has no issues across the whole rev range. Tunes just fine.
Timing that I implemented is roughly 1mm down on the intake, 2mm up on the exhaust and widen to 66% of bore with perfectly rounded edges.
So that's that.
Modified exhaust and intake timing, as well as lightened the piston and flywheel. Also ground down the transfer plate covers. Tightened squish up to ~16-17 thou(which is too tight for my liking, I'll bring it up to .020). Advanced timing via grinding the woodruff key about 1 degree. Carb-wise cut down the pop-off spring to 23-24psi.
Now with all those changes, I don't have no clue what was wrong with it previously but now it runs like a MOFO. It has insane power which I'm sure will destroy the driveline in no time, and has no issues across the whole rev range. Tunes just fine.
Timing that I implemented is roughly 1mm down on the intake, 2mm up on the exhaust and widen to 66% of bore with perfectly rounded edges.
So that's that.
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Next time you mess with timing Mark rhe fly wheel and crank for stock and Throw the key in the trash. It's only purpose in life is to make stock timing easy during assembly. 90% of my 2 strokes don't have keys. Tapered shafts and interference fits keep the flywheel tight to the crank.
Oter then that, glad tou got it working again.
Oter then that, glad tou got it working again.