Too rich on top, too lean on bottom G320RC WT-1107

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biskazz

biskazz

Member
Messages
16
Hey,

I've had my Zenoah 32 with a WT1107 for about a gallon of fuel now. I recently installed a VRC tuned pipe and began to have some issues.
The carb is too rich on top. I've had to close the high speed needle more than half a turn from stock settings to get it to run decent. Then it begins to have insufficient fuel off the line and I've opened the low speed a bit to remedy that, but it still isn't running quite right.
Is it normal to have to close the HSN 1/2 turn or more off of factory settings?

There's no air leaks, exhaust is seated properly. I've not dug into the carb itself.
What should I look for, pop off pressure or perhaps metering lever height?


Any input is appreciated!
 
Are you sure you are tuning correctly? Installation of a performance exhaust should require opening of the high speed needle.

The engine can be related to an air pump, your pipe should increase how much air the engine is capable of flowing. Performance exhaust flows more and all things the same will result in a leaner air/fuel mixture prior to adjusting the carb. More flow, more fuel.

I would try resetting the carb to stock settings then try opening the high speed needle and see how it responds.
 
Bizzer said:
Are you sure you are tuning correctly? Installation of a performance exhaust should require opening of the high speed needle.

The engine can be related to an air pump, your pipe should increase how much air the engine is capable of flowing. Performance exhaust flows more and all things the same will result in a leaner air/fuel mixture prior to adjusting the carb. More flow, more fuel.

I would try resetting the carb to stock settings then try opening the high speed needle and see how it responds.
Click to expand...
He said he had it at the factory reccomended settings in his post. So he never tuned it to begin with.
 
half a turn is a huge amount mate,
if i were you i'd reinstall the stock can and adjust carb back to the settings you were at before, then run it and see if it runs the same as before,
then if it runs good, reinstall the vrc and run again and see if anything changes, then adjust from there,
but as bizzer said , stock settings then tune from there,
if it runs crap on the stock can, then sommats amiss and somethings changed somewhere,
check all the usual, clunk, fuel lines, tank vent, air leaks, bad fuel or bad fuel mix, is the filter clogged or very dirty,
also try a new plug,
in other words, diagnose and rule everything else out before ya start messing with the pop off etc,

edit; just seen seans post about stock settings above ,
 
Thanks for the replies!
I've returned it to factory settings numerous times and it runs incredibly rich. My thinking was also that after installing the pipe it'd need richening.

With the stock exhaust it was running perfect at LSN at stock and HSN 1/8 in from factory.
Now I'm at LSN 1/8 out from factory and HSN 1/2 in.

Plug color is really dark, absolutely confirms the rich condition.

I've been running (and modifying) nitro engines on a decently high level for about 15 years so I'm pretty comfortable with 2 strokes, just do not really have fresh experience with gassers.

Thinking of putting the stock can back on to see how that goes.
 
You need a vacuum/pressure hand pump. Target pop off is 20 psi. Ive done it just recently, not saying sean is wrong it would be the first thing I go to but since you didn't have an issue prior to the pipe I'd be curious if the carb isn't the issue
 
Pop off this pop off that. This isn't that complicated. Factory settings and move the needle left until you like how it sounds if not back to factory settings and turn it right. So simple
 
As I said before, it starts sounding good at about 1/2 turn leaner than factory settings. Do you think that's normal considering Zenoah themselves say +-1/4 max?
 
I did a visual inspection on the metering lever height and it seems to be where it should be, though I'm still waiting on the actual Walbro gauge but at least it's not way off.
Also tested the pop off pressure, although I was unable to make it "pop", it starts letting out air at no more than 27-28psi.

Last run I had to close the high speed needle almost a full 1 turn from factory settings to get a decent top end. Low RPM response gets messed up big time at that setting, though at full throttle when it runs good, it's properly fast. I've now installed the factory muffler to see how things go next weekend.
 
Last edited:
RcJunkie13 said:
i don't really think smoke is relevant unless its nitro. Smoke seems to be more dependent on the oil you use in my experience.
Click to expand...

Could be true, I've only run Castor. The smoke tells me I'm running rich enough to not burn up the engine and the sound tells me it's running proper. No gargle up top but a tad bit of smoke on start up and down low. Idk that's how I been doing it. Never overheated an engine that way.
 
You guys and your caster oils make me laugh....
Any modern 2 stroke oil will mostly if not completely burn during combustion. At the extremely high ratios most tend to run you still won't get much smoke outside of start up and initial warming of the engine. If you physically see smoke at top end your likely too rich.

Op, It's how many turns out from lightly bottomed that matters. Not how far from factory needle settings. All they are is a base line "it should run at this" setting.
Pop pressure is a wet test, carb needs to be full of fuel. Stock engine 30 psi pop is fine. Not optimal, but it should have plenty of fuel to run. Your overly rich issue is starting to sound like you got mad at the needles and over tightened them. Take them out and look to see if you have a ring in the tapered areas of the needles.
 
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