Hello everyone, i just got a great deal on an fg sport 2wd 1/5 with the zenoah 23cc. The thing is basically brand new, everything looks untouched but it has been sitting almost 20 years. I drove it a bit and it was quite rich, and after a few minutes it would bog down if i gave it throttle. Now it barely starts, gets very flooded, when it starts it has a bad idle creep and then dies if you don't give it throttle and sometimes if you give it some as well. I noticed then that the idle would go back down if i pressed down on the intake, so i changed the gaskets and tightened the bolts holding the carb on. Now simply nothing changes if i push down on the intake and it only surges. The membranes in the walbro carb don't look too bad, and still move. What could it be?
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Idle surge on zenoah 23cc
- Thread starter James!
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Take a look at throttle shaft for any wiggle, up ,down,side to side. How's your mixture screw and idle speed settings. Finally is the servo set correctly/radio. Just need to be watched while using throttle and brake to see if anything hanging up without engine even running. Maybe stick a new plug in ......
- Thread starter
- #3
so the shaft has no play whatsoever, and the endpoints on the servo are set correctly, nothing is catching during its travel. Both the L and H screws are set to 1 and 1/2 turns from the tightened down position. I think there may be an air leak after the carb, but spraying starter fluid around the gaskets did not affect the cars running
- Thread starter
- #4
Also, the sparkplug looks brand new, as is the rest of the car and i struggle to imagine its the culpritso the shaft has no play whatsoever, and the endpoints on the servo are set correctly, nothing is catching during its travel. Both the L and H screws are set to 1 and 1/2 turns from the tightened down position. I think there may be an air leak after the carb, but spraying starter fluid around the gaskets did not affect the cars running
Interesting......my 5t 2.0 32 zenhoa had worn throttle shaft bearings giving similar issues. Servo had been pushing to far under braking
Maybe just a few 1/16 turns on low speed in both directions to see if it's just that simple. Idle screw just barely open?? Plugs are cheap and can sometimes be hard to determine if it's the issue. You can try my 50 cent carb cleaning trick.....rev it up,close choke till it bogs down. Open choke till it recovers revs, repeat as needed. This will help pull any dirt out of carb. Maybe try new fuel filter too.
Maybe just a few 1/16 turns on low speed in both directions to see if it's just that simple. Idle screw just barely open?? Plugs are cheap and can sometimes be hard to determine if it's the issue. You can try my 50 cent carb cleaning trick.....rev it up,close choke till it bogs down. Open choke till it recovers revs, repeat as needed. This will help pull any dirt out of carb. Maybe try new fuel filter too.
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Clean the carb! It sat for years and todays fuel being what it is often leads to carb. issues.
The passageways inside are so small if they get clogged up with old fuel that has turned to "jello" often leads to problems.
If you have access to a small ultrasonic cleaner they can work wonders on cleaning things like this.
The passageways inside are so small if they get clogged up with old fuel that has turned to "jello" often leads to problems.
If you have access to a small ultrasonic cleaner they can work wonders on cleaning things like this.
- Thread starter
- #8
All right, i'll give it a try and look at these bearingsInteresting......my 5t 2.0 32 zenhoa had worn throttle shaft bearings giving similar issues. Servo had been pushing to far under braking
Maybe just a few 1/16 turns on low speed in both directions to see if it's just that simple. Idle screw just barely open?? Plugs are cheap and can sometimes be hard to determine if it's the issue. You can try my 50 cent carb cleaning trick.....rev it up,close choke till it bogs down. Open choke till it recovers revs, repeat as needed. This will help pull any dirt out of carb. Maybe try new fuel filter too.
- Thread starter
- #9
So i don't have access to anything like that, is there any other way to clean them properly?Clean the carb! It sat for years and todays fuel being what it is often leads to carb. issues.
The passageways inside are so small if they get clogged up with old fuel that has turned to "jello" often leads to problems.
If you have access to a small ultrasonic cleaner they can work wonders on cleaning things like this.
- Thread starter
- #10
so i thought about that, but at least to the naked eye it looks perfectly straight, even if up against a straight surfaceAnother thing is to check the carb iso block to make sure it is flat. I have had brand new Zens come in the box for us to use parts off and be warped badly on a brand new engine
You could completely disassemble it and soak it in solvent then blow it out with an air hose. Count the turns in before you remove the mixture screws and do not put any of the gaskets or rubber parts in the solvent.So i don't have access to anything like that, is there any other way to clean them properly?
Harbor Fright and Amazon have inexpensive ultrasonic cleaners that work pretty well for something like this.