Box Stock

clone carb jetting, idle

New build, stock clone, dyno cam cl3, not sure who built the carb. Had a ev6 in it, with the 027.

On initial startup it was way too rich, it wouldnt run.
 
Lucky_7 said:
New build, stock clone, dyno cam cl3, not sure who built the carb. Had a ev6 in it, with the 027.

On initial startup it was way too rich, it wouldnt run.
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You reduced the low-speed fuel flow by 50%, that's a lot. What size high speed jet is in it? Is it possible that the carburetor was set up for alcohol?
 
Are you sure the float is shutting off the fuel?

Then I would check ignition timing. May have the offset key in backwards?
 
Do you have an air cleaner on it. If so, do you have a foamie over the air cleaner. Did you try to run the engine without the air cleaner
 
Timing is 34 and a half. Float is fine, no fuel in it. Current high speed jet is 37. I can't find a vacuum leak anywhere. I don't have time to mess with it tonight.
 
When I raced KT100, they would never idle. The low-speed was set way too rich to idle. That's when they ran their best on the track. Who cares what they idle at, not me. Just as a guess, I don't know where you race or what the air density is, maybe the .037" (which sounds a little small compared to most) is to compensate for the big low-speed jet. That's the way we did it in 2 cycles. I know we were doing it right because the EGT told us we had it as lean as it should go, safely of course. It could be that the person who had the carburetor before you, really knew what he was doing. It's possible!
 
Many clone carbs are extremely rich on purpose. Especially restrictor plate carbs. It is done on purpose to make them not stumble when rapidly opening the throttle. They also build more torque when rich. My carb builder strictly says to never let it idle more than a minute or two or it WILL foul plugs. But on the track they RIP!
 
If you let it idle to long it may have Fouled the plug and that is why it wouldn’t start. Like said above, restrictive engines are really rich at idle. My guess is if you put the jet back in and a new plug it will start. On another note, if you spray the filter to much it will act like a choke and further the richness thus fouling the plug. Go back to the old jet, New plug, no air filter and I bet it will start
 
1fasttiller said:
Many clone carbs are extremely rich on purpose. Especially restrictor plate carbs. It is done on purpose to make them not stumble when rapidly opening the throttle. They also build more torque when rich. My carb builder strictly says to never let it idle more than a minute or two or it WILL foul plugs. But on the track they RIP!
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I knew the restrictor plate carbs were rich. We dont let them run long either, but this thing wont even idle.


DynoDon said:
If you let it idle to long it may have Fouled the plug and that is why it wouldn’t start. Like said above, restrictive engines are really rich at idle. My guess is if you put the jet back in and a new plug it will start. On another note, if you spray the filter to much it will act like a choke and further the richness thus fouling the plug. Go back to the old jet, New plug, no air filter and I bet it will start
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It acts the same with the filter off. The plug acted this way on the initial start, It did start and run, but it wouldn't idle. We are not running a restrictor on this motor either.
 
Ok my bad. I thought you had a restrictor. I guess someone jumped to that conclusion and I followed suit. Check the opening on the right side bleed like hodaka said. Sometimes the gasket (really thick) gets squashed and it covers it partially. Do you have another carb to try. Did this engine ever run good or is it new to your possession
 
DynoDon said:
Ok my bad. I thought you had a restrictor. I guess someone jumped to that conclusion and I followed suit. Check the opening on the right side bleed like hodaka said. Sometimes the gasket (really thick) gets squashed and it covers it partially. Do you have another carb to try. Did this engine ever run good or is it new to your possession
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This is a rebuild, I got a new plug, it runs a little better, still rich. Puff black smoke rich, but it idles with the idle screw 90% in... Where do you put your idle screws?
 
Is there an o ring on the low side jet. If not put one on it and see if that slows down the smoking. Several of my carbs are at 3/4 in on the idle
 
DynoDon said:
Is there an o ring on the low side jet. If not put one on it and see if that slows down the smoking. Several of my carbs are at 3/4 in on the idle
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Yes it there. Ill just need to tune the stock jet to run with the screw 1/2 to 3/4 in.
 
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