Rebuilt/cleaned carbs and still runs like sh%^

[slabghost]

Now that they are adjustable. The procedure is in the manual. Basically you get the motor warmed and set idle at 1000 rpm. Pick one carb and set air/fuel mix screw to get the highest rpm you can. Then reset idle and do the same to the next carb and the next. Until all four have been done then do it again on all four as each carb will affect the others some. Afterward there is an idle drop adjustment suggested in the manual that I personally choose not to do.

 

[dan filipi]

Very clever mod!

 

[petefan1]

sounds like something else still. mine run around 2 turns out since i solved my dilemna that sounds like yours, although mine cost me 3 sets of carbs for one stupid reason or another.

 

[Fitz2at]

I tried the idle drop procedure with no success. It says to turn the air screws out until idle drops or raises I can't remember, 50 rpm. I did exactly per manual and nothing changed. The idle never dropped or raised so it was a waste of time IMO. I pulled the plugs and they look to be a bit on the lean side but I haven't really had much seat time.

 

[joedrum]

hmmmmmm that is lean .....that rather consistant too .....something is going on thats seems to effect all four carbs .....hmmmm...is fuel pump working good ....im clueless at the moment of what to check ....flost level to low ....just somewhat strange you dont see like this much ....

 

[petefan1]

so off throttle is poor. driving/cruising ok if you ease into it only? under hard load or wot...is it good or does it try to bog down, spit and sputter or backfire?

 

[dan filipi]

I tried the idle drop procedure with no success. It says to turn the air screws out until idle drops or raises I can't remember, 50 rpm. I did exactly per manual and nothing changed. The idle never dropped or raised so it was a waste of time IMO. I pulled the plugs and they look to be a bit on the lean side but I haven't really had much seat time.

No change in rpm, then I suspect the carbs are not cleaned completely, could be idle passages., or could be floats not quite right.
The drop IS subtle but if all carbs are clean and otherwise working good they will change the rpm.

 

[dan filipi]

Also look for vacuum leaks.
Are the intake o rings new?

Low float levels by just 2 mm will cause a lean condition.

 

[slabghost]

if turning the air fuel mix screws has no effect there is your problem. Those passages are plugged.

 

[petefan1]

So lets just put it out there...I learned (the hard way) the the float level with the new style encapsulated spring and pin, that the level must be set when the float tang just barely touches the pin as any slight pressure against the pin closes off fuel flow. I grew up with old style needle and rubber seats and could turn horn upside down and adjust the level with a closed needle. the new style...if you do that, you starve the system of fuel. I went thru all sorts of ignition and electrical components thinking ignition, then possibly low voltage. Finally, after a long conversation with a buddy who could look into my world, made me realize what I had done. Now, I found you have to hold the horn on its side with a slight angle so the float drops away from seat and then u can gently move it toward the seat and measure at the time the tang starts to touch the pin

 

[slabghost]

So lets just put it out there...I learned (the hard way) the the float level with the new style encapsulated spring and pin, that the level must be set when the float tang just barely touches the pin as any slight pressure against the pin closes off fuel flow. I grew up with old style needle and rubber seats and could turn horn upside down and adjust the level with a closed needle. the new style...if you do that, you starve the system of fuel. I went thru all sorts of ignition and electrical components thinking ignition, then possibly low voltage. Finally, after a long conversation with a buddy who could look into my world, made me realize what I had done. Now, I found you have to hold the horn on its side with a slight angle so the float drops away from seat and then u can gently move it toward the seat and measure at the time the tang starts to touch the pin

yes with the pin seated.

 

[Fitz2at]

The floats are set to the gnat's a$$ and all new o ring's throughout the carbs including the intakes. No air leaks, at least I can't seem to locate any by spraying starting fluid around the intake boots.

 

[petefan1]

So.....I take it youre trying to say you set the float with the pin seated...if so, its too low. Thin pin pushes against a spring and then an internal needle or ball. the difference between when the tan just touches the pin and the pin compressing the spring will equate to a too low float level.
Lets try it this way...the internal needle is always seated cause of the internal spring between the pin and needle. When the float drops..theres only spring pressure holding needle against its seat and fuel psi can overcome the spring pressure and fill the bowl. When the float rises, the spring pressure increases and fuel cannot overcome this higher pressure and quits filling the bowl. So, the correct height measurement is going to be when the tang of the float barely touches the pin.

 

[Fitz2at]

"So, the correct height measurement is going to be when the tang of the float barely touches the pin." Yes, this is how they are set.

 

[joedrum]

its still sounds like carbs tho the 81 carbs jet and emulsion tube combo pressed in ...and conplete stupid design right there is plain retarted engineering ....if the mixture screws aint working it clog up somewhere ....flost levels should be done with carbs standing strait up so gravity dosnt have an effect on them at all ....this way you can check the springyness of the float valve too ....make sure your getting good fuel flow from pump....plugs out switchs off including kill switch and spin strarter for flow rate check ...the gas today is worst crap ever offered in fuel and is just poison to oldwings ...run ATF mix in gas as much as you can .........and there always ignition ....suck on vacume line ti see if you can feel it pull the ignition plate ...sould be able to hear it move unless deaf like me ....if the plate is stuck its not going to run right ....just throwing all the info i can ...sometimes things are elusive my 77 giving me simular elusive problem but different than yours some so were both fighting the nedle in the haystack problem .....then there spark that might be in as a contributing factor but not main factor ......oh the fun fun fun till moma says its time to quit and go to bed :mrgreen: