Still not running right

[Tkosanic]

So I have gone thru and cleaned out all the carbs on my 83. Disabled the YICS system. Still not running right. If i turn the choke on going down the road it runs okay, if i shut it off it runs like crap. two of the cylinders are getting hot the other two are not. if i spray water on the exhaust on the two it burns right off the other two thee water just sits there. the plug cap and wires are brand new as well as brand new ngk plugs. where is my problem. is it just a matter of tune and sync or what?

[mbrood]

Hving to use the choke indicates the idle circuitry of the carb is not working. This is caused by the TINY idle jet in the float bowls jet block is clogged or one of the small passages within the carb body. Gas will slowly form a varnish that coats the passages and jets... while most jets and passages are fairly large, a little varnish won't show a serious effect. The TINY idle jet WILL.

 

You can pop the carbs off and break them into just a left and right bank of two and this gives you access to the float bowls and certain cleaning of that little thing. This also preserves the main sync adjustment hardware and their setting, although it's always recommended to get a new sync when the carbs are seated and the idle mixture screws properly adjusted fo the 'now proper' fule air mix at idle. Spraying the TINY jets with carb cleaner is NOT typically going to clean these out and any ream will change the opening diameter with serious performance degradation.

 

If you don't have access to a speed shop and their ultrasonic acid bath, you migt want to simply buy four new jets... for the 83 this would be 4G0-14142-42-00 about $20 plus freight at Flatout for all four... so it might be cheaper to get them local... it's a standard Mikuni jet, with a 42.5 opening. The 84 and above went to a 37.5 (even tinier) 4G0-14142-37-A0

[Tkosanic]

It still idles alright....that jet still affects how it runs down the road????

[mbrood]

Yes, from your description she's running on two and you have found enough adjustment range to get her to idle... the idle circuitry is still perfoming up to about 2500 rpm and then the flow transitions to the MUCH larger main fuel jets. After a run it is really impossible to tell from heat if the other two cylinders kicked in at cruise speed but bring her home and shut her off immediately and let her cool (don't let her idle), pull the plugs on the offending two to see if they are wet or dry, sooty or slightly black or a nice tan. If white, she's running extremely lean, the blacker means she's running rich and we really want to see them tan to medium grey.

 

Having to use the choke is just a cheat to get a gasoline boost (bypass) that the idle circuit isn't providing.

[Yammer Dan]

Done the Sea-Foam?? A good soak may help. May not but worth the try.