Understanding Evinrude Carb Differences

[cenkaetaya]

Hi, I have 2 1990's Evinrude 40HP motors, however they seem to have slightly different carb designs.

I am trying to understand exactly what the difference is, and what the best way to tune them is.



A few questions:

#'s show in images

1. Both carbs have the, #1 and #2 primer fuel line and main fuel line. However the other carb
labeled as #4 has a small connector that goes to the 2nd carb. What is this and why do the other two carbs not
have something like it?

2. If i were to perform a carb sync with a tool on, where would the tubes connect? Is it not those connectors #4 in image? and if so, how would i do this on the other carb which does not have these connectors?

I am trying to figure out the difference in how these work and how best to tune them.

Thanks

 

[jimmbo]

Can't beat a year specific factory service manual for each engine

 

[Faztbullet]

The cross over tube is a balance tube as these series have always had idle problems...the plastic tops are better IMO. Best to adjust in a barrel as needs backpressure, cant do on muffs.

 

[cenkaetaya]

Interesting. Would it be possible to use a carb balance tool for this motor?