changing carb jet

[diamondlangus]

I bought a boat that came from a much lower elevation. Is there a way I can look at the jet and tell what size it is so I know if I need to change it?

 

[tater76]

Re: changing carb jet

Year and model please

You will need to pull the bowl off the carb or carbs to check the main jet size. It will be the little brass guy on the side of the post protruding downward into the bowl.
The jet will have a number stamped on it. These numbers tell you what size, the size correlates to an elevation. For example: Sea level .074, .072-2,500-5,000ft, .070-5,000-7,500ft, .068-7,500-10,000ft. These numbers are for an early 90's 85hp, and yours may be different depending on the motor.

 

[diamondlangus]

Re: changing carb jet

thanks. It is a 1993 70hp. The boat came from and elevation of about 2000' , I am running it at about 5200'. According to the chart I found for my carb TC 111A , for the elevation it came from it should have a .094 1500'-3000'. for my elevation it says it should have a .090. When I took the boat out for the first time last weekend it seemed to start and run fine. Might have been running a little rich but not bad. My WOT RPM was a little low 4400. I know this is probably mainly due to prop pitch but want to figure out if I need to change the jet also. I will pull the bowl and see what it says.

 

[diamondlangus]

Re: changing carb jet

Ok just pulled and checked. it is a .096. So it looks like I need to change it. What type of performance change could I expect by changing it. Hopefully Iboats has the jetting I need.

 

[jerryjerry05]

Re: changing carb jet

Not much if any. After the change, post the results.
What pitch?
Load and motor configuration will determine the pitch.
Carrying too much will affect it.

 

[diamondlangus]

Re: changing carb jet

how can I tell if I am running the motor to lean after changing the jet? The last time I ran the motor I checked the plugs and they were oily and very dark.

the jet that is in it is for 0-1500' I am at 5200'

 

[jerryjerry05]

Re: changing carb jet

I'd change it just to be sure.
The only check is the plugs.
It burns gas and oil so some residue is still gonna be there but not too white or light brown?
Burning too hot.
If you change the jets,then adjust the air screws.
That's about all you need to do.