Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

[halmc]

Not a word in my service manual about how to adjust the idle mixture screw on the carburetor. Since I've fixed my bowl from running over mentioned in an earlier post, I now want to get the mixture right.

My plan, after waming the engine up is to adjust the screw for max engine vacuum if I can find a vacuum port, but if not, then to set the screw at max rpm and idle.

Good plan? Bad plan? Half-bottomed plan?

 

[Maxz695]

Re: Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

You should start out at 1 1/2 turns from a light seat. When you get it in the water try throttling up, if it boggs then open the screw 1/8 turns and retry throttling up. give it time to burn off fuel then turn another 1/8 When you have a good solid thrust under the gun then it is at it,s best setting

 

[halmc]

Re: Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

Roger, WILCO, gracias.

 

[oldman570]

Re: Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

As Maxz has stated. The four stroke carbed motors are set the same as two strokers. Manual says 1 to 1 1/2 turns out from lightly seated . With motor warmed up and in FWD gear screw idle jet in till motor stumbles, then back out 1/4 turn and adjust out blade with of screwdriver till motor responds well to WOT incresse and boat plains fairly quickly. JMO
Oldman570

 

[carholme]

Re: Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

Not to cause a stir here but I think the reason you do not see an idle mixture adjustment on these carbs as it is hidden under a Welch plug. It can be adjusted but you would have to pull the plug. This is part of the EPA emissions standards. There is an idle speed adjustment in 3B-10.

You will not find the issue discussed in the manuals.

If you look at 3B-6 of the service manual, you will see item 30 but it is not even listed in the parts list underneath.

Gerry

 

[Maxz695]

Re: Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

Good information Gerry glad you posted it. So there is more than likely an issue as it is a preset carburetor. Such as float level clogged ports leaking gasket to manifold etc etc?

 

[halmc]

Re: Idle mixture adjustment, 2005 25hp four stroke model: 1F25412DD Serial: 1B169120

Not to cause a stir here but I think the reason you do not see an idle mixture adjustment on these carbs as it is hidden under a Welch plug.

The wech plug was removed before I got the motor. My question was not one of "what's wrong with my motor" it was specifically directed to the procedure for adjusting the idle mixture screw and it was thoughtfully, thoroughly and accurately answered by Maxz695. Thankya, Max. Thankyavurrymuch.