More power whit out air silencer

[tropic]

Hi . i found out if i leave the Cover,air silencer of the carbs my motor seems to run a lot better . has anybody else tried this ? . it is a 1994 Evinrude 225Hp (twins) . thanks .

 

[F_R]

Re: More power whit out air silencer

Two thoughts come to mind.
1. It may SEEM to have more power because it's noisier.
2. The carbs are engineered and calibrated to run with the silencer. It may actually be a hair faster without the silencer because it is running a bit leaner. But that is a big bad. Running lean will destroy the pistons. Put the silencer back on.

 

[Dhadley]

Re: More power whit out air silencer

On a looper, leaving the cover off leans out the fuel flow. Many times, under a load, it will lean out to the point of damaging a piston. Again. we're talking loopers. If your motor runs better without damaging a piston, then something is making it run rich with the cover on.

 

[Dhadley]

Re: More power whit out air silencer

Sorry, FR....you type faster than me. Didn't mean to step on toes but you're right on.

 

[tropic]

Re: More power whit out air silencer

Thanks, for the replys F_R and Dahdley, i put back a cover box without the BAFFLE (black plastic piece) and the seal baffle to carb, the engines runs great now them rise 5600 at wot , fantastic , can it run without this two things?

 

[Dhadley]

Re: More power whit out air silencer

We'll assume you have the model with the "K" suffix which has the airbox with screws around the outside, not the box with the thumbscrews in the middle.

Yes, you can run it without the inner baffle. That leans it out somewhat but not as bad as without the cover at all. The low top rpm explains why it runs better. We'll further assume that with the full cover on you're at 5500 or maybe even 5400.

At that rpm your performance should be way off. Those motors need to be capable of at least 5800 with an average load in stock configuration. If they were mine I'd put it all back to stock and find out why it's so low on top rpm.

Start with the basics, a compression test is first. If that's good then I'd check fuel delivery and the ignition system including timing. Then work on set up.

 

[tropic]

Re: More power whit out air silencer

Yes the model is 225TXER K and the power head was rebuild in dec 2006, whit new power pack, stator, rectifier, gas hoses, fuel pump, etc...whit the inner baffle the rpm at wot its only 4800-4900.....whitout the inner baffle the rpm at wot its 5600 and more....if i can run the engine whitout this pieces much better.....

 

[HighTrim]

Re: More power whit out air silencer

I think I would listen to Dhadley and FR, they know their stuff. Something is making it run rich with the cover on, do the compression test and let him know what you find. Do you have a manual? IT will cover the procedures for checking the timing and troubleshooting the ignition system, after of course you perform the compression test. Dont forget to go over the fuel system as well. Starting with when the carbs were last rebuilt?

 

[Dhadley]

Re: More power whit out air silencer

At a top rpm of only 4900 rpm those motors will die an early death. Do both motors have the same top rpm? Were they both rebuilt? At a top rpm of 4900 they have to be awful on holeshot.

The key here is "rebuilt". Lets start with compression then check the timing. If I were gonna bet I'd almost bet the timing is backed off.

 

[Joe Reeves]

Re: More power whit out air silencer

Tropic..... If by "seal baffle to carb", you're speaking of the heavy gauge rubber like seal between the craburetor face plate to the carburetors, and if you're running the engine with it removed, that results in have the engine run lean on all cylinders.

The engine may run at a higher rpm for a period of time until preignition sets in or various bearings start to turn blue along with scored pistons.

Some excellent advice above.

 

[tropic]

Re: More power whit out air silencer

Hi guys, i am very thankful for the replys, and i hope you understood my short english, this carbs was rebuilt in july 2007,
maybe the mechanics put the wrong kit and the engines need more air now?
Here (venezuela) its dificult to find the exactly parts for the engines and we have to make some for this....
I don't need to run my boat at 5000 RPM all time just 4000 or 4500 its very fine for my boat performance...if i can let this pieces out much better...thanks again....Carlos

 

[Dhadley]

Re: More power whit out air silencer

He really couldn't have put the wrong kits in, there's only a couple and the basic parts are the same. As for running the motors, it doesn't matter at what rpm you run them at as long as they're capable of 5800+ with a normal load. The way you're running them now is puttin a strain on them at all rpm.

Start with the compression tests. If that's OK check the timing. I'll bet we find something odd there.

 

[tropic]

Re: More power whit out air silencer

Yes the compression are 110-115 on port engine and 115-120 at starboard engine... the timing assume its ok but this weekend we look at that .
How can i look the timing what tool i need for that?
New power packs in both engines, stators, rectifiers, fuel hoses, filters, vro in good conditions, (mix oil and gas 50:1 in the tank), sparks plugs (champions) and the wires new too

 

[Dhadley]

Re: More power whit out air silencer

That's a little high for those motors. I'd be very concerned about how the "rebuilder" got the compression that high. All you need to check timing is a timing light. You should set the timing pointer, just follow the proceedure in the service manual. basically you set # piston at top dead center and line up the pointer with 0 on the timing grid on the flywheel.

BTW -- those motors didn't come with VRO's, they have the OMS injection.

 

[rndn]

Re: More power whit out air silencer

Does he have oil injection and also mixing the oil in the fuel tank, or did I misread something?

 

[Dhadley]

Re: More power whit out air silencer

Definately mixing oil in the tank and may be using injection also. Common on rebuilt motors to verify that the injection system is working properly. That alone may be the saving factor when running lean.

 

[tropic]

Re: More power whit out air silencer

Hi, I premix the oil and gas in the tank (50:1) the VRO its unpluged..

 

[Dhadley]

Re: More power whit out air silencer

Remember, it's not a VRO. Calling it that can / will lead to confusion.

 

[tropic]

Re: More power whit out air silencer

Ok Dhadley, thanks for the advice!