Rebuild Carbs or Not?

[wheyl]

I have a 95 Evinrude 48 with only about 300 hours on it. It has sat up for about the last few years and I figured the Carbs would need to be rebuilt. I ordered the kit and went ahead and pulled them today, but was surprised that the intake manifold looked like I could eat off of it. I know that this is good, but is it normal?

Once I cracked the carbs open they were pretty dang clean too. I didn't see any dirt or crud any where (haven't pulled them all the way apart, just the top plastic cover and the chamber with the float). My question is can they still be "dirty" even when they look relatively clean? Also, should I just shoot it or soak it with somme carb cleaner and replace the gaskets (leaving the needles and float alone), or should I just go ahead and rebuild the whole thing? I don't want to mess with the needles and float settings if I don't have to.

Thanks for any advice!

 

[Solittle]

Re: Rebuild Carbs or Not?

The crud in carbs that kills performance like to hide in passages that you can't see. They come out again when you button things up and do their thing.

Get them buggers and do the job right. When all is clean and ready to reassemble blow every nook & cranny out with high pressure compressed air - not the rattle can type.

 

[HighTrim]

Re: Rebuild Carbs or Not?

and equally as important, rebuild the water pump. Your current impeller is toast.

 

[wheyl]

Re: Rebuild Carbs or Not?

I went against my better judgement and rebuilt the entire carbs instead of just squirting it down and changing the gaskets. I have it back together now, but the motor runs ten times worse than before I rebuilt it. It will not stay running if left in idle and runs pretty ragged when I have it idled up. I tried to adjust the idle mixture leaner and richer to no affect about a half turn each way from original position). Also, Gas is in the water on the ground from the ears.

I took great care in making sure I put it back together exactly as it was before. I double checked everything. The only thing that was not perfect is the main jet on the top carb got a little flared on the top on the way out. I was not sure if this would affect performance or not, and I didn't have an option to immediately replace it anyway. Could this be the reason for it not running properly?

Could I have not adjusted the mixture screws enough?

 

[HighTrim]

Re: Rebuild Carbs or Not?

I went against my better judgement and rebuilt the entire carbs instead of just squirting it down and changing the gaskets.

The judgement you used to rebuild your carbs was the better judgement.

"Squirting it down and changing the gaskets" would have done nothing, they need to be completely dissasembled and rebuilt, getting into each and all orifices and thoroughally cleaning the jets. The damaged jet WILL be a problem for you now. What did you use to remove/install it? If not a proper OMC special tool, you need to make one completely flat and parallel such as the example by FR below.



This may help with the carb rebuild.

http://www.meegsonline.com/tmd/TMDsVideoChronicle2.wmv

As far as adjusting the mixture, look into the FAQ for Joe Reeves Thread, it outlines it perfectly for you. Also dont neglect that water pump or you will have worse problems than a poor running motor.

http://www.meegsonline.com/tmd/waterpump.wmv

Good luck.

 

[bucchb]

Re: Rebuild Carbs or Not?

Out of curiosity, wouldn't a good carb cleaner, run thru the motor, clean all those orifices, passages, jets, etc.???

Why do they need to come off a engine with marginal performance???

 

[Lakester]

Re: Rebuild Carbs or Not?

Why do they need to come off an engine with marginal performance???

hello,

i dont want to sound tacky, but why would u want to run an engine exhibiting marginal performance? especially with gasoline prices where they are today and rising?

well, one reason u would want to "rebuilt" is that new from the factory, as a rule, there is no crud in any of the intricate areas of the carb. and so "signals" and air/fuel ratios are optimal... and yield optimal performance thru the power band. a desireable trait for any eninge... and the goal of any "engine tuner/builder".

a rebuild is geared to restore the carbs to factory specs.

regards,
lakester

 

[tashasdaddy]

Re: Rebuild Carbs or Not?

use the first section, single needle adjustment, adjust only one at a time.

http://forums.iboats.com/showthread.php?t=167352

 

[wheyl]

Re: Rebuild Carbs or Not?

I spoke to a local mechanic and he said there's no chance the flared top of the high speed jet is causing the engine trouble. He was empahtic that as long as the hole at the end of the jet is competely intact that it would not affect performance.

Any other suggestions?

 

[ezeke]

Re: Rebuild Carbs or Not?

I don't have a service manual for your engine, but I do have one for the 1990 48HP engine. The service manual says:

"The slow speed needle in this carburetor is controlled by a factory adjusted needle. This procedure should only be used if the factory seal is gone or the needle adjustment has been disturbed."

It then goes on to prescribe a adjustment procedure to be followed on the water, in gear, with the engine warm and the boat unrestrained.

The instructions are lengthy and may not apply, so if you want them, send me a PM with your e-mail address and I will try to get them copied.

 

[tashasdaddy]

Re: Rebuild Carbs or Not?

my 93 manual states the same.

 

[wheyl]

Re: Rebuild Carbs or Not?

I think I got it now. It was the idle mixture needles, but it was about 1.25 turns leaner from the factory specifications and .75 turns leaner from where it was set before the rebuild. It might be too lean at the moment, but I'll have to put it in the water to adjust it properly from there.

Initially I was freaked out b/c it was not running right a half turn each way from the factory spec and thought it could not be the idle mixture that was causing the malfunction.

I am running premium fuel through it right now. Could the higher octane cause a difference in the optimal mixture setting maybe?

 

[HighTrim]

Re: Rebuild Carbs or Not?

Im not sure whether the higher octane would cause the problems you are having, but do know that it is unneccesary. Regular 87 octane is fine, any more and you are wasting your money.

 

[ezeke]

Re: Rebuild Carbs or Not?

If you had high compression heads or modified heads, you might get some benefit, otherwise stick with 89 US octane or even 87 as HighTrim said.

BTW, BRP Evinrude still says that 89 octane is preferred and that 87 is "minimum":

http://www.evinrude.com/en-US/About.Us/FAQ/Oil.Fuel.htm

The biggest problem now is trying to keep the water out of the engine, so try to find a way to get a full-sized water separating filter between the tank and the engine.

 

[wheyl]

Re: Rebuild Carbs or Not?

I assumed the Higher octance would be better for the engine for the first tank or two after it has been sitting up. Guess I wasted a few dollars on that. Thanks for the info.