9.9 Air Silencer

[Landscaping Wiz 808]

So I was reading up on my '86 Johnson 9.9hp here:

http://www.sschapterpsa.com/ramblings/OMC/OMC info.htm

...and I've learned my motor originally had an air silencer assembly that was installed in front of the carb. My motor does not have this assembly. Does it make a significant difference in noise reduction? I ran mine all last year w/o it and did notice it was kind of loud at higher RPMs.

Does anyone know where I can find the entire assembly? I checked BRP's website and they only sell the parts individually.

Thanks - BOB

 

[Rick.]

Re: 9.9 Air Silencer

You could probably get one from ebay. Take a look for someone who is breaking motors down and selling the parts and then contact one of them and ask. I've had some luck just stopping at marine shops and asking if they have a bone yard and having a look for myself. I don't think it will make your motor much quieter but I imagine it's there for a reason. I'm just not sure why. Rick.

 

[Landscaping Wiz 808]

Re: 9.9 Air Silencer

Thanks Rick, I just checked ebay & found one for a '94 9.9hp. Do you think this will this fit my '86?

http://cgi.ebay.com/ebaymotors/John...023QQitemZ360126089648QQrdZ1QQsspagenameZWD1V

BOB

 

[Rick.]

Re: 9.9 Air Silencer

Are you trying to set me up here? Just kidding but I would not venture to guess. There were lots of changes between 86 and 94 on the 9.9's. I would be more comfortable saying yes to one that was eight years the other way from yours.
Check this site and see if the parts numbers match. Try the Johnson numbers too. The one thing that could be a problem is they switched from black to white and back to black plastic for the silencers so if 86 was white and 94 was black the numbers would not match even though it was an identical part. I have a 90 Evinrude 9.9 yahtwin that looks to be in real good shape with controls and no tiller. I have never really even played with it but one day i will. That is the newest motor I have by 8 years. I finished rehabbing the rest of the fleet this winter so maybe next year.... if I don't find anything more interesting. Rick.
http://shop2.evinrude.com/ext/index.aspx?s1=0241e5fb59fd9672a0e9805a1071aec9


EDIT: Curiosity got the best of me and I had a look for myself.. No way the 94 will fit an 86. They are very different from one another.

 

[bankerjohn]

Re: 9.9 Air Silencer

The part # in that eBay auction is for a 1993-2001 9.9 and 15 motors (and a few later ones) ... and it's only about $18 brand new. Your 1986 air silencer is 2-part (base and cover), and it's a completely different shape.

Here they both are:

 

[Landscaping Wiz 808]

Re: 9.9 Air Silencer

Thanks again Rick, The BRP site only lists the individual parts that make up the assembly and the part# the seller provided isn't showing up. When I ordered parts from the BRP site before they were shipped from a local supplier. They sent a sales flyer w/ the parts, maybe I'll give them a call to see if they can shed some light..

You should definitely get that 9.9 running! I thought I'd start w/ this motor since it's small & simple...I've since changed my mind!

BOB

 

[Landscaping Wiz 808]

Re: 9.9 Air Silencer

The part # in that eBay auction is for a 1993-2001 9.9 and 15 motors (and a few later ones) ... and it's only about $18 brand new. Your 1986 air silencer is 2-part (base and cover), and it's a completely different shape.

Here they both are:

NUTS!!

 

[Rick.]

Re: 9.9 Air Silencer

Some day I will but I just don't have any use for it right now. My buddy is looking for a pontoon boat and I thought I could give it to him as a kicker.

Giving the dealer a call is a good idea. You need the silencer and all the other parts shown. There is about four screw bolts. So with out the silencer is your choke lever bouncing off the carb. connection point? My recollection is the silencer parts is what holds the choke lever in place. Rick.

 

[iwombat]

Re: 9.9 Air Silencer

Without that silencer you need to take a careful look at your plugs and make sure you're not running too lean.

 

[Chinewalker]

Re: 9.9 Air Silencer

The silencer actually has a small bit of a tuning effect on the motor. There is a standing wave in front of the carburetor while running. That wave moves a bit at different RPMS but the end result is that at top RPM the wave can produce a tiny bit of an extra air charge into the carb. A friend of mine who raced the 15hp version of that motor did extensive testing and found about a 50 to 75 RPM increase with than without.

 

[Landscaping Wiz 808]

Re: 9.9 Air Silencer

Thanks for the responses!

Rick - No, luckily the metal choke lever on the carburetor holds the plastic choke push/pull control on one end and the hole in the front fascia of the motor holds the other. Looking at the diagram, it looks like the lever passes clean through the silencer.

iwombat - I checked the plugs when I changed 'em a few days ago and they had not much, but some carbon build-up. Does that sound about right? I'm pretty strict about making sure my oil/gas mixture is correct. I run about 60% at slow trolling speed and 40% at WOT if that helps.

Chinewalker - Thanks, I'm definitely going to get one. I'll look for a complete assembly before I break down & buy all the parts to assemble myself.

BOB

 

[iwombat]

Re: 9.9 Air Silencer

You want to be sure the ceramic insulator is a nice tan/brown color. If it's leaning toward white you're running lean.

 

[Landscaping Wiz 808]

Re: 9.9 Air Silencer

iwombat - I will check the old plugs when I get down to the shop. Which part of the ceramic insulator are you referring to?

Also, I called the parts supplier I got some stuff from before and he said he'd check some old 9.9s he had in the back tomorrow. I'll keep my fingers crossed.

BOB

 

[iwombat]

Re: 9.9 Air Silencer

The ceramic that surrounds the electrode (in the combustion chamber). NOT the porcelain on the outside of the plug.

 

[Landscaping Wiz 808]

Re: 9.9 Air Silencer

The silencer actually has a small bit of a tuning effect on the motor. There is a standing wave in front of the carburetor while running. That wave moves a bit at different RPMS but the end result is that at top RPM the wave can produce a tiny bit of an extra air charge into the carb. A friend of mine who raced the 15hp version of that motor did extensive testing and found about a 50 to 75 RPM increase with than without.

Alright, I found an air silencer assembly on ebay and it was waiting in the mail when I got home from work. I installed it and ran it on the muffs, but didn't notice any discernible difference from before. I wanted to take the boat down to the river to test it but the 'ol lady's letting me take her to dinner......only kidding. I will try to sneak out of work early tomorrow to get some official testing done!

BOB