Carb jet help with a 2005 90hp 3cyl

[homelite]

I have a 2005 Merc 90 3cyl. [FONT=&quot]S/N 1B173557. All 3 carbs have the same jet # on them. .060"

I wiped the top piston and having it bored .015 over. I am checking every possible cause and I am trying to make sure it is not too lean. The carbs are clean as a pin. I am trying to make head nor tails of the jet size vs the Merc factory manual. Nothing adds up. Manual number is 90-830234R3, which is correct according to mercury's website.

Can anyone tell me how to verify mine have the proper jet? Any advise on whether I should go up a size to be a little richer as to insure no piston failure again?

Carb info is:[/FONT] [FONT=&quot]WME[/FONT]
[FONT=&quot]2XK[/FONT]
[FONT=&quot]3301-824854-01[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]108-1A 0665[/FONT]


[FONT=&quot]This engine was bought new by a friend and it was never altered, so nothing was changed from the factory.

Thanks in advance if anyone can shed some light on this for me.[/FONT]

 

[Faztbullet]

What series carb do you have the WME # is stamped on the body. It show that if a .060 jet fits the WME-108 carbs.

 

[homelite]

I'm sorry. I have all that info sitting here and forgot to put it in my post. It is: [FONT=&quot]WME[/FONT]
[FONT=&quot]2XK[/FONT]
[FONT=&quot]3301-824854-01[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]108-1A 0665[/FONT]

 

[Texasmark]

My service manual for the 75 thru 125 3 and 4 cyl loopers lists the carbs by WXX number and the jet required for the position the carb occupies in the engine. Not all the jets were identical. I forget which was which but there was a difference. Apparently has to do with fuel scavenging for the changes in the casting geometry as you move from one extreme to the other and possibly heat on one extreme not experienced on the other.

 

[flyingscott]

Your jet is fine ran 10yrs and no problems make sure the carb is cleaned and rebuilt and assemble the motor carefully. My question would be is it the original water pump. Is the electrical all within specs.

 

[gm280]

I know you stated that all the carbs are clean as pins. But I would certainly remove them and actually verify the jets are totally opened to the initial size they were installed when new. I am certain you can fine the actual drill size for the #60 jets, and then you can take that drill size to see if it fits through the jet opening. That would be my first thing to check. JMHO!

 

[Texasmark]

On the "clean as a pin" comment. Last time I had a look at my carbs, I too thought they were "clean as a pin". However, before I closed things back up I thought I'd give them a blast of compressed air one more time. Lo and behold, this tiny black spec (fuel line degradation particle) comes blasting out of the high speed jet socket on "3. Geez. Smoking gun. Put her back together and ran like a top. Problem solved.

 

[tommarvin]

Im asking the first post he was worried about being to lean, is being to lean mean the idle air fuel mixture screw is set to lean, or can the high speed jet be to lean?

 

[Texasmark]

If the high speed jet or canal gets clogged with debris, it seriously affects a 3 cylinder engine, worse so in a 2 cyl, and death to a single if you want anything more than idle. Many years ago the wizards of design in the marine industry or our overly protective govt. decided that you didn't need a variable high speed jet and quit installing two tweaks on your carb. So now the high speed jet is a brass pellet with a hole in it, hole sized for the engine's requirements. Blocking off a high speed jet means that you are going to get no or sub par performance out of that cylinder and your WOT mph will definitely suffer.

 

[homelite]

ok so I missed most of this info. I just read it all. On the carbs, they are clean as a pin on the inside. No debris. Perfect. On the water pump, YES, unfortunately it is OEM and 10 years old. It has a set, but is in good shape. Maybe this was the cause? Maybe it overheated the top cylinder? I have no way of knowing. It had a strong telltale! I got carb kits and will rebuild them. Got the block bored .015" over on the top cyl and will reassemble and give it a try! Thanks all.