Evinrude 120 Boggs

HC · Apr 17, 2004

I got my '85 120hp rude on the water for the first time. It took a little to get it to start in the start postiion and then fast idled fine. When the handle was moved to idle the engine would die. I finally got it moving but it like to never come up on plane. The engine was bogging big time. The rpm was only about 2K at wot. Once on plane it ran like an ape. Really quick and good high speed throtle response. But off plane it would die and not idle in the idle position or low speed settings. Again it bogged on next wot. A couple times I hit the choke and the engine speeded up then died. I can't tell if it's flooding or starved for gas. My local shop put kits in all the carbs and said he ran it on the dyno before this first tirp. He complained about the gas (old) so this tells me he must have been having a problem making it run but said it was okay. I have new fuel. New oil (VRO). I want to isolate the problem not just shotgun it. Anyone have any ideas?? Also the book calls for QL77J4 plugs for low speed, and OL78V for high speed. I do both. Which should I use? Any help is welcome! TNFisher

Dhadley · Apr 17, 2004

Re: Evinrude 120 Boggs

Were kits simply installed or were the carb bodies and throttle bodies soaked and then the kits were installed? If so what were they soaked in? Are we sure the low and mid range jets were not mixed up? Did you get rid of all the old fuel or just put new fuel on top? What grade fuel? Dynos are a great tool but they should never be used instead of an in-water run. QL77JC4's are fine.

HC · Apr 17, 2004

Re: Evinrude 120 Boggs

I don't know what he did to the carbs. He said he put new kits in each one. I'll have to pay him a visit to find out. I'm not sure I would use this guy again. Don't know about the Jets. He showed me the old parts and the jets were there. I may have to open them up and check myself. Got to locate a good book for this engine firs. My evinrude book skipps over the 120. I completly drained the fuel tank, well best as I could anyway. Didn't see any water or junk. The fuel filter is clean but has some minor sediment in the bottom. Replaced with regular fuel (87 oct). Would premium be better? Like I said once on plane it was real quick on the 15 Skeeter. Thank, TNFisher

Dhadley · Apr 17, 2004

Re: Evinrude 120 Boggs

The jets should be in the carbs, not with the old parts. New ones are not part of the rebuild kit. I see your point about finding a new guy. I think a good cleaning will fix you up. Get the OE service manual and make sure the right jets are where they're supposed to be. 87 octane is fine.

93bronco · Apr 17, 2004

Re: Evinrude 120 Boggs

Dh is the expert. here are some numbers for you. 1985 120 #43 intermediate jet (left side middle of carbs) #14 idle jet (below above) #57D high speed (behind drain plug in fuel bowl). - hopefully what you are seaing are the 4 needle & valve seats for the floats. those would have come in the kit. - if you go to the search above & type in 120 jets, you will find some good posts to read. the 1985 to 1987 120/140 are the small bore loopvee's. good luck

HC · Apr 17, 2004

Re: Evinrude 120 Boggs

Thanks Guys, I ordered a Clymers book. Hope this is good enough. It may have been the seats now that you mention it. It was just a quick look when I picked it up and besides it was snowing too. I may have found a air leak in the stock fuel filter. The top was not screwed down real tight. May take it to the water tomorrow for a quick test before I go into the carbs. I'll keep surffing as you suggest. Thanks, THFisher "fishing time is waisting!"

Dhadley · Apr 18, 2004

Re: Evinrude 120 Boggs

The Clymer is OK but very general. Get an OE manual for more specific details about your engine.

HC · Apr 19, 2004

Re: Evinrude 120 Boggs

DH and 2K, Thanks for the help. I pulled the carb cover and inspected the low and intermediate speed jets. All were in the correct locations however, three of the four low speed jets were plugged. I cleaned them out, reinstalled and fired it up on the muffs. Ran like a charm at idle. Started great too. Idle speed was up a couple hundred rpm from before. About 800 in netural. Put it in gear and run it up just a little and it acted fine. I think this will take care of the problem. Looks like my mechanic only put in new gaskets, floats and seats. Didn't do much cleaning. If this don't fix the problem I'll go in deeper. I'm going to add a little Marvel Mystery oil to the fuel. I've used this stuff for years with only good results. They claim it's good for all marine engines. I know guys that use it in aircraft engines also. I'll let you know how it runs on the water. Again thanks. TNFisher

Dhadley · Apr 20, 2004

Re: Evinrude 120 Boggs

Since we suspect the carbs werent cleaned, I wouldnt run it until thats done. If the low speed jets were clogged (which will make the motor run rich) the hi speed jet may be clogged. When that jet is clogged, the motor runs lean. Pistons react very badly to lean conditions.

HC · Apr 28, 2004

Re: Evinrude 120 Boggs

DH, I got my clymers and you are right, real general!! I pulled the carbs and cleaned every thing. All passages clean, jets, good etc. Really a simple carb. Put in new plugs and reinstalled carbs along with a new fuel bulb. Engine started right up in idle position with just one hit on the choke. Revs have comeup and it idles at about 1K. Idle scred is completle off the stop but I can bring it down by hand. Got to do some checking. Anyway, it seems to run much better on the muffs. Haven't had it to the water yet. I noticed some spitting coming out of the idle jets. Just occasional but coming from all the carbs. What might cause this? Also seems to have a slight miss or stutter during idle and fast idle (1.5K). May be nothing. Just sounds like a high performance motor. Almost like the cam lope in a hp car big block. The spitting is a concern. Any response is welcome. Thanks, TNFisher

Dhadley · Apr 28, 2004

Re: Evinrude 120 Boggs

What brand plugs? If the motor is spitting, its leaking air somewhere. We need to correct that. Dont adjust the idle with the screw in the throttle arm. Go by the book on this one.

HC · Apr 28, 2004

Re: Evinrude 120 Boggs

DH The plugs are Champion QL77JC4. Set at .040 as the book call for on the '85. I'll go over the idle setting tonight. Also think I'll find my compression gague and check that too. May even go buy a timing light, my old one has went belly up. What type of air leak do you suspect? I used the old carb to manafold gaskets. They were in good shape. I found out the boat mechanic did not even rebuild the carbs he charged me for. Didn't look like anything inside had been replaced. The needle seats were tarnished and the gaskets had residue that couldn't have been on a new one. I pressure checked the seats and they are working fine. Everything in the intake area looks shipshape and tight. For an old motor this thing is in really good shape. Could the reed valves be bad? Take care, TNFisher

Dhadley · Apr 28, 2004

Re: Evinrude 120 Boggs

Good choice on plugs. The "sneeze" or cough could be caused by the motor sucking air from anywhere. Could be the old base gaskets. (There should have been new ones in the kits) Could be one of the carb to throttle body O rings out of place. Not likely a reed but it could be a reed gasket. It could be the side plate or gasket. It could just be out of sync. Especially if you adjusted the idle with the screw in the throttle arm. Remember -- you need backpressure to set the idle properly. Are the float levels correct?

HC · Apr 28, 2004

Re: Evinrude 120 Boggs

The floats are set per the book. Used a stright edge to set. Will double check the book just in case. I may have screwed up the sinc. I'll check the proceedure and get back. TNFisher

HC · May 3, 2004

Re: Evinrude 120 Boggs

Here's the latest! I set all the following by the book: Sync'ed the throttle Valve Adjusted the Cam pickup point Set the WOT Stop adjustment Set the Throttle Cable Adjustment (Could not adjust timing. No access to a tank) The above adjustments were made on the muffs. No load idle is about 1k RPM There is a noticeable improvement in the idle but it still sounds like it's loading up on at least one cylinder. Ran a can of OMC Engine Tuner through the thing and let it set for about 8 hours. Still getting spitting fuel out of some of the low speed jets. It's real small drops but for sure coming from the low speed jets. When I removed the carb silencer there is a small amount of fuel in the silencer, about a 1/2 teaspoon or so. This may leak when the motor is placed in the tilt position for towing. No evedence of flooding. No leaking anywhere. I took it to the lake Sunday and it started right up and idled fine. At the lake I checked the loaded idle and it was about 600/650 RPM. The thing is still sluggish getting on plane but it comes up better now. Intermeadate speed and WOT speed is fine. The thing preforms very well on the top end. Pushes the Skeeter 15' at about 50-55 at my best guess. Back at idle it starts to load up. I noticed what seemed to be a little too much blue smoke when I cleared it out with a fast idle. I wonder if the VRO could be putting out too much oil causing all the problems?? I did run a compression check (engine cold): 135, 138, 129, 130. Anyway, it's a lot better but a long way from prefect. Anymore Ideas?? Thanks for the help, TN Fisher

Evinrude 120 Boggs

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