FINAL UPDATE: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

[castiron]

New here to the site! Ya'll have helped me out a lot so far, thanks!

I recently purchased a 1978 85 HP Javelin outboard motor. When I ran it the first time with the then owner, it ran great (of course). It went about 32-34 mph full throttle and had absolutely no problem getting on plane. However, since then I have had trouble with it getting about 2200-2400 RPM. The only thing I did once I bought the boat was add fuel and oil at the 50:1 ratio that I was supposed to. I have checked compression (#1 = 107, #2 = 100, #3 = 105, #4 = 110). It has great blue spark on all four plugs. Removed the outlet hose of fuel pump and it is pumping fuel when cranked. Fuel lines and hoses all look in great shape and the primer bulb is hard when you press it vertically. I sprayed carb cleaner in the carbs and put two bottles of carb cleaner in the gas and ran it on the river just trolling. No difference in speed. It runs great in neutral and will rev to top RPM out of water in wide open throttle. I am at a loss of what to check next?!? Any ideas. TIA.

Pictures are of carb at neutral, Idle, and wide open throttle. These are pictures from top two cylinders.

 

[Chinewalker]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

You have good compression, and apparently good spark, so that leaves fuel. Spraying carb cleaner in the carbs does nothing. The proper way to clean carbs is the remove them, disassemble them and rebuild them with the correct ethanol resistant carb kits.

NEVER rev the motor with no load, either in neutral or out of the water. It serves no diagnostic purpose as the motor will free spin, even when only running on one or two cylinders.

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Thanks for the reply. I looked on ********** for the carb repair kit. Do i need to get 4 of them or just 1?

 

[Chinewalker]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Two carbs, two kits. Available right here on iboats...

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Great. I'll order them today.

I decided to take off the carbs before the kits get here to make sure I wasn't missing anything obvious (gunk, broken part, etc) inside of the carbs. I did notice that the pin connecting to the top carb black floater was not actually connected to it. On the bottom carb, there was a pin with a small metal piece connecting to the pin. When the floater went "out" on the top carb, the pin did not. On the bottom carb, the pin did go out because of this connection.

Is this normal?? I can't see why one carb would have this and the other one not?

Also, how mechanically skilled do you need to be to install the repair kit? Thanks again everyone.

The pics show the two pins once they were taken out and also while they were installed in the carb.

 

[Chinewalker]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

If you can take the carb apart, you can put it back together - ain't rocket science. Getting the float level right is key - explained in the kit instructions. Looks like someone rebuilt one of your carbs at some point with a newer style needle with the clip. Your new kits will each come with a new needle and clip...

Stuck float needle will cause EXACTLY the symptoms you described as it would prevent fuel from entering the bowl of the affected carb, and by extension, prevent fuel from feeding two cylinders. Top revs with two cylinders starved? Likely around 2200-2500 RPM...

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

They'll be here soon enough. I'll let everyone know how it goes. Thanks Chinewalker.

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

UPDATE:

I received the two carburetor repair kits yesterday and put them on the motor today. Easy to install. I soaked the carb in carb cleaning liquid for 15 minutes and then reassembled in the original order. Wasn't that hard. After putting everything back together I started the motor and it seems like its running smoother (just in the driveway). I did not rev it up or put it in gear, just let it idle for 15-30 secs.

I brought it out on the river after and it is STILL only revving up to 2700-2800 RPM. I am completely disappointed. I don't know where else to go after this. I check the spark plugs when I got back to the house and they are all exactly the same, not blue but very white.

Any ideas on where to go from here? Could it be the coils, power pack?? Thanks.

 

[nwcove]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

if a 15 minute soak was all you did, it probably didnt do much to clean the carbs. you need to soak them , preferably overnight, and blow out all passages with compressed air at a minimum.

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

The reason I soaked them for only 15-30 minutes each was because those were what the repair kit instructions stated to do. Specifically it said maximum 15 minutes. I did not have compressed air so all I did was spray carb cleaner throughout the ports. Should I take it down and redo? How much air pressure does an average gas station air compressor have?

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

I guess I'll just have to take them off again and soak them overnight and use an air compressor to fully clear the carbs out. In the meantime, is there another solution as to why I still cannot go above 2500 RPM. Boat idles perfect, no sputtering, starts quick and strong.

Random question, but could this at all be related to the battery?

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Well I just realized that I might have put the core plugs in upside down. The dome part was pointed downwards and I punched them in and made them fit. Would this cause a problem? Sorry for so many questions.

 

[dockrat100]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

If they don't make a good seal and are therefore sucking air, could cause a problem. The dome up should be struck with a flat punch, which pushes the plug outward, giving a tight fit. I doubt your fit is a tight one as described.

 

[emdsapmgr]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Also possible that you are losing spark. Weak ignition components tend to fail once the engine heats up to normal operating temps. Runs fine when cold, then may run as you indicate once the engine warms up. Next time you are out boating, warm the engine up, then remove the cowling and use an inductive timing light to check all 4 spark plug wires for spark. That engine has two power packs, each controls spark to one head. If you find no spark on one head, swap the power packs and see if the problem moves.

 

[castiron]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Thanks for all the replys, I really appreciate it.

I am going to rebuild the carbs with the new core plugs that I had to order again. Hopefully this will fix it, we'll see.

When you say use an inductive timing light to test for spark, do you mean use that tool to just test to see if there is spark or actually use check the timing on the spark plug? What are the exact steps to doing this?

 

[emdsapmgr]

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

The timing light will show the quality of spark on each plug while the engine is running. Snap the spark plug lead over each spark plug wire and check the gun flashes. The flashes from the gun will show misfires, no fires, weak firing-all from the flashes from the gun. Best to have the engine fully warmed up and under some type of load. Test it when idling in gear at the dock. Possible you have one plug not getting strong spark.

 

[castiron]

Re: UPDATE: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: UPDATE: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Hope everyone had a great Christmas!

Update: I just received my new core plugs in and have been soaking my carb for the past 12 hours. I will put the new core plugs in this afternoon and run it over the next couple of days. Also, I will be use an inductive timing light to check for spark plug inconsistency.

One question: when putting the carb back together, do I just screw the screws in as tight as I can get them? I've read that certain parts need so many turns, and if you do it too much it'll run rich/lean. I'm not sure if that applies to outboard carbs or what. Again, I am no carb expert at all. Thanks again!

 

[emdsapmgr]

Re: UPDATE: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Re: UPDATE: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

Those carbs should not have any "adjustable" screws that model year. The internal jets are all considered "fixed." I'd snug the 4 bowl screws, jets, float valve housing and the bowl drain screws so they won't back out-but not to the extent that they are "as tight as you can get them."

 

[castiron]

Re: FINAL UPDATE: 1978 85 HP Javelin SeaHorse (Johnson) won't go above 2200-2500 RPM

FINAL UPDATE:

I have completely redone the carbs for the second time. This time I soaked them in the carb cleaner overnight and then sprayed compressed air into them. I redid the core plugs which I had previously installed uncorrected. Unfortunately, I went and bought myself a inductive timing light ($40) without testing it before I went to the river. However, I went to the river and she got up on plane immediately and was going ~37 mph at 5500 RPM. It had not done this previously.

It seems as if though the carbs either dirty or that the pin in one of the floats was getting stuck and not allowing enough fuel in. Either way, it seems as if though the problem is fixed.

Thanks to everyone who helped and hopefully this thread may help someone in the future!