Johnson 55HP 1978 55EL78S carbs

I just cleaned the carbs because the motor was not idling. The motor now idles a lot better. But the top end is now way off.

I can inch up the throttle and get the boat up on plane, but if I go past about 3/4 throttle, the engine bogs down or can go Whaah Whaah Whaah Whaah Whaah Whaah Whaah Whaah like it's trying to climb up to WOT repeatedly.

If I get the motor running as fast as it will go and shut it down, the advance is all the way up against the stopper and the carb throttles are open about half way.

There's the profound smell of unburnt fuel! And it's burning a lot of gas.

Re: Johnson 55HP 1978 55EL78S carbs

is the vent completely open on the fuel tank?

Re: Johnson 55HP 1978 55EL78S carbs

I've checked the fuel flow = The vent is open.

There may be a problem with the main jets,..
There may be a problem with the link and sinc,...
There may be a problem with the advance,...

All these were affected by the carb removal and cleaning. The advance was changed in earlier trouble shooting and I don't have a book or instructions. I've been trying to tune the motor advance by ear without a book.

I've worked on a few 2 stroke engines. Mostly bikes. I need a clue or two about what it means when the engine is going wah wah like it's trying to open up.

I'm worried about the smell of gas because it's indicative of improper combustion.

Re: Johnson 55HP 1978 55EL78S carbs

It sounds like you are dropping spark on one cyl.

Re: Johnson 55HP 1978 55EL78S carbs

bolter15 sounds like you need to do a link and sync, you really need a manual.

Jeff.

Re: Johnson 55HP 1978 55EL78S carbs

The carbs were very clean.... But the screws had rattled loose. Both Drain screws were loose and one had rattled completely out of the carb. So that's the reason for the WHah WHah running with a lot of extra air getting to the main jet and a lot of fuel just spilling out the bottom of the carb!!

The link and Sinc thing needs doing. Does any one have a link to a good article about it??

Right now, the motor will idle, but not very long. It also has a slight tendency to hesitate that's got a lot better since the cleaning.

As it sits, The screw that sets low throttle and low advance, is almost all the way in. The throttle rod is about in the middle, and the carbs are exactly equal. The max advance stop is about in the middle too.

I've got 130# compression on the top cylinder and about 145# on the lower cylinder. The original carb balancing had the top carb slightly opened at idle.

Right now I'm working by ear and making some progress. The top end sounds very sweet. And it jumps right out of the water if the boat isn't loaded. It feels a little bit more sluggish with a full load than it once did. So I think I have just slightly less power under full load.

I have to lift the throttle lever to get the motor to start even when it's hot.