Sluggish running 85hp

[Buffalo79]

I have a 1978 85hp Evinrude (85890c). It does fine at idle, but has no power on top end. Compression is good on all cylinders. Rebuilt carbs about 1 1/2 years ago. Took apart and cleaned carbs last week (didnt notice any thing wrong) All new fuel lines from tank to carb. New filters. Have even tried different fuel tanks. Has new plugs gapped properly, and all plugs have fire. What is left that I should check Any ideas?

 

[ezeke]

Re: Sluggish running 85hp

Check your setup; you want to be at close to 5800 RPM max at WOT. If you are overpropped, you will lug your engine and coke it up, and you won't get good performance.

You want the A/V plate parallel to the water on plane and in line with the bottom of the boat or slightly higher.

Also check your boat for wet floatation and for for hook.

 

[Buffalo79]

Re: Sluggish running 85hp

This is same set up I have ran for years, havent made any changes as far as any of that goes. Always ran good before. It just has nothin past half throttle. Should I go ahead and do another complete carb rebuild or should I look at something else?

 

[Buffalo79]

Re: Sluggish running 85hp

Also forgot to add that after I try to run at full throttle and then idle back down it will die and not restart for 10 or 15 minutes.

 

[iwombat]

Re: Sluggish running 85hp

I see you did a compression check, did you do a spark check too?

When you rebuilt the carbs did you remove the jets and clean behind them?

The no start symptom could be caused by a flooded carb. When you open them back up check the float settings carefully.

 

[Buffalo79]

Re: Sluggish running 85hp

Did spark check, its good

As far as the jets, yes I did when i did the rebuild over a year ago. But since it hadnt been very long since rebuild, this time only sprayed carb cleaner and used air to clean. Floats seem to be working good, maybe I just need to do another complete carb rebuild, just wanted to see if there was something i was overlooking here.

 

[iwombat]

Re: Sluggish running 85hp

Wouldn't hurt to check your fuel system for leaks or restrictions too. An air leak will cause poor performance like you describe.

 

[Buffalo79]

Re: Sluggish running 85hp

Thanks

I will check for air leaks one more time to make sure i didnt miss something.

If I go ahead and do another complete tear down on the carbs any tips on seating the jets after cleaning? How many turns I should put in etc. for the best possible performance?

 

[iwombat]

Re: Sluggish running 85hp

Make sure to craft a tool to remove the jets (do a search). Remove what you can, then get yourself a one-gallon can of carb cleaner and soak everything for an hour or seven. Run some copper wire (not steel) down the jet orifices. Blast aerosol carb cleaner or (better) compressed air through everything and reassemble.

Those are fixed jets - there's no adjustment. Put them in, and tighten until snug (with the jet tool).

 

[ezeke]

Re: Sluggish running 85hp

All of the jets are fixed and require no adjustment once seated. You will need a proper driver. If you abuse the jets they will not come out and they will not work properly.