1987 Evinrude 25 hp idle issue

AaronS76

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Jan 30, 2017
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Hi all

I have been having problems getting my motor to idle. I have put a carby kit through it, with no change. My question is this - how does the fuel get from the bowl to the idle jet? I thought I had cleaned everything out but now wonder if I missed something and I need to pull it down again and clean out some more.

THanks
Aaron
 

racerone

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Nearly every novice starts with the carburetor rebuild.-------------First report the compression values.------And when did it run / idle ok last .
 

AaronS76

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Do not have a compression gauge, so I cannot answer that question sorry. Here I was thinking these things are just a motor. Sheesh it has been a steep learning curve. I have only had it 8 months. It ran well when purchased but didn't idle. Idled well after I fiddled with it a few months ago but it ran terribly. Then I fiddled more. And fiddled more trying to figure this thing out. I hope I understand the timing now and need to get it back out to check. Then I need to fix the idle. When I bought it it could push my 14 ft alu boat at 45 kph. Figured that was pretty good.

Am thinking of taking into local shop but I like to understand how things work.

Aaron
 

racerone

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Have you adjusted the stop on that thin rod that goes to the back of the motor , yes or no ?--------Is there a gap at that stop in slowest throttle position ?
 

AaronS76

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Thanks for this Racer. Starting to get interesting. To answer your question - yes I have moved it. No there is no gap between the stop with a screw in it and the bit of the motor it rests on.
 

AaronS76

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I will also add that I have access to a manual. But I stuffed things fiddling and trying to figure things out. These things are different and complicated.
 

racerone

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People often adjust that stop because when it is correct it " looks wrong " to a novice.---At dead slow idle there usually is about 3/16" gap.-----try that.
 

AaronS76

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OK. Have to head away for work so will reply in a week or so. Appreciate the assistance.

As I said I have fiddled with this. I have set the WOT timing to 26 degrees as per the Mr Reeves process. I set the roller on the cam so at idle it is between the two prongs on the cam (if it called a cam), and I adjusted the butterly on the starboard side so it is horizontal at WOT and moves once I open the throttle. That was my interpretation from the manual. Does this seem correct? Am a little confused though. Do I set the roller back before the two prongs at idle so that when it gets between them that is when the other bit hits the stop and starts opening the butterfly (I hope this makes sense).

Once again. Appreciate the assistance and I will give moving that stop a go.

Regards
Aaron
 

AaronS76

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Ok. So put a gap in between stopper and thing it rests on but no difference. Now the roller sits to the port side of the timing marks and lifts off inbetween them.

The way the WOT timing is set up is the cam hits the stop around 2/3 throttle and stops and then the butterfly in the carb continues to open as you open up the throttle. Is this right? Or the root of my problem?
 

hardwater fisherman

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If anything like some older models. The cam of the throttle plate should just start to move when the roller or pointer line up with the marks.
 

AaronS76

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Thanks

Reading the manual for the umpteenth time, the timing comes before sync if the powerpack is replaced. So, that is the first thing to do? It also says to set the throttle at a minimum of 3500 RPM and adjust so that it hits the stop at that. Now a minimum is confusing because if I set it to hit the stop at 4500 instead the idle timing would be different. But I will borrow my mates tacho and set it to hit the stop at 3500. Then make sure the roller is between the marks at idle etc.
 

AaronS76

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SO I bought a compression gauge. Both cylinders @ 95 psi. Manual says difference is more important than actual. Anyone have any thoughts on these numbers?

THanks
 

oldboat1

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Understanding readings can vary between gauges -- your readings are a little low. If accurate, the idle can be affected a bit, but you might be able to compensate. Your '87 carb should have an idle adjustment needle on top -- top of the carb has idle passages that need to be open and clean. If you are going to go back into the carb, I would concentrate on the idle passages. (The bottom h.s. jet is fixed. Clear it with some soaking or carb spray.) Spark needs to be strong at about a half inch.
 

AaronS76

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Thankyou.

I also put some oil in cylinders and saw no increase. So if shagged, they both are.

I also tested spark but only while pulling on manual starter. Wiuldnt jump a 1/4 inch. Will now troubleshoot electrics.

Thanks again.
 
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