Idle Adjustment 1993 Evinrude 50 Hsp

[gnrboyd]

I have a 93 Evinrude 50 Hsp that I am needing some advice on idle adjustment. I bought the boat a year and a half ago and the owner had just had the pistons replaced. The mechanic that worked on it said it needed 3 tanks (18 gallons) run through it at double oil to break in the motor. (It has the VRO so I was mixing 50:1 in the tank also.)

Last year, I just ran the last tank of double oil dry before putting the boat up for the winter. All season, I had trouble keeping the boat idling. It wouldn't idle without dying most of the time. I attributed that to the double oil causing the problem so I left it alone. As I recall, the tach said around 600-700 at idle. (But I could be mistaken.... I'm over 40 so the CRS is kickin in.)

After pulling the boat out this spring, I realized that the plugs that were in it were the wrong ones. It had QL78C plugs and the motor calls for QL78YC. I don't know if that makes much difference or not. (Not sure what the extra Y means) I replaced them with new QL78YCs gapped at .030.

I also decided to replace the fuel filter and notices it had the wrong one in it. It had part 398327 in it which has 5/16 nipples on each end. The motor called for part 435918 which has a 5/16 nipple on the supply side and a 3/8 on the delivery side. Also, the direction arrow was going in the opposite direction of the fuel flow so it was installed backwards. (However I don't know if that matters that much ... I blew on it from each end and couldn't tell any difference in restriction.)

After a few cranks to get the gas flowing, it started. The motor seemed to run less sluggish at idle than last year and it doesn't die. (At least on muffs in the driveway) In fact, I think is idling too fast. The tach shows about 1500 at idle. I'm not sure what the recommended idle speed is, but it sounds a little too fast to me.

My question.... I've heard that idle speed on muffs is different than while on the lake. Is there a rule of thumb to set it on muffs so that it will adjust accordingly at the lake? What are the recommended rpms on the water and on muffs?

I thought I probably shouldn't mess with it until I at least try it on the lake but if the experts around here have some standard rules of thumb that work, I might go ahead and try it.

Also... I assume I only need to adjust the idle screw which I think is located on the side of the motor and has a bolt with a rubber tip on the end along with a nut to lock down the bolt once adjusted. Is this correct?

(See red arrow in photo) Thanks for your help.

 

[tashasdaddy]

Re: Idle Adjustment 1993 Evinrude 50 Hsp

i have the same motor. you are correct. red arrow, is idle speed stop screw. disconnect our throttle cable, and adjust the screw. then adjust the trunion nut under the clamp to meet motor, without moving motor linkage. these adjustments should be made in the water, and with the motor running in forward gear. it is not hard to do. you idle rpms in gear should be 600-750, the lower the better, as long as it does not stall when shifting.

also add seafoam to your fuel per directions on the can. and get a can of BRP engine tune, it has a hose that attaches to the primer, schrader valve (Red) handle. and clean out the engine after running all that oil thru it.

 

[gnrboyd]

Re: Idle Adjustment 1993 Evinrude 50 Hsp

I did run some sea foam through all the tanks last year hoping that would help cut down on problems the extra oil can cause.

I'm afraid I'm not quite following you on the adjustment. When you say, "disconnect your throttle cable" are you saying to remove the bolt holding the retainer plate that keeps both cables secure? (I've never had a boat with throtle cables before.)

Then you say to "adjust the trunion nut under the clamp to meet motor, without moving motor linkage." Again, I'm not following. What is a trunion nut and what clamp are you referring to? (Sorry.. I have not done too much motor work.)

If the rpms should be 600-750 while in gear and in the water, do you have an approximate amount of what it should be using muffs in neutral? Should it be the same or would it be higher? If you say to adjust in gear, I assume you mean just to ajust the throttle lever at the point where it just first goes into gear. Correct? As a side note, mine seems to have a fair amount of distanct to travel from neutral until the motor starts picking up. Is this normal ?

Thanks for your help.

 

[Silvertip]

Re: Idle Adjustment 1993 Evinrude 50 Hsp

The throttle cable is the cable that runs from the throttle/shift control box at the helm to the motor. The sheath (outer casing of the cable) is held at the motor by a clamp. You disconnect the inner (moveable) part of the cable from the throttle linkage by removing the retainer and pin. Now you can adjust the idle. If you don't disconnect the cable the adjustment can bind up the linkage so it still won't idle right. When the idle is correct, you need to reattach the cable but pay attention here. You hold the throttle linkage against its stop. You then bring the end of the cable up to the linkage. If the pin does not slide into the linkage freely (do not move the throttle linkage to do this). Instead, turn the knurled adjustment wheel (trunion) on the threaded portion of the cable sheath. This lengthens or shortens the cable so the pin will slide back in. The trunion can be adjusted without removing the clamp. It is spring steel piece and prevents the trunion from turning by vibration but allows manual adjustment. Engines will always idle slower in the water than on land due to the back pressure on the exhaust so this adjustment needs to be done in the water.

 

[gnrboyd]

Re: Idle Adjustment 1993 Evinrude 50 Hsp

After re-reading both Silvertip's and tashasdaddy's posts and studying the motor, I think I understand what to do. I think I was trying to make it more difficult than it is.

Are the paper clip looking retainer clips on the throttle linkage re-usable or do you need to replace them. It looks like they slip through the hole and then wrap around the pin. I'm guessing I won't get that one out and be able to get it back looking as neat as this one does.

If you replace them, is there anything special about the wire? I pulled up the part number that I found (333774) and it says 1.96 retail and they come in a 10 pack. I know Evinrude sometimes packages small parts in multiples but prices them individually. Anyone know if these are really priced 1.96 each or if this is really a 10 pack?

Thanks tashasdaddy and Silvertip for the help.

 

[tashasdaddy]

Re: Idle Adjustment 1993 Evinrude 50 Hsp

the clips are reusable. remove the clip, and the connector, now adjust your idle. when it is right, with the controller in neutral and idle. you can remove the nut holding the clamp, then turn the black trunion nut so that the connector fits the motor linkage.

you always adjust the cables to the engine, not the engine to the cables.

That is a great motor, keep it maintained, it will give you great service for many more years. Good luck

 

[gnrboyd]

Re: Idle Adjustment 1993 Evinrude 50 Hsp

Just to clarify, I don't have to disconnect the shift cable at all during this process.... only the throttle (upper) Correct? The photo you edited in green looks like a line drawn across the shift cable instead of the throttle cable. I'm assuming you were just trying to show the trunion/adjustment wheel on the upper cable so I just wanted to clarify that.

I know this is as about as simple as a outboard repairs get but with me, I can take something simple and mess it up in no time.

Again, thanks to both of you.