1988 Yamaha 130 won't idle just bought it

[fishon71]

Re: 1988 Yamaha 130 won't idle just bought it

Rodbolt, thanks. I was a little concerned to pull sending unit even though it probably is a good idea to clean and best way to get all the gas out. But my concern is the gasket on this 1988 Sea Ox boat, you think I’m going to be able to find a new gasket? I think its an aluminum tank, could be stainless I doubt it though. Also the concern of braking some screws or something.

 

[rodbolt]

Re: 1988 Yamaha 130 won't idle just bought it

it should have the standard 5 hole gasket. its one of the few things that are standard as long as it was not some off the wall custom tank.

 

[fishon71]

Re: 1988 Yamaha 130 won't idle just bought it

Okay, fired up with rebuilt carbs, WOW what a difference but new problem. They engine idles at 1500 and set screw does not seem to reduce idle even when all the way out. Some questions:<br />1) I assume this 1988 with manual choke does not have an electronic high idle circuit like my 97- 250 did and should idle right down even when cold? Right/Wrong?<br />2) What do the pilot screws do? Before re-building they were set to 1 ½ out, Rodbolt say set to 1 ¼. Book says 5/8 – 1 1/8 . If I bring them all in does this reduce idle

 

[Ray Neudecker]

Re: 1988 Yamaha 130 won't idle just bought it

I would suspect the idle timing adjustment to be off. Back off the screw facing to the rear in the control arm. They have a tendency to vibrate out of position. When this is correct, you will need to increase the fuel adjustment screw on the carb to balance it out.

 

[fishon71]

Re: 1988 Yamaha 130 won't idle just bought it

Okay that was the answer, idle perfect at 800 now with little fluxation. I need to under stand a few things here though:<br /><br />I backed off on the large screw on the arm that ties into the timing advance and idle is reduced. Why is there a second small screw on the carb linkage to adjust idle as well?<br />What do the needle screws on the carbs do that are to be set at 1 ¼” turns out? <br /><br />Soon I will speed test this engine and see what happens under load and at WOT.<br />I plan to shock the gas with ring free and was thinking of doing the de-carbon spray treatment through the carbs, what do you think?<br /><br />I’m not sure what previous owners used for oil, I doubt it was Yamalube.

 

[rodbolt]

Re: 1988 Yamaha 130 won't idle just bought it

by backing off the large screw you have moved the engine idle ignition timming. it needs to be checked. sometimes they vibrate other times someone monkeys with them trying to compensate for another problem. the idle timing normally is about 4-7*ATDC on those motors the pickup timing, the timing that the throttles actually stat moving is usually 1-3 degrees less. <br /> I dont recall making any idle mixture screw adjustment reccomendations, I usually will say that if everything else is correct the factory service manual specs seem to always work. its just been an observation over the years. there are 2 ways to increase or decrease idle speed. one is to advance ign timing and the other to increase the amount of air/fuel induced in the cylinders. I would imagine the previous owner was poking and hoping before the sale and in trying to make it idle they played with the screw. may not hurt to check the timing at wot when your all done as well. 3 methods, use a dyno, use a test wheel in the water or have a trusted helmsman ,preferably one that is not connected to your life insurance policy, and do a high speed run above 4500 and inspect the ign timing.

 

[fishon71]

Re: 1988 Yamaha 130 won't idle just bought it

Okay Rodbolt sounds good and as the engine does in my drive way. By messing with the timing at idle I was concerned with the synchronization which is talked about in my service manual but for the life of me I can't find how to set it up. Basically I backed of large screw until idle fell to 700 and then tweaked small screw on carb linkage up to 800, any concerns?

 

[Ray Neudecker]

Re: 1988 Yamaha 130 won't idle just bought it

Take the screw driver with you and when you get to the water, let the engine warm up and adjust the idle to between 900 and 1000 Rpm's. You will only need to adjust the fuel idle adjustment on the carb.<br /> You can manually check the timing on that motor by following the manual without starting the motor.

 

[fishon71]

Re: 1988 Yamaha 130 won't idle just bought it

Success, dropped boat in water today for test run, she idled well and we cruised out of the harbor. Ran for a few minutes at 3500 and it started to skip and run on three, ran it a little harder at about 4000 and she cleared up right away. Ran like that for a while then higher and higher all went well. On the return I gave it all she had, right up to 5900 for a bout 2 minutes, not a skip, yahoo!<br /><br />I don’t know what kind of 2 cycle oil in there but I have a full tank of something other than Yamalube. I’m gonna run it down and flush everything and go to Yamalube as soon as I can and then de-carb the engine as well.<br /><br />Now to start fixing up the boat and adding the toys.