Idling high how do I adjust it.

[flydoc]

I have a 99 Yamaha c115 hp 2 stroke carbed engine. The boat starts up nice and forward and reverse work like a charm. However the boat idles at about 1400 rpm even after a ten minute warm-up. She sputters/coughs while idling every 3 minutes or so.

I am going to read the Owners manual but does anyone have any pointers on adjusting the idle. I read a post by Dale on a different forum that too high an idle can mess up the gears.

Thanks.

 

[Megabyte]

You are right, 1400 rpm is too high an idle. That motor should be in the 800 rpm range in neutral.

But, the first thing I must ask is... at what point did your idle go to 1400 or has it been that way since you bought the boat?

Before I went adjusting anything, I think I'd look for a kinked cable or some other anomoly causing the problem. Motors don't just increase rpms on their own, so finding the root cause is the first thing I'd do.

 

[flydoc]

This boat is new to me and I've used it 5 times. about four hours of run time.

I only recently paid attention to the idling rpm not knowing what normal is.

I'm going to run her up again this weekend and do some trouble shooting.

 

[gw204]

Find the throttle linkage under the cowling and "tinker" with it a little while she's running. See if that produces any change...

 

[rplas48]

A couple of suggestions. Make sure the choke lever is all the way in. I think your engine also has a manual choke with a lever on the front of the engine. That may explain the sputtering.

There should be an idle adjustment screw. On the 1997 150 I had it was on the starbord side of the engine in back of the air intake and at the end of the throttle linkage. Clockwise to increase and counter to decrease rpms.
Just remember how far you turn any screws so that you can return them to the original position if you don't get the correct one on the first try.

Go to yamaha motors web site and click on parts, enter your engine and then click on intake. The position of the chock lever will be shown and a linkage (part 21 accelerator ). The idle adjustment screw should be somewhere arround that location.

Finally I believe you bought the boat from White Water. talk to them and better yet stop by and have them show you.
You need to get those rpms down to about 700 as you are grinding gears when shifting at 1400. No good.

Good luck
Ray

 

[goinsfishin]

If the linkage and both the electric and manual choke is OK then you will need to get the carbs adjusted.
If it's sputtering at a high idle then the mixture is way too rich and the engine is "loading up". An excessively rich mixture will also cause a higher idle and burns a lot more fuel.
NOTE*- If you're not comfortable and experienced working on engines and carbs then NOW is the time to STOP and take it too the dealer....you can cause serious engine damage messing with idle and mixture settings if you don't know what you are doing.
The correct idle for that motor is 650-700 and the correct "trolling Speed" is 650 RPM (trolling speed is refered to as slow as the engine will run smoothly with forward gear engaged), not necessarily the speed at which you would troll for fish.
If you are OK with engines, and everything else checks out OK, then get the factory manual follow the instructions for that engine.

 

[dave-j]

One more cheap thing to have checked...

My 2000 Yamaha SWS II was doing the same thing and then not running as smoothly as I thought it should when I first took delivery last August. Turned out to be a faulty thermostat that never read the engine as properly warmed up, so the RPM's never dropped. Simple fix and now purrs like a kitten.

 

[flydoc]

Brought the idle down by adjusting the screw. Funny what happens when you take the time to read the owners manual.
Now she runs more smoothly. Gears are not grinding.
Thanks again CP for all your help.
Now how can I find where the fish are?

 

[Megabyte]

Now how can I find where the fish are?

One word... "structure". :wink:

 

[Outta Here]

I had the carb Yamaha 115 Saltwater Series (great motor) on an 18 Parker. Had some troubles with carbs clogging/corroding/gumming up or whatever other excuse the shop could come up with to sell a re-build.

Cured all above problems with some 99 cent Walmart carb/fuel injection cleaner. Treats about 20 gallons at a time. One sign of carb trouble is stumbling idle. Maybe previous owner raised idle to cover problem?

"Where are the fish?" one word...HARDBOTTOM or OVERBAIT

 

[flydoc]

I think my carbs need some attention. I am slowly getting more comfortable with the motor. Last time I fueled up I added RIngfree in the constant treat amount. If the motor still gives me trouble after the next few outings I may apply it in shock amounts.
I am so happy with this boat. It floats in less than a foot of water. The next additions will be a transom mounted trolling motor.