60 triple hesitates....

[longshanks]

Mercury 1998 2-stroke 60HP three cylinder, called the '45 Jet'. It came from the factory with a jet shoe instead of a prop. I bought the motor 2 years ago, and prior to my getting it, it sat unused for 3 years. Carbs were badly varnished, and I had them re-built and cleaned by a local mechanic. The motor has since been quite dependable for me.

One thing about the motor has always kind of puzzled me. When powering up the throttle from idle to WoT, it is definitely not a smooth transition. Particularly in the last 1/4 of throttle twist, there seems to be something funky going on. If I twist and hold the throttle at WoT, RPMs seem to 'stick' at 3/4 throttle for about 3 seconds, then surge sharply to WoT setting. Otherwise, the motor runs great, idles well, and uses little gas. When getting out of the hole however, it would be helpful to give the motor a steady shot of WoT, as the boat is not over-powered.

Any ideas what this might be? I know that OB jets seem to accelerate slightly differently than props, but I am thinking that there might still be some crud in one of my carbs. If so, how tough a job is it to take them off and clean them? I have a shop manual, and some mechanical ability.

thanks guys

Shane

 

[Laddies]

Re: 60 triple hesitates....

You may have a cyl. misfiring or the engine may need to be synchronized

 

[longshanks]

Re: 60 triple hesitates....

so the best thing to try first would be to replace (and properly gap) plugs?

What is involved in re-synchronizing the motor, and is it something a shop should do?

thanks Laddies

Shane

 

[Lakester]

Re: 60 triple hesitates....

so the best thing to try first would be to replace (and properly gap) plugs?

What is involved in re-synchronizing the motor, and is it something a shop should do?

thanks Laddies

Shane

hello,

fresh plugs would be a good first base start. i am not sure what "re-synchronizing the motor", never heard the term. but perhaps a check of the timing would be a good idea. and maybe timing to carbs, or tbs...linkage wise.

dont forget to torque the spark plugs and double ck them oft to be sure they havent loosened. if it were mine i would add a dop of anti seize to the plug threads...each side and spread across the threads with a toothpick. a used one on one end is best as it will act as a brush.

regards
lakester

 

[Laddies]

Re: 60 triple hesitates....

Shane, timing and synchronization is a fairly simple job with a manual and timing light if you take to a shop they would charge about a hour labor I would think. If you have a light you should buy a OEM manual, they are good reference for many things and if your mechanically inclined will pay for its self quickly - Bob

 

[longshanks]

Re: 60 triple hesitates....

another question on this thread... is it possible that I might solve this hesitation by adjusting the idle mixture screws? I read that Mercury's factory settings are 1/2 turn out on the top carb, then 1.5 to 1.75 turns out on the bottom 2 carbs. I suspect mine is set up this way to idle more smoothly. Based on what I've read, this might affect the motor's ability to accelerate smoothly.

If I wanted to try turning out the idle mixture screws, would it be best to try the top one first, or all three? As long as I pay close attention to the settings, is there anything that I should be wary of?

I know that triples can be somewhat difficult to tune properly, and I don't have a lot of experience working with carbs, which is why I am asking all this.

thanks for your help

cheers

 

[Laddies]

Re: 60 triple hesitates....

Shane, those are only basic settings the engine needs to be set in the water in gear to the best idle mix and if it's set a little lean the engine will stumble on acceleration.