Fine Tuning inline 6

[ianmoore]

Hello,
I've been trying to finetune my '88 merc online 6 115. This is the second motor of this type I've had and both have behaved similarly.
On this one, it is timed perfectly, all cylinders have good compression. I have rebuilt the carbs. Everything is set up per the manual to fine tune the idle setting.
I have had a really hard time getting a good idle setting between neutral and in gear.

If I follow the instructions and fine tune the idle jets, and reset the idle stop to around 800rpm, when I put it in gear the Rpm are too low and it will typically die. I know you want your neutral below 1000rpm, and I can get it to about 900-950 at the lowest without the motor dying when I put it in gear.
I have gone through the procedure multiple times and this is about as conservative as I can get it, which. I know still beats up the gears.
The other thing is that after WOT the idle jumps up a bit, to around 1100. It will eventually drift back down, but again, it makes it hard to definitely set your idle correctly.
I have not checked the idle stabilizer. That is the only thing that jumps out as a possibility, but I find it odd that both motors operated almost exactly the same, and it makes for a stressful docking!
Anybody have wisdom on this area? Is this the deal with these motors? They run great opened up. Would be nice to have an idle that wasn't chewing up the gear box
Thanks in advance
Is

 

[racerone]

In good condition they idle really nice in nuetral and in gear.--------Some times they are adjusted TOO LEAN on the low speed mixture.----------That leads to bogging and stalling.----------Have you looked at the bleed inserts found inside the tranfer covers ?

 

[Faztbullet]

Throw the idle stabilizer away,set RPM at 1100 on a hose, always shift a Merc fast into gear,

 

[ianmoore]

Thanks for the quick responses!
racerone I spent quite a bit of time messing with the low speed mixture screws. I think i found their sweet spot. Seems to be around 2 turns out, in general. Beyond that it started to miss again. I did my changes very slowly, one carb at a time, and would open up the throttle occasionaly to clear the carbs
. I have never opened up the transfer covers. Are they under the switch boxes on the port side? I did a little bit of research and those bleed inserts sound like they could be a pain in the ass to deal with. Can you get to all that stuff without totally dissasembling the motor?

Faztbullet you recommend disabling the idle stabilizer? I actually was testing the boat in the water today, as when i have done it on muffs in the past i end up turned up side down. When you say Mercurys like to shift fast, are you talking above 1000 rpm? I'm pretty green, so i would love to be schooled on this. Just trying to maximize the life of my lower unit. It that's not an issue, I can get the engine running pretty well. It seems to have it's sweet spot right around 1000 in neutral, which keeps it out of the stalling area(right when i engage the gear there is a drop in RPM) and keeps it around 800 or so.

one other thing- ive seen a lot of threads on cold starts on these guys. Typically takes me a couple of minutes to start the engine. Not that big a deal, but just trying to understand anywhere i can improve the motor. I typically will push in the enricher for about 5 secs. It will turn over but die a few times. If i goose the throttle I can speed up the process a bit. Any way to improve this, or is this part of the older motor thing as well('88)?

 

[racerone]

The enricher does NOTHING if the motor is not cranking !!-----Push the key in and hold it in while cranking !-----And have you inspected starter / load tested the battery ?

 

[Faztbullet]

When shifting do not shift slow ...

 

[ianmoore]

I thought the enricher opened the valve that lets gas from the carb bowl flow through the circuit. For what it's worth, I have always tried it, pushing in, while starting the engine. I had read somewhere to push it in for a few seconds before starting, and just tried that recently. I haven't done a battery load test yet. The starter seems pretty hardy, at least to my eye. Seems that it catches fine on the starter level, but that it helps to goose the throttle to boost the RPMs so it can catch
Faztbullet ok. would you say something like 1100rpm would be fast? coming out of neutral. Sure seems like it kicks into the lower unit kind of hard

 

[Faztbullet]

Set it at 1100rpm on amuffs, this will give you about 925-1000pm in the water...all Mer'sc shift a tad hard