I have a 1991 xr4 which runs great on the muff ,would I see a power increase by removing the idle stabilizer, and changing the lower unit to a large hub unit,are these motors a reliable motor??.still working on the boat so it has not been run on the water
Following this too, just bought one myself...
looks like we may not get any answers to the post
I dont know much about those, but do know they were considered to be pretty reliable. My Dad had one and it was always good to us. Hopefully some of the guys that know those better than me can chime in with better info.
2021 Phoenix 920 Elite / SHO 250
Bullet 21XD / 250 XB (Gone to a great home in LA)
"There is no such thing as a bad day fishing!"
Two issues. One trick mercury used was the skinny lower unit. Produces less drag. Gears are pretty strong, but when you reduce the diameter, you reduce the ability to handle a high load. And the bearing carriers are known to chatter at high engine heights. Ask me how I know. If you can the small gear case, you will lose some top speed, gain some reliability, and spend some money.
The idle stabilizer is a favorite thing to hate for me. It has two functions, one of which was classified "top secret". It's advertised function was to kick up the timing when the RPM dropped below 600 RPM or so. The idea being that when you shift into gear with a big prop and a smallish engine block, the prop could stall the engine. So in comes the idle stabilizer, ramps up the timing a couple of degrees and the engine speeds up to avoid stalling and going dead. So far, so good. But after a year of working with several people trying to figure out why my XR6 (2.5L 150, first year made - 1992) would not spin past 5600 no matter what I did. I ended up with a volt meter on the idle stabilizer. While I don't remember the voltages, when you manually slowed the motor on muffs, the voltage would swing and the idle would pick back up. On the water, as the motor reached 5500-5600 RPM, here comes that idle stabilizer again, but this time the voltage polarity was reversed, and it ended up retarding the timing about 6 degrees. Removed it and it ran better overall, although an occasional stall when shifting would happen. But suddenly you could turn the motor to 6000 or higher (if you wanted).
Most remove the thing, completely.
2008 Bass Cat Pantera Classic
2014 Mercury Pro XS 200
Definitely recommend losing the stabilizer/advance module on this engine.
On a moderately heavy bassboat, you'll not really miss the smaller diameter gearcase that much (as you'll be able to swing a full-size prop in a nice, efficient pitch).
Just keep in mind, it is still a carb. model engine, that was never really designed to run on this "stuff" we call fuel today. It's also 27 years old now...
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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Only other bad part on them in the 2.4 fatblock was the water cooled voltage regulator, CDI made a conversion kit similar to the 2.5 promax dual vr setup, most guys went that way,even b4 the stock ones went nla.
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