Yamaha F100 stator testing...

[GrilseFish]

Hi,
Recently the rectifier/regulator went up in smoke on my F100, total meltdown, etc. So after removing it, I've been testing the stator output, and according to the manual, it should be 18v AC at 3500rpm from any two wires(there are three in the connector). When I hook up my DVM, I get about 65v AC at 3500rpm. And upon further reading, it appears that I should be testing with the R/R in place and using a test harness to measure peak voltage DC? But if I put the burnt R/R back in place, I believe I'll get more smoke and flames?

So this is not good, but I'm no mechanic, just a guy trying to save a few bucks. This F100 has well over 1200 hours on it, carbs are a perpetual problem, and the thing makes oil like no other. Don't have the bucks to repower, so keeping it running is my only option.

Assuming the stator has gone bad, is this something a guy with average tools can replace? I'm thinking that I may get a marine shop to just remove the flywheel, as I have no puller, etc.

And, after removing the regulator and replacing the 30A fuse, it seems to run fine, as long as I have a charged battery. From what I've learned, this F100 should run fine with no rectifier/regulator, as it's only used to provide charging and house power. Any reason to think otherwise? I've made a few short trips in this configuration, haven't noticed any issues yet.

thanks for any help,
Jeff

[boscoe99]

The F100 rectifier/regulator is known to be problematic.

There is no known repair to a burned R/R. Why not just buy a replacement (a much improved component) and move on with life.

Be glad the R/R did not take out the CDI and other expensive stuff with it.

[TownsendsFJR1300]

Jeff,

Just a couple of friendly tips...

Re tools/ pullers- If your in the US, alot of auto parts stores will lend you the
tools/pullers, no charge, just a deposite.

Re the carbs-Todays fuel (ethonol is crap). You must use a fuel
stabilizer and also a fuel system cleaner. Even if you run the
carbs dry, enough fuel stays in the bowls to varnish closed the
jets. Yamaha's RingFree works very well, 1oz / 10 gallons. Gas Shok
is a good stabilizer. If you use both of those, you won't be pulling
those carbs off anymore...

Good luck with the elctrical fix too...

[rodbolt17]

unloaded it can make close to 100Vac.
that's why the test calls for a peak DC loaded.
with no rectifier there is no load and NO DC.
there is a peak voltage reading, cranking, unloaded.
about 7.1v.

[GrilseFish]

Thanks, I do plan to replace the R/R, but my larger concern is what caused it. Not sure if my testing is correct, in that the stator is bad? If I install a new R/R, will I fry it while testing the stator output?

I have been using Ringfree and a fuel stabilizer, and only using ethanol free premium gas. So that helps with the carbs, but the making oil issue persists. I've installed the hotter thermostat, and limit idling if at all possible.

And thanks for the tips on tools, I'll look into that.

Thanks,
Jeff

[rodbolt17]

typically the regulator smokes due to a bad cconnection.
some just smoked.
two ways to generate an AC voltage.
spin a magnet past a coil or spin a coil past a magnet.
from there we can increase the frequency and voltage with RPM or the size of the magnetic field or the coil.

[TownsendsFJR1300]

So that helps with the carbs, but the making oil issue persists.
Thanks,
Jeff

If your engine is "making" oil, (from what I've read here), the fuel pump gasket/diaphram is leaking fuel into the crankcase.


http://www.boats.net/parts/search/Ya...201/parts.html part #16 (Guessing the year)

[99yam40]

make sure you use the proper peak reading voltmeter made to take these readings to and out of the CDI, or use a DVA adapter with your regular meter

[GrilseFish]

Thanks everybody,

I've read up more on the peak voltage measurements, and the DVA, so now I think I get what's going on.

And as far as the fuel pumps, I have checked them, didn't seem to be leaking. But what I find really annoying is that the diaphragm is not much less than the whole pump assembly! ($100 or so).

Thanks again for the help, much appreciated.

Jeff

[arny]

A bad thermostat will made your motor to an "oil maker" with thin black and stinky oil