200XS spark plug advise...

**H20WKD** · 08-28-2017, 11:04 PM

We be love'n the new 200XS on the GSE....but, we have an extended no wake zone out of the launch, plugs are getting very sooty with a very lumpy idle, compression is five @125 and one @120. I'm thinking of going one heat range hotter with the NGK Iridium Plugs...any advise appreciated.

**hsbob** · 08-29-2017, 04:16 PM

be sure your using premium plus oil and are adding merc clean. i've never had a idle issue but how long is your no wake zone. make sure the temp is above 130 when you shift.

**H20WKD** · 08-29-2017, 06:23 PM

Takes about 15-20min to get to open water.
It is running cool, usually between 110-120* at 500-800rpm.
Found a small leak around the poppet valve, checked and replaced the gasket, diaphragm and spring ok. 3-5psi at idle.
Using Amsoil HP full synthetic.
Dark soot on the ceramic of all plugs, definitely idling too cool.

Cleaned the Plugs,(NGK IZFR7M, 4214, ran well until we hit the no wake zone again.
I do have the next hotter heat range NGK's on order.

Bob

**hsbob** · 08-30-2017, 03:25 PM

try going back to prenium plus oil. the plus oil is what merc racing used to qualify the 200xs and therefore the suggested oil. the amsoil may lub ok but does it burn cleanly??

**2jz** · 08-30-2017, 09:11 PM

Your asking for trouble running a hotter heat range plug. You have no way to compensate for more heat in cylinders via timing, more fuel, or higher octane. Detonation will take effect with hotter plug. Check water temp and air intake sensor ecm uses data from them too calibrate fuel delivery

**H20WKD** · 08-31-2017, 11:34 AM

First thing I did when we got the 200XS was order the Shop Manual from Merc Perf. That manual specified NGK IZFR7M, so I ordered a new set, might as well start off on the right foot. Motor just wouldn't idle smooth, even with the new plugs

Next thing I noticed was that some of the illustrations in the manual looked different than my motor.

Called Merc.Perf. and sure enough they forgot to send the Supplement Manual for the Gen2, the Manual just came this morning.

In the Supplement the correct spark plug for the Gen2 is IZFR5G, Two steps hotter than the 7M's that were in it.

Anyone want to buy 6 7M's with 3hrs on 'em.

Guess I was just too anxious to do the right thing....

Bob

**hsbob** · 08-31-2017, 01:57 PM

there are several errors in the orginal manual.

**Bullet89** · 11-03-2017, 10:29 AM

I would have the injectors cleaned, change back to Premium Plus (synthetic blend) and use Quickkleen. Mercury doesn't recommend full synthetic oil in any Optimax.