1995 200 Xri acting funny

[86cj7]

Sn og282520

Hello all, 1st post
I bought a 1995 20' pro craft that has a 200xri that was running great for about 6 trips . I launched the boat it started up just fine drove about 5 minutes at half throttle came to a stop and let it idle a couple minutes shut her down fished for about an hour tried to restart the main engine and it wouldn't fire . I got it back home turned the key in the driveway and it fired right up.It did the same thing the next two outings. I turned up the idle and that seemed to help but it would run rough on the second starting. I went to the local merc dealer and asked for a set of plugs at 1st they handed me a set of ngk bu8h and then asked me if I had electronics and switched them out for a set of Ngk 7447 buz8h, the boat started up every time and ran great until the last outing it seems that I need to turn the idle up some more. This seems a little off.
Doing some research turns up some different answers as to which brand plug I should be running, I talked a local boat guy and he said that every blown up merc that he's ever seen has had ngk plugs in them.
Any recommendations would be appreciated
Thanks in advance, Rich

[JOE54]

BU8H,BR8HS-10, plugs not gonna cure it, ( BECAUSE they are suppose to have ngk in um) and another brand wont save it either

[EuropeanAM]

Also- HOW are you "turning up the idle". Exactly what are you adjusting to accomplish that?

BTW... plugs really should be replaced ANNUALLY on that engine.

[silverbullet02]

BTW... plugs really should be replaced ANNUALLY on that engine.

I’m curious where this recommendation comes from? Those surface gap plugs will run for years and years. Changing annually is just wasting money.

[EuropeanAM]

Manufacturer recommendation (even in the Owner's and Service Manuals of this vintage) was to inspect and clean the plugs Annually, or every 100 hours, whichever occurred first.

Later engine models simply indicate replacement at that interval.

At a bare minimum, INSPECTION and CLEANING is required (which may be sufficient if you don't mind occasionally finding out you've lost a plug while on the water).

Given the relatively low cost of that plug... I personally wouldn't even think twice about replacing them.

[86cj7]

Also- HOW are you "turning up the idle". Exactly what are you adjusting to accomplish that?

I push the idle lever up where the throttle lever is looked at the linkage at the motor and there is a set screw. I simply turned the set screw to add more rpm's

Somehow I get the feeling that may be bad

[EuropeanAM]

It sounds like you changed the THROTTLE STOP (the set screw at the very bottom of the black throttle arm). This screw is what determines the base synchronization of the throttle linkage (and should not be altered once set properly).

There are three (3) screws on the black throttle arm- none of which are idle adjustment. The idle adjustment screw is hidden behind the VST assembly (and alters the air gap on the UPPER throttle plate). It is the VERY LAST adjustment to be made when performing a Complete Sync-n-Link Procedure.

Good idea to obtain a factory service manual before making any more changes.

[86cj7]

Thank you for your reply
I will look into a service manuy

[luvdmymerc]

I highly recommend the said Mercury Service Manual.....I purchased one from European Marine a year or so ago when I was rebuilding a '95 175 EFI Xri. It is a great resource for EVERYTHING on that motor......not just for properly setting the idle.