1999 NS90A Nissan outboard engine retarding after 1/2 throttle

Hello all. Hoping someone can help me. I just replaced the head gasket. Put the head gasket on. Also took off the exhaust cover and broke two bolts in the process. Tried to get one out with an EZ-Out but that broke in there, so I just RTV-ed the heck out of it and put new gaskets and sealed it up. Also, I took out the thermostat a while ago and put the cover on, but it's got a top bolt broken in there somewhere so I also RTVd that and tightened it up best I can. Still squirts out some water, but not much.

Last, I replaced the impeller and now she pisses good. I went to start the engine with the water muffs and she pisses good. No leakeage on the head. Some at the thermostat cover, so I took it out for a spin on the ocean only to find out she retards after 1/2 throttle or so. Don't know why. Idle to 1/2 throttle is good, but after that, "bum-bum-bum-bum". Retardation. So I put it back on land and she's got good compression on all three cylinders. I cleaned out all the carbs just to make sure too. Nothing in the low or high speed jets. I didn't try to mess with the idle timing rod nor the throttle timing rod since I didn't mess with those before.

What could be causing the retardation? Oh, last thing...the tips of the NGK spark plugs were a little bent but not bad. They were sorta new. Any ideas?

You do not know the timing (advanced nor retarded) until you use a timing light. Get the Factory service manual and go through link and sync, etc. Beware that this motor is obsolete. If you want to run it long term, you must run a thermostat, and fix those broken bolts.

pvanv said:

You do not know the timing (advanced nor retarded) until you use a timing light. Get the Factory service manual and go through link and sync, etc. Beware that this motor is obsolete. If you want to run it long term, you must run a thermostat, and fix those broken bolts.

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Another question: Before putting the head cover back on, I pushed the piston heads in and out to check the cylinder walls, etc. Could that affect the timing? Because I didn't touch any of the timing linkages.

I live 30 miles above the Arctic Circle and don't have a timing light nor do I know how to use one.

Qaluraq said:

Another question: Before putting the head cover back on, I pushed the piston heads in and out to check the cylinder walls, etc. Could that affect the timing? Because I didn't touch any of the timing linkages.

I live 30 miles above the Arctic Circle and don't have a timing light nor do I know how to use one.

Click to expand...

No, cycling the motor does not affect timing. If you are going to work without a timing light, just follow the Link and Sync information in the Factory service manual (available from any dealer, even me), and set the rods and stops as per the manual.

Regardless, you definitely need a thermostat, especially in cold waters. You will want to repair the broken bolts so that you can get everything buttoned up properly.

You may not be getting timing retard... may have a different issue. Many times, fuel delivery is the problem.