93 lacks power, 98 gtx has loud knock

[93sp98gtxltd]

As you can guess by the username, I have a 93 sp that starts and idles fine, but as soon as I try to give it gas it starts to sputter. In 2002, it got an SBT rebuild, and ran great until about 2005 then started to act up. At first the problem would go away with careful use of the choke under accel, but has since gotten to the point to where it doesn't want to accelerate at all. It has had two carb rebuilds, and I'm wondering if it is not a carburation issue. One of my friends suggested that with the amount of usage that it sees (50-60 hours per season) that it could be in need of a new set of rings, but I would like to know what all the causes of these symptoms could be before tearing it down.

Also, I have a 98 gtxltd that has between 100-150 hours on it, not quite sure because it has been so long since it has seen the water, that when last fired up had a loud knock and wouldn't rev past 4000-4500 rpm. When it started to knock, I throttled down and limped it back to the dock, maybe 1 minute of run time. I was outside today looking at it, and by hand spun the engine over by the pto, and I could hear grinding coming from the pto side of the engine. I'm thinking that the crank side rod bearing on that cylinder bit the dust. I'm wondering if it would be more worthwhile to get a new crank once it is ripped down, or just a full engine with the 2 year warranty in case something else in the engine is on the fritz. Any other possibilities on what would cause that kind of noise on the 947/951 engine?

Any help would be appreciated,
Thank you

[dsolie]

Re: 93 lacks power, 98 gtx has loud knock

On the 93. Most likely carb, or something in the fuel delivery dept. Fuel selector valve needs to be cleaned, carbs cleaned, possibly rebuilt etc. Just in case, what's the compression?

On the 98. Sounds like crank is gone. If you are handy with tools and have a thirst for knowledge, do the crank. Feel like just getting back on the water? New motor, drop in and ride.

[93sp98gtxltd]

Re: 93 lacks power, 98 gtx has loud knock

After looking at the 98 again after getting a new battery, I wanted to see if it would make noise being spun over by the starter. I did that, there was no noise other than normal sounds, and when I pulled the plug boots off to put them on the grounding posts, I noticed the plugs weren't the correct ones. Someone put a set of champion RN2C plugs in there between the first season of ownership and the season when it didn't run. I'm wondering now if the knock that I was getting from the engine was detonation/preignition from having the wrong heat range of plugs. I wasn't overly clear when I explained the knock last time. I was out riding for between 5 and 10 minutes before any noise started and that's when it wouldn't rev up. But when it was winterized for the season there was no knocking noise. Does this sound like a reasonable diagnosis or just like a stupid idea?

[dsolie]

Re: 93 lacks power, 98 gtx has loud knock

Sounds reasonable. I would check with a compression test real quick though.