Anyone ever do this?

[550headache]

So my 1990 440 has Ben sitting in the barn for a decade. We decided to use it for my daughters YamaSaki build. 440/701/750 pump.

Got it on the water Sunday. Had a bad vibration that i think i figured out. Besides that it ran like a raped ape! When i got it back in the shop working on the vibration i noticed this! Air intakes totally sealed with rags in the pipes and gorilla tape to keep the mice out!

What a dumb A$$ I am! I cant believe it would run for as long as it did! We were tuning it so rode it for 3-5 minutes then come in and check plugs and adjust. The one wired thing it was taking on a lot of water. It’s a good dry hull. I’m wondering if it was creating a vacuumed inside and pulling water by the driveshaft seal(RHAAS 550SX conversion bearing). We ran it with the hood off and didn’t see a drop coming in after bailing it all out. Just wanted to share my story!


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[E350]

Thank you for keeping up your posts. I really want to know what is causing your vibration before I start down this path with my extra Yamaha 650.

I can put it in my 1993 550sx or in my wife's original 1988 js300 (eventually converted to 440 superstock for racing, then engine blown, then normal 440 installed, now seized).

Do you (and others) have a suggestion which?

My understanding is that the pump and the through hull driveshaft arrangement in the 550x makes it a more appropriate conversion than the js300. In fact, someone said that even with the race brace on the crankshaft through hull bearing, putting too much power into the js300 could rip that fitting off.

 

[550headache]

Hoping to get it in the water this afternoon. Will report back.

As far as the hulls, the SX hull hands down! Will be quieter from the rear exhaust and give you more water box options. I’m running a super trap and it fits nicely up in the front and sounds like a stock super jet.


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[550headache]

Any updates?


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