96 speedster running lean?

[Speedjunky]

Hi, just sold my twin engine speedster to a good buddy of mine and after maybe an hour of use, had a hole in center of piston on port side engine (rear cyl.)

Now, prior to this I had all carbs cleaned so that should not have been the cause?

So, I repaired the engine and had that specific carburetor checked again, thinking it ran out of gas for some reason.
Now to be on the safe side I put some oil in the gas tank to help the brake in on the new parts.

All seemed fine testing her out in the driveway but back in the water I did maybe 200 yards and had some hesitation on the fresh engine.
Off came the plugs to reveal a real dry gray looking plug, the other plug looked normal brown in color and a little wet.

The fuel filter was as clean as could be, all fuel lines looked in perfect conditions.
Gas valves where both open.
Gas tank was half full, oil tank was full.
So what am I missing here?

Don't want to end up blowing up this thing again!
Thanks for any help!:cheers:

 

[seadooya]

to late

hopefully, that aint the case, but with grey condition, think the cylinder/piston, is done.

What your missing, is, its not that its not getting gas, but it aint got enough oil. The brass fitting on that side, on the manifold, is plugged up. Pull carbs, and use a skinny allen wrench, and jam it into the oil fitting, to break it free.

 

[Dr Honda]

Yup... make sure that oil nipple is clear.

But... a hole in the center of the piston top is from pre-ignition.

I would check a few things.

1) verify the crankshaft is indexed properly. Since the Mag jug is good, but the PTO is not... the crank may have slipped. (it's just pressed together)

2) Make sure your rear crank seal is good. If it went bad... or popped out... that jug would be running lean.

3) verify the timing hasn't moved. This is the least likely, but it can happen. If it moved a couple degrees, the mag jug is a little more tolerant than the PTO jug.

Finally, just for giggles... check your static compression.

Good luck, and let us know what you find.

 

[Speedjunky]

Thanks guys!

I've past the information to my mechanic, hopefully it will be one of these.

Pretty sure the crank seals are ok as I had filled the base with gas and did not notice any leakage.
My luck needs to change soon....
(Monday 750$ to replace rear bucket and support plate on newly purchased 200SC Speedster, today bad news from dealer.. my approx 50 hrs boat turns out to have 116!
My 500RPM diff. in engine from left to right turns out to be a bad supercharger and will need to be replaced. total bill including overhauling second SC 2 500$)
Hopefully wife won't read this...

 

[Speedjunky]

Well, so far no luck!
Boat is still at the shop and pretty much everything as been checked.

1.Oil fitting checked and cleaned (not dirty)
2.Seals (not leaking)
3.Crankshaft checked indexing (good)
4.Cleaned yet again carburetor (a little water was found)

Next step he said was put the hoses on it and shop test it, if nothing goes wrong, he will put it in water and test again.
Hopefully something will be found on it so I don't pass on this problem to a friend.

Any further checks he should be doing?

 

[Speedjunky]

Still no luck on this..
The mechanic at the shop changed both carburetor gasket kits prior to doing further tests.
This time it didn't want to start at all on that engine under 3000 (or so) RPM.
He now believes it's the electronic module not working properly (would explain the hole in piston).
He wants to test it further on Monday by changing left engine stuff to the right one and see if he can duplicate the problem on the good motor.

Might be looking at a used e-module in the near future.