Considering rebuilding a Rude 70hp

[CalicoKid]

E70ELCOS I have this motor and am considering parting it out or rebuilding it and using it on my boat. I have not run it myself, just got it but the previous owner had some trouble with it recently. Without running it I pulled out the spark plugs, removed the kill tether and sprayed fogging oil in the cylinders. I put on the muffs and cranked the starter a couple times and then checked the compression cold.

#1 100psi #2 100psi #3 15psi. There is obviously a problem with #3. I know I can't get a good reading without warming up the motor but thought 100psi cold was good on #1 and #2??

My questions are: If I pull the head and the cylinders look good can I just re-ring the #3 piston or should I re-ring all 3? Should I put in a new piston? Or 3 of them? If the cylinder or cylinders are scored, how bad can they be and still be able to bore or hone them? What gaskets will I need to replace, crankcase, powerhead, head? Anything else I should be doing while the powerhead is off? I'd probably rebuild the carbs at the same time and I do like the idea of fiber reeds maybe..

There is a set of factory service manuals in a binder for this motor we just need to find them. I guess I'd like to get this motor running as easily and inexpensively as I can and not do a lot of unnecessary things to it trying to be a perfectionist if that's possible.

Any opinions or experience shared is very much appreciated

 

[CalicoKid]

Re: Considering rebuilding a Rude 70hp

Two more quick ones. This motor is a 1985 I believe, is it hp rated at the prop or powerhead and is the VRO the first or 2nd generation type? Thanks!

 

[tashasdaddy]

Re: Considering rebuilding a Rude 70hp

vro is 1st, go to premixed.

 

[Silvertip]

Re: Considering rebuilding a Rude 70hp

By all means rebuild the carbs as part of the engine rebuild. Chances are a gummed up high speed jet could have caused the failure of #3 cylinder. As for the rebuild, if cylinders #1 and #2 are not scored, I would simply hone them a little and install new rings. Pistons don't need to be replaced unless they show signs of scuffing. Cylinder #3 may be as simple as broken rings or a nasty case of carbon build up. However, if the cylinder is scored it will need to be bored. As for other parts, you will need to check the crankshaft journals for signs of wear. An entire gasket set is required. You have the engine totally disassembled, do not reassemble it with used gaskets. As a minimum, I would pull the head and examine the cylinders. I suspect you will see the damage on #3 but then again, maybe not.

 

[Dhadley]

Re: Considering rebuilding a Rude 70hp

On a 1985 motor I doubt if you'll find the cylinders within spec. Once you measure them I think you'll find you'll end up boring all 3. It's really not that big of a deal. If the pistons aren't hurt and the cylinders measure within spec, a hone is all that's required.

 

[CalicoKid]

Re: Considering rebuilding a Rude 70hp

Thanks a lot for the info. The manuals have been located now, I just don't have them in hand yet. This is a low hours motor. I'm third owner, both previous owners didn't get much use from it. I'm hoping for the best right now.

When did they start rating outboards at the prop?