1974 JLO 400 Crankshaft Rebuild

[whip74]

I am new to Scorpions and the entire restoration process.  I recently was handed a 1974 Whip 400 in "so-so" condition.  Currently, I am excited for a chance to hopefully bring it back to near new condition.  Anyways, that is my goal.  The engine was seized due to a large amount of rust in the MAG side cylinder.  The (2) associated crankshaft bearings feel rough and I would like to consider rebuilding the crankshaft.  The Spare Parts List found online for this engine identifies the end bearing as part #000-39-075-23. The other bearing is not identified and is a component of a crankshaft Assy part #291-86-902-0.  Engraved on the end bearing is SKF 6206.  Does anyone have a cross reference list for the JLO part numbers to SKF numbers and can anyone identify the other bearing I need?  Any pointers on disassembly and reassembly is also appreciated.

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[80sting440]

whip74, welcome to this site.

Two more things that you may want to check closer before spending any money on bearings.

I see a lot of rust on your mag side end shaft...can you clean it up enough to have a smooth and even surface for your seal?

I also see that your con rod is very rusted. That would lead me to think that your big end bearing and pin would be rusted.

3 years ago I had my Rotax engine in a similar situation and had to get those parts replaced. I had it done at a crank shop and had to pay a small fortune...just a heads up on these parts.

Rene

ps. also make sure that your centre seal is good.

[Deleted]

Sometimes its better to find a "different" engine!!! Most engines are not worth putting tons of money into. When I go through an engine,for whatever reason,I always use,serviceable used parts,NEVER NOS. Never had a problem,I must live right.

[whip74]

Thanks for the response fella's. Good observation on the shaft rust. It looks like the seal actually houses in the fan case and contacts the shaft outboard of all the rust you see on the shaft. I do expect to have to clean up the conrod pin and replace the bearing there too. I would like to find a parts breakdown list of all those crankshaft parts including the centre seal so I can have all the parts I need when I disassemble/reassemble the crankshaft assembly.

nitroking72 - I do appreciate what your saying. However, my enthusiasm (at least for right now) is to rebuild as much as possible attaining a like new condition. As I learn more about the $$$ involved, my course may change. I like the quote 80sting440 has in his message about the journey vs. the destination. I am a rookie in this project and perhaps what I don't know now will bite me later.

[weverat]

I do not think we have ever been able to find a source for the center seal, but some of the guy,s on here have used two pto side seals back to back for the center seal. Normally the center seal is ok, and does not need to be replaced, but if you are changing out a rod bearing etc., this is the time to do it.

You need some one experienced re-building snowmobile engine crankshafts to change out the rod, and true the shaft. Find the guy's racing sleds in your area, they will know who does that work.

In this case you also need to replace the mag side crank stub and wheel, as the rusty shaft will cause the seal to wear out and leak.

I would find another Cuyuna engine, and rob the crank. The 290, 340,and 440 engines all use the same crank.

I often disassemble 2 or 3 engines in order to select the best parts. Sometimes I find cylinders in near perfect condition and just need a new standard size piston and rings. Most of the cranks are good, simply replace the seals and your set. The center seal I leave alone. Those are great little engines, enjoy!