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see chart for common size bolts
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It’s pretty rare…maybe never….that I have taken apart a 20 to 22 cube two stroke engine of ANYBODY’S manufacture, that there hasn’t been a least a little scoring of rings and pistons. Yeah, yeah, I know what they say; but if the scoring is light on the pistons, I gently clean them up, reuse them with new rings and always have had good results. (Heck, some of these guys will break free a seized-up engine and run it. Usually in those engines, the rings aren’t just scored, they’re STUCK.) As for the sealant, I like the anaerobic kind. I have tried Yamabond, which is probably like the Honda stuff (Gray?) and have noticed that it really doesn’t totally resist ethanol fuel. It’s great on four strokes but I personally wouldn’t trust it on the crankcase of a two-stroke. Just my opinion, on both subjects.
Long live American manufacturing!
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This reply was modified 3 years, 4 months ago by
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This reply was modified 3 years, 4 months ago by
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OK, my second attempt at posting…. Don’t know if it is my laptop or this site…
Like Bill says, disassembling most of these engines will reveal some minor flaws. Kind of hard to judge yours without seeing pictures. The beauty of these engines is that they run just fine even with some minor flaws. But, yours is apart now, so I’m guessing you want to make as close to perfect as possible. I’m confused about just what happened here though. Is this engine new to you? Was it seized? Why were you attempting to remove the upper seal?
In any event, you have to be careful when honing, because you are actually boring the cylinders just a bit. Over honing to get rid of all the perfections can easily lead to an oversize bore. You should take the time to measure the bores carefully before proceeding. Check them for out of round and oversize conditions. That being said, this is difficult to do accurately without good measuring tools and the ability to use/read them properly. I would invest in the proper OEM manual for this engine, they are out there, not too tough to find. I would avoid those generic manuals that try to cover many different years/models, they are confusing and can be inaccurate.
OMC originally sealed these crankcase halves with the OMC type M/847 sealer. This stuff works great but is tough to apply neatly and dries very quickly. OMC came out with their anerobic sealer “Gel Seal” in the late 70s, this can be used instead of the type M/847. It is easier to apply, and like the term says, doesn’t really dry until the air is removed/crankcase halves assembled. But, proper prep is extremely important, or this stuff won’t seal properly and the crankcase halves may leak. The gel seal is usually only applied to one side of the crankcase, the front side, only because it is easier to apply it here without having to work around the crankshaft/rods. Like I said, prep is super important. The crankcase halves must be perfectly clean (no old sealer left over) and flat. Too much sealer applied will get into the crank bearings/oiling passages, too little sealer might create crankcase leaks. Using too much sealer can actually “shim” the halves apart slightly as well. There are so many sealers on the market, but this job is critical, so I wouldn’t use anything other than the type M or a quality anerobic sealer made for sealing two stroke crankcase halves.
Feel free to post pictures of your engine parts if you have more questions.
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As others have noted, these 22ci motors can be pretty forgiving. I once had a 1972 Evinrude 25hp that was stuck with rust in one cylinder. After freeing it up with penetrating oil, I tore it down and found some minor scoring in both cylinders and stuck rings on both pistons. I cleaned up the pistons, installed new rings and flex honed the cylinders. At that particular time, I didn’t have any OMC gel seal for the crankcase halves on hand so I used Permatex Motoseal (similar to the Honda bond or Yamabond) which seemed to work fine, but I think the anaerobic sealer is better. After reassembly and a run-in period, I had 130psi compression in both cylinders and it ran like new. I sold that motor several years ago and I’m told it still runs great.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."1 user thanked author for this post.
The one big killer of 22 cube, OMC 25s has always been separation of the water jacket aluminum and the steel cylinder sleeve. You can see how narrow the head gasket sealing area is, already, where the cylinders are closest together. If corrosion starts to work it’s way into the steel/aluminum dividing line in those areas, it’s good bye, engine. It will never hold another head gasket. When you said, “I’m surprised it hadn’t cracked away in that section,” that’s not what you’re talking about, I hope.
Long live American manufacturing!
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