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Post by silverbullet on Dec 14, 2020 22:57:56 GMT
I have been refurbishing a 1970 Oly this year. Track changed out, new sprockets bearings etc. Carb has all been gone through, clutches cleaned, aligned and had successful test firing a few weeks back. While waiting for snow I decided to proactively clean points. With the starter off and starter cup removed I was disappointed to find there is play in the crankshaft at the mag end. I can lift it up and down. Ugh. (not sure if video will post). Can't really quantify how much it's moving but I don't think it should move at all. Does anyone know from experience if these old 299's will bang away all day even if a little loose? i.imgur.com/y0yVLn0l.mp4[/img]
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Post by bones on Dec 16, 2020 3:17:32 GMT
You are correct there should be no movement up/down in that set up. How much could there be and still function fine....I cant answer that, good chance if it starts good and idles good she would thump along for many miles ??
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Post by olyman on Dec 16, 2020 12:23:55 GMT
Bones is that a cone bearing or a roller bearing on a 299? The video link didn't work for me Grant..?
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Post by bones on Dec 16, 2020 14:22:19 GMT
The 299 should have a ball bearing. The 69 - 320 and 70 - 335 have the two piece bearing on both ends that you will feel movement.
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Post by silverbullet on Dec 16, 2020 19:07:41 GMT
Thanks for input guys. Yes it starts and runs fine on the stand. Am contemplating running it as is to see if it runs tolerably but the thought of it breaking/leaking the end seal and leaning out 3 miles from the trailer is not appealing. FYI, some feedback I had from a machine shop that specializes in vintage rotax crankshafts was to check the fit of the bearing in the crank case, as that’s sometimes the culprit. For one reason or the other, appears this motor should come apart.
I've watched GaWajan's videos a couple of times over. Am mulling over whether I should work up the courage to have a go at changing the bearings. Buying another used motor (if one can be found) may only buy me another set of unknown issues. Hmm....
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Post by ericr on Dec 17, 2020 2:31:50 GMT
Taking a single apart and doing the bearings is really not hard, I remember my first time. She smelled of cigarettes' and cheap beer... oh back to engine rebuilding- You'll need some sort of puller to get the bearings off the crank, a flywheel puller obviously.
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Post by joeolympique on Dec 17, 2020 6:25:33 GMT
Hi Grant, I have a complete 299 sitting on the shelf that I won't be needing. Let me know if you're interested. I'm in Massachusetts. Where are you located?
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Post by silverbullet on Dec 18, 2020 1:31:28 GMT
Your offer is much appreciated; however, even if I could cross the border I'm a very long day's drive away in southern Ontario. I've chatted with a local shop that can replace the bearings for me so I'm leaning towards outsourcing the bearing change up and doing the tear down and reassembly myself. I'll keep you all posted on how that goes.
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Post by silverbullet on Dec 27, 2020 2:53:07 GMT
Got verdict back from machine shop and the problem is the crank case mag half itself. Bearing sits loose in it. Fixable but shop suggests might be cheaper to find another parts motor. Does anyone know if the 247 250 292 299 300 302 318 320 335 337 bottom ends are interchangeable? It appears some e bay vendors think so ( I copied that list right off an ad) but I'm not sure based upon comments above by others. I believe the motor I am working with is a 68 e start rotax 299. So am interested to find out what other motors shared the same bottom end to help my search.
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Post by bones on Dec 27, 2020 3:39:44 GMT
silverbullet, a 70 - 300 should have all steel cylinder, is that what you have ? If you have a all steel cylinder then you have to get a crank case from the mid 60s to 70. A 250 or 300 case will work. The base gasket area changed basically with the introduction of the aluminum cylinders.
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Post by silverbullet on Dec 27, 2020 3:53:34 GMT
Thanks for that info. Good to know. Mine is definitely the steel cylinder. So my search criteria is 70 and earlier 250 or 299/300. The rest of this motor is pretty good. I have one other 299 in the shed but am reluctant to cannibalize it just yet. Will see if I can find a decent bottom end from a motor that's already been pieced apart, has a bad top end.
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Post by silverbullet on Jan 3, 2021 3:06:41 GMT
Thanks too the good people of this forum I am making progress! First an offer of a complete but too distant motor from JoeO; then info on 250/299 interchangeability from Bones followed by Olyman offering up the bottom end of a pooched 250 that he had stashed away. I met Vince on Thursday and today pulled the top end off the donor motor. The piston was missing the top ring and chunk from its top immediately above the exhaust port but the bottom feels nice and tight. So tight and smooth I'm not going to take it apart. Am going to presume/trust/chance the missing piece of piston went out the exhaust. Learned some things this afternoon on how to remove stuck studs, circlips that refuse to come out and how to improvise a wrist pin pusher/puller.
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Post by olyman on Jan 3, 2021 4:13:01 GMT
Right on Grant, sounding good with the progress. Happy I could help.
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