olympic
Full Member
Fresh gas first pull got be a DOOO
Posts: 201
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Post by olympic on Apr 3, 2021 1:07:52 GMT
 I got the jug back this week from the machine shop so I decided to put it together today and found this wrong. The 335 died on my son out in the field mid February couldn't get it started so towed it back to the garage to try to get it going. Compression was 95 so decided it needed to get a top end done but I think this was the problem all along has anybody had the key shear on them before. |
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Post by olyman on Apr 3, 2021 13:22:10 GMT
That would definitely keep it from running right. Is the groove in the crank still ok? I havent had it happen before but the 292 I run has had a repair on that before I ever got the engine. Someone made the groove in the shaft 2x wider for a bigger size key, and then the actual key has been ground narrower on either side to fit the flywheel. Been working that way for a long time. I would imagine they did this because it sheared a key or two and ruined the original groove in the crank. Not much else you can do when that happens to save the crank. But if yours is still good on the crank and the flywheel then all you need is a key.
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olympic
Full Member
Fresh gas first pull got be a DOOO
Posts: 201
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Post by olympic on Apr 3, 2021 14:20:51 GMT
Olyman it isn't perfect but still doable to work. I made a block of wood to go underneath the shaft and put a ball peen hammer on the raised part and gave it a few taps to push the metal back down. Not what some people would do but I going to try it and if it shears again then I will tear it all apart and fix it but for now it just buzzes around the field out back towing kids on their sleds and hoping my littles one will drive it on her own also.
I put a new key in last night and bingo fired wright up runs very nice better than before.
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Post by olyman on Apr 3, 2021 18:22:56 GMT
Right on. May never be a problem ever again. If it starts running crappy some year you will know exactly where to start then. Drive on!
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Post by Admin on Apr 29, 2021 13:02:46 GMT
On a 1968 ski-doo Oly 250 had a key shear and it really made a mess of the crankshaft area around it. I made a key out of persimmon wood (I bought a 1970s golf club driver at a second hand store for a dollar just for the wood). Placed it in the slot and used JB Weld (with small pins drilled into the crank) to build it up. Dremel tooled it out. New key, put all back together, and worked great for years and sold it (told the new owner). Still running! Now, I would never "doo" this on a high HP sled.  |
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Post by snocrusher on May 8, 2021 19:27:52 GMT
Just some thoughts to keep in mind.
The key is only for locating the flywheel to the crankshaft for correct timing purposes. The taper match of the crankshaft and the flywheel bore correctly tightened together is what keeps the flywheel from moving. Think of the tapered PTO end of the crank to clutch bore (on later engines) all the power output of the motor goes to the drive through that taper fit with no key. As long as the taper is not loose, damaged or worn due to some problem or possibly pre-ignition is present the flywheel should not move on the shaft and shear a key.
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