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Post by Raizer on Feb 28, 2016 19:48:25 GMT -5
Good idea, I'll pull the whole variator off to rule out the rollers rattling too.
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Post by Raizer on Feb 29, 2016 21:19:54 GMT -5
Lets play a little game shall we? It's a simple guessing game I like to call name this knock, big or little end bearing? There's no variator or flywheel on the engine. I've got my fingers crossed it's the (pricey reinforced) wrist pin bearing. but place your bets now!    Oh and yet again the variator bush is a burnt brown and starting to stick inside the variator. |
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Post by drc174 on Feb 29, 2016 21:24:02 GMT -5
Erm.. do you have a piston stop in  ? |
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Post by Raizer on Feb 29, 2016 21:29:31 GMT -5
Sure sounds like it, but nope no stop, just rocked it on the spot to highlight the noise.
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Post by tsimi on Feb 29, 2016 21:36:42 GMT -5
Not to paint the devil on the wall but that does not sound very good.
You sure it is not something on the variator? If it is the needle bearing wouldn't there be broken pieces inside the cylinder?
Can you remove the pipe and check or listen through the exhaust port?
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Post by Raizer on Feb 29, 2016 21:42:41 GMT -5
tsimi there is no variator fitted in the video, just it's bush and backing plate to take up the space so I could attach the fixed face to give me something to turn the engine with! Noise is the same plug in or out. Going to have to pull the engine and remove the top end, fingers crossed I can get away with just swapping in a new bearing and not have to split the cases again or worse find a ruined cylinder!
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Post by Raizer on Feb 29, 2016 23:17:01 GMT -5
Needle bearing looks ok to me, but unsure.      Going to polish it with some emery for now.  Can't feel that with my nail, light hone should sort it.  Is rich at some point, likely cold start as that's all the running it's done to day and it was a rich pig to try to start! Pulled the top end off the engine I'd been using, big end seems to have less side to side play. Dunno what to do now. |
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Post by spaz12 on Feb 29, 2016 23:19:05 GMT -5
I'm going to assume small end since it's the weak link. That's just a guess though.
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Post by niz76 on Feb 29, 2016 23:22:53 GMT -5
Is that a Technigas pipe you're running with it? I say run it! Technigas aint got enough power to pull her apart! muwahahaha
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Post by spaz12 on Feb 29, 2016 23:25:00 GMT -5
It figures that there is another page. I know that I looked up and didn't notice another page.
Guess I guessed wrong. At the beginning of the second video you see/hear the play. That crank me thinks is shot.
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Post by Raizer on Feb 29, 2016 23:35:05 GMT -5
I think for now I'm just going to polish the piston a bit then chuck the BBK onto the engine I removed and run that. One day when my bank account has more than $2 in it I'll look at getting a top racing crank and 47.4mm piston then rebuild this engine again. Is that a Technigas pipe you're running with it? I say run it! Technigas aint got enough power to pull her apart! muwahahaha Lol! I've got the stage6 pro rep to go on in the future though! |
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Post by tsimi on Mar 1, 2016 2:36:35 GMT -5
The piston and cylinder show seize marks, I guess.
Could it be that you actually didn't seize it because of a lean condition but because of that crank or bearing issue? Or maybe a bit of both?
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Post by 190mech on Mar 1, 2016 4:55:37 GMT -5
Looks like a '4 corner' seize to me,common on new builds,(tight piston to bore),sand out the aluminum in the bore and knock the scuffs off the piston with a needle file and it'll be good..Sounds like the top end bearing to me in the vid..  |
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Post by Raizer on Mar 1, 2016 5:09:59 GMT -5
My plan for tomorrow is to clean up the piston (I was thinking 400 grit wet paper the scuffing is worse in photos than in person) and the bore.
I'm thinking I'll fit the stock 50cc piston, bearing and cylinder to the new engine, if it still makes the knock with this combo it's got to be big end, if not I'll order a new bearing and keep running this bottom end.
I've got my fingers crossed it's just the top end bearing, I can get a new Malossi bearing delivered overnight for $20.
That gudgeon/wrist pin to me looks like it's seen a bit of heat, was very tight in the piston too.
It's hard to tell from the video, but the play in the big end is side to side only, I can't feel anything when pulling/pushing on the rod.
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Post by tsimi on Mar 1, 2016 5:49:48 GMT -5
Raizer Don't forget to get some piston pin circlips.
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