antos
Drag-strip hero
Posts: 298 
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Post by antos on Apr 3, 2017 14:54:46 GMT 1
Guys just left Grampian motors after my crank rebuild and rebore, the mitaka pistons says 4lo 31k on the box I asked the guys if these were the correct ones for an f2 and they've assured me they are ? can anyone confirm this please, only difference I can see is the cutouts on piston skirt for intake isn't as high as the old ones? Thanks antos
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Post by 4l04ever on Apr 3, 2017 21:01:45 GMT 1
There should be a tab sticking down below where the inlet windows are on the piston for YPVS pistons. This runs over the bridge of the rear inlet port.
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Post by bare on Apr 4, 2017 3:30:15 GMT 1
Valvie/Banshee pistons have a tang on the skirt directly below the port hole divider.
LC don't.. but they only have a pair of small round holes as ports. Fairly unmistakable differences.
That said there are Many varieties of Crappy aftermarket pistons.
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Post by dusty350 on Apr 4, 2017 7:47:45 GMT 1
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antos
Drag-strip hero
Posts: 298
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Post by antos on Apr 4, 2017 19:08:22 GMT 1
Thanks lads 😊 Much appreciated and yes the mitakas supplied have the tang 👍👍 cheers dusty 👍
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Post by dusty350 on Apr 4, 2017 22:06:27 GMT 1
Hi Antos The "tang" caused some debate in my thread - I ended up removing it to be on the safe side after some horror stories - easy enough to do with a hacksaw. Interesting that the latest Motorcycle Mechanics mag has Stan Stephens rebuilding an Lc engine, using new Ypvs style pistons - tang intact !! Dusty  |
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Post by steven on Apr 4, 2017 22:16:33 GMT 1
Hi, Oh,More "tang" discussions.  So thats, Yamaha, Paul at PJME and now Stan Stephens that reccomends leaving the tang on. And still, people are attacking their pistons with all sorts of cutting equipment !  Each to their own I suppose. In saying that, im posative I read sonmewhere that Mitaka now do "proper/origonal" type 4L0 pistons do they not ? steven. |
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Post by JonW on Apr 5, 2017 0:46:28 GMT 1
And yet people have proven time and again in threads on here that if you leave the tang on it can ruin your motor... I did wonder how removing it affects the balance, if there is any while Our engines plough their oval course 'through' the cyls... hmm... I'll cut mine off i think, engines cost too much to chance it...  What is also interesting and has been mentioned above is that the later pistons have huge windows, the LCs dont. So does the larger window do anything good for the LC? Im assuming it flows slightly more air/fuel? |
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Post by dusty350 on Apr 5, 2017 7:39:07 GMT 1
Hi Jon When I had my barrels and pistons checked by Paul at PJME, I did ask about the tangs - I was well aware of debate on them in the past. As you can imagine, Paul has dealt with countless Lc's over the years, and has never seen a fubar'd motor due to tangs being left intact. I know the question was directed to Stan Stephens in the past too, and he was of the same opinion as Paul - the tangs don't snag the ports. They are more likely failing due to excessive wear - the tang area being a weak point on a well worn piston. I know that there will always be debate about it, and to be honest, I have other things to worry about, so to be absolutely sure I removed mine. I even weighed the pistons afterwards to make sure they were the same. I'm happy I did mine as it would always have been in the back of my mind, but in all reality, they probably wouldn't be a problem on an engine within tolerance. Dusty |
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Post by midlifecrisisrd on Apr 5, 2017 9:10:21 GMT 1
I'll join the debate lol
Personally I would take it off as nothing lost really but the only way I see that tang catching is if the bores are worn so much it's allowing the piston to rock and catch an un radiused inlet floor.
Steve
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Post by muttsnuts on Apr 5, 2017 11:46:31 GMT 1
yep, have seen cracked pistons and the tang smashed/broken, but always on worn bores, so I think it only comes into play when things are worn and the piston can rock, I remove them, but only for piece of mind and the fact it takes a few mins to do.
You can get the right pistons again now for lC's, so if you can, I'd fit the correct ones and have done with using YPVS ones, also the LC pistons are heavy and also thicker walled, so less likely to cause/hear piston slap
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Deleted
Deleted Member
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Post by Deleted on Apr 6, 2017 7:01:37 GMT 1
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Post by JonW on Apr 6, 2017 12:58:54 GMT 1
Ooooof! that is nasty!
Tang off for me as I said... and has been said above, it takes no time at all, and costs nothing to do.
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