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Post by stusco on Mar 4, 2017 20:16:41 GMT 1
Nice n shiny
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Post by ibby4585 on Mar 4, 2017 20:50:13 GMT 1
that's lovely. great job.
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Post by dusty350 on Mar 4, 2017 20:52:37 GMT 1
Hi No, only on the studs. Lots of oil on the bores to help it all slip into place though Definitely gonna have to choose my moment for first start up, it's gonna smoke the street out !! Dusty  |
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Post by oldelsieboy on Mar 4, 2017 21:06:30 GMT 1
I thought you would have removed the tangs on the skirt of the YPVS pistons before refitting the barrels. OEB |
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Post by dusty350 on Mar 4, 2017 21:36:58 GMT 1
Hi Nigel I did ask Paul at Pjme about that when I took the barrels and pistons up to him. He said there was no need to do it. I know there is some debate about it, but as they have been running fine in this motor before I bought it, I have left them alone. Dusty |
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Post by oldelsieboy on Mar 4, 2017 21:48:48 GMT 1
Hi Nigel I did ask Paul at Pjme about that when I took the barrels and pistons up to him. He said there was no need to do it. I know there is some debate about it, but as they have been running fine in this motor before I bought it, I have left them alone. Dusty If it were me I'd have played safe & removed them, a guy on FB had a perfectly good running LC till this happened.  OEB |
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Post by dusty350 on Mar 4, 2017 22:06:26 GMT 1
Yea, I saw that pic, and have read in the past about people removing it. That's why I was keen to know Paul's thoughts on it. If he had said definitely do it then of course I would have, but he was sure there was no need. Be interesting to know how many guys have removed it or not, considering most here must have had rebores and new pistons in recent years. Maybe Muttsnutts has some info as I know he builds plenty of Lc's. Dusty |
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Post by Tobyjugs on Mar 4, 2017 22:47:24 GMT 1
I have always removed them as well, but the bore and stoke is the same for both engines. Could never understand why it has to be done, so always stuck to better safe than sorry.
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Post by stusco on Mar 4, 2017 23:00:54 GMT 1
The Pv has a post in the middle of the inlet the lc doesn't maybe the tang catches sometimes
maybe just chamfering the tang would do so it won't catch when the piston rocks
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Post by wallcraft on Mar 4, 2017 23:04:28 GMT 1
I have always removed them as well, but the bore and stoke is the same for both engines. Could never understand why it has to be done, so always stuck to better safe than sorry. Just in case the piston rocks in to the bridge-less inlet on the LC, especially when they've got a few miles on them. |
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Post by dusty350 on Mar 4, 2017 23:21:56 GMT 1
I did think about doing it - there has been plenty about it in the past. The seed is sown now though so tomorrows job is to whip the pistons out and sort the tangs !! I wont be happy now unless I do it and no better time than now. This will be a £1k engine by the time I finish so wont take any chances. Thanks for the input Dusty |
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Post by Tobyjugs on Mar 4, 2017 23:24:45 GMT 1
Thanks for the simple explanation lads |
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Post by wallcraft on Mar 4, 2017 23:25:16 GMT 1
Just seen the Very amateur engine rebuild thread, perfect case in point , check out the piston damage!
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Post by ibby4585 on Mar 4, 2017 23:39:25 GMT 1
Just seen the Very amateur engine rebuild thread, perfect case in point , check out the piston damage! yep I wondered what happened to them, both have deformed and cracked. |
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Post by dusty350 on Mar 5, 2017 0:51:06 GMT 1
Hi No problem. I am well aware of the debate surrounding the tab. These pistons are Ypvs fitments that work in the Lc, and the Ypvs has no issue with the tab being there. Head is already off - I did it whilst waiting for the boxing to start !! I'd rather do it now then think about it when the engine is back in the frame. I certainly don't want to take a risk with it. It's a standard bike that will have Allspeeds and I wont rag it around much, but I think, on reflection and the experience of you guys, that it would be a sensible thing to do. Tabs will come off tomorrow, circlips will be ordered Monday - it will be back together before the weekend !! I did ask Paul at Pjme, and he said the bores would have to be very badly worn for the pistons to rock enough for the tangs to catch the inlet - the only way it would happen. Cheers guys Dusty |
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Post by ibby4585 on Mar 5, 2017 9:02:39 GMT 1
So stupid question, do you just remove the middle tang or all three and how do you remove it?
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Post by dusty350 on Mar 5, 2017 9:39:46 GMT 1
Hi It's the middle tang only. Best way is to use a Dremmel or something like it. I'm doing mine today and will do some pics. Dusty |
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Post by oldelsieboy on Mar 5, 2017 9:44:12 GMT 1
So stupid question, do you just remove the middle tang or all three and how do you remove it? Just the middle one. Only necessary if running YPVS pistons in 350LC barrels. If you are having a rebore it is now possible to buy 4L0 specific Mitaka pistons which have a solid skirt with not tang.  OEB |
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Post by KevtheRev on Mar 5, 2017 9:44:49 GMT 1
'Kin Sweet Dusty ! Only problem is the shame I feel when I look at my own maggoty LC lump sitting on the bench , lol !
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Post by dusty350 on Mar 5, 2017 10:18:57 GMT 1
Hi I guess as pistons wear with use maybe they rock a little more in the bore, allowing the tang to catch maybe ? They don't do it when newly fitted, and these particular pistons have seen some miles already, although not enough to show wear beyond an acceptable tolerance - as measured by Paul. The sensible thing to do is take the tang off to be absolutely sure it will never snag anything. I've got spares of everything except circlips so it's no biggy for piece of mind I'm glad it was mentioned and debated - it would always been in my mind otherwise, and I've spent a lot of money trying to make sure this will be a reliable motor ! Dusty |
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Post by wallcraft on Mar 5, 2017 10:56:45 GMT 1
Yep that's the beauty of theses engines being able to pull them apart in an instant and fix, having said that like you said , it would of been a pain if all connected with everything.
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Post by ibby4585 on Mar 5, 2017 11:10:04 GMT 1
Hi Dusty. I dont want yo jump on your thread but im guessing it could be useful. Some pics of my pistons, looking at them do you think this is what has happened to mine.   Just looked at new pistons which are standard size and dont have the ypvs tabs   |
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Post by lrcarl on Mar 5, 2017 11:26:38 GMT 1
This came out ypvs engine I got off eBay (good running engine)😡  Wear could be the issue |
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Post by lrcarl on Mar 5, 2017 11:53:40 GMT 1
Yep no tang,bridged inlet same problem?
Carl
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Post by dusty350 on Mar 5, 2017 12:00:06 GMT 1
Hey Ibby Feel free to jump in. That's what I want people to do. There is always someone that knows about issues that arise when building/restoring. This will hopefully be a thread that someone can read and end up with a really good engine, and that may mean that lots of other members add their ideas/tips/experiences. That's the beauty of the forum - there are lots of guys who have a lot of experience that are happy to share, and that can only be a good thing. As for your engine, it looks like a small nuclear device was inhaled through the carbs and detonated in the bottom end !! Seriously though, maybe that damage is consistent with the tang on a worn piston hitting the inlet port - the pattern of damage seems consistent with other pics posted. One thing is certain though - I'm glad Nigel mentioned it in the first place and started the discussion - I don't want to be posting pictures like that in the future !! Dusty |
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Post by ibby4585 on Mar 5, 2017 12:25:34 GMT 1
Thanks Dusty.
With regards to my engine im quite pleased we have found a possible cause, as the previous owner had put it down to some sort of electrical seizure which clearly isnt the case.
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Post by steven on Mar 5, 2017 12:40:39 GMT 1
Hi Dusty,
Your engine looks delicious, all cleaned, polished and painted.
I do like a good "tang" discussion !
I was like you and tried to build my engine as meticousely as I could.
Paul at PJME did my re-bore and re-built my crank also.
When he phoned me to tell me it was ready, I got chatting to him.
While chatting to him on the phone, before I even mentioned tangs he said......
"your going to ask me about tangs now, arnt you?"
I laughed and said yes, that was my next question.
Paul said that in his oppinion, removing the tangs is an urban myth.
He said that he had done loads of LC engines and NEVER removed the tangs, and never had any issues.
He said that if the piston can rock that much in the bore, that the piston hits the casing, then there is obviousely something else far wrong.
Another thing he said was that if you type the LC piston part number into the computer, it says "now superseded by".....and gives the YPVS piston part number, which is obviousely the YPVS pistons with the tang.
So pistons with the tang on them, are what Yamaha recommend.
Im no expert on LC engines, so I could only go on the advice of Paul at PJME, who I would say was an expert on Lc engines.
I thought long and hard about it at the time, and decided, to go with the advice of Paul and Yamaha and I left the tangs on my pistons.
This year will be the fourth year I have ran that engine with the tangs still on, and so far so good.
I suppose time will tell.
Cheers,
steven.
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Post by 4l04ever on Mar 5, 2017 22:08:51 GMT 1
I have seen pistons with just part of the lower skirt damaged due to the tang being left on. In fact the piece was completely gone! I now remove the tangs on all YPVS pistons going into LC cylinders.
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Post by dusty350 on Mar 5, 2017 22:19:40 GMT 1
Hi Well, my pistons have been de-tanged today Simple job really, even considering I had unknowingly run out of cutting discs for my Dremmel, so resulted to a good old fashioned hack saw blade. So a bit of tape gives a cutting guide;  20170305_151927 by David Miller, on Flickr Then gently start sawing;  20170305_152134 by David Miller, on Flickr Then a before and after pic;  20170305_151559 by David Miller, on Flickr The cut gets you more or less right straight away. I used a fine file to clean the pistons up and it's job done. And the bonus was both pistons weigh exactly the same;  20170305_153039 by David Miller, on Flickr  20170305_153027 by David Miller, on Flickr That measurement is in oz's. I double checked the weight using grams and both came out at 204 so pretty pleased. Whether it needed them doing or not, my mind is happier knowing I've done it  Dusty |
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Post by ibby4585 on Mar 5, 2017 22:36:53 GMT 1
Nice
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