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Post by jon on Mar 4, 2022 19:18:35 GMT 1
I know this has been discussed before. I also know the width difference is more than 2mm.
However, some say they fit in certain circumstances.
I was just wondering if fitting LC conrods to YPVS webs and grinding the big end pins down by 1mm would give a more real world fit without machining the cases?
Jon
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Post by midlifecrisisrd on Mar 4, 2022 19:38:04 GMT 1
Is the centre pin not longer too?
Steve
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Post by reedpete on Mar 4, 2022 19:40:17 GMT 1
Most of the dimensional difference comes from the width of the lab seal. Very obviously wider on the YPVS.
So if you are thinking of a making a conversion crank then having the YPVS ground to suit the LC lab seal would probably be the route to look at.
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Post by midlifecrisisrd on Mar 4, 2022 19:49:06 GMT 1
Just make it like a honda
Single bearing and 1 oil seal
Steve
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Post by midlifecrisisrd on Mar 4, 2022 19:50:02 GMT 1
In fact there is enough room, 2 bearings and an oil seal in the middle 😀
Steve
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Post by muttsnuts on Mar 4, 2022 19:55:38 GMT 1
5mm is the difference, bit more involved than you think, getting the pins ground down isn't a 2 min job as they are as hard as nails and need to be done accurately
been through all this when I built the 4mm stroker crank for the LC, took a far bit of messing about before I found a good solution to the problem - just need to get round to making the 4mm stroker cranks now !
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Post by Tobyjugs on Mar 5, 2022 1:28:16 GMT 1
I've done it twice and I honestly think the easiest way forward is ask mutts or chippy. If they don't want to do it supply crankworks in America with the correct specifitation and they will make you one.
You can machine your engine cases to fit a YPVS crank but it leaves less area for the sealing of the cases.
Morgy has used a YPVS crankshaft in LC cases and to be honest I'm gagging to know how it performs.
By that I believe in the performance, but how will it cope with reliability over time.
This statement is not a nee sayer over Morgy' s choice. Just curiosity on my part.
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Post by shaunthe2nd on Mar 5, 2022 1:31:20 GMT 1
Jon can I ask what's the logic of doing this, is it because of performance, availability or non-conformity? I've only done stock builds and always put in an original crank to an LC or ypvs.
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Post by Tobyjugs on Mar 5, 2022 1:42:06 GMT 1
Hi Shaun I'm not answering this for John but.
I think we are still boy racers at heart even though we can't bend so much or are a bit rusty and full of cobwebs.
Why put a YPVS engine in a 4Lwhatever when you can produce good power out an original engine with the correct modifications. It's in the DNA of us.
Plus it's sticking two fingers up to the YPVS brigade who have always had the luxury of more power.
I now officially apologize to Steve and Matt from the YPVS maffia.
No bollocks power valves are for hairdressers
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Post by jon on Mar 5, 2022 8:18:55 GMT 1
I said in the original post I knew it was more than 2mm difference as the labyrinth seal is wider.
Some say they’ve managed to squeeze a YPVS crank in an LC with no mods. Therefore just wondering if 2mm was enough?
As for reasoning Tobyjugs is partly right. I have a spare YPVS crank that needs a rebuild, and most of an LC engine.
Just curious at present.
Jon
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Post by muttsnuts on Mar 5, 2022 8:54:25 GMT 1
one good reason is the price of cranks, an LC replacement is neck end of £450, whereas a YPVS one (hotrods at that), can be had for £320, its a big difference, and of course, you can also modify/fit a 4mm stroker if you can get the YPVS crank to work, which is why I am trying to find time to get back on and sort out building some - that's new ones of course, refurb'd cranks are a bit cheaper, but not by much these days and have a finite number of times one can be rebuilt
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Post by ganzeeguy on Mar 5, 2022 11:16:28 GMT 1
I managed to fit a banshee crank into 4L1 cases in the hybrid I currently have, the RHS outer crank web just wiped the casing so I was lucky and just had to remove the high spots on the crankcase and ended building it with 0.10 mm clearance in the end.
Some cases will accept the YPVS crank but most will not.
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Post by Tobyjugs on Mar 5, 2022 18:11:03 GMT 1
I just can not understand how a standard YPVS crank center will fit into a 4L0/1 set of cases without being modified.
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Post by chippy348 on Mar 5, 2022 18:48:59 GMT 1
Been discussed to death, no one ever asks about the center line of the rods LC V YPVS
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Rob123
Thrash Merchant
Posts: 382
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Post by Rob123 on Mar 5, 2022 19:54:35 GMT 1
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Post by bare on Mar 5, 2022 21:42:48 GMT 1
Some Canadian LC cases readily accept a Valve crank. Some don't. Personally haven't yet seen one of those though TBH :-)
Regardless.. it's only a very slight skim of the cases outer bearing faces.. IF that's required.
A V simple job with a bespoke fly cutter.
Altering bearings' Circlip groove.. as it's shifted a wee bit with a Valvie type crank.. is Far more significant.
Centre Lab seal width is of No concern, IMO.
Simply easier to fit a Valve Engine... as it has at minimum 10 more Hp from the outset. And it's innards are more evolved /stronger.
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Rob123
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Post by Rob123 on Mar 5, 2022 23:19:01 GMT 1
If I remove a slight bit of material (.10 mm)from the generator side bearing face it will shift it all over a fraction and will clear all sides of the webs I think as bare says. Looks like the webs will have .010 mm gap all around each side once moved over. Is that enough clearance tho seems abit close for comfort 🤔   |
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Post by Tobyjugs on Mar 6, 2022 1:17:37 GMT 1
Rob thanks for the pictures. It clearly shows the crank can fit. Which makes me more curious to the tolerances used when manufacturing the cases.
I know there are a few different ways to construct the cranks.
I actually took all my measurements from the center of the crank outwards.
You need to have clearance for the crank webb's. As you probably know the crankshafts can spread. You need to take this into consideration.
I just stuck to the same tolerances that I think were standard. By that I mean I copied the dimensions of a 4L0 crankshaft which I believed to be standard.
Off the top of my head I would say minimal 0.30mm.
I've measured a few cranks that have spread. They can move open to give an axial clearance of 0.90mm and the Webb will still not touch the casing.
Check the original 4L0 Webb clearances to help you decide.
One thing I have noticed on 4L0 cranks is the use of two different thickness thrust washers and I often wonder if these are used because it's easier to use YPVS parts when manufacturing a 4L0 crank?
Maybe chippy can pour some light on this observation.
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Rob123
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Post by Rob123 on Mar 6, 2022 8:51:09 GMT 1
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Post by chrisg on Mar 6, 2022 13:40:22 GMT 1
When you mentioned tight toletencrs, these are all cold measurements. What about when its warm, better or worse?
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Post by midlifecrisisrd on Mar 6, 2022 14:22:11 GMT 1
Am I right in thinking the centre crank pin is a separate part?
Does it interfere with the big ends if it were pressed through an extra 1mm or so into the web if an LC lab seal was used?
Steve
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Post by Tobyjugs on Mar 6, 2022 16:38:51 GMT 1
Ironically, I have a modified 4L0 crankshaft that is fitted to my 400cc YPVS engine.
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Post by Tobyjugs on Mar 6, 2022 16:46:37 GMT 1
Am I right in thinking the centre crank pin is a separate part? Does it interfere with the big ends if it were pressed through an extra 1mm or so into the web if an LC lab seal was used? Steve The first crank I built was with a separate center pin so it was very easy as I think it is 2mm longer than a YPVS. This crank was bought second hand. I then bought a new +4mm crank which the center pin came as one piece with a web. I know a man who can repair camshafts so I gave it to him to make it longer. There seems to be a few versions for crank construction. |
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Post by charles13 on Mar 6, 2022 23:55:59 GMT 1
There is a machine shop near me that turns down the outer webs slightly on rz +4 cranks to fit into lc cases on a regular basis
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Rob123
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Post by Rob123 on Mar 7, 2022 18:33:00 GMT 1
There is a machine shop near me that turns down the outer webs slightly on rz +4 cranks to fit into lc cases on a regular basis Does anyone think it would be possible to do this on there lathe take say 1mm or so off each Web (4 sides/edges)? Can anyone see an issue with doing that? |
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Post by charles13 on Mar 8, 2022 0:09:09 GMT 1
They only take the protruding outer perimeter rings off one side until it is flush with the rest of the crank face, and only on the 2 outside edges of the crank; far left side and far right side so not much really. They have been doing this for a while so it must work.
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Rob123
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Post by Rob123 on Mar 8, 2022 9:02:38 GMT 1
Mines tight on the inner Web one side outer Web the other side so it wouldn't work with just the outers turned down. Plus to keep it balanced I'd of thought the same amount needs to come off all sides?  |
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Rob123
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Post by Rob123 on Mar 8, 2022 9:29:15 GMT 1
Not a bike crank but interesting to watch the
Follow up vid also good of how much the crank is out of balance and how they re balance them.
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Post by Norbo on Mar 8, 2022 10:39:08 GMT 1
Its no big deal just use lc rods and big ends and grind the pins back to fit do it all the time when lc inner webs are shot and i have ypvs ones . must have done 100 over the years . then you dont have to mod the casings . If you want to fit a ypvs as they come you will need to mod the casings but simpler if rebuilding to just use lc stuff and do the pins .
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Post by jon on Mar 8, 2022 14:35:32 GMT 1
Its no big deal just use lc rods and big ends and grind the pins back to fit do it all the time when lc inner webs are shot and i have ypvs ones . must have done 100 over the years . then you dont have to mod the casings . If you want to fit a ypvs as they come you will need to mod the casings but simpler if rebuilding to just use lc stuff and do the pins . Norbo, that answers my initial question exactly. Thanks. Good to know you’ve done this many times without trouble. Jon |
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