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Post by charles13 on Nov 12, 2021 0:12:05 GMT 1
I have been going through all of the finished lc projects and noticed that a few of them have stroker cranks in them. How easy is this? nobody seems to mention how they did I it.
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Post by JonW on Nov 12, 2021 1:41:39 GMT 1
OX? Is that a typo for LC?
Anyway, not much out there about bigger cc LCs really, these days people just fit a ypvs bottom end and use the modern aftermarket banshee top ends which give more power and are all new parts.
Im sure there was a lot of info in the old days but it seems to be mostly gone now.
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Post by Tobyjugs on Nov 12, 2021 6:02:55 GMT 1
You can either get your cases machined to fit a +4 YPVS crank or get some one to make you a +4 crank for your LC.
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Post by steeley on Nov 12, 2021 6:58:12 GMT 1
Hi , about 15/20 years ago i was talking to a chap at Piston Broke Engineering in Bristol UK. He said he built a near 500cc twin for a customer of his . He said it was the time before Banshee parts . He built a crank using Rd400 con rods . The cylinders were fitted with Bultaco 250 liners and ran the 250 pistons . The head was modified and ran o rings . He did say the transfers were narrow but said the owner had lots of fun on it blowing away larger machines he met while out and about .
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Post by rigga on Nov 12, 2021 9:07:28 GMT 1
Dave (Muttsnuts) on here, has done some development work on LC engines, amongst his large customer work, and pretty sure he was working on a stroker crank version, time and other constraints have slowed it up a bit, but there are options should you want to not go down the ypvs route.
Keeping the LC engine appeals to me, so I'm waiting on what he finally reveals.
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Post by muttsnuts on Nov 12, 2021 12:39:14 GMT 1
ok, so the 421LC is a reality, mine has covered around 1000 miles so far, a few niggles, but overall I am pleased with it. This is a custom made crank, so no machining of the crank cases required, the barrels where machined and had larger liners fitted, I've a few mods to do and some more testing etc I am in conversations with a company that reckon they can cast me some custom made barrels, these will look like LC barrels and fit LC cases, but will be 68mm bore etc, I've yet to finalise the porting etc and I am also thinking if I am going to do this, then I'd be as well making the reed block a bit bigger so that the YPVS reed blocks fit with no machining required, this will help the engine breath much better and therefore more power, I'd be looking at a 392cc and 421cc kit configurations I've had the 421 run 72bhp with performance pipes and 68bhp with mid range pipes, all set up pretty conservatively, there is defo more to be had, the porting is pretty conservative With some more development I am sure I can get it to hit 80bhp and still be very reliable, clearly its a trade off between BHP and reliability, I need to pop my LC on the dyno now that its done approx 1000 miles to see how its holding up, power wise etc and then at some point strip it down and make some more changes The one thing that could scupper the whole thing is costs and numbers, the development costs just for having the mouldings made for the barrels is ££££'s and then I've still to machine the barrels, then get the barrel lined, then the cost of forged pistons (the ones I am using are over £200/pr as it is) - if I could get the barrels to come out at say £750/pr then sure I'd sell some/loads, but I suspect it could be nearly double that, then the crank will be around £500, so the kit could easily be £2k+ - how many people would really be interested at that cost, although it does mean your LC looks stock, those who have seen me out and about on it, haven't realised its not what it looks like until they have been behind it - then it flies !  I'll try and pop some charts up with the 2 different setups I've tested so far (the mid range set up does stock 350LC power (40bhp) at 6500rpm ) |
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Post by beardy on Nov 12, 2021 14:22:49 GMT 1
This is great news ⬆️ 👍🏻
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Post by charles13 on Nov 12, 2021 17:02:59 GMT 1
I’ll definitely buy a crank, I am in the process of setting up a Company in order to open a business account with our Canada Post so that I can order stuff from Dave and Norbo with no bother on their end aside from printing out labels.
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Post by bare on Nov 12, 2021 18:20:37 GMT 1
I’ll definitely buy a crank, I am in the process of setting up a Company in order to open a business account with our Canada Post so that I can order stuff from Dave and Norbo with no bother on their end aside from printing out labels. Doesn't really help very much (have an incorporated business, for years) But hey.. good for you. |
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Post by charles13 on Nov 12, 2021 20:43:29 GMT 1
I’ll definitely buy a crank, I am in the process of setting up a Company in order to open a business account with our Canada Post so that I can order stuff from Dave and Norbo with no bother on their end aside from printing out labels. Doesn't really help very much (have an incorporated business, for years) But hey.. good for you. It is an unfortunate necessity because neither Dave or Norbo are shipping internationally so, for me to arrange the shipping and pay all the fees up front; let’s them just print a label and drop it in the post, also, they don’t have to deal with problems they may have encountered with shipping product internationally. In Canada the only way to do this is with Canada Post and to have a corporate account |
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Post by rigga on Nov 12, 2021 22:14:43 GMT 1
Well I've got a spare bottom end that needs a rebuild, also some barrels that need sleeving anyway ..... so I'm interested, a 70 to 80 HP LC sounds perfect.
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Post by puddy on Nov 12, 2021 22:48:25 GMT 1
Sounds like a 4l1 250lc will be the ideal donor bikes for these conversions , no need to pay 4lo prices |
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Post by muttsnuts on Nov 13, 2021 20:32:51 GMT 1
couple of graphs mid range pipes versus performance pipes (little peaky for my liking the performance ones)  same graph with torque curve one (crossed lines)  Ideally I need to develop the mid range pipes a little more for this engine so that they peak around 9200rpm with 1000rpm over rev, think that would be the ideal pipe, time will tell I suppose ! |
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Post by midlifecrisisrd on Nov 13, 2021 21:01:55 GMT 1
When it comes to a +4 ypvs crank into LC cases am I right in thinking the issue is the ypvs big ends are 1mm wider so the outer webs sit 1mm further out
This means the cases need the outer end face of the cases machined?
If this is right could a YPVS crank be modified?
As in either the outer face of the outer webs machined to give more clearance
Or even better machine all 4 crank webs to recess the area at each big end pin so the big end thrust washers sit 0.5mm recessed each side and shorten the big end pin 1mm
Surely the crank could be supplied unassembled for machining and pressing to fit
Steve
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Post by midlifecrisisrd on Nov 13, 2021 21:03:44 GMT 1
Or can you get thinner thrust washers?
Steve
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Post by muttsnuts on Nov 13, 2021 21:08:52 GMT 1
Steve, the YPVS crank is 5mm wider, but as you say you can machine the LC crank cases so it fits The one off crank I made for this test engine will be coming out soon and then I'll be seeing if I can get the parts seperately to make new ones up, the only down side is the guy who machined me one of the key parts died so I need to find somebody else who can machine that part for me, not a difficult task as such, just needs the right machinery, I have a few people to call and speak to about it, just finding time is the problem at the moment Just having the 4mm crank would be a good start as it means I can build 385cc LC engines like the YPVS and I've got them pushing mid 70's bhp upwards now and being 100% reliable, so getting the LC engine to push mid 60's upwards with loads of torque is very acheiveable without needing to open the ports up too much Hoping to get on it again next year, along with my turbo bike and a few other projects that have been in the back burner for a few years now  |
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Post by midlifecrisisrd on Nov 13, 2021 21:13:34 GMT 1
Brilliant news Dave 👍
Steve
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Post by Tobyjugs on Nov 14, 2021 4:04:15 GMT 1
The distance of the inner webs are different as well.
I've made 2 now but both times the way the cranks have been constructed I've had to make them differently.
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Post by muttsnuts on Nov 14, 2021 13:07:01 GMT 1
The distance of the inner webs are different as well. I've made 2 now but both times the way the cranks have been constructed I've had to make them differently. yep, that's why it took a while to suss it out, but got all the dimensions etc now, as I say, had a specific part made so that it all fitted correctly |
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Post by chrisg on Nov 14, 2021 13:56:42 GMT 1
A very interesting thread with some serious engineering thinking.
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Post by Tobyjugs on Nov 14, 2021 14:32:46 GMT 1
The distance of the inner webs are different as well. I've made 2 now but both times the way the cranks have been constructed I've had to make them differently. yep, that's why it took a while to suss it out, but got all the dimensions etc now, as I say, had a specific part made so that it all fitted correctly The second one I made was from what I believe to be more common type. I know a man who reclaims the hard surfaces on camshaft and then re-profiles them. I asked him to lengthen the middle pin. It's all made I just need to fit it to an engine with 68mm pistons. After all these years I can finally make an engine that looks stock but with a bit of a punch. |
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Post by 4l04ever on Nov 14, 2021 14:50:40 GMT 1
How about using a 4mm stroker YPVS one and skimming 1.25mm off the outer faces of the webs?
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Post by midlifecrisisrd on Nov 14, 2021 15:14:53 GMT 1
How about using a 4mm stroker YPVS one and skimming 1.25mm off the outer faces of the webs? That's what I meant with the outers but yes if you shortened the centre pin you could lose 5mm across all 4 Either that or offset big end pins, an extra roller squeezed in the big end and 5mm longer rods made for the LC crank 🤔 Steve |
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Post by Tobyjugs on Nov 14, 2021 15:39:05 GMT 1
How about using a 4mm stroker YPVS one and skimming 1.25mm off the outer faces of the webs? I recessed the outside thrust washers into the webb's and pressed the pins further in. |
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Post by midlifecrisisrd on Nov 14, 2021 15:48:12 GMT 1
How about using a 4mm stroker YPVS one and skimming 1.25mm off the outer faces of the webs? I recessed the outside thrust washers into the webb's and pressed the pins further in. That's exactly what I meant Good to see it worked 👍 Steve |
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Post by Tobyjugs on Nov 14, 2021 16:38:07 GMT 1
I recessed the outside thrust washers into the webb's and pressed the pins further in. That's exactly what I meant Good to see it worked 👍 Steve We will have to get it running first 😀 |
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