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Post by JonW on Mar 26, 2015 4:35:40 GMT 1
Quite a few people seem to have strengthened the YPVS frame, not all in the same areas which is interesting, but Ive not seen much (if anything) about adding strength to the LC frame, has anyone got any thoughts on this?
The reason is that I am running a 421 motor and I know the YPVS in sub 400cc form can crack some of the mounts, so im thinking the LC might be the same, or worse... Im also running RGV front and rear ends so I know Im putting more strain on the swingarm and headstock as well.
I reckon the tie bar mounts need a bit more strength, and something in the vicinity of the swingarm. Anyone think thats good or bad, or have a better plan?
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Post by JonW on Mar 27, 2015 9:08:46 GMT 1
Wow... not often the brains trust here dont have something to add to a topic, have i finally found the one thing no one has ever done to an LC?  |
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Post by dusty350 on Mar 27, 2015 9:22:52 GMT 1
Hi
I am sure I have seen a thread on one of the US forums regards bracing, but I think it may have been on a pv frame. I would think the same areas apply to an Lc though. Worth a search over there.
Dusty
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Post by JonW on Mar 27, 2015 12:54:14 GMT 1
Yeah, Ive seen lost of different YPVS frames thats have been done, but as I said, most people seem to try something different to the last person but generically they run a 2nd perimeter rail beneath the other spars, but thats not going to work on an LC of course. Ive looked and not found an LC strengthening, hence the question... bear in mind the USA never got the LC when new, so there are few there, Canda did get em, but few are modded. I guess racers might have a feeling about what they think needs doing, but few run double the bhp like I am, so I asked here as there are more big engine LCs on this forum than any other nowsadays  |
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Post by LC_BOTT on Mar 27, 2015 13:11:57 GMT 1
Is the headstock area really necessary, as it's obviously steel rather than later alloy? (rgv/tzr etc)
I've just found a couple of small plates (one each side) welded onto the area at the bottom of the side panel/above the swingarm pivot that would stop the two rails 'pulling apart'
I hadn't noticed it before, but just took the engine out and it hasn't got a rear brakelight switch because of this? Doubt it does anything of benefit myself?
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Post by Tobyjugs on Mar 27, 2015 18:18:45 GMT 1
A short while ago i plated the head stock to give it some additional support because i have fitted an R6 front end.  At first i was going to box it in completely then i settled for this. I am still thinking about the back. The chassis it self looks quite stiff, i think the weakness lies in the two thin plates which holds the swing arm in place. Botty can you make a photo for us. I would also like to see what other people have done. |
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Post by JonW on Mar 27, 2015 22:59:43 GMT 1
Nice gusset Toby! (Had to be said, how often do you get to say that?!)
I agree the head stock is a good area to do.
Botty, yes a pic would be great, Im trying to see how tying that area would help, but Im keen to see.
As Ive said, my thoughts are that the whole swinger area is weak compared to the swingarm forces when adding something like an RGV, Im wondering about a secondary plate over that area? and I also have seen YPVS crack at the front tiw bar mounts with a 385cc motor ridden hard, so was tempted to add something there as well perhaps?
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Post by 4l04ever on Mar 28, 2015 0:23:39 GMT 1
I have some pics I can email you.
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Post by Tobyjugs on Mar 28, 2015 8:03:17 GMT 1
I have some pics I can email you. Yes please  |
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Post by jon on Mar 28, 2015 9:16:39 GMT 1
jonw, if you look at most modern bikes they have a very stiff frame section between the swing arm pivot and headstock. Modern suspension softens the ride.
The way I see it in a very basic way is there are essentially two different types of condition to overcome: bike upright under power or breaking, and cornering.
I think with an LC frame you can sort the first condition out easily by bracing the headstock and swing arm pivot, but twisting during cornering is more difficult with the central spine. Remember to drill holes for cables and wiring in any headstock plates like tobyjugs.
IMO the swing arm pivot should be made similar to the YPVS. I was going to do this on my LC hybrid, but bottled it and only welded on what could be ground off again to return to standard like rear master cylinder plates and steering stop. If I ever re-do it, I will strengthen the frame, as if I am honest I am never going to restore it.
I would machine a spacer and weld it on the original swingarm pivot plate, then fabricate another plate the same shape as the original and weld that to the outside of the frame tube so the whole pivot was the same wide as the tube.
Glad to see in hindsight I have no such restrictions on my latest hybrid YPVS and have gone the double frame tube route.
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Post by JonW on Mar 28, 2015 9:25:46 GMT 1
Thanks guys, good stuff!
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Post by LC_BOTT on Mar 28, 2015 11:56:07 GMT 1
Took a pic of what's been done, (needed some pipe pics too) I can see no reason for it myself, but I suppose the previous owner, had made 'significant handling mods' Same bit welded to both sides. Can't see any other areas modified so a bit confusing as to why.  |
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Post by JonW on Mar 28, 2015 13:17:50 GMT 1
Yeah Im not really seeing how that would add much strength to the frame really as you say, its not really helping the pivot or the shock mount or the headstock or joining any of those parts together, just stoppin the attached 'rear subframe' stay in position a bit batter, maybe he was a fatty and worried it might snap off LOL!
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Post by LC_BOTT on Mar 28, 2015 18:29:36 GMT 1
I have just found some more bracing on the bottom rails, (just compared it with another 250 frame I'm trying to register) there are three more sections that have been triangulated with the centre stand tube (the stand mounts have already been cut off) was hoping to make it into a 'minty' standard bike, but not sure I'll bother now.
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Post by Tobyjugs on Mar 28, 2015 21:18:32 GMT 1
Have been thinking about your question again, whilst tinkering with me engine. If you look at the chassis and follow the lines of the top rails, you will notice one small spot which could be weak. Over exaggerated it looks like a kink  If you look at the top rails they are fairly well supported except in one place here.  I am not a design engineer but i would say that the forces from the front and back of the bike would be transmitted to the ends of their bracing. This just happens to be here and there is only a small amount of support from the overlapping weld. I have also been thinking something in this area would be good, but this would be major surgery for me and first i want to get it all running before i get too radical. Next step for me is the swing arm area.  |
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Post by bare on Mar 29, 2015 3:24:51 GMT 1
Why? My Yama TZ's fielded for Yama (in 73/74) were flexi frames (20 ga tubings were lighter:-)
NOT a problem for My guys riding them.
Why is it deemed one now...with the heavier gauge tube frames of Retail grade LC's... Obstensibly for Shopping uses?
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Post by Tobyjugs on Mar 29, 2015 9:22:26 GMT 1
Why? My Yama TZ's fielded for Yama (in 73/74) were flexi frames (20 ga tubings were lighter:-) NOT a problem for My guys riding them. Why is it deemed one now...with the heavier gauge tube frames of Retail grade LC's... Obstensibly for Shopping uses? The same question could be asked on a lot of topics on here. The one that gets me the most is the discussion about boyessen reeds. One man was very happy with the results he had and then he got a lot of critiscism about them and we are only talking small hp win/losses. The main thing is that he is happy, after all, it is for most of us a hobby. Same could be said about all the different wheels and suspension mods. It is because we like it and are interested in the subject. |
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Post by JonW on Mar 29, 2015 9:23:11 GMT 1
LOL @ bare, why not improve something if you can? a few of us have improved the brakes and performance, why not the handling?
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Post by jon on Mar 29, 2015 9:42:46 GMT 1
Bare your right with you nostalgic views there was nothing wrong with the flexi frames in the past, however things move on.
Shock and engine technology has moved on. After all you can get around 100BHP from modern kits now.
Another important thing to remember is these bikes are for the pot holed roads, not the smooth Tarmac track.
If a race bike cracks a frame it is not such a big deal as it is probably regularly stripped down, and cosmetically the weld job will probably just be dusted over with paint. Not so for most people's road bikes.
The fact this is the way modern bikes are designed can't be wrong. However I totally agree with you that we are chasing an ideal we can never really achieve properly. You are never going to make an LC frame as good as a modern bike, but any improvement is better than none.
I remember taking the new CBR600 out for a test drive. I drove to the bike shop on my YPVS without noticing anything. Took the CBR for a ride. Rode my YPVS back home, and could not beleive how the frame felt like it was made of jelly which I had never noticed before.
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Post by paulsx on Mar 31, 2015 8:48:58 GMT 1
The ones I have seen on bigger bikes extends the swing arm pivot area so you keep the same bolt location but use a plate which is much wider and then welded to the original. Also another member running side to side above or below the swing arm pivot would help.
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Post by bare on Apr 2, 2015 17:20:34 GMT 1
LOL @ bare, why not improve something if you can? a few of us have improved the brakes and performance, why not the handling? Well... MY 600RR feels entirely different than my lc/valvie. But still I choose to own Both. My issues with 'Improving' the LC is in that when you dick with one end.. then you absolutely must dick with the other end.. And ultimately everything else in between. By the time it's 'fully' accomplished.. eventually :-) the thing bears small/no resemblance to what it was in the first place. LC's left the Factory as Complete designs .. Foibles were well balanced... by design /ecomonics. DIY meddling IS risky. Yesss we All love to improve.. I'm guilty too. But tread carefully. Wanna Fast Bike?? Buy one it's Really Easy to do:-) these even come with a warranty. PS: TZ350 Yama owned frames were cut up and discarded at each season's end, they invariably cracked in several places. Privateers patched and perpetually dicked around with theirs. Some still survive. Just like the infamous Headsman's Axe in the Tower: The shaft has been replaced trice and the head once.. But it's Original.. they claim with a straight face. |
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Post by stusco on Apr 2, 2015 17:30:09 GMT 1
LOL @ bare, why not improve something if you can? a few of us have improved the brakes and performance, why not the handling? Well... MY 600RR feels entirely different than my lc/valvie. But still I choose to own Both. My issues with 'Improving' the LC is in that when you dick with one end.. then you absolutely must dick with the other end.. And ultimately everything else in between. By the time it's 'fully' accomplished.. eventually :-) the thing bears small/no resemblance to what it was in the first place. LC's left the Factory as Complete designs .. Foibles were well balanced... by design /ecomonics. DIY meddling IS risky. Yesss we All love to improve.. I'm guilty too. But tread carefully. Wanna Fast Bike?? Buy one it's Really Easy to do:-) these even come with a warranty. PS: TZ350 Yama owned frames were cut up and discarded at each season's end, they invariably cracked in several places. Privateers patched and perpetually dicked around with theirs. Some still survive. Just like the infamous Headsman's Axe in the Tower: The shaft has been replaced trice and the head once.. But it's Original.. they claim with a straight face. I thought that was Triggers broom |
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Post by paulincayman on Dec 7, 2016 3:42:55 GMT 1
Very well maintained that broom , that's why it lasted so long..wonderful stuff !!
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Post by 4l04ever on Dec 7, 2016 23:51:51 GMT 1
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Post by JonW on Dec 21, 2016 2:58:48 GMT 1
I am looking at my frame now with a view to doing some work on it... yeah yeah i could buy a modern sportsbike, blah blah... lets not bother going round that again, id like to stick to the topic in hand please: Strengthening the LC frame. Ok, I have a question... the welding on some of the tubes does not go along all the seams. I know when building race cars often people fully seam weld to add strength, ok these bike frames are not just spot welded but I wondered if people thought that finishing off these welds might help? See the pic below as an example:  |
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Post by JonW on Dec 21, 2016 3:04:02 GMT 1
In the meantime if anyone feel like drawing on a pic where they thing the frame lacks strength, here is a good pic from Xavier's site. Please do also write why you think something needs attention of course, otherwise we may as well just draw a circle round the whole bike LOL  This is my first take on what would be some key areas:  My reasoning is that with better front and rear ends, and stickier rubber that the headstock could do with more attachment to the spars, the spars are not well welded where they are triangulated at the top (and could probably be joined in places to form a better 'single spar'), the swingarm pivot is very thin and the front engine mounts can be cracked with the twist from the motor. |
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Post by JonW on Dec 21, 2016 3:11:27 GMT 1
FWIW Ive googled TZ350 frames and not found any decent pics of the OEM bare unit as supplied ex yam. I wanted to see what they did and also what the welding was like. Pretty much everything I found was aftermarket as I guess most OEM frames have been scrapped a long time back if they needed to be replaced every season. If anyone has any pics i'd be grateful.
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Post by JonW on Dec 21, 2016 8:09:44 GMT 1
Interestingly when comparing to the YPVS, it seems Yamaha actually took on board some of this: Swingarm pivot point is a folded sheet with a bush in it, it now locates on both sides and is much stronger:  Rear frame cross member braced on both sides:  Headstock plating welded up fully and triangulation braces are much thicker:  triangulation joiners welded fully:   So, it seems doing these simple things would help.... or so yamaha thought... the ypvs frame is no RGV, but its much better than the LC. And while I cant fix the general design, this might help... right? Ive also decided to fix the obvious elephant in the room too and fit the RGV swinger pin, Im going to redo the swinger mounts anyway to make them stringer, so why not upgrade to the thicker pin. |
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Post by veg on Dec 21, 2016 9:46:48 GMT 1
Jon interesting points you raise and yes the pv frame would be a good guide. if you research early 80's AMA superbikes they show how the bigger inline 4's were braced. Then if you want furthe detail research plastic model kits of AMA bikes these are mini versions in plastic form but also actually contain lots of info and photos of the real things, Be interested to see how you progress.
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Post by JonW on Dec 22, 2016 4:33:04 GMT 1
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