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Post by mangocrazy on Jan 23, 2024 18:31:15 GMT 1
I'm talking about the jack-up kit that NK Racing supply - this one:
I'm intrigued to know what difference it makes - I've jacked up the rear end on other bikes to make them steer faster, but was wondering what people thought about the mod on LCs. NK Racing say: Direct bolt on to standard swing arm to jack up the back end approx 50mm. It's £80 + VAT (£96).
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Post by jessy03 on Jan 23, 2024 20:13:07 GMT 1
I’d probably put the money towards a new shock with ride height adjustment 👍
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ajh
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Post by ajh on Jan 23, 2024 20:46:42 GMT 1
i used a 2nd hand wr125 shock which is maybe a bit too high without rider on it but is a good improvement on handling, reduced wheelies and supports heavier riders better Only cost about 25 quid on ebay (See profile pic for stance)
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Post by mangocrazy on Jan 23, 2024 21:52:02 GMT 1
I’d probably put the money towards a new shock with ride height adjustment 👍 That would be some shock with 50mm of ride height adjustment...
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Post by donkeychomp on Jan 23, 2024 22:19:46 GMT 1
A common mod back in the day. Looks cool, ruins the handling in my opinion.
Alex
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Post by billbott on Jan 23, 2024 23:13:33 GMT 1
I have a 125Lc shock on my 250 which jacks it up so the centre stand just about touches the floor when it’s down but you can’t spin the wheels. On my 350 I have an SV650 shock which again jacks it up but not quite as much. It makes the steering a bit sharper but I can’t remember just how much as the one on the 350 must’ve been on well over 10 years, never rode the 250 with standard on.
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Post by mangocrazy on Jan 24, 2024 0:06:22 GMT 1
I've fitted a YSS shock which has a small amount of ride height adjustment and I've maxxed that out, but wouldn't mind a bit more. I'd say that billbott's 350LC looks about right in terms of rear ride height - would you happen to know how long the SV650 shock is eye to eye, compared to stock LC?
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Post by charles13 on Jan 24, 2024 1:30:04 GMT 1
When I ordered my YSS shock I asked for it to be 2” longer and I still have the adjustment, although, I have 41mm sv650 forks and triples with racing internals that may be a tad longer and don’t dive like the stocker’s under braking.
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Post by billbott on Jan 24, 2024 7:32:32 GMT 1
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Post by dusty350 on Jan 24, 2024 8:26:20 GMT 1
I got a local engineer to make some extension bars that fit to the YSS shock; 20210115_134516 by dusty miller, on Flickr That was for the 400 hybrid twin shock build. You have to be careful how much you jack the back end up by. The chain will start dragging across the top of the swingarm, and can also permanently come into contact with the exhaust if you go too far. Also do yours maths with different shocks. I once fitted a remote reservoir Rgv shock to a monoshock Ac400, and it was like a pogo stick, and waay too hard. Diesel shocks off bigger bikes are designed for a heavier bike to start with, so spring rates often dont suit the lighter Lc. They might seem better than a shagged out 40 year old standard shock, but in use they wont perform as well as a shock designed or the Lc, imo (I've tried all sorts of shocks in the past, from bigger bikes), that's why the YSS shock is such great value for money I think
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Post by JonW on Jan 24, 2024 8:36:45 GMT 1
I agree with Dusty on this. Ive tried a bunch of other bikes shocks and was never convinced.
Shocks are a bit like brakes, only more confusing... I'll explain:
In the same was that a 12mm brake master cyl is great with a 4pot Brembo on one bike, a 12mm with a 4 pot Tokico on another might be awful. Even if the maths says its ok.
Shocks are like this too, but its made worse as there is more maths involved... and its even more confused for the LC as many bikes youre stealing a shock off actually use a linkage to transfer forces and the LC doesnt, its direct.
What suspends a CBR/R6/RGV etc etc etc is all good for that bike, but with a different knuckle or linkage or orientation it'll be horrible even if the weight of the bike seems right etc.
I also like the YSS, its a great compromise between price and quality etc.
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Post by JonW on Jan 24, 2024 8:38:46 GMT 1
I do like the jacked up look, its proper of the era. ie. It looked cool even if it didnt help the handling etc. This was very much like most of the kit we bought for our bikes in the 80s lol. IMHO, I'll agree with whats been said that sorting the shock is the better option, but Im also pleased Bill likes how his works.
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Post by mangocrazy on Jan 24, 2024 22:37:15 GMT 1
Thanks guys! All really helpful, well thought out suggestions based on personal experience. It doesn't get any better.
Having seen dusty's post (and taken on board the warnings from JonW) I'm definitely tending towards the shock extensions that he talks about. I have a local engineering firm that I'm a regular customer with who could knock parts like that up in minutes. I could even get them to make up a bunch of them, of differing lengths, to try out and decide which I preferred. I'm such a regular visitor some of the guys have suggested I start clocking in...
I'm really happy with the YSS shock I have - it's brilliant value for money and is more shock than I (or the bike) will ever need, so keeping that is a no-brainer. But thanks to Bill for his suggestion - if I didn't already have a YSS shock I'd probably go down that route.
Having messed about with suspension on bikes since the mid 80s I'm well aware that taking a shock that works perfectly well on one bike and then expecting it to work equally well on a totally different bike is just asking for trouble. Even using an Ohlins shock from an RSV Mille of the same vintage on my Falco caused some headaches due to differing linkage ratios. I either had to use RSV linkages or get the shock re-valved to suit the Falco linkage ratios.
Thanks again!
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Post by billbott on Jan 24, 2024 23:22:50 GMT 1
I got a local engineer to make some extension bars that fit to the YSS shock; That was for the 400 hybrid twin shock build. You have to be careful how much you jack the back end up by. The chain will start dragging across the top of the swingarm, and can also permanently come into contact with the exhaust if you go too far. Also do yours maths with different shocks. I once fitted a remote reservoir Rgv shock to a monoshock Ac400, and it was like a pogo stick, and waay too hard. Diesel shocks off bigger bikes are designed for a heavier bike to start with, so spring rates often dont suit the lighter Lc. They might seem better than a shagged out 40 year old standard shock, but in use they wont perform as well as a shock designed or the Lc, imo (I've tried all sorts of shocks in the past, from bigger bikes), that's why the YSS shock is such great value for money I think My 350 won’t go much higher with the metmachex fitted, if I rotate the eccentrics down to lift it more, the chain fouls it as you say Dusty.
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Post by billbott on Jan 24, 2024 23:25:42 GMT 1
I agree with Dusty on this. Ive tried a bunch of other bikes shocks and was never convinced. Shocks are a bit like brakes, only more confusing... I'll explain: In the same was that a 12mm brake master cyl is great with a 4pot Brembo on one bike, a 12mm with a 4 pot Tokico on another might be awful. Even if the maths says its ok. Shocks are like this too, but its made worse as there is more maths involved... and its even more confused for the LC as many bikes youre stealing a shock off actually use a linkage to transfer forces and the LC doesnt, its direct. What suspends a CBR/R6/RGV etc etc etc is all good for that bike, but with a different knuckle or linkage or orientation it'll be horrible even if the weight of the bike seems right etc. I also like the YSS, its a great compromise between price and quality etc. With you on this Jon. Both mine have progressive springs and heavier oil in the forks - the 250 (RD125LC) shock definitely rides nicer than the SV650 one on the 350, so the ratio won’t be correct, but it’s not bad, cost a tenner and I’m not chasing tenths on the track I tried messing around with springs and shocks on my GPz and in the end whizzed a ZZR1100 full front end on with a wilbers shock (made for the bike) mated to the original linkages and it’s absolutely lovely now.
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dex46
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Post by dex46 on Jan 25, 2024 0:31:00 GMT 1
Untitled by Andy Dexter, on Flickr I found a Nk Racing jack up kit in my stash tonight didn’t know I had one 🤷 so I thought I’d give Frenchy a bit of a lift certainly gives it a bit of lift Im only going to use it until I strip it and start the hybrid build though. Picture with it fitted
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Post by donkeychomp on Jan 25, 2024 0:47:43 GMT 1
I take it you're going to use this on a stock bike. Got to ask why? LCs handle surprisingly well, and the shock is situated as is for a very good reason...it works like that. Jacking up the rear (as I mentioned) looks cool but the handling is awful. Unless you just want to ride in a straight line you'll be fine though.
Alex
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Post by mangocrazy on Jan 25, 2024 1:21:15 GMT 1
I take it you're going to use this on a stock bike. Got to ask why? LCs handle surprisingly well, and the shock is situated as is for a very good reason...it works like that. Jacking up the rear (as I mentioned) looks cool but the handling is awful. Unless you just want to ride in a straight line you'll be fine though. Alex I think you need to give more detail on how jacking up the rear makes the handling 'awful'. If I do this I'll be taking it in small steps and testing out each incremental change. If I don't like it, I put it back to standard. It's quite amusing how the idea of raising rear ride height a few mm means the sky will fall in, when this site is full of examples of extreme modifications that (for the most part) people are very happy with and don't cause loss of life.
I've raised rear ride height on most bikes I've ever owned and in every case it's improved the handling, not made it worse. I'm curious as to why you think doing it to an LC will be different.
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Post by charles13 on Jan 25, 2024 1:24:11 GMT 1
Untitled by Andy Dexter, on Flickr I found a Nk Racing jack up kit in my stash tonight didn’t know I had one 🤷 so I thought I’d give Frenchy a bit of a lift certainly gives it a bit of lift Im only going to use it until I strip it and start the hybrid build though. Picture with it fitted Actually the geometry looks very good in that picture maybe there is a reason the are so popular, it will certainly corner better.
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Post by masonmart on Jan 25, 2024 5:39:47 GMT 1
My overall thoughts on this are as follows. I have a good degree in Engineering and that included a lot of statics, dynamics and control engineering. No expert in bike design but I have some idea. If somebody asked me will jacking the rear suspension improve handling I would say no (or perhaps say, please define "handling?"), it will have the effect of making the bike turn faster but at the expense of stability in a straight line or longer corners. It will also increase the risk of tank slappers on bumpy corners. It can only ever be used as one component of setting and even then only under specific circumstances. By far the most important component is to have the suspension set up for a person of your weight. Is the standard suspension OK? Yes, it is fantastic for a wide range of conditions and as long as it is set up for you, I seriously doubt that any non-specialist could improve on it for a broad range of riding. The best money I ever spent was a Maxton drive in, new rear suspension, upgraded front springs and damping and all set up for me. The improvement was staggering.
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Post by Robbieben on Jan 25, 2024 8:41:37 GMT 1
My overall thoughts on this are as follows. I have a good degree in Engineering and that included a lot of statics, dynamics and control engineering. No expert in bike design but I have some idea. If somebody asked me will jacking the rear suspension improve handling I would say no (or perhaps say, please define "handling?"), it will have the effect of making the bike turn faster but at the expense of stability in a straight line or longer corners. It will also increase the risk of tank slappers on bumpy corners. It can only ever be used as one component of setting and even then only under specific circumstances. By far the most important component is to have the suspension set up for a person of your weight. Is the standard suspension OK? Yes, it is fantastic for a wide range of conditions and as long as it is set up for you, I seriously doubt that any non-specialist could improve on it for a broad range of riding. The best money I ever spent was a Maxton drive in, new rear suspension, upgraded front springs and damping and all set up for me. The improvement was staggering. For the most part I agree with you, especially having quality suspension set up to suit you and the bike, ask any racer, suspension set up is key to fast lap times, a bike can be 20 Hp less than another but a quality suspension set up is worth 50 or 60 Hp on track. Jacking up the rear has benefits and is in many cases within the design perameters of the bike, manufacturers test different suspension heights on test mules and usually go for somewhere in the middle of their range for the production bikes, in most cases its to achieve a certain seat height rather than for any handling benefits. Geometry is affected by raising the rear and can do everything you say but IMHO not if raised by 20-25 mm, this will benefit turn in but also be within design parameters. Jacking up shouldn't be used to deal with poorly set up suspension though.
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Post by liffy16 on Jan 25, 2024 9:23:12 GMT 1
As a road bike stock always works best as it was developed by the factory, used to raise the rear on my race bikes to improve turn in especially on the r6 ,r1,but track is a lot different to road so for me jacking up the rear on an lc is just for looks fine if your not going to ride it and just look at it
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dex46
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Post by dex46 on Jan 25, 2024 11:59:01 GMT 1
To be fair totally agree with all that’s been said no substitute for suspension that is developed for a specific bike I certainly wouldn’t be spending £90 on the kit to use on a 40+ year shock that money would be well spent towards a YSS shock or similar something which this will have when the hybrid build starts I personally wouldn’t run it with a jack up kit as a permanent fix I only fitted it to show what it looks like fitted I like the look though 🤣 it will stay on for the next few months before it’s stripped down for the build
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Post by Tobyjugs on Jan 25, 2024 12:33:45 GMT 1
I have helped jack the rear end up on an LC which was track orientated. We were jacking the back up to help with ground clearance. After jacking it up using only the adjustment on the Wilbers shock, the rider started to feel the back wheel was losing grip and sliding. It was the combination of the BT45 getting too hot and the rear ride height. We ended up backing it off a tiny bit and raised the front end up a couple of mm as well.
Later I was doing some maintenance on the bike I was surprised to see how high it was compared to my RD. It feels sharp possibly nervous and has only felt unstable using it over cobbled roads at classic demos.
It makes my hybrid bike feel a bit more soft and lazy in comparison.
I would say it comes down to rider preferences. Raised or not raised.
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Post by mangocrazy on Jan 25, 2024 13:31:19 GMT 1
If we followed some of the advice given above (to leave the bike exactly as it left the factory) then we'd all be riding round on completely standard LCs.
I don't see too much evidence of that...
It's widely accepted that OE suspension is a) built down to a price and b) a compromise to try and suit as many different shapes, weights and sizes of riders as possible. I'd suggest that approach also extends to suspension geometry - bikes leave the factory with (for the most part) stable but slow-steering geometry. By modern standards the LC has a very conservative (i.e. shallow) head angle and also is fairly rear-biased in terms of weight distibution. Raising the rear ride height will help to counteract those two traits, and I will be getting some distance pieces of differing sizes machined up to try out. If it makes the handling worse, it will go back to standard. If it improves the handling it will stay. Simple, really.
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Post by dougw on Jan 25, 2024 16:19:31 GMT 1
As a road bike stock always works best as it was developed by the factory, used to raise the rear on my race bikes to improve turn in especially on the r6 ,r1,but track is a lot different to road so for me jacking up the rear on an lc is just for looks fine if your not going to ride it and just look at it Not always ! One example I know personally, My GSXR750J bought new by the 23 year old me had serious ground clearance issues on the road , I was quite light back then but had to run with too little sag front and rear and fork position in yokes changed to stop grinding lumps out of the exhaust and scraping the belly pan. Next years GSXR750K had same suspension but the rear shock mounting bracket changed to give 15mm more rear ride height. I found the 350LC I had new in 1983 quite twitchy and wouldn`t have wanted to raise the back end back then. Current 350LC however on modern tyres , YSS Rear shock and fork emulators seems pretty stable and would maybe not be adversely affected by more rear ride height.
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Post by jon on Jan 25, 2024 20:03:48 GMT 1
I understand that this thread is about the NK jack up kit for a standard LC swingarm. Therefore its characteristic short wheelbase may be affected more by jacking it up a bit?
However I can tell you when I turned my LC from standard into a hybrid with a jacked up TZR arm it certainly didn’t turn in quicker, or become more twitchy. In fact the handling was improved IMO. Much less twitchy. Then again I also had TZR forks so it was probably raised front and rear.
Totally agree with suspension/geometry to suit the rider. I’m 6’3” and 113kg, so a standard LC jacked up probably is around the same as ride height as someone of less stature/bulk on a standard LC when I sit on it.
So IMO trying the NK kit is relatively heap and little work. As said if it’s not for you move it on. Sure you may loose £30+ quid, but at least you’ll know if it doesn’t work for you.
Jon
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Post by donkeychomp on Jan 25, 2024 22:16:19 GMT 1
What I can tell you is this. Aged about 18/19 a group of us all had LCs and each weekend was the normal hooligan behaviour. One bloke called Andy had a bog standard 250 and would go faster than anyone else, including the 350s as he was such a good rider. None of us could keep up with him. One Saturday he shows up and he'd raised the rear end about 8-9mm. A subtlr difference but we all agreed it looked better than stock. Off we all went for a blat and for once he was tailend Charlie. He said the steering was too fast and the rear end hopped all over the place. Sunday it was all back to the usual 'catch me if you can' as he'd put the bike back to standard.
Don't get me wrong, it will make your bike look fantastic in my opinion but like you say, try it and see. If it's pants you can easily remove it.
Alex
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Post by abar121 on Jan 26, 2024 12:00:07 GMT 1
It depends on what you are trying to achieve.
I raised the back quite considerably with shorter dog bones on my R1-Z 250. It did make it turn in much quicker, but also hold a line much better too. That was after reworking the front and rear suspension.
With only 40bhp on the dyno, it was never unstable on the throttle, so I was pretty happy with that.
Back in the proddie days, we always used to drop the front through the forks first of all, provided there is the ground clearance to do that. My TZR had the forks dropped 10mm or so as per the race manual which transformed it. I did the same on my road RGV VJ22, which steered like a truck in comparison, stock. That really helped apart from eventually trashing the lower fairing panels.
Can't say I've been tempted to raise the back of an LC on the road as yet. It's compromised in too many other areas stock, let alone tuned.
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Post by mangocrazy on Jan 26, 2024 12:36:30 GMT 1
Some years back I spent a fair amount of time with Derek Chittenden, main man of Hejira Racing, and he always set bikes up 'on the nose'. He maintained that far from making them unstable it loaded the front end and helped with front end vagueness and made them hold a line better. I've raised the rear and dropped the front on several bikes I've owned; three VFR750s, an Aprilia Falco and a Ducati 888 SP3. As standard all were slow(ish) steering and all benefitted from 'the treatment'. I don't see why an LC should be any different, although I admit the frame/swingarm isn't as well designed or as rigid as the 3 bikes I've mentioned. However my LC has YSS emulators and springs in the front fork and a YSS shock, so that has already improved it a fair bit. The motor made 43 hp on Dave's dyno, so pretty much standard.
Bottom line is, I like tinkering and trying to improve and make bikes suit me better, so this should be a low-cost learning exercise.
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