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greg_in_london

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Everything posted by greg_in_london

  1. greg_in_london
    Mine is an '83, so check on the parts fiche that they are the same. On mine it was a five (ten with bleeding the brakes) minute job when I finally did it - unbolt the banjo, unbolt the valve, replace the banjo without the valve and bleed the brake lines. Do it quickly so you don't have air somehow getting into the front brake line.
  2. greg_in_london
    My understanding is that the gubbins near theheadstock is basically a restriction so that the front brake acts less effectively than the back brake. The proportioning valve between the rear brake banjo and the master cylinder has a ball bearing that slides as the bike slows (ie during heavy braking) to make the back brake less effective. The sole purpose is to make sure that even an idiot can't brake to heavily, by making both brakes less effective (although not affecting the other front disc controlled bythe handlebar, but taking away all feel) according to the manual. If the pedal won't move, then either both have simultaneously jammed (unlikely) or you have a mechanical problem with the master cylinder and/or its linkages. You won't be surprised to hear that I junked the proportioning valve with no ill effects to the back brake and then fitted a larger bore front master cylinder to operate both front discs so the other disc could function properly.
  3. greg_in_london
    Sorry - having problems pasting the table - it's fine in the edit window, but goes haywire when I try and preview or save the edit. I'll keep trying.
  4. greg_in_london
    I've been expermenting periodically with suspension settings for the past few years, especially since the air assistance began to leak. Initially I added a 1cm spacer which helped a little, but was not enough without the air pressure. Then I went to a 650lb spring, before deciding to upgrade. before the new spring arrived I fitted the spacer to the 650lb spring, but the thicker spring became coil bound on bumps in Irish roads and broke the spring seat. I fitted the upgraded shock after we'd limped home. ************************************************** [Problem with pasting table, please see attached excel worksheet] ************************************************** In case it's not clear, the columns are: spring rate, the free length of the spring, the fitted length, the amount of precompression (assuming no sag) and then the force on the suspension. When I had the new suspension made I asked for it to be a 1/2" longer, so the next column gives the load after that 1/2" of travel - at would be fully extended on the standard shock. I made a few assumptions (like about seven square inches internal area) to guess the force generated by the air pressure which I estimated as 500lb or 225kg, so the next column gives the combined spring and air pressure at rest (assuming no sag). The last four columns are the equivalent figures at fully compressed, which is important as you need to be sure that springs not only don't become coil bound, but have some movement left so they do not weaken through over-compression. To work out the air assisted max compression load I have used the same pressure figure. This could be grossly wrong, however, as the pressure may triple on full compression. I don't know for sure, though. At present I have an 850lb/in spring fitted and it sits way too low - with little ground clearance and not much suspension travel left. I'm not sure how much preload I wound on on the coilover Gaz shocks, but it's not enough. I'm guessing that I preloaded it 1/2" and then it compressed another 1 1/2", leaving 15mm, just over 1/2" of movement (equating to nearly 2" movement at the back wheel) - meaning that static, without a rider, by bike needs about 700kg force, 15-1700lb just to support its own weight. Without a sidecar, or with a lighter one you'd need less, with a trailer you'd need more. In the next couple of days a 1000lb/in spring will arrive and I'll preload it at least 1/2" and prefereably closer to 1". If you're thinking about upgrading your suspension, maybe the above will help - some car suspension manufacturers will find it hard to believe that spring weights as high as this are needed. Coilover springs are much safer to fit than the standard type of shock. WARNING If you fit a heavier spring to your standard shock, DON'T RELY ON SPRING COMPRESSORS (you won't compress them enough anyway) - make up a jig, preferably with 12 or 14mm studs (4 off) to wind down the spring. If the spring were to break free when fully compressed and if you were too close it could kill you. :240:That's because you have to compress the spring enough to fit the circlip into the groove and with the 650lb spring that's practically a tonne of force on the spring.
  5. greg_in_london
    I had a new shock made up to order which is 'coilover' and fully adjustable for preload. I didn't choose the right spring first time (alright, second time, they supplied the wrong one first time) but I've been petty happy with it. I think it cost about £120 three or four years ago, but would cost less for you 'cos there's no VAT. I had mine made 1/2" longer than standard to give me a little more flexibility too.
  6. greg_in_london
    Well these aren'tthe best pictures in the world, but I thought some might be interesting. This bike was my first experience of towing. I was a mobile motorcycle mechanic, specialising in fixing punctures on couriers' bikes around London. The trailer had fifty or sixty inner tubes, a tool box and axle stands etc with half a dozen tyres on top. The bike carried two or three more tyres, a CO2 bottle for tyre inflation, a radio, spare cable and assorted other stuff. At 40mph-ish the bike went into a violent weave, but with experience and a strong upper body you could keep control. At the time we just thought that was what you had to accept pulling a trailer. The biggest hazard was climbing a kerb, when one trailer would hit before another, jerking the back of the bike to one side. http://i252.photobucket.com/albums/hh10/greg_in_london/venture/cx500andtrailer.jpg Later I picked up a trailer to pull behind a Suzuki GT550 bike and sidecar. I haven't found a picture yet, but I'll keep looking. I later fitted over-run brakes because I began to pull a lot of weight. After the GT (which I still have and is for sale..) I began using an XJ750 and also had use of a motorcycle trailer, so in answer to the thread about whether you can tow a bike with a bike, here are a couple of pictures of just that - a GT550 and a ZZR250: http://i252.photobucket.com/albums/hh10/greg_in_london/venture/towinggt550.jpg http://i252.photobucket.com/albums/hh10/greg_in_london/venture/zzrontrailer.jpg And here is a picture of a sidecar body on a trailer: http://i252.photobucket.com/albums/hh10/greg_in_london/venture/towingsidecar.jpg This was the only time that I ever got pulled by the police about towing. It was actually after I had dropped off the sidecar body and was returning the trailer (mine was possibly too small for the sidecar body). :cop:He was a young bloke and walked around the trailer, saying, 'You can't pull that trailer, it's too long, no it's too wide, no it's too heavy, er..' 'No it's not,' I said as I picked up a corner and put it down again. It was probably difficult to tell me that something was too heavy if I could pick it up with one hand, so he muttered something about a public weighbridge and went to consult some booklet he had on his bike. He then came back saying that the trailer couldn't be wider than 1m, max weight dada, max length dadada and that I really should check these sort of things. I apologised, but said that people in the sidecar federation had checked them and that the title on his page clearly said the regs applied to solo motorcycles. He went on for a bit longer, calling his desk sergeant, telling me it was a grey area, saying that I was doing something wrong and that he'd have taken me to the weighbridge (although he didn't know the weight regs..) if thetraffic weren't so heavy. I avoided saying that Construction and Use Regs, section (then) 81a (later 83a, maybe in the nineties by now), subsection one paragraph C says that a sidecar may pull a trailer, not being a broken down vehicle, which has an unladen weight of not more than 254kg, as that would have made me sound like a smartarse and nobody likes them... I'm sure there must be more pictures of us with a trailer on our travels, but this is a recent one of us after camping with the trailer tent hitched up. http://i252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/DSCF2071.jpg And again while the tent was erected. http://i252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/DSCF2011.jpg No particualar purpose to posting these, except I said I would in the 'can a bike tow a bike' thread. Hope they're of some interest.
  7. greg_in_london
    Okay well I'm going to take the advice here and buy the 1.2kg/mm Sonic Springs. I must admit that I'm a little worried about the massive difference between the strength of the Yamaha springs and sonic springs, but doing the maths, sonic seems right. What I mean is, the fork travel is 5 1/2" (140mm)total. The yamaha spring weight (according to the manual) is dual strength - for the first 4 1/2" (112mm) the weight is 0.4kg/mm and thereafter 0.8kg/mm. 1.2kg/mm is 50% more than the maximum spring rate and double the aggregate, whereas most heavy duty fork springs are quoted as being 15% heavier. Having said that, though, even solo I found the suspension woefully soft, even more so with a sidecar. Over time I have increased the preload as much as possible - the only reason I haven't done more is that I couldn't push any more spacers in ! There is a little preload as standard as the caps screw down, but without dismantling to check I'm guesstimating that I have 2" (50mm) of preload at present. Using the weighing figures from my last MOT test, the load on the front end is 165kg, or 82.5kg per leg. This means that the loading/movement is taken up as follows: 2"/50mm preload ........ 20kg ...... zero movement rest of .4kg.mm ......... 25kg ...... 2 1/2" /62mm and either: fork pressure 22psi ..... 12.5kg ..... zero movement .8kg/mm ................... 25kg ....... 1 1/4" /30mm ****leaving (5.5-3.75) 1 3/4" /(140-92) 48mm fork travel remaining or: no fork pressure .......... 0kg .8kg/mm .................. 37.5kg ...... nearly 2"/48mm ******leaving just over an inch ~ 30mm fork travel remaining And that's what I've got - hardly any travel on the forks - admittedly I've added weight with the sidecar. Your bikes will probably weigh less, but I'm not taking the sidecar off to get a figure ! With 12kg/mm springs the weight will be carried by nearly 70mm spring compression (60mm with 22psi) in imperial let's say 2 1/2". With the stiffer spring let's say the max preload I can use is 30mm (1 1/4") then I have a sag on the road of 30-40mm or 1 1/4 - 1 1/2" which is what sonic springs recommend. It might mean that the springs are stiff over the remainder of the travel, but I've a lot of weight transferring on to the front end under braking and don't think that will be a problem. Hopefully I'll have better braking. A big difference, but as I said, the numbers seem to stack up. Now, can I get it delivered and fitted before we go on holiday ?
  8. greg_in_london
    No -no - that wasn't what caught my attention - it was something in the sub-heading....
  9. greg_in_london
    Hi All, Anybody want to take a guess what caught my attention on this Ebay auction ?? http://cgi.ebay.com/ebaymotors/Motorcycles___YAMAHA-Venture-XVZ12-1983-loaded-GREAT-GAS-MILEAGE_W0QQitemZ120287223793QQddnZMotorcyclesQQddiZ2283QQcmdZViewItem?hash=item120287223793 Answers on a postcard to the usual address. I wonder what his engine number is .......
  10. greg_in_london
    I've been looking out for something that might fit, but not find a car tyre yet that will (see page one of the thread). The 175 might be close, but I suspect it will contact - I haven't bought one just to see, though. I've always had Continentals on the back, except for a short lived mistake with a Kenda, the Chen Shin Hi-max that I fitted to get me home and the current Avon as I couldn't get a Conti.
  11. greg_in_london
    Hi maineac, did you post the right link ? This one just compares tyre sizes - it doesn't tell you the effect of changing the rim diameter. To save anyone else going there, the overall diameter 'should' be 0.41" greater with the car tyre - nearly as much as the difference between a worn and a new tyre. The width diference should be 1.38", or 15mm less clearance on each side. Maybe a bit of exercise with a file would be enough ?? PS conventional wisdom is that using a wider rim gives you a lower profile and wider tread, a narrower rim gives you a higher, possibly more rounded profile, but also narrower tread width. 4" to 3" is a fair difference in rim size, though, and could affect lateral stability of the tyre when you slam an outfit through the bends.
  12. greg_in_london
    A lot of (well, some) old sports cars with large wire rims used motorcycle tyres - something cheap with chunky tread or Avon SM11 3.25x19" or Avon sidecar triple duty. I don't know that there's an equivalent car tyre in that size, but I understand that the bike tyres seem to work.
  13. greg_in_london
    I certainly like the idea of fuel injection - and fuel management in general - but I'm not sure of many examples where the new injected model has been more economical. My commuting bike is an XTZ660 which does mid 50s to the gallon (UK) in a range of riding conditions including heavy traffic ~ slightly more on a long run. The new version XT660 apparently can't equal that. Why not ???? Why should I buy a new bike that will do the same speed, but use more petrol doing it ? I've heard that the later BMW funduros can be pretty good on juice, though. It doesn't seem much of an explanation to say that these are first generation systems as they must have at least fifteen years' experience designing these systems by now.
  14. greg_in_london
    . Something affected mine. I may not understand it, but it's what I get - 30mpg (UK) is about 25mpg (US). I know that's with a sidecar, but I only ever had a couple of mpg more solo - and that's regardless of speed, unless I go above 75mph (above 65mph with the trailer) when it drops further drastically. Anyone figure out the secret, let me know. PS - I'm still adding figures on that spreadsheet as it comes in.
  15. greg_in_london
    I like to think I'm smarter than lots of people, but then I've got a degree in mechanical engineering and am a teacher now - if I don't have confidence in my own abilities I'd have to give up. The simple facts are that a heavily loaded motocrycle (like mine - with a sidecar and 300kg trailer) is pushing the design limits of existing m/c tyres. Secondly, almost all design is a compromise between a number of factors and some requirements for a product will not apply when you use them. (I don't do 150mph). [Most motorcycle manufacturers say don't fit a sidecar, full stop, not because you can't do it, but because some people could do it wrong.] If existing products don't meet your needs, you either have to stop (or change) what you are doing, or find something else that will. On a solo, I don't believe that a car tyre will perform as well as a good motorcycle tyre, but for some people that won't matter. (I know some have claimed that certain riders with car tyres could show anyone else a clean pair of heels on the twisty bits - well if that's a challenge, come on over and I'll take you along some nice local roads - except I don't think it was meant as a challenge, but if you're here, drop me a line anyway.) Motorcycle tyres aren't designed for what I do, but they work. If you learn to ride within your vehicle's lmits then you will be safer and possibly ride faster too.
  16. greg_in_london
    Dump the linked braking system and remove the proportioning valve to the back brake (unbolt and connect the banjo bolt directly). Fit a new larger diameter master cylinder on the front, preferably off another cruiser (so the angle is right - otherwise the reservoir will be at an angle and air can get drawn into the system), to operate both front disks. At the same time, replace the old rubber brake hoses with stainless steel braided hoses throughout. A big improvement throughout with more braking power and more control over the brakes.
  17. greg_in_london
    I've been running them for years, even before I put the sidecar on. I always felt that they were good for comfort, tyre life and stability, but there was a trade-off against wet weather grip. Nothing dramatic, but they became remote in the wet and I felt they were close to slipping. That's what you expect when you buy a tyre with harder rubber so it will last longer, though isn't it ? A tyre for mileage and motorways, not back road scratching. The matching tye for the back has become difficult to obtain over here, although Continental still list it on their website. Oh yes, very reasonably priced too. (Although a dealer may try and get a large mark-up)
  18. greg_in_london
    My girlfriend was given a Reliant Rialto (three wheeler) when her friends emigrated to Canada ten years ago, largely because they were told that they are illegal in Canada. Subsequently they found out that that was not actually true, but my girlfriend still has the car. And it's beautiful (so she says).
  19. greg_in_london
    It would be a shame to see you put off - sidecars are very different to solos, but they can be set up to be manageable, particularly if you use leading link forks. My g/f says she wants to learn to drive an outfit and had a go on a 400 and chair last weekend. She's had very short gos on the XJ750 and Venture outfits - that's a long way from driving on the road, though. Sidecars have historically had a record of very good safety, probably BECAUSE you have to drive with caution (of sorts) and within your limits. The throttle is NOT an on-off switch and you need foresight. People without these capabilities, or the patience to gain them, get switched off sidecars very quickly. One previous girlfriend learnt to drive an outfit, another did not. I don't know whether you'd get on with it or not; but I'd not recommend taking your kids out until you've gained a lot of experience and decided that you want to keep with it. There's a big difference between driving something set up even nearly right and fun and driving something unstable that needs to be wrestled around. I need to modify something I posted earlier about Velorex chairs, though. I still say that they're MUCH too lightweight for a Venture, but here is a quote from the UK importers about the sidecar wheel axle and suspension: I was rather concerned about the US website fitting instructions, though, with the fitting to the footrest having an eyebolt at each end. Jawa and Velorex did not believe that this was strong enough for their 1960s two stroke twin. This is the picture ofthe fitting kit in the UK: http://www.f2motorcycles.ltd.uk/f2images/velorex%20images/mountings%20for%20the%20UK%20clear.jpg There is a box clamp in the top left of the picture - I presume that that should be the middle sidecar fitting - NOT an eyebolt or an attempt to save a few pennies by re-using the bracket that was made to fit a Jawa. I don't know that I'm explaining the issue very clearly - it's difficult to describe without just grabbing the sidecar and pulling, or waving hands about and pointing at the bits. Tell me if it's worth making more of an effort.
  20. greg_in_london
    Advantage is that the c/t is designed to take sideways cornering loads whereas the avon isn't - so the c/t remains much more interesting for bikes and sidecars. Shame I can't get a 145x16...
  21. greg_in_london
    That's okay, don't mention it.
  22. greg_in_london
    Re: the forks, I think Mike's were privately made - someone in the club had patterns and made them over many years. I should know who it was, but can't remember the name. Probably the most common leading links in the UK are made by Unit Sidecars, aka Heddingham Sidecars. I have them on two outfits, but think that they've just not been well developed. Leading forks provide a massive improvement in suspension over telescopic forks, allow a chance to change wheels and brakes and can be used to reduce trail. But, if there is any wobble on the handlebars can make things worse as they have more inertia when they start to move. A damper will sort that, though. Which side should sidecars be on ? I thought we invented them - shouldn't we get to choose ? Sorry but I know nothing about the BMW outfit, except that a friend had a test ride and was surprised at the agricultural gearbox. When I took the picture the owner's brother-in-law was there and didn't know much about it. You that they were racier in the states - are you sure that's not one-upmanship ? it is a semi-offroad sidecar in any case - possibly a Heddingham. Yes, the tent is pretty roomy - when we go to folky events it gets used as a base by most of our friends, especially late at night.
  23. greg_in_london
    I've posted some of the pictures that I took of the rally last weekedn at http://s252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/ I hope that you find some of them interesting. There are a wide range of bikes, sidecar styles and fittings, plus a few with conversions to car wheels and/or tyres. This is my outfit and the tent (erected) http://i252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/DSCF2011.jpg And this is it as it is towed. http://i252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/DSCF2071.jpg A friend came down from Lancashire with his XVZ13 and sidecar. There are also a few pictures of his car wheel rear conversion. He is running a 145x15, but may have to switch to 135x15 as he says he's having trouble finding the 145. http://i252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/DSCF2020.jpg This is a particularly flashy BMW and sidecar. It has car tyres front and back, hub centre steering and a sidecar wheel powered from the single sided swingarm. http://i252.photobucket.com/albums/hh10/greg_in_london/sidecar%20rally/DSCF2028.jpg As I said, browse the rest of the pictures and I hope you like them. Some are of different bikes and some are different views of the same ones.
  24. greg_in_london
    Hi Muffinman, Follow the basic ideas and you won't go too far wrong. The sidecar wheel has to 'toe-in' slightly towards the bike (like tracking on a car) or you'll have a hard time on the bends. The bike should 'lean-out' slightly from the sidecar so it pulls slightly that way, counteracting the pull of the sidecar when cruising. The sidecar wheel should be 9-12" ahead of the rear wheel, else it will wear dramaticallt through scrubbing on bends and possibly also reduce front wheel braking. (Needs to be a long way forward, but can be noticeable). The thing that you want is to check the way you attach the fittings - somewhere around Friday afternoon, when setting the outfit up, you'll be tempted to just whack in a fitting which attaches to the bike at one end and the sidecar at the other without thinking about the job it has to do. Post some pictures and we'll all point out possible problems if it looks as if it won't be rigid. [Common problems are using eyebolts all round and then watching the outfit hinge in the middle !]
  25. greg_in_london
    Don't forget - Yamaha specified different float heights for different carb specs - don't know why though, surely it's the same carb. Maybe it makes a difference, maybe not. Range was about 14 ~19mm depending on model, so it's quite a difference.
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