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XV535: Boanerges in my mind's eye

Discussion in 'Modifications and Projects' started by mattb, Mar 28, 2011.

  1. G'day All.

    I've just posted the below photos in another thread with a specific question, but here I will begin a thread documenting the slow work on my 1992 Virago XV535.

    I've always thought the 535 could make a great v-twin version of my SR500, a bike that is half the fun through having twice as may cylinders, but which is much more pleasant on the highways. I took the bike out today for 450km and two bad things emerged: I took a hammering from the riding position, and there's something wrong at 1/4 throttle - bogging. I think. (Or is it just the oddities of the drive shaft?)

    Anyway, below is the bike as it is, and further below with one of the mods represented: a raised seat. I will raise it and flatten it so that it looks like one long seat. This will be much more confortable and give the bike the look I'm going for. I want something which, when I'm riding on a back road, can allow me to imagine I'm Lawrence on his Brough Superior. The engine is good for it - torquey yet revvy - it's sweet and satisfying. My current plans:

    Get a larger tank fitted. The bike has two tanks - one under the seat - and a fuel pump for getting pertol to the carbs. This is strictly against mattb philosophy - "keep it as simple as possible" - and both must be replaced with a larger normal tank with gravity fed fuel. The carb boots have closed off nipples - I assume I can fit a vaccuum tap utilising these. The larger tank will look less 'chopper' and more 'old bike'.

    There's a carb problem, as per above. Also, the bike sounds like an industrial sewing machine. So: keep the gorgeous exhaust headers, which feed into some odd beige-maniacal under-the-swing-arm box and into the mufflers. Have Craig at Mishief makers cut the headers before the box, ditch the box and stock mufflers, and make and fit simple long pipes into the headers with mild baffles experimentally inserted: more body, but not too much volume - enough to sound good and to sound like a motor bike. We'll experiment and our concept will be a brass musical instrument, or a be bop drum solo, not an undefinable spew/rumble. Deal with the carb problem at the same time: rebuild and rejet them.

    Replaced the stuffed rear shocks. Replace the new tyres when I can: they're Duro, which I'd never heard of (PO fitted them), and are the scariest tyres I've ever experienced! Do not, ever, buy these! I think they're plastic rather than rubber.

    If the seat doesn't solve the riding-position problem enough, set the pegs rear-ward 15cm. Craig could do this and it looks simple enough given the peg and lever on each side are a single unit.

    Winscreen; not because it looks good but because this is a highway bike. Saddle bags: metal cases, covered in old-looking leather to make hard vintage-style lockable cases such as I have on my SR500.

    Fit 7" headlight up front. I wonder if I could find a 9"?

    Lower handlebar mounts and low wide bars.

    What colour should this bike be? With a new tank, there will need to be painting done. Unless I just take it back to metal and buff it?

    I'll post up my progress as it happens. This will be a real budget project, but I should have a very pleasant middle-weight road bike when I've finished. Perhaps the SRV500 that Yamaha should have but never made? People get into SR500s and such for projects. For a long while I've reckoned the XV535 was a canvas awaiting some great work by the cafe racer / tracker / Brit retro crowd - unsung potential.


  2. Some great ideas there matt, I'll keep an eye on this one. Agree with the new tank, but not the vacuum tap, use on old fashioned 'on, off, reserve' manual tap...keep it simple. Luckily its got spoked wheels, you can get rid of that ridiculous looking rear rim and lace on an 18" one, that and a narrower tyre. Slightly longer shocks will give you a bit more ground clearance and reduce the effective rake on the forks, make it handle more like a real bike. You definitely need to move those pegs back! The tail light has to go, 'fugly' doesn't do it justice. That and the chromed tupperware box over the front cylinder.
    I like the look of the engine, and that its air cooled; that thing has potential as a "Brough"!
  3. there was a 535 bobber up on ebay for a while, looked great!

    interested in this.
  4. Some great ideas there MattB,

    As far as lamps go - you can always get an old car headlamp and bowl, I saw a great one at Camberwell market last week that was probably 8 or 9 inches across, and it had a mesh grill over the glass.

    Tank colours - would you consider a matt finish, possibly olive green with a white stripe?
  5. I did a track day on the old K100 with a 10 year old Duro on the back. It was OK. Well,once I'd got it up to operating temperature. Which was somewhere around the melting point of lead. :shock:
  6. Steam punk? Maybe I need some gauges attached to it? :)
  7. What fuel are you using?
  8. I'm thinking I might prioritise the single-carb conversion - one thing I've learnt about owning and doing bigger kms on older bikes: replace the old carburretor and get rid of half your problems! Don't waste time tuning an old one, when new ones are so cheap and you will spend less money and time in the long term. This is especially true in the case of a bike like mine, which has two old carbs.

    So, weighing up whether to get a piggy bank happening for the KJS above, or to have Craig make the manifold:

    KJS: $600. Comes tried and tested for 10yrs and ready to bold on and ride away. Uses stock cables. Only need to buy an air filter. $600 is a decent outlay for me, but probably worth it.

    Craig: price of manifold? It will be a prototype, but we wouldn't have to go as fancy as KJS in design - it could bolt into my new carb boots, as per further below. Carb: $120 on eBay. Modify cable to fit. Make mount to hold carb. Rubber boot between carb and manifold: $60-120. Gaskets $?. At some point get it professionally tune I guess: $? But, I can engage in this expenditure one bit at a time. It might turn out easy and cheap, or hard and just as expensive.

    I'm undecided.


    Home-made manifold:


    The boot for the new carb bolts on to the face of part C.

    The plastic chrome cover on the left hand side of the engine is empty - in California they fill it with emissions bits - and I could keep the air filter in there, fed to the carb via some flexible large hose.

  9. I would honestly keep the twin carb setup. I can't see one reason why a single would be better. 2 flat slides would be brilliant, and they should be relatively easy to find, ex 250 MXer's.
  10. No balancing.
    Lower parts count.
    Simpler linkage.
    Easier troubleshooting (any problem affecting one pot almost certainly not carb related).
    All that's needed unless you're looking for absolute maximum horsepower (and even then it can be marginal).
  11. KJS answer the question here http://www.kjsmotorcycleworks.com/faq.htm and here http://www.kjsmotorcycleworks.com/one_manifold_better_than_two.htm
    I can't argue the science of fuel distribution, but for me it's about simlpicity Patb mentions first of all, and secondly Virago riders consistently report improvements that are of the sort I like: engine feels more torquey / pulls more immediately - better down lower to mid, and pulls more smoothly up the revs.

    Also, reading threads of rebuilds of carbs, there's so many niggles people can experience during / after the rebuild, plus the rebuild kits are so often criticised (I have Keyster kits given me by the PO), that once the manifold is done it seems the rest is as hard, or perhaps easier, than stuffing around with the originals.

    One thing though: if after riding the bike for a while I find there's no real problems (currently I think there is), then if it ain't broke I won't fix it.
  12. Sorry, can't agree with that. I agree, the Hp difference should not be noticable on the arse dyno, but throttle response, crispness and rideability will be far far better with a properly adjusted twin carb setup -especially if you use flatslide/pumper carbs. The difference between my Flat slide equipped 625 LC4 KTM and my brothers CV carbed 640 Enduro is nothing short of astounding. Mine explodes -for want of a better description, when you crack the throttle, his just accelerates. I know which one is more fun to ride, and isn't that the point of riding, when you stop and think about it :)
  13. On the face of it I like the simplicity of the single carb, but for the effort involved in conversion, I think I'd rather spend less time and money and overhaul the originals. I've also seen issues with single carb setups giving different mixtures to each cylinder, I know it sounds counterintuitive but it does happen, particularly with the uneven intake pulses of a V-twin.
  14. Yep, every V configuration engine I have ever owned and worked on, has had different jetting on the rear cylinder/s than the front. This includes both twins and V4's. Both air and liquid cooled. Reason being, as I understand it, that the rear cylinders run hotter, and generally have a less torturous path for the air/fuel mixture to travel.
    The other thing that I have noticed, is that single carbs are most likely to be found on understressed overweight plodders. :)
  15. Son of Thunder? That's quite a name to live up to...
  16. You mean like: "All my life everybody's expected me to be like my Dad. Well I'm not!"

    It's ok. The movie will resolve with Thunder coming to accept Rainbow and his orientation for who he is.
  17. This intrigued me enough to look up the KJS justification for a single carb, I quote :

    "Since we came up with the original KJS Virago Manifold there have been a lot of Yamaha riders wondering how having only one carb can possibly be more efficient than two? We have tried to provide a little more insight into this area.

    With one manifold balanced what does this mean?, each cylinder receives its fuel charge equally or this?, so the bang is the same, thus producing an even power thrust. Its a V-twin, the intake pulses are uneven, so the single manifold and carb has uneven pulses going through it. Unlike one carb per jug, when the valve starts to open, it has to draw from the belly of the carb, this is just crap!and only gets the charge near the end of it’s stroke WTF?. With the single manifold supplying both cylinders there is constant intake manifold pressure again, WTF does this mean, the pressure varies with each inducion stroke and there are now two of them, unevenly spaced!. When the valve opens, I use the term, the fuel charge just falls in thus creating an even power thrust. Utter BS!

    Will a single carb give you more HP & torque? Yes, at the bottom end where it's needed, and you will still have all your top end I don't think so!. If you're a drag racer, then experiment with cams, pistons ,etc to give you the performance you require. But for great ride drivability the stock Yamaha configuration is perfect. At 65 MPH stay in 5th gear while passing and feel the power climb without having to drop into 4th gear to pass safely.

    The power you need, when you want it!

    Remember if having one carb per cylinder was so good, how come a V8 Chevy doesn’t have 8 carbs, and why has Harley -Davidson used only one carburetor for over a 100 years? Why does every high performance engine have multiple carbs? Why are Harleys so slow for their engine size?

    A single carb may well deliver slight benefits in tractability at the lower end of the rev range, as it is operating closer to its best volumetric efficiency, but this will be at the expense of output at higher rpm. Its all a compromise, there's no magic answer, but these guys are using BS to justify the expense of their product. I note the distinct lack of dyno results, its all subjective opinion.](*,)