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Neat stuff inside the Kawasaki W650

Discussion in 'Maintenance and Servicing' started by QuarterWit, Jun 19, 2012.

  1. I recently helped MattB do the valves on his W650 and after having a play with it, I'm quite convinced it's a bit of engineering genius. While the bike itself, by modern standards, has pretty questionable brakes, shonky suspension, flexible frame and sluggish engine it's gorgeous to work on.

    The first thing I noticed that was different about this it's shim-over bucket. So instead of removing cams, setting them blah blah you just grab the rocker arms, pull them aside and remove the shim. Really, really easy to do...


    Interestingly, the inside of the head cover has some rubber sealant applied liberally to dampen the sound of the valves tapping away...


    Another cool thing - a small hole recessed in the head with gathers oil, which, according to the manual, is designed for you to slide your feeler gauges into before you measure the clearences. Neat shit.


    Matt demonstrating his home made chopstick-glued-to-a-magnet device to get the shims out.


    Bevel driven cams. Methinks that with such low compression and engineering like this the bike would last a very, very long time...



    It's amazing. I love it and would love to have one in my garage. That being said, I just bought a mag-wheel Bonneville that I'm very happy with. It's only a temporary bike for the next few years. After that I'm quite convinced I'll get a W650 or W800, shonky brakes, slow engine, wobbly suspension and all.
    • Like Like x 2
  2. Looks nice (y)

    Does the bevel drive make a noise like a washing machine at speed?
  3. fascinating stuff

    I wonder how much it would cost to keep all that neat stuff you discovered inside and upgrade the shonky brakes, slow engine, wobbly suspension and all????
  4. I'd be interested to see an uncorked W engine in something like a Rickman frame. I reckon that would be a potentially very enjoyable special. Entirely consistent with the pseudo Bonneville theme too, given that wholesale replacement of the chassis was the only certain way to get a pre-OIF Triumph to handle properly at high speed.

    As for the neat touches in the engine, I've always thought the W engine looked very thoughtfully engineered and those just confirm my suspicions.

    Maybe I should give one another go, now that the memories of rides on fire breathing Brit twins have faded a bit so I'm not making unfair comparisons.
  5. Some people comment on it, but I don't notice any noise at speed, and my model is very late in the W run - with extra quiet/restrictive exhausts (which, at the same time, still sound great, surprisingly).

    Don't listen to the man...he exagerates! :) Second to the Hornet, this is the best handling bike I've owned. But yes, it's all basic stuff that could easily be upgraded.

    Do it! Keep an eye out for QW's and my comparison, soon, of my W and his Bonneville.
  6. PatB can block his ears, and start shouting la la la la la, but the engines that impress me are the early to mid 90's VFR's. The gear driven cam ones. Especially my VFR 400R (NC 30) engine. That engine is so far ahead of its time it's not funny.
    It runs a similar valve train setup to your W engine, but is DOHC, and the cams run directly over the valve. The rocker arms are not really rockers, but followers, that also slide to the side the same way as your W engine, to allow you to remove the shims from the spring retainer. The same setup that BMW are trumpeting about in the S1000RR, except 20 years earlier.
    Has gear driven cams with scissor gears to eliminate backlash, so no timing chains or tensioners to fail.
    Lots of little features that never made the advertising brochures. Like slipper clutch, and diaphragm clutch spring.
    Look in the air box, and there are lovely velocity stacks staring back at you.
    They weren't afraid to experiment with different firing orders either, different models featuring both screamer and big bang variants.
    Every time I work on it, I find myself stopping and staring at it, marvelling at the design and thought that went into it.
    Enough of my rambling, back to you.
    • Like Like x 1
  7. Hmm... high compression pistons, performance cam, remapped, 2-1 performance exhaust, decent everything else. Could be project (like I need another dead bike).
  8. as a recently-converted '95 VFR owner, don't get me started :LOL:
  9. So this may seem slightly off topic but here goes:

    I understand the point of shim over/under bucket and that you replace the shim to increase/decrease the valve clearance to spec. What I don't get is the VT250F I'm working on how adjustment screws, which take literally about 3 minutes to adjust all of them.

    So my question is, why are shims a better alternative to the adjustment screw type? Something to do with they cant get loose like the nuts or...?

    Also, since I'm learning about all this now, could someone quickley explain how the bevel driven cam works? I assume that instead of the timing chain, it connects with another cog type thing that rungs up and through where the timing chain normally runs?


  10. 24,000 Km service interval on the valves are common with shim & bucket systems.
  11. I'll concede that the gear drive cam VFR engine was probably a good 'un. Thing is, it had to be because Honda had taken their engineering piss-taking a step too far and built a bike so badly (VF750) that even the most starry eyed innocents woke up to what utter crap the Big H had been peddling for years off the back of the reputation of their 60s bikes which were actually quite good. They needed something to reestablish that reputation and the VFR seems to have been it.

    Bucket and shim has a number of good points. Short of a shim coming out (and some designs do do this occasionally, early Kwak Zs being one example) the adjustment is very stable. I know of bucket and shim engines which, after initial bed in, have gone 100,000+ miles without going out of spec. High quality valves and super hard valve seats also play a role in this, of course.

    Bucket and shim valve trains are very rigid. They all (all the ones I've seen anyway) have the cam riding directly on the bucket, whereas screw and lock-nut set ups generally have an intervening rocker or lever. More wear points, more joints with the potential for free play and more tendency to distort under extreme stress. Not too much of a problem with a relatively "cooking" engine but when you're expecting to operate regularly at high 5-figure rpms it becomes more significant. Rocker bearings also need pressurised lubrication which costs more to install whereas buckets are generally happy with splash feed from what's floating around inside the cam covers anyway.

    The valve train will also generally be lighter. This again is significant at higher revs because every component downstream of the cam has to be accelerated from rest every time the valve operates, then the valve spring has to stop it again and then accelerate it the other way to close the valve. When this is happening 100-150 times a second, a couple of extra grams in the componentry makes a significant difference to the forces seen by the cam and the valve spring.

    The lack of levers/rockers also means the cylinder head layout has the potential to be more compact because there are simply fewer parts to be fitted in.

    I also suspect that buckets and shims have an advantage in parts count and ease of assembly line manufacture which, however the manufacturers like to portray otherwise, is a very common reason for the adoption of a great many supposed developments in vehicle technology.

    OTOH, screw and locknut set ups can be made to function well enough for most purposes, are quick and easy to adjust and allow the cams to be placed wherever is convenient rather than directly over the valve stems.
    • Like Like x 3
  12. And PatB with the answers yet again.

    I really think you should take a look at the W again mate. I'd go the carb'd one over the newer fuel injected model. It rides really well and has enough poke for its design brief. It'd be a little unfair to compare it to the fire-breathing twins you'd be used to, although I'm certain you could get the thing revving fairly easily if you wanted to. But it'd be sacrificing the really long life they seem to have. (People selling them online in the states with 90,000 miles and no problems.)

    If, nae, when I get one my problems with it could be pretty easily rectified, as Hornet said. New springs, some preload at the front and different oil. Some Ikons or Hagons or something on the rear would do it wonders.
  13. Cool, thanks for the link hornet, it was better getting a visual picture of what's happening.

    PatB, thanks for that thorough explanation! You not only covered my questions but also filled me in on heaps of stuff I wouldn't even thought of (like the extra weight equals extra force on the cams etc).