Build a Bultaco TSS from scratch

Discussion in '2 smokers' started by blaine.hale, Feb 21, 2012.

  1. snarlyjohn

    snarlyjohn Human money repellant

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    They work well, at least as good as a VM in my opinion. On the downside though jets and parts aren't as readily available as they are for say Mikunis or Keihins and the slides tend to wear quicker than the Japanese ones. But if it's in good condition I'd keep it; they run very well.
  2. DieterDDP

    DieterDDP Adventurer

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    Which Keihin or Mikuni would you recommend for this bike?
  3. snarlyjohn

    snarlyjohn Human money repellant

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    Check your rulebook, there are some racing classes for vintage bikes that won't allow non-period-corrrect items like flatslide carbs. If this is the case you'll have to run something like a Mikuni VM, and these are available in sizes up to 44mm.

    If the carb choice is open then you'd probably want to consider modern flatslides like the TM/TMX or the Keihin PWK. Both are very good but the Keihin is much easier to work with when it comes to needle changes. They aren't available in as big a size as the VMs but having said that a 38mm flatslide will flow as much as a 40mm VM so a 38 or 39mm may be all you need.

    Be aware that these big bore air cooled cylinders are just looking for any old excuse to seize up, so you really need to have your wits about you when you jet them. They'll even stick the piston running on light throttle if you're too lean or too advanced. You can generally hear them detonate if you're riding alone but if you're on the track with other bikes you probably won't hear the warning signs.

    But again, if the existing carb is OK I wouldn't change it. In fact I wouldn't change anything until I had some track time on it to see what it needs and what it doesn't.
  4. DieterDDP

    DieterDDP Adventurer

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    Great advise, John - thanks. I'll stick to the Amal for now but will keep your references in mind. BTW, on Spanish Bultaco fora I was told my frame is a modified Metralla GTS one. The engine "seems to be a Pursang MK-8/10 engine that has actually changed output shaft below the chain." For more references, I need to look for three small numbers near the rear sprocket, they told me?
  5. snarlyjohn

    snarlyjohn Human money repellant

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    Er, no, your output shaft is where it normally is on any chain-primary Bul engine. I wouldn't be too concerned about what the cases were from originally or what numbers they are marked with; the interchangeability of Bul engine parts means it's quite likely that any engine is very different to what it was originally.

    If I could give one piece of advice that I feel is more valuable than anything else I could say it is this: take anything you read on a web forum with a grain of salt, view anything you are told on the web with skepticism. And that of course includes anything I write here.
  6. DieterDDP

    DieterDDP Adventurer

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    Words of wisdom indeed.
  7. knudln

    knudln Been here awhile

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    The cases are definitely
  8. knudln

    knudln Been here awhile

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    I think you'll find the Amal easier to tune, if only because it is a cruder carburetor with less jetting options than the alternatives. I ran an Amal Mk2 38mm on my 250 Metralla roadracer and it worked very well. It's been reported that the Amal Mk2 flowed better than the equivalent sized VM series Mikuni, but I never put one on a flow bench. Another good period option would be the Dell'orto PHM series with the accelerator pump blocked off. Easy to tune and they worked well on Buls.

    Been a long time since I saw a later model six speed Metralla, I read the BS suffix as B5 so it threw me off. On most of the early Buls the B or BS is the prefix to the model/serial #. BS is short for bastidor (frame) of course. The engine cases are from a later model big bore (85mm) long stroke (64mm) bike; perhaps they were new unstamped cases and were stamped afterwards. Why they were stamped with a model 23 designation is curious. Not important, as John pointed out. Actual #23 cases have a narrower stud spacing and smaller transfer tunnels; a 85mm cylinder would not fit.

    If you don't have a six speed and one is allowed per your rules, the #162, 194, 200 and 214 six speed transmissions will fit and have different ratios than the six speed Metrallas.
  9. snarlyjohn

    snarlyjohn Human money repellant

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    What are the six speed boxes like strength-wise? I don't have any direct experience with them but have heard of problems with them in dirt bikes and imagine that a 370 road racer would be pretty tough on them.
  10. knudln

    knudln Been here awhile

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    The six speed is no better than the five speed, which is not particularly robust. The six speed in a well tuned 360 wouldn't have an easy life, but would probably be acceptable in a race bike, although I would consider it a "wear item''. Paying close attention to shimming/setup is important for good engagement. A properly designed and maintained rear hub cush drive would be a priority as well. You could also try experimenting with different hardness cush rubbers. The six speed in my 250 held up fine, although it put out only 38hp on a Dynojet 150 dyno. The gearbox in a Bandido derived TSS350 looks like it came out of a big truck in comparison.
  11. Tanshanomi

    Tanshanomi Your Favorite Uncle Supporter

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  12. GarageRat

    GarageRat Been here awhile

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    Is that a good price for a Montedero? I am curious of your opinions on the value of the 5 speed Matador. I have a few of those, in similar condition to the Montedero here, as well as a Sherpa S that needs to find a new home.
  13. Tanshanomi

    Tanshanomi Your Favorite Uncle Supporter

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    The Montedero is probably worth a good bit more than a Matador in similar condition, not because it is a better machine, but because gear-drive parts have become so scarce.
  14. Tanshanomi

    Tanshanomi Your Favorite Uncle Supporter

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    BTW, the Montedero did not sell for $2.5k and has been re-listed @ $2000
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  15. GarageRat

    GarageRat Been here awhile

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  16. axlepressbutton

    axlepressbutton n00b

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    Some vintage slides that I own of a racing TSS.
    Enjoy!!


    [​IMG]
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  17. axlepressbutton

    axlepressbutton n00b

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  18. Tanker4me

    Tanker4me Old, just effn old. Supporter

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    DSCF1211.JPG Some Buls spotted at a local track a few years ago.
    I think I have some shots of the TSS Buls that were there.
    I post if I find em.

    ONE 118.jpg

    DSCF1159.JPG

    DSCF1611.JPG
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  19. berniecal

    berniecal n00b

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    This is me in 1976, down the straight at Mondello Park, near Dublin. TSS250 water-cooled, geared primary. Went like hot snot, but that gear drive broke my heart, it used to explode through the case and dump oil. I didn't have the cash for new parts, and eventually I put a Triumph 500 in the frame and had a good few years of fun. Oh the nostalgia!
    Bike 003 (Large).jpg
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  20. Bullnut

    Bullnut n00b

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    I have joined this site because of this thread. There seems to be a lot of Bultaco knowledge on here. I have just picked up a rolling chassis with no motor and hoping someone can help me with identifying it?
    This is what I have got
    image.jpg

    Frame number 600693
    Any help gratefully accepted