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Mikuni TM34 German Topham Setup

Discussion in 'The Garage' started by Moonmanzn, Jan 9, 2017.

  1. Moonmanzn

    Moonmanzn XS650 Enthusiast

    Morning folks

    From sunny london, have bitten the bullet and ordered the Mikuni TM34 setup from Mikuni-Topham.de.

    They will be arriving tmrw at 5pm..they state they are prejetted for pods or stacks, so hopefully they should run alright :)

    Ill update here with some pics etc one they are installed.

  2. Moonmanzn

    Moonmanzn XS650 Enthusiast

    If anyone can give me any helpful advice etc on them for rephased stock 650, open yo mama exhaust and its all in a bobber plunger frame. Thanks
  3. grizld1

    grizld1 Grumpy old man

    Moonman, rephase work won't affect jetting. You'll probably wind up with PJ size 17.5 or 20 and MJ between 130 and 135. Your carbs will be equipped with needle jets (AKA atomizers) and jet needles that will work fine, probably on the middle setting.

    Topham did the right thing mounting the bell crank outboard on the left, but I'm surprised that they used the left carb accelerator pump and disabled the one on the right (it only takes one, folks). I retained the right side AP for ease of access. The fuel rail and vacuum barbs are custom touches by Topham--nice!

    Remember Rule One of carb tuning: everything else first.
  4. Moonmanzn

    Moonmanzn XS650 Enthusiast

    Im going to go through everything first, but as im a newbie, everything that i check has to have 3 hours research to learn how to do it lol :) Its just been rebuilt so im hoping everything was dialled in correctly. But only getting eyes on will tell.
  5. fredintoon

    fredintoon Fred Hill, S'toon.

    Hi Moonman,
    like grizld1 sez, rephrase (see, that ignorant auto-spellchecker did it again, I typed REPHASE, eh?) won't affect a dual carb set-up.
    But running an exhaust with no backpressure might.
    And a plunger frame? Hmm. Got a photo?
  6. grizld1

    grizld1 Grumpy old man

    Fred, in my TM36/68 pumpers on a 700 cc. motor with porting by Jack, Shell #1 cam, and free flowing exhaust (1.75", MMM's inserts front and back, straight-through glasspack muffs), I run 17.5 PJ, P6 NJ, needle unchanged with clip at #3, and 132.5 MJ, #2 PAJ, and open MAJ. Even with straight pipes (they won't help your performance one bit, Moonman, far otherwise in fact), I'd be very surprised if that essentially stock motor required more. I'm also factoring in the smaller venturi (34 mm. vs. 36 mm.) which, while not a major factor, would tilt the jetting very slightly toward the leaner side.
    Last edited: Jan 10, 2017
  7. racerdave

    racerdave ^ Gone not forgotten ^

    Nice looking set of carbs. Cost?
  8. JRay77

    JRay77 XS650 Addict

    What do you experienced guys think? To take out guess work on any combinations of carbs, exhaust, air filters, etc. I'm going to weld bungs into exhaust systems and use an AFR gauge to dial in. After tuned, thread plug into exhaust.
  9. Moonmanzn

    Moonmanzn XS650 Enthusiast

    Thanks for replies Gentleman, I have stated that Im a newbie so its experienced ppl like yourselves that I rely on to steer me straight, i bought the pipes I have because i think they look amazing...I will now have to work around them to get the bike to run right.

    These set me back 780£ which is around 950USD, I know is alot but bike is a keeper and i got it for cheap so it can be spoilt abit and Grizld stated that these are a beautiful bit of kit.

    Please see pics attached, 81 Frame with BSA Plunger rear, 16" Akront wheels front and rear, wide trees, rephased stocker with PMA and 277 Ignition, running loom through a Motogadget Munit and capacitor, kick only.

    Also its still being finished, paint etc next and tidying up switches, clutch etc. This site is soooo helpful in everything!!

    15820867_10154865036224747_494465285_o.jpg 15820650_10154865036364747_116706398_o.jpg
  10. fredintoon

    fredintoon Fred Hill, S'toon.

    Hi Moonman,
    BSA plungers, eh? Oh! The nostalgia.
    I had a plunger frame BSA Gold Flash back in the day and remember flinging the bike into roundabouts with it's teles pogoing the front wheel up and down, it's plungers twitching the rear wheel sideways and it's inboard muffler going spat-spat-spat as it hit the asphalt.
    BSA's plungers added comfort but they didn't corner too well.
    Critiquing your bike:-
    No mudguards? In England? Where it's (as I remember) always raining?
    The rear brake rod appears to work in compression? Kinda skinny for that duty?
    Yes the pipes look really nice but to run them unmuffled with no backpressure will make it a bitch to tune.
    Apart from the minor nitpicking, that's a beautiful machine.
  11. littlebill31

    littlebill31 Smells of Raw Fuel

    How are you running an M-unit without a battery? They must have a battery to work.
  12. Moonmanzn

    Moonmanzn XS650 Enthusiast

    Ha ha ha lol loving the sound effects, its literally getting built as we speak, so thats just a mock up, I will have full rear mudguard and no front mudguard as i like the open front end. I wont be riding much in the rain lol...pretty much just for summer.

    Brake rods just on a pivot and pulls rear drum brake lever like stock...seems to work fine? ( in my unexperienced opinion)

    Yes seems to be the same consensus on the pipes, now wondering what to do with them to make tuning easier.

    Im in the army so never really home much, just a chance to learn and see what i can make by myself, and I love working with my hands.
  13. Moonmanzn

    Moonmanzn XS650 Enthusiast

    They dont lol, I just ran simplified loom to the Munit, then to capacitor. Runs fine, everything works, only slight headlight flicker at idle.
  14. Moonmanzn

    Moonmanzn XS650 Enthusiast

    Well I think they dont unless I have just created a scientific marvel here as i was winging it, as I dont know a thing about wiring and learning as I go.
  15. littlebill31

    littlebill31 Smells of Raw Fuel

    If your headlight is flickering, then I think you have bypassed the M-unit and are using it as a fuse box instead.
    The M-Unit is to provide constant power, and simplified, to all the accessories.
  16. Moonmanzn

    Moonmanzn XS650 Enthusiast

    Ah ok, Understood..seems to be doing the trick though?? Horn and everything works through the unit? and I can change break light pattern etc?
  17. littlebill31

    littlebill31 Smells of Raw Fuel

    Well, as long as it works.
  18. weekendrider

    weekendrider Iron Horse cowboy

    littlebill explain or point me to something where I can learn how it provides constant power.
    First I will admit I have never held one in my hands. I did go to motogadget site and read about the product.
    My assessment it is a simply a fusebox that uses a micro-processer with digital switches that adds the capability of an alarm system.
    I don't see where it supplies anymore or less power than the system. So it isn't a power supply but a distribution device.
    It can reduce the manual switches. Instead of a light dimmer switch, a lights off switch and a kill switch on the '77 I could have one button(switch)?
  19. littlebill31

    littlebill31 Smells of Raw Fuel

    I misspoke. I meant that it supplies power to all the accessories that are hooked into it as one unit and didn't mean that it supplied different amounts of power. Instead of having several "hot" wires that supply power throughout the harness, it's all one. So, yes, it is a power distribution box. Only one "hot" wire in from the battery that supplies power to all the lights, ect.

    As an example, you would have 1 wire from the horn switch that goes into the M-unit and 1 wire that goes out to the horn itself. (not including ground)
    If you add a M-Button, you have all the wires from your handlebar switches (i.e, headlight hi/low, turn signals, horn, starter) go into the headlight bucket as normal. But then only 1 wire back to the M-unit. The M-Button is also small enough to fit inside the handlebars for a much cleaner look.
    So, 1 wire from the headlight back to the M-Unit (under the seat) and 6 wires that run back to the headlight, signals, horn, ect across the top tube.
    Only 7 (input included) wires running forward across the top tube, from under the seat, and 3 wires running rearward to the tail light/rear signals . Not bad.
    Oh, want to disconnect the headlight? Unplug it. Want to move the entire unit to another bike? Then move the whole thing.

    Revival Cycle has some good videos about it's capabilities.
  20. mrtwowheel

    mrtwowheel Honda Etched On Brain

    The first thing that strikes me is, the seat is very far back, but the bars and pegs are forward, that could balance the riders weight.

    I mean, it might be too easy to wheelie.

    Last edited: Jan 10, 2017

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