mikuni on TLR200

Discussion in 'Trials' started by weldingrod, Sep 14, 2012.

  1. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    Hi guy's,
    bought a Tlr200 a while back and it came fitted with a mikuni copy(pz22....but outlet side is acctualy 26mm ).Long and short of it is I now have it running great from tickover to 3/4 throttle....then stutters, making me think main jet not right....but plug looks chocky brown at chop. It will pull full throttle from low revs, but when revs get high it stutters. So, my question is, maybe it's not the main jet, but rev limiter or just plain crap cdi ignition curve? I have heard a pit bike cdi is an improvement....but which one? Could also be the airbox which has a nasty kink in the standard inlet rubber tube which hooks on to the carbie...this might be ok with standard keihin shit performance carb, but not suiting the Mikuni?. Made a less restrictive muffler as I thought maybe it was choking it...but no difference. Any advice most welcome......been trying to down load some pictures, but didn't work....well it kinda did.
    [​IMG][​IMG]
    #1
  2. lineaway

    lineaway Long timer

    Joined:
    Oct 1, 2011
    Oddometer:
    3,282
    Location:
    nm
    #2
  3. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    thanks bud, i have seen that....I am bashplate on that channel, but I couldn't use that handle on ADV as someone else was already using it.
    to add to the report on my TLR, have checked the cam timing and valve clearances....all spot on, also tried hotter and cooler plugs....no difference.the standard airbox had no snorkle and I opened up the inlet hole in the top of the boxto let more air in, jets in the mikuni are 20 pilot and 95 main. the 95 mikuni is equivalent to 105 keihin, so maybe still a little rich???but from the amount of stuttering I would have expected the plug to be sooty(megga rich) but it's not. this was what made me think it may be the ignition side which wasn't up to scratch.
    #3
  4. Pete-NZ

    Pete-NZ Been here awhile

    Joined:
    May 8, 2011
    Oddometer:
    798
  5. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    Thanks Pete. Interesting the 24mm OKO carb for the TLR....they junk the airbox and put a UNI-filter on. This is something I have been thinking of trying, as I have a UNI-filter on my XL200 trials special...and it works very well on that.
    #5
  6. Twin-shocker

    Twin-shocker Long timer

    Joined:
    Jan 28, 2012
    Oddometer:
    1,673
    The firetrap gauze is what restricts the stock TLR air box, and its easy enough to remove this and fit a foam filter inside the stock air box. Do not remove the stock air box, as bikes will not run as well without this.

    However as it looks like you have a low volume/restrictive exhaust system on your bike, before anything get that sorted out, as the TLR never runs well without a good exhaust.
    #6
  7. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    thanks for that twin shock.....will try the air filter mod. the muffler is small volume but straight through so shouldn't be restricting the motor.
    #7
  8. Twin-shocker

    Twin-shocker Long timer

    Joined:
    Jan 28, 2012
    Oddometer:
    1,673
    You will find you have a lot more torque if you can find a large volume straight through exhaust. Remove the flame trap inside the stock air box, and you should find a foam spigot mount filter which will fit the stock air box, and then you simply need to make a spigot and fit it the air intake to attach the new filter to.
    #8
  9. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    thanks for the ideas twinshock....will try them out
    #9
  10. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    ok folks, took the filter and flame trap out of the air box but left the airbox on. I had already opened up the top to let more air in, so just covered that with alloy mesh and some filter foam to filter the air as it entered the airbox. went and did some sections and the bike performed as before and when given wide open throttle, got exactly the same result as before. so this would suggest that lack of air flow is not the problem. here's some pictures.[​IMG]
    #10
  11. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    [​IMG]
    #11
  12. Twin-shocker

    Twin-shocker Long timer

    Joined:
    Jan 28, 2012
    Oddometer:
    1,673
    You will find power is reduced by cutting the top of the air box. All that is required here is to leave the top standard and drill a couple of 16mm holes.


    However unless your exhaust is working properly you will find it very difficult to get a TLR running properly, and altering the intake isnt going to make that much difference to how it runs.
    #12
  13. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    Yeh, thought I would try the airfilter first as it was easy....fabricating a new exhaust set up is going to take a while. Cheers.
    #13
  14. twinjet

    twinjet Been here awhile

    Joined:
    Apr 28, 2009
    Oddometer:
    306
    Run the bike up a hill with the throttle wide open and slowly apply the choke. If it runs better wide open with the choke on, the mainjet is to lean.
    #14
  15. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    Thanks Twin jet, will give that ago. Believe it or not....your the second person today that put that idea forward.
    #15
  16. Twin-shocker

    Twin-shocker Long timer

    Joined:
    Jan 28, 2012
    Oddometer:
    1,673
    TLR's often seem not to rev out fully almost as though there is some form of rev limiter function in the CDI unit, which means changing main jets is not going to make an awful lot of difference. Cheap pitbike CDI units provide a much better spark over a wider range of engine speeds, and in combination with a good exhaust, correct alterations to the air box, and properly set up carby will mean running is greatly improved.
    #16
  17. weldingrod

    weldingrod Adventurer

    Joined:
    Sep 11, 2012
    Oddometer:
    88
    Thank you Twinshock, this was part of my question at the top of the thread. Can you give me any clues as to which CDI unit to go for? I need one with 6 wires and I think it's an AC unit....most units I have seen on web are plug in... the TLR has loose wires, which could be joined in to plugs to fit I guess....but which wire goes to which pin?
    #17
  18. Twin-shocker

    Twin-shocker Long timer

    Joined:
    Jan 28, 2012
    Oddometer:
    1,673
    Sorry cant help if your bike needs a 6 pin CDI unit.
    #18
  19. Brewtus

    Brewtus Buffoonery, Inc.

    Joined:
    Jul 30, 2008
    Oddometer:
    3,215
    Location:
    Albuquerque, New Mexico

    And here we all thought you were the guru of adapting cheap Chinese garbage onto '80's Honda Trials bikes. Guess we were wrong. :huh
    #19
  20. Twin-shocker

    Twin-shocker Long timer

    Joined:
    Jan 28, 2012
    Oddometer:
    1,673
    Cant help with 6 pin CDI units as these are 12v DC, and not sure they would work on a TLR? They are easily available from Ebay though, but no idea of how to wire one up. The 5 pin Chinese CDI units are a very good idea for TLR's as they provide a much stronger spark, and advance curve at lower rpm means more power at lower engine speeds. Best of all though they can be found on Ebay for less than £10, and are bulletproof reliable (had one on a TLR for 5 years no problem at all).
    #20