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  • Top End Related
    56 Topics
    678 Posts
    S

    I already ordered what I thought was a full set and everything else is the right colour but the cowl was listed as blue instead of sky blue, it looked the right colour in the picture but it was taken in a shadow so was hard to tell and when it has arrived it doesn't match any yamaha colours, not sky blue, not endurance blue and not deep purpleish metallic blue so now I'm trying to sort it out with them but looking for a genuine one incase they can't get one

  • Bottom End Related
    7 Topics
    42 Posts
    Hark_PtooieH

    Sorry for commenting on a 3 year old thread, but I have worked a little with balance shafts on humongous machinery and wanted to post a little for posterior knowledge.

    A single balance shaft on a single-cylinder doesn't really do much. It mostly just phase-shifts the vibrations so they go in another direction. Back and forth instead of up and down, like.

    Dual balance shafts is another thing. They cooperate in the right direction, and counteract each other in between - and if you put them slightly offset each other vertically they can even mitigate some rotational moment.

    But balance shafts also have another interesting effect - they can reduce the bearing load. There are actually two different optimums - one which gives the least vibrations but a bit higher bearing load, and another that is the opposite.

    So when I see that small engines have a single balance shaft, I usually assume it is to allow it to manage high revs by means of lowering bearing forces rather than reducing unpleasant vibrations.

    There was a bike back in the 90's(?) - some european single-cylinder 2-stroke 250 cc enduro (cross?) - that had a balance shaft and managed to output 70+ hp when all the balance-shaft-less big-brand competitors only gave 55 hp or so. Because it revved to like 12000 when the others quit at 9000 or whatever.

  • Carburetor Related
    96 Topics
    953 Posts
    MadGyverM

    Maybe it's from the 3ET DT200R,has the same carb as the DT125R but uses different numbering in jets, the main is 150 but is not smaller than the 210 of the DT125R.

  • Return the bike to how it was intended to be!
    24 Topics
    383 Posts
    HOTSHOT IIIH

    @Hark_Ptooie I found with the Tecno expansion chamber (basically identical to the Athena) it fitted a lot easier using the genuine Yamaha rubber grommet and spacer on the upper mount. The ID of the spacer is quite large and allows a little more movement to line it up than the grommet/spacer supplied..

  • Choppy power band

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    CalumC

    Happy days 😃

  • Resonator build thread

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    R

    @Rallyfinnen I think you might be right about the timing angle, one of my repeated measurements came out as cca 185°. I could have used the wrong technique when measuring; Shined a flashlight through spark plug hole and basically measured between the times I can see any light coming through, used the magnet rotor to set marks. A solid, definite number would be useful; my machine has a 3MB00 cylinder and a standard thin gasket, it is not marked with "P" and has never been bored or ported.

    As for the temperature, I didn't get reliable numbers with a multimeter probe at the flange with the exhaust off, so I opted for calculating it via BMEP which turned out right around 7.10
    The temperature would be lower at the middle of the pipe and even lower at the convergent cone, the highest temp is supposed to be right at the exit of the cylinder and if I'm not wrong, that's the part that creates the pressure wave.

  • Fly wheel weights

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    M

    @Calum that’s makes sense you seem pretty knowledgeable on the bike front pal

  • Airbox mod

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    3 Posts
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    M

    @Calum to be fair I did read it for the 200 engine, but I also remember my 125x having let’s say a 40mm hole cut in the side of the air box with some mesh that was done when I purchased it, so now idea if it benefited from it or not

  • V force reeds dt

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    declanD

    @dan28 yeah I did it as I said the blaster 200 are a better fit the cr 125 ones are a little too small but you can make them work

  • Unburnt oil from ypvs Left side help

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    261 Views
    S

    @waale2004

    You changed the seal as well as the o~rings. I don’t know if the Athena kit uses special or standard parts? 2 o~rings & 1 bush seal. These are the only parts that can be a problem...

    Do you premix 50:1?...

  • inlet 38mm

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    CalumC

    For completeness

    alt text

    This is my old inlet manifold that I opened up to easily accept larger carbs.

  • DTR Ignition Maps & Timing

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    2 Votes
    13 Posts
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    M

    @Calum Ah ok. Thanks

  • DT 230 Lanza engine parts from china

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    443 Views
    declanD

    @Sven-Hackbarth there was already a thread on this it’s a good looking bike and more parts is never a bad thing in my experience AliExpress is pretty good quality I like the carbs especially

  • How to adjust the power Valve

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    418 Views
    DTleeD

    Thanks mate

  • Carb setups.

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    Walney-ReptilesW

    @frazer-c i know this is an old post but i know a site were you can get flat carbs from for the DTR not sure if im allowed to post the link tho.

  • Cylinder head tuning and machining

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    Glynn123G

    @Calum I'll take a picture of the head I've got, it's stamped 3MB but it's the one with the ridged, I'll have a look at the book cheers
    I planned on skimming the deck down at the end to create slightly higher compression than standard ideally

  • DT125R Dyno Tuning with Zeeltronic (By Practical Sportsbikes)

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    3 Votes
    6 Posts
    862 Views
    P

    I didn't need to read that, damn it :grinning_face_with_smiling_eyes:

    Good read.

  • 3MB00 "P" barrel, head and powervalve

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    9 Posts
    977 Views
    T

    Hi, what is it you want to buy. cheers🙂

  • Power valve rotating one way then stopping

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    425 Views
    NINJAN

    @shally Which company is doing the test & repair? Share a link if you have one please???

  • 1st gear plug chops?

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    628 Views
    declanD

    @Glynn123 yeah but I’ve heard loads over the years about what you have to do to push the bikes without getting it impounded but the problem is practices change from one police branch to another and my specific police impound no matter what they essentially do what they want all of the main criminals and such have the police payed off so there’s no way I’d chance a near 2 grand bike)

  • DTR 200cc ignition map

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    R

    No worries. I will start with the RE curve and go from there ☂

  • Derestricting a 2002 DT125R

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    NINJAN

    @Bluestoesonnose See hear for the 411 bud;

    https://dt125r.co.uk/topic/578/derestricting-guide

  • Jetting help

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    R

    Okay I'll Do a plug chop when I get chance they normally come out black because I premix and all ways
    Tend to do the mix a little rich to be safe I deffo think it needs up jetting tho

  • Best powervalve setting for higher revs?

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    declanD

    @finnerz89 😓