Yamaha TX750 starter clutch mod!!. OH YA!!

Discussion in 'Old's Cool' started by CalsXS2, Aug 3, 2013.

  1. CalsXS2

    CalsXS2 Been here awhile

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    That's right guy's. Someone was finally smart enough to figure out a mod for these poorly designed starter clutch's. :D

    His name is Argo. He is from Estonia. Which is just west of Russia I think. He will be along soon I hope.

    I have in my possession what he calls a pre-series unit. It is a much more expensive proto type. He will have another less expensive version available in the very near future.


    First. Here's some before proof that my starter clutch is toast.

    <iframe src="//www.youtube.com/embed/YDE0m52i6Eg" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>



    So let's get started. :evil



    Here is the proto type.

    [​IMG]

    [​IMG]





    Here's is the meat of the new unit. This sprag,,, also known as a one way bearing,,, he acquired from over sea's. He say's it's of top quality. It has 20 contact point's to grab the starter gear compaired to the original which only had 3.

    [​IMG]





    I'm sure you guy's can do these first step's with no problem. But I did take the pic's. :D

    Remove outer and inner cover's to get to the flywheel.

    [​IMG]





    Remove the flywheel.

    I borrowed a flywheel puller from someone. But the nut part was too long. It didn't leave enough thread exposed on the bolt. While holding the flywheel with a pry bar, I just screwed the screw right in, and the flywheel popped off.

    Take note. You do not thread a bolt into the end of the crank shaft. You use a bigger bolt in the end of the flywheel. You'll see what I mean. The bolt needed is a M16x1.5&#65279; about 50mm long. It should be at least a 10.9 grade.

    [​IMG]





    Remove starter clutch from flywheel.

    [​IMG]

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    Old compared to the new.

    [​IMG]





    I am at the point now where I have to drill and tap the hole's for the M8x1.25 screw's that secure the clutch to the flywheel. I'll get this done tomorrow.

    [​IMG]





    I used some Gorilla tape and taped the outer ring to the flywheel so it wouldn't move. You could just clamp it too. I then screwed it to a board.

    I used a 8mm drill bit to just barley dimple the flywheel. Then I changed bits and drilled the proper hole for the 8mm tap. As recommended by Argo, I drilled and taped one hole at a time to ensure nothing was able to move.

    I actually argued with a guy about how to do it. He said drill all six hole's at once. But if you do it like that,, if you get just one hole off a little,,, you're screwed. And not in a good way.

    [​IMG]





    A little taping action.

    [​IMG]





    Argo recommends beveling the edge of the starter gear for ease of installation.

    When you go to put the gear into the sprag, you have to turn it in the correct direction to get it to go in.

    [​IMG]





    Here's the finished product. The procedure was pretty straight forward. No problem's at all.

    [​IMG]





    Here's the first time trying the mod.

    Do you guy's think this video makes me look fat. :augie

    <iframe src="//www.youtube.com/embed/Vlr_Hp0pL-M" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>
    #1
  2. CalsXS2

    CalsXS2 Been here awhile

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    reserved.
    #2
  3. concours

    concours WFO for 41 years

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    Whazzat sprag outta? :1drink
    #3
  4. CalsXS2

    CalsXS2 Been here awhile

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    I need a little help from you guy's.

    Have any of you had your starter clutch out.

    I'm not sure if this is an issue or not. But on my big starter gear, the bushing sticks out .50mm past flush of the hub. It's on the side that the shim is on.

    I have 2 different gear's and they are both like this.

    Is this normal. I hope you can tell what I'm talking about.

    [​IMG]

    [​IMG]
    #4
  5. CalsXS2

    CalsXS2 Been here awhile

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    I don't know. :dunno
    #5
  6. farmrjohn

    farmrjohn Been here awhile

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    I picked one up from him just after I got my TX. It's a Borg/Warner starter clutch that he's modified to fit the TX. I haven't installed mine yet as the stock starter is still working, but did get a spare "generator" that will need six holes machined to take the Borg/Warner unit instead of the stock starter, just haven't taken the time to do it. Having a lot of small engaging cylinders vs. the three the stock unit has seems much better in theory so that's on the list when the stock one craps out.
    #6
  7. Foot dragger

    Foot dragger singletracker

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    Yup,you TX750 guys need to stick together.

    Ive got a nice valve cover and maybe some other odds and ends here still.
    #7
  8. jimroid

    jimroid Been here awhile

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    This flywheel/starter clutch looks identical to the TX/XS500. A sprag clutch allows the starter to drive the engine,but not let the engine spin the starter.The oblong bearings grab in one direction and then are pushed clear by small springs so it does not drag once the engine starts.One-way clutches are found all over in industry.
    #8
  9. CalsXS2

    CalsXS2 Been here awhile

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    Ok guy's. I'm all finished. Everything went very smooth. I'm very pleased with the mod.

    I must admit though. When I pulled the starter clutch off, it didn't look like there was anything wrong with it. I had rebuilt it a few month's ago. When I took it apart then,,, piece's were broke, missing, and falling out. :huh

    So basically. I thought I wasted $100 on this mod, and was going to have to change my starter. But it was the starter clutch. :1drink

    Please feel free to ask any question's, and leave some input. Let me know if I need to add or change anything.

    I've sent a link to Argo. Hopefully he will join in. He was a very good guy to work with. Communication was spectacular.
    #9
  10. farmrjohn

    farmrjohn Been here awhile

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    Nice tutorial, thanks. I agree about communications with Argo, and looking forward to him posting here, he has a lot of knowledge for the TX750.
    #10
  11. far2389

    far2389 Adventurer

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    Nice writeup on this mod - thanks

    Any idea if Argo planning on making and selling some of these? Quite a few of us TX750 guys out there with toasted starter clutches getting tired of kick starting. I had a batch of the r65 oil filter adapters machined couple of years ago and sold them quickly. Based on the number of oil filter adapters I sold Argo could sell a bunch.
    #11
  12. appiebroomer

    appiebroomer Adventurer

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    Nice Job Calvin. Thanks for posting. How did you find Argo ?
    #12
  13. CalsXS2

    CalsXS2 Been here awhile

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    Yes. He is going to be selling these. The one above he calls a pre-series. Very expensive to make. He did a small handful just for research and development.

    He now has a less expensive unit in beta testing. I'm not sure if he has anything for sale at this exact moment or not. I think he might.

    Hopefully he'll be along soon and join in, or start his own thread and introduce himself.
    #13
  14. CalsXS2

    CalsXS2 Been here awhile

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    I found him on youtube. :D

    <iframe width="420" height="315" src="//www.youtube.com/embed/TiBoHcET9Xk" frameborder="0" allowfullscreen></iframe>
    #14
  15. argo1974

    argo1974 Adventurer

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    Hi there guys! Calvin was kind enough to invite me joining that thread. At first, I'd like to thank him for detailed pics/instructions about installation procedure of the modified starter clutch.

    This one way bearing is called Borg Warner type since that company invented and patented it back then. That's why Japanese manufactures continued using the out-dated and fragile 3 roller starter clutches on their bikes at 70-ties.

    Both of the two starter clutches I sold to US (John (farmrjohn) and Calvin (CalsXS2)) were pre-series as I call them. They already have the updated inner bearing bodies since first prototypes were just machined by hand with standard size engaging rollers fitted.

    The new design is very similar to pre-series unit but I was able to drop the costs by simplifying the machining and hardening procedure of the outer ring. I'm still testing the new version, especially with the spring tightness of the one way bearing. This is because most of you guys will use it together with more or less worn (out of specs) starter gear.
    I think I will have the tests completed within 4 weeks. Our summer is short in Estonia, so I really don't like messing around with metalwork when I could ride my bikes instead ;)
    Here are my two 73" Yamaha TX750:
    http://www.bilder-hochladen.net/files/big/bfqr-cu-f5f8.jpg
    http://www.bilder-hochladen.net/files/big/bfqr-cr-9a96.jpg

    That one on first pic is taken to bits and pieces for complete restoration and engine mods though.

    Argo
    #15
  16. concours

    concours WFO for 41 years

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    I'm in :clap
    #16
  17. CalsXS2

    CalsXS2 Been here awhile

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    I mentioned this earlier, but no one replied. I now think this issue may be worth looking at.

    In this pic of the starter gear that goes on the crank, if you look close, you can see that the bronze bushing in the starter gear is sticking out .50mm past the end of the hub. This is forcing everything outward .50mm. This would include the washer that goes behind the flywheel/rotor, the flywheel itself, and the bolt holding the flywheel on. Would this not mean technically,,, my flywheel is not all the way on.

    [​IMG]





    I could be totally wrong. But I think it's worth checking into. I have 2 different starter gear's, and they both are like this. However. I did call a dealer today and have him look at a starter gear. He said the bushing did not stick out past. It was in fact, recessed a little. Argo confirms his is below the surface also.

    If you look at this pic that appiebroomer posted, the bushing is not letting part #16,, plate washer,, ride in the proper spot.

    [​IMG]




    I think it may also be causing this damage. You guy's need to check to see if yours looks like this. I have 2 different motor's and they both look the same. I don't know if the clearance is that tight have the flywheel sticking out that tiny bit would matter. But I won't sleep good until I know. :huh

    [​IMG]

    [​IMG]
    #17
  18. appiebroomer

    appiebroomer Adventurer

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    Cal, yes my rotor and stator also have that damage. I also checked one of my spare sprocket wheels and the bushing is also pushed out a bit. These conditions may also be the source of some of the noise we are experiencing. Gonna have to look into this a little further.
    #18
  19. CalsXS2

    CalsXS2 Been here awhile

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    Now this is funny. Last night before I went to bed, I had this whole chain noise figured out. So I thought. I posted in this thread about it, and the other thread,,, cross linking the two.

    Then in the middle of the night, half asleep during a nature call,,, it came to me I was totally wrong in my way of thinking. So I hurried up and deleted everything before you guy's seen it, and I lost credibility since I was so far off. :huh

    Now you post this. I'm so glad you did. All though I was talking about a different noise that I was after,,, chain slap,,, this is definatly a noise I have to.

    Sometimes I hear what I think is the balancer chain grinding away like we know it does. This motor I'm running right now does not have the tensioner.

    So the point is, I was so caught up in the chain noise, I was over looking at the obvious noise that this rotor has to be making. Good catch. :1drink
    #19
  20. appiebroomer

    appiebroomer Adventurer

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    Cal, You had me wondering about that noise on the left side and the galling on the rotor and stator so I took mine apart today. I made up a chain tensioner out of a piece of Ultra high molecular weight plastic kinda like what shows in the parts manual. I also put a set screw in the sprocket that sits on the starter shaft to prevent the chain and sprocket from wandering around on the shaft. I figure those two things should stop the starter chain from slapping around and making any noise.
    I also looked into the galling on the rotor and stator. I took a die grinder with a sanding roll on it and cleaned up all the surfaces that were galled then I coated all those areas, including the area where the chain was rubbing on the cover with die makers blue and reassembled it, cranked the engine over for about a minute and then took it apart and checked for any new contact. None. Put it back together, ran it, no noise. Maybe I'll take it apart in a week or so just check. But it sounds better now.
    Al
    #20