Trans mounted clutch... TRX90

Discussion in 'Modifications' started by kirrbby, Nov 17, 2017.

  1. kirrbby

    kirrbby Well-Known Member

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    How about a little Yamabond insurance policy for my head gasket??
    IMG_20180411_232705328.jpg

    That's my old gasket...but I'm thinking that if I were to put the sealant on and let it dry overnight...it can't hurt?? Might help?

    My local AutoZone is supposed to have the copper gasket spray on the shelf. I'll pick up a can and spray the new gasket with it, then install it dry and torque it heavy.
    If I still suck oil, I might try the extra sealant on the next try. Hope that isn't necessary.

    I haven't disassembled the head to look that over yet, but I'm pretty sure my oil problem is at the head gasket.
     
  2. kirrbby

    kirrbby Well-Known Member

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    Check, check, check...cap nuts, head gasket with copper spray, new fibers in the clutch...torqued to nearly 11 foot pounds. Installed the motor back into the bike, then it sat for about 6 weeks before the first startup. The smoke seems to be gone, clutch doesn't slip. But I haven't ran it much at all since i don't have it jetted right yet. I have 100 main Jets, but not the RIGHT main jet...125 or 30 I think.

    The bike shifts great and the clutch setup is pretty cool. I'll post a little more about that once I get the jetting right.

    My oil control issue had to have just been the head gasket. Lesson learned there...I need to be mindful when installing and torqueing them, especially on the bigger motors.
     
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  3. kirrbby

    kirrbby Well-Known Member

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    Well I think I got it jetted right yesterday. Dropped to a #20 pilot and ended with a 125 main. Might still be a touch rich with the needle set 2nd from leanest.

    No oil cooler, but no heat issues during my testing. Head gets plenty hot, but dipstick reads less than 85 Celsius.

    Motor runs good and shifts nice. It's not a monster at 114cc with the 49.5mm crank. I notice the missing torque compared to my 117cc with a 51mm crank. Big difference from my old 124cc trx engine...54mm crank. (I miss that bike)

    Gearing...might be a bit too tall. Can't remember, 16 or 17/35.

    I did add 2HD springs when I rebuilt the clutch, and still no problems/complaints with that.


    I had some smoke again tho. When I came home from a ride, it was blowing smoke again, but cleared quickly and didn't return. I didn't get any oil dripping out of the exhaust or anything...but it was definitely smoking again..?

    I think I mentioned my flat rear tire previously. Well I patched the tube and put a old Bridgestone on...that went to hell too. Had to change it again...to a good old Nitto, tire and tube. Hoping it'll fly for a while...I'm the king of old, used, rusty, cracked, and warped parts. Most of them end up on MY bikes. lol

    I still need to make a video to show you how this clutch setup works...and how the 114 runs.
     
  4. racerx

    racerx Administrator
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    It'll make horsepower, just not a whole lotta torque, especially down low. What this setup should do is breath freely; the large bore unshrouds the valves and that means rev-happy, top end power. Expect it to be peaky & tweaky compared to your long-stroke tunes...stomper vs screamer. Three guesses whatcha got here, the first two don't count:whistle:

    FYI, one of the drawbacks of larger bore diameters is the loss of metal and with it, sealing surface. It's possible to go as big as 56mm with these motors. Fatcaaat did this and the motor "ate head gaskets". You may need to get a little creative, if that's what you're dealing with here.
     
  5. kirrbby

    kirrbby Well-Known Member

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    I've spent VERY little time messing with this engine, It's been a bad year for minibiking, for me. But I have a video loading that I'm hoping is good...haven't even watched it yet.
    I'm still dealing with oil control issues which I now think are because I didn't put much effort into heat cycling the new motor...so the rings didn't set. I'm stubbornly learning my lessons instead of heading good advice I spose.

    But...I'm hoping the vid will tell the...rest of the tale of this cheap and easy, 113cc 4speed manual with the stock trans mounted clutch.

     
  6. racerx

    racerx Administrator
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    It really doesn't sound too far off, maybe a tad rich, as you've guessed. What I heard could also indicate gearing that's a bit taller than optimal, or a high-rpm tune that's just below the sweet spot in the revband. No doubt, the heavy rotating mass is a factor.

    That said, I wouldn't be overly concerned, thinking toward lightening any of the 3 "flywheels". The only thing affected will be acceleration. Power and usable road speed will be the same, regardless. It'll just be an unusual setup...which has a coolmess factor of its own.

    As for the oil control issue, more annoying than serious. At this late date I reckon you can R&R a top end in your sleep, if necessary.
     

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