TY250 project

Discussion in 'Trials' started by Junglejeff1, Nov 1, 2018.

  1. Junglejeff1

    Junglejeff1 Long timer

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    Thanks,it's alot of dinking around but having fun.We are having insane snow here so nice to have a garage project.Can not wait to see how the frame turns out.Hoping it's done by friday.
    #81
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  2. Junglejeff1

    Junglejeff1 Long timer

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    I read somewhere that emulator valves for the xs650 forks fit the ty.I think I'm going to order them from Mikes xs.There like 55 bucks.Will also get fork springs from B&J to replace my sacked out stockers.I like the emulator because it sort of acts like a cartridge fork and sort of self adjusts. Looked into the damper rod drilling mods and not impressed.
    #82
  3. Junglejeff1

    Junglejeff1 Long timer

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    Going to have to play around with it some.The 2 I have read about ended up with 15w to control rebound with nearly zero spring tension on emulator.The thinner oil would not work as it fully controls rebound.could weld the rebound holes shut and redrill them smaller but I will most likly just play with oil wt.
    #83
  4. Junglejeff1

    Junglejeff1 Long timer

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    20190301_133552.jpg 20190301_163131.jpg Taped off my case and loaded my Eastwood powdercoat gun in truck and ran over to friends house to use his full size electric cook stove in his garage.Got some 30% reflective powder off amazon for 12 bucks (mit brand).Pia to tape off.I taped edge of seal holes and used foil to pack.I tried something new and sealed foil to tape with copper silcone to make sure bearings were protected from powder.It worked well as the 400 degrees did not bother the silicone a bit.This powder said cook for 10 minutes for Satan and 30 for gloss.I cooked the cases 1st to de gas aluminum and sprayed powder on while case was hot.Trouble is it came out shinier than planned because I hot flocked it and did not start from cold.If any of you guys reading this ever play with powdercoat hot flocking is good and bad.It,s bad in that you can get powder sort of thick.It,s good as there is this wierd effect that blows the powder out of tight bends in metal on room temp steel that the heat stops.I learned alot from a old biker friend that did powdercoat out of his garage back in 06 when I got my Eastwood rig.Was a cool guy but have not heard from him in years since he moved to Oregon to grow pot.
    #84
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  5. Junglejeff1

    Junglejeff1 Long timer

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    I talked to Rick at cogent today.He has a system called DDC that is a upgrade of the emulator valve.More than just a simple pop off valve.Going to see if I can fix one into the forks on this bike.
    #85
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  6. villageidiot

    villageidiot Long timer Supporter

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    Used DDC’s in my dr650, night and day!
    #86
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  7. Junglejeff1

    Junglejeff1 Long timer

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    Cool,last summer I did some beta testing for a Africa Twin heavily modded shock from Rick.I was very empressed with it.Guy really knows suspension.
    #87
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  8. Junglejeff1

    Junglejeff1 Long timer

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    20190309_120827.jpg picked up frame from powdercoat.can start doing the fun work now.
    #88
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  9. Junglejeff1

    Junglejeff1 Long timer

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    20190315_181519.jpg 20190315_140323.jpg waiting for a lost transmission shim so working on other parts.Going to powdercoat brake backing plates and forks black.
    #89
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  10. Junglejeff1

    Junglejeff1 Long timer

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    20190315_200858.jpg 20190315_211413.jpg finished my big pieces, did them with flex black because it does not chip easy.
    #90
  11. twinrider

    twinrider Pass the catnip

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    Put them in my XT250, huge improvement combined with the Cogent shock.

    Btw, picked up this trials bike for $90 last week. Time for some cross-training... :ricky
    #91
  12. Junglejeff1

    Junglejeff1 Long timer

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    Super deal
    #92
  13. twinrider

    twinrider Pass the catnip

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    Yeah, wife's coworker so he gave me a really good deal. Needs a fork overhaul (leaky seals) and new front brake pads but otherwise seems in good nick. It has the TTR125 motor. Need to get the maintenance info for that motor.
    #93
  14. Junglejeff1

    Junglejeff1 Long timer

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    The manual for ttr125 was change oil every 60 hours but I always gave it some new oil about every 20.just pull the side drain,dump and drop a new qt in.I put 10/30 standard honda oil in mine.Some guys in warmer climates than me useb10/40.Daughter kept sinking that bike underwater.Had to push start it one time and water blew out exaust like a super soaker. Pulled top end after a couple years of that abuse and damn thing was still in nice shape.thrue new rings and gaskets on it and still kicking nice 2 owners and 2 years later.
    #94
  15. Junglejeff1

    Junglejeff1 Long timer

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    It's coming along.

    Attached Files:

    #95
  16. Junglejeff1

    Junglejeff1 Long timer

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    Had some issues.Did the pb blasterfor 2 days and heat thing on the spokes.Back wheel went great but front wheel no good.spokes broke like glass.Ordered a spoke kit from speed and sport to respoke.Big issue was my left fork.The lower slider tube was bent or bruised.I thought my forks were tweaked but they were straight .Purchased a set of forks off ebay for 80 shipped just to get a slider.I modified the brake pedal to drop it down to the new lower peg position and have some adjustment to put it were I like.Check out that beautiful talon dished sprocket I got from trials and trail in Europe. Running into a few issues but happy with my build.Costing more than I planned but a fun build.

    Attached Files:

    #96
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  17. Junglejeff1

    Junglejeff1 Long timer

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    this is my friends bike.He collects vintage dirt bikes (mainly yamaha,s).I told him what a blast I am having in my new sport of trials.He is going to do his 1st meet with me in door county Wisconsin Screenshot_2019-03-30-10-20-45.png this summer. His bike was in even worse shape than mine.when he pulled motor down the rod was even missing bearings.He has it up and running well now.He is working at making it completely original unlike me.Looking forward to riding our old beasts together at his 1st meet.
    #97
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  18. Junglejeff1

    Junglejeff1 Long timer

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    I just measured my squish band clearance.It is .129".Crazy loose and not doing much for combustion since it should be around .050".Checked it without the .040" head gasket and got down to .089".Going to shave head and cut a thinner head gasket. I have seen talk about running no head gasket and just sealer and the bikes run better,now I know the reason.
    #98
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  19. PMK

    PMK Been here awhile

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    I snagged this image of a TY250 head from EBay. No doubt the large clearance on the squish band can be improved upon.

    From experience building race engines, seeing this combustion chamber shape and reading the squish clearance dimension, myself, I would consider more than skimming the head.

    First measure the head chamber volume very accurately and record it. Next, calculate the squish band area percentage.

    Based on those parameters, decide on how best to modify the squish area and squish clearance.

    That head design runs a high squish area percentage, and with that requires a greater squish clearance, essentially what Yamaha did.

    Fuel has changed since these machines were produced. Because of that alone, the combustion chamber can be better optimized.

    Ultimately though, use caution if you modify the head so that you alter the volume very little. Adding compression can be a plus or a negative. I do not know the cranking PSI of a TY, but increasing compression can make power, but also create a finicky low rpm that is prone to stall.

    upload_2019-4-2_3-42-56.jpg
    #99
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  20. PMK

    PMK Been here awhile

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    For comparison, the dual plug head is a stock 73 OSSA MAR 250, vs the 74 Yamaha TY250A head. The red cylinder head is a S3 for a modern bike. Note, they all use a similar “Top Hat” style combustion chamber. The OSSA utilizes an even greater squish band area. I have never measured squish clearance on the OSSA. The modern head has less squish area and can likely run a more optimized squish clearance.

    From experience, I do know the OSSA runs noticably better on a fuel blend based more on what was available in tne 1970s.


    upload_2019-4-2_4-14-44.jpg upload_2019-4-2_4-16-3.jpg




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