1974 Honda MT125 Elsinore VMX Racer Refresh.

Discussion in '2 smokers' started by RustyStuff, Sep 14, 2015.

  1. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
    Jan 14, 2012
    Oddometer:
    13,223
    Location:
    Crakima,Wa
    Picked this up today. Long story, but the seller was a brother of one of my Dad's childhood friend's, it's a small world. Had a great afternoon BS'ing with him about riding and what they all did as kids. The plan is to rebuild this for VMX racing, My Dad's exited about it as he raced a 1973 CR125 Elsinore when he was in High School, so this is like a slower, more reliable time machine.

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    It's mostly there, Missing the whole rear brake lever/cable setup, but the brake gut's are there. Someone welded brackets onto the back of the swing arm at some point for lay down shocks( as best as we can figure). It still has the original Dunlop Sport knobbie on the front.

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    The good-
    Brakes work, Suspension works, Compression is good and the Spark is strong. Frame isn't cracked or bent. Most everything is straight. Goes into gear and shifts. Even has the oil injection system still.

    The bad-
    Intake rubber is bad(NLA, going to have to fab something). Carb is full of rust and varnish. Kicker spring is FUBAR. Tank is a rusty varnish mess. Need the entire brake lever,cable adjuster,etc for the rear. Pipe has some dents and the rear mount is MIA, looks like the silencer has been gutted from the pipe. Front Magneto cover lug is cracked off the case, but it's not structural. Swing arm is cracked where one of the PO's welded that crap on.
    Nothing that can't be fixed.

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    Yummy-
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    The plastic's are cleaning up nicely-
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    The plan is-


    Cobble an intake together, Thinking I can weld up a spigot and use some rubber hose as a new intake, as the real part is NLA everywhere I can look. If it runs, we'll start fixing everything else.
    #1
    Gamequeazy likes this.
  2. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
    Jan 14, 2012
    Oddometer:
    13,223
    Location:
    Crakima,Wa
    It lives! Got it to fire up and run, made an intake rubber out of a rad hose. No bad noises and the Oil pump started pumping, which caused it to foul out.
    Anyone know the test procedure for the oil injection?

    Tomorrow's goal is to get the muffler opened up and cleaned out, it packed full of carbon and mouse nest. Long term goal on that front is to build a new chamber this winter. That ought to wake this motor up.
    #2
  3. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    Oddometer:
    13,223
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    Crakima,Wa
    I got to ride it, fogged out the neighborhood running both premix and the auto luber(works perfectly, no more premix!) :clap: Shifts well, quite a more power than expected, want's to wheelie on the 2-3 up shift. Uncorked it must make more than the 12hp that cycle et al. said they made at the wheel. It must make at least 14. :D

    I want to Hi-five whoever invented Evaporust. That tank was horrible, thick flaking rust inside. 2 days of soaking and it's clean bare metal. :super
    Now I know that I should start buying part's!
    Trying to decide between using the stock filter holder with some roll your own Uni foam, or a Uni Pod filter.
    #3
  4. Scootern29

    Scootern29 Long timer

    Joined:
    Sep 4, 2012
    Oddometer:
    1,075
    Location:
    In the hot, hot, dezert
    Use the stock filter holder. Pod filters are not good for two strokes.

    I've built a couple of air filters using the Uni foam. Cut out your pattern and hot glue the pieces together. It works great.
    #4
  5. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    Well the bike drew some blood today. Cutting some shorty levers to fit the perches,it jammed and the bandsaw ate my index finger, cut to the bone. spent 5 hours at teh ER. might need surgery this week.

    It does run nice though, hope it's w0rth all this.
    [​IMG]
    #5
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  6. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    Oddometer:
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    With my hand outta commission I've only been doing some light work. Painted the fenders with some silver spray paint, waxed the tank. Ordered some parts.

    The big issue right now is the fact that the intake boot is NLA everwhere. I have a plan on a hopefully reliable intake. I'm going to tap and bolt/glue/braze/weld some alumnium "rings" onto the aloy insert from the rotten stock boot. Hopefully then I can just clamp rubber hose on and be done with it. As it is now, the lip on the boot is too narrow for the clamp to get a good grip. It only stays on long enough for short test rides.
    #6
  7. jimroid

    jimroid Long timer

    Joined:
    May 14, 2013
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    Ouch,hope the recovery goes well. Nice bike you have.
    #7
  8. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    Thank You, I'm exited about racing it next year.

    Used some of my impromptu vacation to work on the bike. We got the tire's mounted with some struggle. The front Dunlop Sport was even older than the bike, carrying a 7-67 date code. The rear was glued to the rim by the thick ductape someone wrapped over the rim. I chose a Maxxis IT Desert front( they turn well in my experience) and a Chen Shin knobbie rear. I would have preferred a more modern tread on the rear, but this was the best choice in the correct size.

    Today my rear brake peddle and new CR250M cable showed up, so now it has brakes on both ends! Very good, because the front is a bit... weak. Had a few exiting rides on it when I first bought it.:lol:
    [​IMG]

    I also won a auction for a 28mm CR125 carb and NOS intake boot. I've been talking with a Elsinore guru about Port specs and Pipes. My plan is to do a port job on this jug over the winter, not going to be too extreme but I want some power! Also going to pull the baffles and restrictions out of the stock pipe and run an external muffler/ sparkie. His recipe is- Gutted stock high pipe, port to the specs he provided, 28mm carb, thin copper head gasket for improved compression. Based on the Info he gave me, I'm expecting power in the upper teens, instead of the 10 this model had stock.

    Then I made up a Side panel out of ABS today. Painted it to match. The number plates are going behind the seat due to the pipe location.
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    I gotta find some decent shocks. The ones on there are bent and leaky. They are 14.25". I have some nice Progressive Suspension's, but they are only 13.25". Not sure if they would work or not.

    Was going to use some Showa's from one of my Suzuki's, but they fell apart as I swapped bushings.
    :(
    [​IMG]
    #8
  9. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    Oddometer:
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    Lot's of news parts arriving here.

    Kiehin 28mm carb from a 74 CR125.NOS Intake Boot to connect 'em.
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    Bought a CR125 downpipe.
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    Number plates arrived. I'm Trying to decide on Euro(rear fender) or Japanese(side panel) placement. I've decided to paint the rear fender up like the tank.

    Huh, something is up with photobucket. Most the pic's wont show.
    #9
  10. RustyStuff

    RustyStuff Long timer Supporter

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    MT High Pipe VS CR Low Pipe.

    [​IMG]
    #10
  11. RustyStuff

    RustyStuff Long timer Supporter

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    MT High Pipe VS CR Low Pipe.

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    It will be very interesting too test these after the motors modded.The MT pipe is gutted, no baffles packing and the sparkie is removed, CR has none of those to start with.

    MT- very short, steep divergent cone, large volume and a very long gradual convergent cone. Gives a mellow hit but a larger powerband. Flat sides means unhappy pressure waves and less power. Its heavy. Needs External silencer/sparkie.

    CR- Long divergent cone, smaller volume belly with a shorter convergent cone. Gives a narrower powerband but a higher peak. Round profile means the greatest possible pressure wave. Very light, thus the crack repairs. Has internal silencer, though mag reviews said this years pipe was an "Ear Raper" even with the baffle. :lol:
    #11
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  12. Vince

    Vince Long timer

    Joined:
    Oct 1, 2006
    Oddometer:
    1,015
    My first bike, only 41 years ago. O crap I am old
    #12
  13. fast1075

    fast1075 Not a Lemming

    Joined:
    Dec 28, 2013
    Oddometer:
    2,007
    Location:
    Flaw'da
    Ahhh, the Gen 1 Honda 125. That looks like a good find. I worked at the local Honda shop back then, and owned/rode/raced the CR and MT 125. The MT is a civilized trailbike version of the CR, although most parts are interchangeable. The CR had alloy wheels and tank. The CR had Cromo frame, the MT mild steel. The CR had the earliest version of electronic ignition, and a tiny button rotor for fast revs, the MT has a full charging system and a conventional flywheel to smooth torque. The CR had a close ratio transmission, and the MT had a wide ratio transmission.

    The MT is VASTLY detuned compared to the CR because of it's intended function. You can put a CR cylinder, head and pipe on an MT engine and make the same power as a CR. Honda offered an optional upgrade kit for the CR that included cylinder, head, pipe, and carb for even more power, however at that point it became a hand grenade with the pin pulled.

    I had a hybrid MT/CR café racer that I built. It was fun and fast. It ate 350's for lunch. (The fact that I only weighed 110 pounds at the time helped). Racing the old CR is a terrifying thought by modern standards. I motocrossed the CR and broke several bones in the process. It did far better at short track on the smooth clay.

    I thought recently of finding an MT and building another café racer out of nostalgia, but scarcity of parts has put me off. By the way, the new downpipe is aftermarket. All Honda CR pipes of the era had stingers and clamp on silencers (if they were used). Most likely a Bassani or Hooker, and were hydroformed with a seam at top and bottom running the entire length. Good luck with the project!!!!
    #13
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  14. RustyStuff

    RustyStuff Long timer Supporter

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    I'm not sure if the pipe is a Honda or not, I know the 74 used a pickle silencer, but I'm fairly sure this is the stocker '75. I see the same pipe on all the "stock" 75's so that muddies it a bit.

    I'd love to have a CR motored MT250 as a road bike. Love the look and really like the motor.
    There wasn't a title for this bike, but for what I paid I can live with it. I can imagine it would be fun on the back roads.

    I've been fighting a endless battle with the stock 24mm carb, so I just changed it out for the 28 this afternoon. I also modded the downpipe spigot to fit the head and hooked it together with some safety wire.

    It's beautifully loud now. Has the proper 2 stroke crack. The 28mm carb has much better throttle response. It's also a lot faster. Still lack's the bottom end, but it busts the back end loose on the 1-2,2-3 up shifts.

    Next up is the CR copper head gasket, new air filter and Jetting. I'll do the port work once my right hand is fully functional again.

    I'm also fairly sure that this bike has ether had a rebuild recently or is low hours, as the piston is completely pristine and the bore is very nice looking.
    #14
  15. RustyStuff

    RustyStuff Long timer Supporter

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    I got shocks! Well, so long as they are repairable, I picked up a lot of 3 gas charge showa's from a 76 Elsinore 125. 1 looks usable the others may need to be cannibalized to make one. We'll see when they get here.

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    #15
  16. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    My uni foam showed up.
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    The frankenfilter Lives!
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    Some cutting and bending on the air box to unshroud the filter.
    [​IMG]

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    #16
  17. RustyStuff

    RustyStuff Long timer Supporter

    Joined:
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    We have shocks.
    May or may not work, but for $20 I'll try and fix them. Can't be any worse than whats on there. Shafts have some rust though.


    [​IMG]
    #17
  18. Skowinski

    Skowinski opposable thumbs

    Joined:
    Nov 23, 2009
    Oddometer:
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    Location:
    High Desert NM
    Love it, one of my favorite bikes of all time was a 75 Honda CR125 that I raced motocross and hare scrambles on. :thumb
    #18
  19. RustyStuff

    RustyStuff Long timer Supporter

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    I'm really loving it, at least the little bit I've been able to ride it. Once I port it and install the CR CDI it should really make some power.

    After tearing the shocks down, I might be able to make one good shock. :/ Might have to hunt another 1976 CR125 showa shock down for more parts.
    #19
  20. RustyStuff

    RustyStuff Long timer Supporter

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    Oddometer:
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    Shocking!

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    Bent like a boomerang.
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    Not sure what the stock oil weight and ammount was, so I used 6oz of 10weight. Pumped it up to 100psi. Not sure how long it will hold a gas charge, but air is free and 78% nitrogen.
    Now to find one more. I found a guy who says he has some, gotta give him a ring and find out what he's got.
    #20