Mid-80's KTM 2-Stroke

Discussion in '2 smokers' started by CrazyD2.0, Feb 1, 2013.

  1. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    Was going to get the engine reassembled this week, however going out for dinner, sending oldest son to Australia/New Zealand on his school's rugby tour, Mrs Crazy's birthday dinner, and then discovering I had received 2 lower piston rings instead of a lower and upper ring has delayed that progress. No biggie - still have 4 months to go:*sip*.

    I sent UNI-Filter an email requesting info on supply - not a peep! Same for that suggestion about the KTM racer/dealer link suggested earlier - no response. One would think they'd at least respond a simple yes/no....
    #41
  2. PSchrauber

    PSchrauber Been here awhile

    Joined:
    Jan 3, 2011
    Oddometer:
    997
    Location:
    Summer: Kemiö, Finland; Winter: North Germany
    Try André Horvath in Austria for parts, one of the best ressources to get parts for these KTM machines.

    http://www.enduroklassiker.at/artikel/index.php?&lang=en
    #42
  3. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    Whoa! Nice find, that! Thank You much...
    #43
  4. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    Cleaned up the steering head bearings and re-assembled the front and rear suspension (temporarily). Engine has been reassembled and just going through the process of timing the magneto/ignition system.

    [​IMG]

    Also gave the fuel tank a coat of fusion paint spray - had gone all yellow as can be seen in the first picture posted. Now at least it looks original white. Updates to follow...
    #44
  5. Foot dragger

    Foot dragger singletracker

    Joined:
    Dec 27, 2006
    Oddometer:
    13,858
    Location:
    chico,just below rag dump(nor-cal)
    Sachs engine? No its a KTM engine.
    Penton's had Sachs engines but that was early 70's.

    I had a 79 420 that looked much like that,also a twin shock 495.
    Either was very hard to wear out,the stock piston is forged and lasts a really long time,I wouldnt toss out the piston that's in it unless its ruined.
    They are set up at loose tolerance due to the forged piston expanding more at running temperature. 6 0r 7 thousandths clearance if I remember rightly.

    They are fun smooth running bikes,easy to ride and win races on when I had one. Parts are a little hard to find just gotta hunt around.
    #45
  6. Foot dragger

    Foot dragger singletracker

    Joined:
    Dec 27, 2006
    Oddometer:
    13,858
    Location:
    chico,just below rag dump(nor-cal)
    Have you ridden one? I raced and trailrode one for years,they are as smooth as could be desired.
    And fast enough.
    KTM sells 7 different thickness base gaskets to tune the engine for what you want to do with it. I dont know if those are still available but I detuned my 495 a little with thicker base gaskets.

    I also had a 77.5 250 GP model for years,flattracked it,trail rode it,MX'd it,then scrambles raced it,then rode some enduros with the same bike.
    It never broke and it won some races.
    #46
  7. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    When I ordered the engine gasket kit, I did get the various thickness gaskets. I set up the height according to the engine manual for the 250, which called for 1.2 to 1.3 mm from the top ring land to top of cylinder. The manual warned that too short a distance would cause "pinking" which I take to mean running too hot and causing pre-ignition, and of course too high would lose compression and power, but I didn't know that there would be an acceptable range. So I set according to the spec.
    #47
  8. Foot dragger

    Foot dragger singletracker

    Joined:
    Dec 27, 2006
    Oddometer:
    13,858
    Location:
    chico,just below rag dump(nor-cal)
    I think it varies on different KTM's,I had an 04 MXC250 and guys go as far as to use the piston/head from an SX model to get compression to where it should be,otherwise they are weak off the bottom rev zone.
    Ive got an 09 XCW 200 now and guys run thinner base gaskets to get more low end out of them.
    KTM has the X factor which is exactly where they want cylinder heidth set at.
    Guys do experiment some and compression can be checked once its torqued down,160/170 psi would be good.

    Id love to have a good running 1980 420MC,they are a sweet running smooth big bore.
    #48
  9. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    Have the engine loosely mounted and I think the carb is mounted correctly. I know where the main fuel line connects to, but there is another nipple above the main inlet line I'm not sure what is needed for that. Does anyone have any detailed pictures they could email me for guidance on fuel line/throttle and cable routing for this machine. I checked that link provided from that site in Austria, there's a couple nice pictures but don't quite show enough detail of the carb and what I'm looking for...(pics to follow)
    #49
  10. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    I think my choice of paint is a little too much on the shiny, silver side of things, but its what I had on me when I reconditioned the front engine cover on my GS, so figured I'd use it here.

    [​IMG]

    Its apparent that the large nipple would be the fuel inlet, but I don't know if/what is needed for the smaller nipple above it, plus the one on the other side...

    [​IMG]

    [​IMG]

    And for routing the throttle/clutch cables, fuel lines, ignition leads would be where convenient...(?)
    #50
  11. Scootern29

    Scootern29 Been here awhile

    Joined:
    Sep 4, 2012
    Oddometer:
    792
    Location:
    In the hot, hot, dezert
    If you spray the motor with clear coat it should take the "Mesican Chrome" look out of it.
    #51
  12. Spikester300

    Spikester300 Roll Tide!

    Joined:
    Feb 19, 2009
    Oddometer:
    141
    Location:
    Killen, Alabama
    Those little nipples are for over flow tubes that run down. I had a '82 model back in the day and raced it 3 or 4 years, great bikes. It was much like yours but the 1st year mono shock and had reeds, nice motor. Good old Bing carb with the tickler, messy but starts good.
    #52
  13. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    So does that mean I simply connect some short tubing and route them down below the bike frame?
    #53
  14. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    Ok, moment of truth. Got all the basic stuff done, just a temporary securing of wires, exhaust, etc.

    [​IMG]

    Slightly raining outside, kinda chilly, but whatever. Multiply the following pic by about 100, to get an idea of how long it took to get the bike to fire up...good thing I went to cycle-fit class this morning - got my legs conditioned to pumping a lever...

    [​IMG]


    Hooray - it fires! Had to maintain some throttle to keep the engine running, obviously there's some carb issues to deal with. Our neighbour, Tim, came out - he's been playing with dirtbikes forever, gave me some assist.

    [​IMG]

    I've got an oil leak from the clutch actuator cover - will have to drain some of the oil and apply some sealant to the gasket to fix this...

    [​IMG]

    Quite the process. Fuel all over the engine, dripping out of the float bowl... took the carb off, removed the bowl and during discussion with neighbour discovered one the floats cracked, then came apart. Its been exposed for 10 years, after having been used since 1980, so figured its probably brittle and needed replacing anyway. Going to replace the little float needle as well. I noticed when I had the carb apart the first time, the jet needle was slightly bent - I tried to straighten it but still has a bit of curve to it - figure may as well replace that too.

    [​IMG]
    #54
  15. anonny

    anonny What could go wrong?

    Joined:
    Mar 20, 2007
    Oddometer:
    6,067
    Location:
    Beautiful Revelstoke BC

    Just lay the bike over and you wont have to drain it.
    #55
  16. CrazyD2.0

    CrazyD2.0 We Havin Fun Yet?

    Joined:
    Feb 15, 2007
    Oddometer:
    234
    Location:
    Abbotsford, British Columbia
    Almost too afraid to do that too - I replaced the kick-start shaft seal and the shift lever shaft seal too, but didn't want to tempt them leaking. I ended up leaning the bike against a support post in my garage, then pulled the drain plug and let whatever amount of oil flow back into the ATF bottle for return to the crankcase when fixed.
    #56
  17. Spikester300

    Spikester300 Roll Tide!

    Joined:
    Feb 19, 2009
    Oddometer:
    141
    Location:
    Killen, Alabama
    Get used to fuel all over the place when you prime it with the tickler, run longer fuel lines from the vent tubes behind the motor to get the fuel to the ground.
    #57