1968 Bultaco Matador m26

Discussion in '2 smokers' started by blaine.hale, Mar 20, 2011.

  1. blaine.hale

    blaine.hale Long timer

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    I'm all too familiar with these procedures...given I had to build the r90 from the ground up :D
    It's nice to have a mental checklist of things to go through now though!
    The petcock has been rebuilt. The carb is an AMAL 30 mm round monoblock which was never really used when the bike was retired. It's simply missing the plastic float needle. I've just been filling the bowl then shutting off the petcock to do test cranks. The air filters is brand new, oiled and the boot is sealed (I can hear it give a nice suck suck suck when I kick it.) Also has fresh lines.
    I'm going to wager it's getting some dirty fuel in combination with timing that is reaaaally off. I'll clean the jets, ensure it gets clean fuel at least for the first start and well...I still need to get that timing thing down. I was hoping I could guess good enough to get it cranked and shoot a timing light at the TDC marks I made on the fly wheel. I guess not :(
  2. blaine.hale

    blaine.hale Long timer

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    Did some run starting the other night on it just for the hell of it. It sure grunts like it's wanting to start but it's a no go :(
    That tells me the timing is way off and the jets possibly are clogged now from the 40 yr old tank gunk that hasn't been fully flushed out.
    Thursday night will be the night!

    In the mean time, we got some riding in on the alpina (god I love Bultacos!)

    Urban Atlanta trails are fun :)
    [​IMG]
  3. PSchrauber

    PSchrauber Long timer

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    Great pic, very cool vintage urban trial. :thumb

    Btw: I would love to see the Alpina in Detail, model and year?
    It looks like it is a model of the mid to end 70's?
  4. blaine.hale

    blaine.hale Long timer

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    It's a 73 Alpina (250cc version.)
    Found it on CL couple of weeks back for an absolute steal price and my brother bought it. Has all the factory stamped bolts and safety wire and metal fenders. Just missing the lights and gauge. It does need a bit of a cleaning and going over but it runs! Haven't really taken any pictures of it yet.
    This is the video before we got it tuned a little and idling properly:

    <iframe width="560" height="349" src="http://www.youtube.com/embed/VlvbQ2792W0" frameborder="0" allowfullscreen></iframe>

    My brother just got off the phone with Hugh's and apparently they were shocked and surprised that the Alpina was the first model run of Alpinas...guess thats a good thing :D
  5. PSchrauber

    PSchrauber Long timer

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    Yep very cool bike and collectable as you already stated, the sound is still more two stroke wise* compared to the "newer" Alpina and Sherpas I'am used to and are playing around, but very pretty.

    * When Bultaco switched to the banana and then to the clubfoot rear exhaust the bikes Alpina and Sherpa got this crazy "blo-blop-blop-blo-blop-blop" sound.
  6. stainlesscycle

    stainlesscycle Long timer

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    yeah, the timing is so critical on a 2 stroke. without a dial indicator, there is no way to get it even close. once you get the dial indicator in there and see how much difference there is between .090" and .110" you'll see there ain't no guessing... you only have about a .5mm window of where it will run correctly.. everything else is just kicking it for exercise sake.
  7. blaine.hale

    blaine.hale Long timer

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    Sounds like once I get my timing precise (tonight) it will crank right up!
    Seriously, this is the worst bike I've set timing on haha.
  8. stainlesscycle

    stainlesscycle Long timer

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    yeah, it's got the points setup which is a pain. the motoplat is simple...
  9. east high

    east high Been here awhile

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    Be sure to mark the case and stator plate when you get the timing right. Also be sure to do a few plug chops at WOT. There's a fine line between a fantastic running 2T and one that's just about to seize.
  10. blaine.hale

    blaine.hale Long timer

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    Correct me if I'm wrong but that means run the bike at WOT for a period (I'd say half a mile is all I can spare haha) and kill the engine with still pegged to see the condition of the plug at highest operating temps. This allows proper and precise carb tweaks, I believe?

    Been years since I've had to the pleasure of tuning 2 strokes :D
  11. stainlesscycle

    stainlesscycle Long timer

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    that is correct, hold throttle open, hit kill and pull in clutch.. best if done up a very long hill. best to start rich on the main jet. if it blubbers on top and won't rev out it's rich.
  12. darmst6829

    darmst6829 Been here awhile

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    Yes, mark the stator plate and the engine case for ease of reassembling in the future. All the Bultaco motors I own have the marks scribed on them already. Once timing is established you never have to do it again, you only have to make sure the point gap is correct. Point gap will radically change timing on these motors.

    Dave
  13. PSchrauber

    PSchrauber Long timer

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    I had to look up what you mean with WOT, this means at highest rpm right?

    If so I would say don't do that, you have fresh rebuild motor now, this is an old motor design and you have to break in or running in the engine first.

    The WOT method is not healthy and does not cover all adjustment possibilities you have. There is an much more easier and not so "abrasing" method to determine the right carburator adjustment.

    There are 5 different systems in a carburator that controll the gas flow, each of them is responsible for a different rpm range you see them in the picture below:

    [​IMG]

    The trick is to mark these ranges on your throttlebody, with a duct tape and foil pencil for example.

    Befor you start to adjust your carburator be sure that every jet, needle slide, ... is OK the carb is cleaned, you have fresh gas and a new plug installed. The timing of the ignition should be right too. (1)

    Then you search a light slopy road that is about 600m long.

    Now you get the bikr running until the engine has warmed up to operating temperatur.

    Now you ride along the road really gently accelerating in every gear.

    If you notice that the engine runs "unclean", abnormal, is unwilling to deliver power then you notice the position of your throttelgrip.

    Start again riding up the road and hold the position of your throttlegrip
    where the engine did not run right.

    If the engine starts to behave like a four stroke or start to "chop" the engine is running to fat.

    If the engine is running to lean the rpm of the engine will rise although the throttlegrip position is unchanged. Mostly you also hear a slight knocking. If the engine start doing knocking don't ride further otherwise the piston or cylinder can seize.

    Now you can look up the picture where the position where you had the running issue of the gas throttle is combined with the system of gas delivery. Now you can do your changes if necessary.

    If you are unsure you can use the plug method, (engine is again already at running temperatur). Now change the plug, (a real fresh one), und ride the road again with the fixed position of your gas throttle where you have the problem. Stop at the end and unscrew the plug to determine how the plug looks.

    Saludos coriales :wink:

    (1) get a mm gauge to adjust your timing, every time you replace your point you mostly have to find the correct timing again anyway.
  14. stainlesscycle

    stainlesscycle Long timer

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    yep, you definitely have to break it in. everyone does it differently.

    i ride around up to about 1/2 throttle, then decel without pulling in clutch. don't hold steady throttle. just ride around, varying throttle postion (don't wind it out...) - do this for maybe 10-15 minutes. then let engine cool for awhile - maybe 30 minutes - an hour... then do it again. repeat a couple of times, and you should be good to go. each time you can increase throttle position a little bit. the key is to not coast with the clutch pulled. slow down with engine braking. this may be difficult to do if your jetting is way off. having a nice big yard/riding area with some hills in it helps a lot... you want to keep the motor loaded. don't pull the clutch in and zing it. although neato - it's not good for break in.. :)

    as pschrauber said marking your throttle grip at 1/4-1/2-3/4 is an excellent way to find where your jetting is off. i use a sharpie on the grip and a mark on the throttle to reference.


    wot plug chop only does the main jet. you will find the main jet is the easiest to dial in. i rarely do plug chops. i start way rich on the main, and work down till it stops burbling, then do a plug chop to verify.
  15. stainlesscycle

    stainlesscycle Long timer

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    p.s. your alpina sounds slightly lean on the pilot or airscrew.. it's got a little bog when you wack it, then it's slow to return to idle..
  16. hardwaregrrl

    hardwaregrrl Can't shoot straight Supporter

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    Couldn't this also point to a possible air leak?
  17. stainlesscycle

    stainlesscycle Long timer

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    could be. if airscrew has no effect, it could be an airleak. but i'm guessing that alpina has an amal on it, and they're solid mount which have less tendency to leak.
  18. blaine.hale

    blaine.hale Long timer

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    That was pre-tune up video ;)
    The just got it excitement.


    Tried to time and crank the matador, lost my spark again, got pissed and decided beach vacation this weekend will do me a world of good.
    It gets spark when I file the points...so I may replace em.
  19. PSchrauber

    PSchrauber Long timer

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    Best thing You can do! I replace them regularly, depending mileage or operating time (I do it mostly after operating time because I use them for trials riding) so around every 50 hours I change them, after 50 hours I got so much consumption on the electrodes that they don't work as good anymore, filing the point helps only for a short time.
    (BTW.: Had this issue also with my Italjet T350).
  20. stainlesscycle

    stainlesscycle Long timer

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    definitely replace points. if you've not replaced condenser already, might as well do that too, since you're in there. also, reroute condenser up to near coil, and put it in the airstream. they last longer if they don't get hot. and a lot easier to replace when they're not under the flywheel - do it once and you probably won't need to ever replace it again..