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Thread: 2014 SR50 MT; smokey start & poor running

  1. #1
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    2014 SR50 MT; smokey start & poor running

    First post..

    I bought an SR50 MT last week to get me around Perth while I'm here for a couple of months. Unfortunately after a couple of days it started showing its true character I'm very familiar with car engines but have never owned a 2-stroke so am a bit out of my depth and any help would be appreciated! It's a 2014 model and has done 12,000 km.

    Basically it starts fine, idles fine and seems to run cleanly and make reasonable power with the throttle fully open. As I understand, it has had the inlet restriction removed but those in exhaust/CVT/elsewhere are still in place; it'll do 65kph on the flat quite happily.

    However - at anything between idle and throttle wide open it doesn't run well at all, by which I mean it stutters and pops and generally doesn't sound happy.

    Alongside this, with the exhaust removed, the side of the piston is a little scored which is a bit of a worry. There's clean oil on the surface of the piston so I think it's getting lubrication, but I guess it's been got hot or something in the past? Haven't had it apart further so no idea on state of rings/bore etc.

    The last issue is that if left overnight and especially after a long run the previous day it's generally pretty smokey on start up which doesn't seem to clear until it's been ridden a hundred metres or so. I don't really understand why this might be, but I know very little about total loss lubrication systems or two strokes full stop. It's oil smoke rather than rich-mixture type smoke.

    My first thought was to put a new piston and cylinder on it and see how it goes, but I can't seem to find anyone selling a suitable kit at all, in WA or elsewhere. I think the engine is shared with Piaggio so I was hoping parts would be available, but maybe not?

    Thanks..

  2. #2
    apriliaforum Junkie 2Strokesforlife's Avatar
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    Welcome to the Forum! There's not a lot of info on the 2t Motards floating around. Sounds like the needle jet is incorrectly adjusted. This controls the fuel delivery for 1/4 to 3/4 throttle. Remove the sparkplug and post a picture of it so we can see if it's running too lean or rich. Also, if the throttle cable has been adjusted, there is a chance that the oil pump is putting out a little too much oil causing the smokey startup. I couldn't find a picture of what the oil pump looks like or the exact location of it. On the Piaggio engine SR's, its behind the transmission cover next to the variator. I'm guessing yours is in the same location. It's really easy to take the cover off and check, Pictures would help for this too (close up).
    2009 SR 50 Factory
    Malossi 70cc BBK
    Malossi HPC Crankshaft
    Stage6 Waterpump Impeller
    Arrow Extreme Pipe
    Malossi VL 13
    Ecu De-restricted 2.8.0
    7 Gram Dr. Pulley Sliders
    Stage6 Soft Contra Spring
    Water Trap
    RS 24/10
    Stage6 260mm Front Brake
    Stage6 Torque Control MKII 107mm
    Stage6 R/T Clutch Bell 460g
    Malossi Special Belt
    Malossi E5 Air Filter
    Stock Gears Installed

  3. #3
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    sounds like the bike found a good home. i agree it needs a new sparkplug first thing. i like the champions. the ngk dont seem to do well in the piaggio aircooled bikes. champion has aircooled plugs that cost a little more and run for ever.

    the needle clip height sounds to rich but it could be the sparkplug.

    ---------
    clean everything with misted wd40 like. if there is a new leaky spot it will show itself. the drooling fuel and oil are vacuum leaks on a 2stroke and they need to be dealt with.

    --------
    check the compression. needs to be 100psi or above. they stop running at 80-90psi.

    -------
    the sticker says to use synthetic oil.

    -that is a 2stroke tune up-
    --- diploma for engine repair in 2012 ---

    derbi bullet 2006 - piaggio AC - malossi T.C. half - custom GPS dash - TPR 70CC - topperf crank - vl13 reed and spacer- yamaha rt180 kickstand - giannelli shotV4 - phbg 21mm - doppler mesh top venturi filter

    complete wtp volta bmx 2012 - sanko seamless japanese cromoly heat treated and blue printed frame - 21lbs

    1992 lt250r suzuki quadracer - maier plastics -chromed shearer pipe - chromed works suspension - ++++++++ - 220lbs

    previous vehicles - subaru legacy turbo 1991 - mazda mx6 turbo 1990.

  4. #4
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    Thanks both.. I'll have the plug out and report back..

  5. #5
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    So..

    plug:

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    TDC:

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    mid-stroke:

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    more in next post..

  6. #6
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    Oil pump:


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    carb:

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    - piston doesn't look too good, does it!

    - plug's a bit black but tip looks alright in terms of deposit colour to me, thoughts? It's an NGK rather than Champion but is new according to previous owner.

    - nothing externally amiss with carb, no obvious air leaks from the body or hoses around it with wd40 misted around it while running, but I appreciate that there may still be air leaking in somewhere or other. I guess maybe I need to take the tail farings off to get a better idea?

    - oil pump is as suggested, behind transmission cover. From the look of it, it's regulated by a cable running parallel to the throttle cable?

    All help appreciated, thank you.

    My compression tester is 12,000 miles away unfortunately

  7. #7
    apriliaforum expert
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    new cylinder. 50 or 70cc.
    new rollers 7.5grams 19mm size
    new belt
    new wrist bearing

    ---
    let me know. looks like 100-150 bucks maybe.

    --
    feel like a 70cc? try the airsal sport 70 with no head. use your own head. goes for around 100 bucks. you would need a main jet kit from 60-80 in the 6mm sized jets
    --- diploma for engine repair in 2012 ---

    derbi bullet 2006 - piaggio AC - malossi T.C. half - custom GPS dash - TPR 70CC - topperf crank - vl13 reed and spacer- yamaha rt180 kickstand - giannelli shotV4 - phbg 21mm - doppler mesh top venturi filter

    complete wtp volta bmx 2012 - sanko seamless japanese cromoly heat treated and blue printed frame - 21lbs

    1992 lt250r suzuki quadracer - maier plastics -chromed shearer pipe - chromed works suspension - ++++++++ - 220lbs

    previous vehicles - subaru legacy turbo 1991 - mazda mx6 turbo 1990.

  8. #8
    apriliaforum Junkie 2Strokesforlife's Avatar
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    In one picture (without flash?), the plug looks good. In the brighter one, it looks lean and slightly blistered.

    The oil pump is pretty dirty. Is it wet or is that just old belt dust? Wipe it off to see if the two lines match up. This should help...
    http://www.apriliaforum.com/forums/s...t-PPJ-oil-pump

    The pics aren't doing any justice for the exhaust/piston/cylinder. I tried to take a similar picture and it looked much worse in real life. If it's deeply scratched or gouged, it's time for a top end rebuild at the minimum. Only a compression test will really tell you. There's a lot of goo and carbon in there too. I'm guessing the oil pump is set a tad too rich. Take your variator off if you can and see if it's wet around the crankshaft seal. If it is, you have leaky ones that need to be replaced. Leaky crank seals will cause you to run lean...
    Last edited by 2Strokesforlife; 03-20-2017 at 04:37 PM.
    2009 SR 50 Factory
    Malossi 70cc BBK
    Malossi HPC Crankshaft
    Stage6 Waterpump Impeller
    Arrow Extreme Pipe
    Malossi VL 13
    Ecu De-restricted 2.8.0
    7 Gram Dr. Pulley Sliders
    Stage6 Soft Contra Spring
    Water Trap
    RS 24/10
    Stage6 260mm Front Brake
    Stage6 Torque Control MKII 107mm
    Stage6 R/T Clutch Bell 460g
    Malossi Special Belt
    Malossi E5 Air Filter
    Stock Gears Installed

  9. #9
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    Thanks, again.

    Piston doesn't look so bad in reality but obviously can only see part of surface through exhaust port. I agree that it looks a bit carboned-up and generally not very clean in there. The colour also ooks like it's been pretty hot which clearly isn't good. A local shop is going to quote for a standard piston/cylinder kit, if it's pricey which it might be I guess I'll look at aftermarket or a 70cc. Seem to be struggling to find parts here in WA, many suppliers seem to be in the UK which is where I've just come from!

    The darker pic of the plug is a fairly good likeness of reality, it looks ok doesn't it, I was expecting worse.

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    oil pump marks look to line up with throttle closed. Don't have a rattle gun although I can probably borrow one sometime but for now variator can't come off and I can't assess crank seal... I'll run it for a little bit cleaned up then have the cover off again and see if if/where oil is appearing.

    Thank you

  10. #10
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    it looks like currently bad compression and oil choice. it says to use synthetic injector oil being allways red i believe.

    --
    you doing awesome so far. stick around....

    the oil seals maybe ok. if the crank can be yanked side to side by hand and thunks the crank main bearings are bad.

    ---
    pull the cylinder off please. remove the piston and check if the rod is dead straight with the cases center line. its much easier than it sounds. rotate the crank by hand and eyeball the top of the rod and the case halves.

    ---

    if those 2 things are ok your all set for an airsal 70 sport.
    --- diploma for engine repair in 2012 ---

    derbi bullet 2006 - piaggio AC - malossi T.C. half - custom GPS dash - TPR 70CC - topperf crank - vl13 reed and spacer- yamaha rt180 kickstand - giannelli shotV4 - phbg 21mm - doppler mesh top venturi filter

    complete wtp volta bmx 2012 - sanko seamless japanese cromoly heat treated and blue printed frame - 21lbs

    1992 lt250r suzuki quadracer - maier plastics -chromed shearer pipe - chromed works suspension - ++++++++ - 220lbs

    previous vehicles - subaru legacy turbo 1991 - mazda mx6 turbo 1990.

  11. #11
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    Ran it 20km and had the belt cover off again, all clean and dry in there still so hopefully crank seals are alright; there's oil very very slightly weeping from the pump inlet & outlet connectors between hose and union, which I think is why it was a bit of a mess. So all good there.

    I stuck a new exhaust on because the old one had had it, large bits had come loose and were rattling around inside than can, so it sounds nice now if nothing else!

    The shop here in Perth have quoted ~$250 (AUD) for a standard piston-cylinder kit, doesn't seem excessively expensive. Any thoughts on where I might source a decent 70cc kit as an alternative as you have both suggested, here or abroad?

    I'm very keen to have the cylinder off and see what's what, obviously not wanting to spend more money on a cylinder kit if the rod's bent and the engine's had it anyway. Can I disturb (i.e. remove and replace) the cylinder without replacing gaskets/seals/whatever's in there? As I'm using the thing for transport alongside sorting it out!

    Cheers.

  12. #12
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    its easy enough. the cylinder kit has everything you need except the copper exhaust gasket. cost half what the mech quoted.

    try a google for scooter parts australia and take advantage of the free shipping. post some links that look promising. maybe ebay too. post the links.

    good job so far. the leaky pump sounds like trouble. you can disconnect it and premix at home with blue synthetic oil. or replace it. people replace them alot. perhaps it just needs a new seal or something.

    ttyl
    --- diploma for engine repair in 2012 ---

    derbi bullet 2006 - piaggio AC - malossi T.C. half - custom GPS dash - TPR 70CC - topperf crank - vl13 reed and spacer- yamaha rt180 kickstand - giannelli shotV4 - phbg 21mm - doppler mesh top venturi filter

    complete wtp volta bmx 2012 - sanko seamless japanese cromoly heat treated and blue printed frame - 21lbs

    1992 lt250r suzuki quadracer - maier plastics -chromed shearer pipe - chromed works suspension - ++++++++ - 220lbs

    previous vehicles - subaru legacy turbo 1991 - mazda mx6 turbo 1990.

  13. #13
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    So the bike seems to be running a good bit better with the replacement exhaust.

    The shop who supplied the ehaust included a Dell'Orto 56 jet which they suggested I fit. Haven't done so as yet, but obviously I'm concerned that I risk running it lean and getting it hot.

    With existing jet the plug looks like this - what do you guys think? This is after a 140km ride yesterday, very little stationary, mostly at 50-65km/h, only short periods of full throttle.
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    Is it ok or do I need more fuel?

  14. #14
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    yes it looks good.
    --- diploma for engine repair in 2012 ---

    derbi bullet 2006 - piaggio AC - malossi T.C. half - custom GPS dash - TPR 70CC - topperf crank - vl13 reed and spacer- yamaha rt180 kickstand - giannelli shotV4 - phbg 21mm - doppler mesh top venturi filter

    complete wtp volta bmx 2012 - sanko seamless japanese cromoly heat treated and blue printed frame - 21lbs

    1992 lt250r suzuki quadracer - maier plastics -chromed shearer pipe - chromed works suspension - ++++++++ - 220lbs

    previous vehicles - subaru legacy turbo 1991 - mazda mx6 turbo 1990.

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