Engine Trouble 47cc Tanaka stalls

Discussion in '2-Stroke Engines' started by locksmith, Sep 3, 2013.

  1. locksmith

    locksmith Member

    i need help tuning my tanaka 47cc motor. it was acting weird... it would start if you're pulling the throttle, but die as soon as you let go.

    so i tuned it according to the recommendations. H needle 3/4 open, L needle 1 and 1/4 turns open, but the same problem. I moved the L to 1 and 1/2 turns open

    the engine does seem to flood easily, so if i had to guess, i'd say i'm running it too rich. but i don't want to break it by running lean

    i've never tuned a 2 stroke before, so i don't want to mess it up. please tell me what i should do.

    the spark plug is fine.

    ps... when i first got it, it ran great. lots of power, but i think it's just out of tune. the guy i bought it from had it tuned before the summer, then it just sat all summer


  2. HeadSmess

    HeadSmess Well-Known Member

    and there you are. probably with out draining the tank or making sure the engine had been idled until the carb was completely DRY.

    split carb, clean, check for holes tears in diaphgrams, reassemble, run.

    my fave way is to open the hi and lo an extra 1/2.

    set idle a bit high, let it warm up.

    full throttle! if it has a wheel and stuff attached, give it some brake so its dragging. then turn hi in until it peaks, and back out again, just a touch.

    idle. lower idle speed some. start turnin in lo needle.

    idle gets higher. find the peak, and back off a 1/4 turn.

    try throttle. if it coughs, open lo a bit.

    if its stopped peaking at full throttle, touch the hi again.

    back to idle, and then its sort of a lil fiddling between nice crisp acceleration from idle to full throttle, and finally set the idle screw back to a nice low idle.

    if it starts coughing when accelerating, again...just nudge the low out a lil. you may have to set the idle a bit higher again...

    if it takes a long time to settle down to a steady idle, the lo is too RICH. or if it tends to sit and finally splutter out and die in a cloud of unburnt oil and fuel vapor.

    only difference with tuning if it doesnt have any load...ie, a chainsaw... is instead of "peaking" the hi end... you just want to be on the edge of where it STOPS 4 stroking at full throttle.(pwo-o-o-o-o compared to neeeeeeeeeeee) dont let it peak out or it may blow! then adjust slightly when in use to get it perfect.
    locksmith likes this.
  3. 5-7HEAVEN

    5-7HEAVEN Active Member

    I run a Tanaka 47R engine on my bike. It runs flawlessly, unless the oil/fuel ratio is off.
    No need to rebuild carb. Simply drain the old gas and refill with 50:1 mixture.
    If you want to spend $$, install a Champion/NGK/Motorcraft sparkplug,
    an SBP petcock and clean the air cleaner element.
    locksmith likes this.
  4. locksmith

    locksmith Member

    Thank you all for your help! I appreciate the tuning advice as it's never been clear to me

    5-7, do you like your 47 tanaka? do you ever adjust the hi/lo on yours?

    I gotta say when it was running, the 47 was amazing! it's got a ton of torque and feels stronger than my 40cc tanaka
  5. 5-7HEAVEN

    5-7HEAVEN Active Member

    I absolutely love my 47R. It is very reliable and powerful.
    Yes, I've adjusted the carb a few times.Usually I do this when I screw up the oil/fuel mix.
    The 47 muffler is very loud. However, with the right pipe, noise leve drops greatly.
    I use the 3-piece Tanaka-specific pipe. They're out of production, so hard to find.
    The 47 has enough torque to push you off the seat from a standing start,
    if you're not hanging on tightly.
  6. locksmith

    locksmith Member

    Good to hear, the motor is a beast. I absolutely love my 40cc. Does the 47cc go out of tune easily? Will it work fine one day then not be able to go up hills the next or is it consistent? Do you adjust it by much, or just small turns?

    The reason I'm paranoid about tuning is cause I have a goped cruiser http://www.amazon.com/Go-Ped-Cruiser-Powered-Scooter-Black/dp/B000VM3A7W with a 29cc chinese motor and the motor sucks... it goes out of tune easily and always needs service and adjustment... It's no where as reliable as the tanaka. the 40cc is my commute bike!

    I have the tc-4700, not the r, but i found this manual helpful cause it's got the 47cc coverage
    http://www.tanakapowerequipment.com/PDF/All/TBC-500 TBC-550_DX TBC-600_OM.pdf
  7. 5-7HEAVEN

    5-7HEAVEN Active Member

    Unsure if we have the same carb. With mine, it's set it and forget it.
    Methinks the quality of gas AND the fuel/oil mix (human error, my fault) throws the tune off every few months.
    ALWAYS use fresh gas. When that happens, I adjust the carb.
    As you keep adding the correct mix, the engine would then need to be reset to the exact factory recommendations.
    Spark plug color is light chocolate with expansion pipe. I change the plug about once a year, no matter if it needs to or not.
    Clean the screen annually too. It's a great engine, very dependable. The only thing that wore out was the pullstart.
  8. locksmith

    locksmith Member

    Thanks, good to hear. my 40cc is the same way, it never gives me ****, knock on wood. i like the fat pull start on 47. the 40 has a smaller one

    looking forward to getting it back from the shop
  9. 5-7HEAVEN

    5-7HEAVEN Active Member

    What's it in the shop for?
  10. locksmith

    locksmith Member

    i took it in last week for the guy to look at the motor. it was stalling. it's ready today
  11. locksmith

    locksmith Member

    ok, i went to the shop yesterday to pick it up and started it only to find the exact same problem... it stalls.

    he ran carb cleaner through it and adjusted the jets. then his son came out and told me he's gonna have to put a new carb on. i'll see what happens... looks like headsmess was right

    the next part is a bit strange... he's a small engine mechanic (mostly mowers) and told me he hates weed-eater engines because he always has trouble with them. he said tanaka is junk and they sell them for a lot more than they are worth... as an "insider" he can get one for like $100 bucks. he said it'd run a lot better with a chainsaw motor attached... frankly, i think he's crazy. i've had 7 stand up scooters and one bike and they've all been great

    the one thing i did notice is that the tunable carbs are a huge pain in the ass. my 35cc tanaka always started and ran well as does my 40cc purefire...

    so yeah, what do you think?
  12. 5-7HEAVEN

    5-7HEAVEN Active Member

    I used to have a starting problem with my Tanaka. My arm would hurt yanking that pullstart.
    Now it starts fine after a few pulls and a warm up. Why would you need a new carb? Just rebuild it, if you must.
    You DO have a fuel filter, correct? Are you using the OEM saddle tank alone?
    On my brand new Mitsubishi TLE43 engine, the engine would stall after a mile.
    Thank goodness I had a SECOND engine on the front, so I "hobbled" home on one engine, lol.
    Problem was the tank not venting. When I loosened the gas cap, engine started up and ran fine.....as long as the cap was loose.
    So I put a toothpick in the tank's fuel line grommet, next to the fuel line.
    After 50 miles running, all the gaskets and grommets loosened up. I removed the toothpick and the engine ran fine ever since.
    Does it stall as you tip into the throttle, or cruising at speed? Did you try raising the idle?
    Did you clean out the muffler? When it stalls, does the engine start right back up?
    I liked the no-hassle nonadjustable carb on my Mits engine.
    However, I like the tunable carbs, especially if you screw up the fuel/oil mix.
    Yeah, Tanakas are junk. That's why I keep running them. (sarcasm)
  13. HeadSmess

    HeadSmess Well-Known Member

    if a petrol engine is left for any length of time, ie over a season, ensure there is no fuel left in the system or it dries out and gums everything up.

    that is ALL petrol engines.

    across 90% of small twostrokes i work on, i invariably smell rotten fuel in the tank/lines/or carb as i dismantle it.

    90% of these are running engines after a simple strip and clean.

    the other 11% require more serious work to get running, some just being scrap metal. the blocked vent on the fuel tank and perished fuel lines comes close second and third place for usual problems.

    loss of chrome plating, from straight fuel is pretty common. they start and run for a few minutes then wont start till cool again. ad nauseum.

    strip and clean the carb yourself. 4 to 8 screws and compressed air... it sure sounds like the shop you go to doesnt know what theyre doing. id hate to think what they do if they come across an early slide walbro... or the LPG carbs used on some of the lil 4strokes...

    thing with adjustable carbs is you can adjust them. theres a reason the guys that compete replace the new unadjustable carbs for dual needles...

    the best small engines to use? the same ones that you see commercial lawnmowers and landscapers using...Honda, Kawasaki, Shindaiwa...

    the worst engines to use? take a trip to the scrap yard one day :) though they also hold to that 90% rule...most are just gummed up carbs owned by people that know no better, and its cheaper to buy another ryobi than fix it...

    where else can you buy 50 walbro carbs for 30 dollars?
    Last edited: Sep 14, 2013
  14. locksmith

    locksmith Member

    i just spoke to the shop today... he told me it's not even starting. i dunno if he broke it or what, but he told me he was soaking the carb, and he may have to buy a new one if i want which would be 100$...

    i'm really starting to question their competence

    I will check the fuel tank and try the toothpick trick... The problem was it would start, rev, and then die upon returning to idle

    It does start back up (or did, i dunno what state it's in now)

    that's what the previous owner (retard) did. :(

    would this be any good?


    thank you both for your support


    also, my biggest fear at this point is these jerks have just run the poor thing to death troubleshooting and broken it

    they make everything sound like it's a shot in the dark.
  15. HeadSmess

    HeadSmess Well-Known Member

    zippy zippy zippy this is just my post to make the post long enough to post :jester:

    and, lol! as an "outsider" i can get a honda 25 for a grand total of $100... heh heh heh :) aussie dollars, tooooooo
  16. locksmith

    locksmith Member

    got it back today... they didn't charge me, and he told me its 90% chance that the carb is broken.

    he told me the two jets (for lack of better term) that suck the fuel in and spit it back into the tank are broken and not doing their job.

    any ideas?

    i'm prepared to work on this myself and will take it off for pics or whatever if necessary.


    here is the exact carb: http://www.ebay.com/itm/Original-Wa...851?pt=LH_DefaultDomain_0&hash=item5ae8bb362b

    i'm gonna see if i can find one that's the same size... it's basically just a large chainsaw carb

    possible similarity:

  17. 5-7HEAVEN

    5-7HEAVEN Active Member

    Glad you got it back w/no charge.
    You need to fix it yourself. Like heads said, the carb has few moving parts.
    "Jets" are not broken. Maybe the diaphragm which sucks fuel is ripped.
    You have absolutely nothing to lose by disassembling the carb and inspecting it.
    FWIW, the walbro carb on my CY460 engine had a return port on the carb.
    Instead of installing a return line to the tank, I just pluggedf the return line.
    Engine ran fine with plugged return port.
  18. HeadSmess

    HeadSmess Well-Known Member

    return line can be blocked or not. if it has a primer, leave it unblocked or you wont prime too easy. just um...be aware it will squirt fuel everywhere when primed :) back in the day i fitted a 1oz rc fuel tank as a lil baby priming tank just for this reason. one line to tank only, at other end of bike... that brushcutter fuel line is freakin expensive stuff!

    normally, being me...id just let it squirt :jester:

    it wont squirt when running. that is fine :)

    your ebay link.

    middle row, left hand side. that lil black thing is the valve diaphgram. those two lil flaps line up with holes drilled in carb body. plain simple reed valves. one in one out.

    you pull apart your carb, you should see all those pieces.

    be careful of the gaskets unless you really do want to buy that rebuild kit ;)

    but. basically. note which way its assembled and it should go back no probs.

    check everything for holes or tears. CLEAN THORUGHLY WITH COMPRESSED AIR.

    very rare for the pump to give trouble.

    if its acting up, like these morons are saying...once again, check the pulse feed for the pump FIRST!

    just unscrew the carb and see!

    cus if its blocked... simple fix.

    i wont repeat where it is ;)
  19. HeadSmess

    HeadSmess Well-Known Member

    close, but COMPLETLEY DIFFERENT. that strange oval vent on top looks suspiciously like some sort of strange pulse feed.


    and that first one, all i get is a walbro symbol, no pic.

    what you want is something that looks like this...


    but not this exact one!

    you want a bigger bore one, as fitted to a 50cc polesaw or similar...wlabro has heaps of lists of carbs ;)
  20. locksmith

    locksmith Member

    ok... today i took of the carb and it was a lot of fun. it's really cool to see how this stuff works. i found this guide that helped me too


    i took a lotta pictures hoping you guys can see something i can't or think of ideas... below i will illustrate what i did and with detailed pictures. oh, and the problem is that the engine suffocates... it's either not getting enough fuel or air and the return jets don't work

    walbro hda-97

    1. first i took it apart
    ^this is the diaphragm in question

    2. i used compressed air to blast nearly every hole out
    ^this part is the one with the jets in question... i'm really not sure what the deal is but i blew compressed air into every hole (that sounds weird lol). it's not like blowing through a straw. i dunno how big the holes are or how much air is going through, but blowing into them was like drinking through a coffee straw but even more restricted

    3. could the membrane below be blocking anything?


    so this is my guess.... please tell me what you think. thanks again.