Yamaha 1981 LB50 PH Chappy resurrection

Discussion in 'Japanese Mini's' started by twosmoke, Apr 28, 2015.

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  1. Apr 28, 2015 #1

    twosmoke

    twosmoke

    twosmoke

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    Hi Riders, I am new to the club, and found the site by chance surfin the boards for some knowledge about my lil project. I am the not-so-lucky owner of an 81 Yamaha lb50 chappy. some1 had given be this scooter awhile ago and finally got a chance to get the lil ol girl running for my trips to Fenway Park where I manage a pizza shop, (yeah, I'm from Boston, USA). Well I got a few questions for all you experts out there and I hope you guys can help me out, Well here goes, I took the fuel & oil tank off and douched em out as well as the carb. Had to get a new kick starter all the way from Thailand! it's got a nice,fat spark and great compression. well, got it runnin yesterday, it smokes a lot, only runs w/the choke closed and dies when I open it up to full-throttle and dies immediately when I open the choke! I don't know what the carb setting should be nor do I know which screw is which. I think the carb is a small mikuni. also not sure what the needle clip position on the main jet should be either, it's set @ the 2nd from the top, is this correct? It seems like it's flooding out, does this sound right? I also have a leaky fuel pet****, took that apart too, cleaned it ,put it back together and it still leaks! any ideas/fixes? any and all help would be greatly appreciated! thanks guys!---------------twosmoke
     
  2. Apr 29, 2015 #2

    my67xr

    my67xr

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    Welcome to Minirider's

    Drop in an Introduce Yourself here too


    If you search Ebay (worldwide) you should be able to find a fuel tap seal easy enough, otherwise any Yamaha dealer will be able to get one in for you.
    I have seen complete new fuel tap's on Ebay Taiwan for around $20 too.
    Here's the Yamaha dealers' part's list for them- 1980 LB50PG Yamaha Motorcycle Parts


    With the carby/running problem, have a look at this page 1980 LB50PG Yamaha Motorcycle CARBURETOR LB50PG - PH - PJ Diagram and Parts
    It show's the main jet (#3), pilot jet (#4), and emulsion tube (#2)
    Make sure that the hole's through each of them are all clear/open
    Poke a thin strand of copper wire through the hole's to make sure there's no gum/varnish built up in them.
    Also on the emulsion tube, make sure it's clean inside, and all the small hole's across the jet are open too, and where the emulsion jet sit's in the base of the carby.
    While the pilot jet is out, look into the base of the carby where it screws into.
    You should be able to see light though into the main bore of the carby, through the tiny hole at the bottom of the threads
    The needle clip is usually on the middle (3rd) slot down
    And the mixture screw (#14 in the boats.net link above) should be around 1.5 to 2 full turn's out.
    Have you checked and cleaned the air filter ?
    A blocked filter can make it run overly rich

    Smoking lot's can be from sitting around for a while.
    The fuel evaporate's and leave's the oil sitting in the bottom of the crank case etc
    The oil pump's can also weep oil into the carby, which make's it's way into the crank cases too.

    Have a look at my Chappy thread too, it might give you some idea's
    The link for that thread is down below in my signature ↓

    Cheer's Craig
     
  3. Apr 29, 2015 #3

    twosmoke

    twosmoke

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    Thanks craig, I had that carb apart, douched it from head to toe, its squeaky clean, the clip was set in the 2nd groove from the top, prob the wrong setting tho, i'll change it, but b4 I do, gotta str8ten out that fuel leak, I saw some on ebay, but I can't justify spendin 15-20 $ on a piece of rubber the size of a dime! I have no idea what the carb mix screw is set @, it's almost impossible to get a screwdriver in there! exactly what screw is the mix screw? there are 2 of em side by side! If it was a good ol American small block chevy, I wouldn't be typing this right now, hahaha, yeah, I was thinking that the smoking prob was due to the fact that I sprayed bout a gallon of marvel mystery oil in2 the cylinder to make sure everything was moving, bad idea, hahaha but I'm sure' in time, we'll have this all figured out, Thanks again---------twosmoke
     
  4. Apr 29, 2015 #4

    my67xr

    my67xr

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    The mixture screw is the one to the left of centre.
    The central one is the idle speed screw
     
  5. Apr 29, 2015 #5

    twosmoke

    twosmoke

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    Thanks again, thanks for the instant response! that xplains it, I was turnin the other screw! DUH! I will chk the RIGHT screw this time and adj it accordingly. as for the air filter, I couldn't find a direct replacement, so I Mcgyvered a dyi element outta a piece of foam, ty-rapped it to the cage and oiled it w/k&n filter oil. could this be the cause of it draggin in too much fuel, still don't xplain why it doesn't run w/the choke open tho. 1 way or another , I'm gonna have this runnin like a digital watch. I was also thinkin of upgrading to a polini big bore kit for an additional punch and possibly that ghiradelli pipe for the xhaust, really don't wanna get run off the road by those idiot boston drivers on the way to Fenway, know what I mean ? -------twosmoke
     
  6. Apr 29, 2015 #6

    my67xr

    my67xr

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    The 50cc Chappy carby look's the same as the one on my '75 model 80cc.
    Mine had been sitting for a few year's before i got it.
    Iirc i ended up having to rejet it to suit.

    With it not running with the choke open, there might be a blockage in the pilot circuit somewhere?
    Pull the carby down again and blow some compressed air in through the 2 or 3 small port's on the filter side of the carby.
    You should be able to feel air coming out the pilot jet hole in the base of the carby.
    Also take out the mixture screw when blowing it out, the blockage might be restricting the amount of fuel the pilot can get.

    The standard air filter are about $12 new for genuine one's.

    When you oiled your filter, try and squeeze a bit of oil out into a paper towel, they reckon you can't take too much out.
    Just leave enough to leave a bit of oil on your finger's when you press it in.

    Yeah there's a few hot up's for them.
    The Malossi 7 port alloy/Nikasil 70cc 44.5mm cylinder kit looks nice, but it's $230
    The Polini kit is only $169
    treatshq treatland.tv moped puch superstore discount parts for the people!
    And those o'ringed high comp cylinder head's look sweet too, can't go wrong for $37
    Gianelli Race pipe $169 yamaha chappy giannelli performance exhaust pipe

    [​IMG]

    [​IMG]

    [​IMG]



    I see Polini also do a big bore intake manifold for them too now, 19mm
    I think my Chappy one is about 15mm.

    Carby wise, you should be able to fit a bigger one there under the cover,
    i bought a Mikuni off a Suzuki 70cc scooter for my sons' PW50 it fit's straight on with out any mod's (The PW50 run's the same size o/d intake manifold as the Chappy)
    That little bike fly's at WOT now
     
    Last edited: Apr 29, 2015
  7. Apr 30, 2015 #7

    twosmoke

    twosmoke

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    Hi my67xr, Thank You for the Yamaha parts link, it was very helpful, they have some chappy parts in stock, & some are unavailable, don't know if that means Yamaha stopped producing em, or they just can't get em, but I'd much rather get a genuine Yamaha part than a cheap pos from Thailand that takes 3 wks to get here w/the shipping cost far exceeding the part price and no where near the quality & workmanship of the real McCoy! ya know what I mean? I just picked up a kick starter from there, cost 10$, shipped for 15, & the rubber is torn to s#@t after less than 50 kicks! Well enuf of that, I also have a carb off an old mx80, diff manufacturer, looks like it mite fit, same config, only prob is , I don't know if the reeds/manifold will fit tho. If I can't get the stocker tuned & runnin rite, I mite try & finagle something. do ya know offhand if it will fit w/minimal mods? Oh BTW, that rubber valve that fits under the fuel selector switch that I need, that Yamaha parts dealer has it! whuddya know? They have some of the other parts I need too! Thanks again buddy,-------twosmoke
     
  8. Apr 30, 2015 #8

    my67xr

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    Some of the part's that are now obsolete, if you copy down the part number's off the Yamaha site, and do a search on ebay, there are a few people still selling them.
    The last 2x 00 in the part number are foe American model's, so taking them off can also bring up a few more result's
    Also removing the - from the part number's and leaving a space can help find more part's too

    A brand new genuine Yamaha kick start rubber is $3.99 - $6.29 off eba, postage's vary too
    Yamaha Kick Lever Cover Fits Many Models | eBay
    Yamaha DT BW MX PW SR Genuine 156 15618 01 Kick Start Starter Rubber 27 009 | eBay
    156-15618-01 | eBay


    I would have though the MX80 carb would be flange mount ?
    I reckon you might have found a GT80 Carb ? they are a clamp on style like the Chappy, PW50 PW80 etc

    The PW80 carb would fit too, but would need rejetting, also the mixture screw and idle speed screw's will be on the wrong side
    The Suzuki scooter i got the carby for my PW50 off is an older FR70, 2 stroke, and uses a cable choke
     
  9. May 1, 2015 #9

    twosmoke

    twosmoke

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    Hi again 67, Just ordered up a bunch of parts from boats.net, they'll be here Monday. Hey, I got another question for ya, I am debating putting on that mx80 carb, 2 probs, 1-the plastic bushing that goes into the carb bore is too small to fit over the manifold and 2- the 80 carb doesn't have a cable operated choke, which means I would have to carve up my beautiful, newly painted plastic carb cover that goes in the middle of the frame! do ya have a clue as to what I should do bout that plastic spacer? or do I hafta use the stock carb? It's too bad, cuz the 80 carb has a wayyy bigger bore! or would it matter much w/that big bore kit and pipe? sorry for all these stupid questions, but you've helped me out a lot already! Thanks,-------twosmoke
     
  10. May 1, 2015 #10

    my67xr

    my67xr

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    Have you tried swapping the plastic sleeve from the 50 carb over into the 80 carb ?

    Also have you seen this carby ?
    It's off a PW80, they have the same size plastic bush and also have a cable choke.
    Only thing is the idle speed screw and the mixture screw's are on the opposite side, shouldn't be a problem though
    They've sold a lot of them- Carburetor Yamaha PW80 Y Zinger Carb | eBay


    The bigger carby will give it a better top end with the big bore kit, but you might be able to just rejet the 50 carb too if you can get it running better first
     
  11. May 1, 2015 #11

    twosmoke

    twosmoke

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    Hi 67, Yeah, I tried to fit the old bushing, but it doesn't fit in the carb bore, so I sanded down the O/D of the stock bush and made it fit both the carb and the manifold, finally got it to fit tight, I hope I don't have an air leak between the carb and the manifold, as there is a slot in the bush, or its back to the stock carb, but prob gonna have a problem cuz I made the O/D too small to fit it! I also had to modify the throttle cable fittings cuz it needed an an angle on it to clear that cover, got it all str8tend out, but I'm still gonna hafta cut a slot in it to get to the choke lever, but it's nbd. Thanks again, buddy--------twosmoke
     
  12. May 2, 2015 #12

    my67xr

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  13. May 2, 2015 #13

    twosmoke

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    Hi 67, Yeah, I will as soon as I can figure out how to do it, I'll check out that link, or maybe I'll connect my phone directly to the laptop to upload em, Thanks, ------twosmoke
     
  14. May 4, 2015 #14

    ringo

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    Wow, I never realised Chappy's were two stroke, must pay more attention in future!! :egg:

    I like them a little more now!!!
     
  15. May 4, 2015 #15

    twosmoke

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    Hi Ringo, Yesssss, they are 2 strokes! But I ain't gonna be racin mine! It's just for short trips to Fenway Park where I work at a pizza shop. I just got it runnin bout a week ago and my67xr has been holdin my hand the whole time, hahaha, thanks 67. If all goes well, think im gonna go for that polini big bore kit and that gianelli pipe to round it out to 74cc. I already put a carb from an old mx 80 on it, which has a bigger bore, I think it has a 16mm bore, and the old mikuni is wayyy smaller, but I ain't sure of the make tho, but I gotta find out if I have to re-jet, I want to get up to @least 45-50 mph to get outta the way of these moron boston drivers! shoot me some carb info if ya know any offhand? Thanks Ringo, ------twosmoke
     
  16. May 7, 2015 #16

    twosmoke

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    Hi All, Just a quick question for all of you electrical geniuses out there. Like I was telling my67xr, I recently got the chappy running, ok, sort of running, more like a smoke show! but running! I was debating buying a new battery, but when it was runnin, the taillite came on(the headlite was disconnected) If the lites come on, then what's the battery for? I doesn't have an electric starter, does it? Plz help, I'm stumped! ------twosmoke
     
  17. May 7, 2015 #17

    my67xr

    my67xr

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    There's 2x position's for the ignition key.
    First positition it will start and run, second position is the same but with the headlight's on
    For the headlight not being on, it would have a blown bulb, if not the bulb then a bad earth.
    It uses a 15W/15W 6v P15D MPF 6V (AC) bulb in them standard
    I prefer to use a brighter one, as it help's the bulb not to blow if you are doing higher speed's/rpm's all the time
    I use either a 25W/25W P15D MPF 6V, or a 35W/35W P15D MPF 6V
    You could also use a Halogen equivalent bulb too, they're about 20% brighter than an incandescant bulb.


    The head lamp and tail lamp run directly off the lighting/charging coil on the stator
    The battery, brake light, horn and indicators also run's off the lighting/charging coil, but through a rectifier to convert the voltage to DC
    So if your battery is dead, running the bike with the light's on will put a high load on the lighting/charging coil and could make that prematurely fail.
     
  18. May 8, 2015 #18

    twosmoke

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    Thanks 67, Well, the bike didn't have a key when it was given to me so I had to break the ign switch to get a spark, gonna pick up a new aftermarket switch off ebay. Funny thing bout those switches, they all have 5 wires and the scooter's switch has 4 in a plug, what's up w/that? The reason the headlite didn't come on is cuz it was outta the bucket, had to take it out cuz I was painting the blinkers. The scooter did come w/a battery, but it had all dried up from sitting for god knows how long, so I tossed it, I'll prob go to a bike shop and pick up a fully charged 1 so the chargin system don't hafta work too hard. The headlite is good cuz I can see the filaments,so I don't think it needs replacing, but if it ever does, mite try to get an led bulb if they make em, ya know? Well thanks for the info, my67xr ------twosmoke
     
  19. May 9, 2015 #19

    twosmoke

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    Hi All, Well, I just got the scoot runnin today w/the new carb, well, wouldn't ya know, it fired up 1st kick! but I have another question, the blinkers don't work, but the headlite does, Do I need a battery for them to operate? I'm pretty sure I wired em rite when I reinstalled em, I marked the wires. would a bad flasher cause em not to work? IDK, wiring isn't my strongest suit! So if any of you electricians out there can help me out here, it would be greatly appreciated, Thanks-------twosmoke
     
  20. May 9, 2015 #20

    my67xr

    my67xr

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    The brake light, horn and indicators run's off the battery
     

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