1. turbofiat124

    turbofiat124 Premium Member Forum Donor

    My co-worker is into 4 wheelers. We are going to fix his Yamaha Bruin 350 whenever he decides to bring it over to my house. Something about the brake caliper holes won't line up in the holes in the control arm. And probably give the carb a good cleaning since it's been sitting. Cleaning carbs is hit or miss. I've taken about 20 carbs apart on just about everything and it either works or it doesn't.

    So he gives me this Bravo 110cc ATV in trade. It's got a busted rear shock so I have it tethered with a bungee cord to keep it from coming loose. The bolt holding the rear swing arm was broken. I couldn't find a 1/2X12" bolt so I had to cut down some 1/2" threaded rod and use two nylon lock nuts and washers.

    The battery is from the fire alarm system at work. They swapped them out the other day so I grabbed the old ones before they went into the recycling bin.

    The carburator was awful. The insides had turned green! I had to sand blast the funk off the bottom of the fuel bowl and the brass pieces. The jets I could not get cleaned by ordinary means. So I had to heat them with a propane torch. This black stuff started oozing out.

    So I got it running but after it cools down it doesn't act like it wants to start. So I pulled the spark plug and it's carbon fouled. I bead blasted it and now it starts.

    No amount of adjustment on the idle mixture screw or speed screw has any effect!

    Luckily new carbs are only $14.

    Last edited: Mar 4, 2017
  2. kev the builder

    kev the builder Loyal Comrade

    You could try leaving the stripped carb and parts in vinegar overnight this usually removes old crud and only costs pennies a quick blast of compressed air down the drillings usually sorts them,you can tell I'm a tight northerner
  3. turbofiat124

    turbofiat124 Premium Member Forum Donor

    I meant to add more to this post but had to go unload some skids (I'm at work).

    I think this ATV is a copy of a Honda. Either they made an illegal copy of it or they bought they tooling from Honda when they were done with it. I've got an AC generator that has what is known as a Chonda engine. Which is a Chinese copy of the widely produced Honda 5.5hp side shaft engine.

    It seems the Chinese have perfected the art of reverse engineering but when it comes to actually building what they copy, they cheapen the hell out of it. I'm surprised their own missiles and bullets don't blow up in their damn faces.

    My friend gave me this thing because he said he was tired of messing with it due to it's poor build quality. I've got a blue pocket bike and the build quality on that thing is horrible. The Chinese do not know how to add lock washers or Lock-tite on anything. Two of the three bolts that holds the recoil starter to the engine fell out. So when I yanked on the starter, the remaining bolt pulled the tab off the engine block! What's ignorant is the starter is plastic. I've never seen plastic that was stronger than aluminium! Luckily it being porous I was able to apply some 2 part epoxy and so far it has held up!

    This carburetor baffles me. I'm guessing it's also a copy of either a Keihin or Mukini. It actually has Japan stamped on the throttle neck but could just be the name of the factory or mean absolutely nothing. There was some urban legend ages ago the Taiwanese built a plant called "USA" to make it appear their products were made in the "U.S.A". Like those MEMEX cassette tapes and Sharpei markers.


    It's similar to my Dellorto on my Tomos TX-50. On that carburetor there is no idle mixture screw but the bike runs fine.

    When I pulled the idle mixture and speed screws out of this ATV carburetor, instead of them being tapered like a typically needle valve, both look like dummy plugs. The end on one is like a ball. What's weird is I can remove the idle mixture screw completely and it has no effect whatsoever. By all accounts the engine should lean out and stall.

    I'm also not 100% sure if what I am seeing is un-burned fuel or burnt oil. The oil level is not changing but the smoke looks blue to me. On the first day I got this thing running it was 61F. In typical Southeastern US weather fashion, the next day the temperature was 34F. On the 61F day (the day the video was taken) I did not see any smoke but the next day I did. I don't think it was condensation I was seeing because it never went away after an hour of riding. My friend says this thing probably has less than 20 hours on it. One guess could be a stuck ring from where it has sat for so many years. Maybe I need to pull the intake manifold and fill the cylinder and crankcase full of PB Blaster and let it sit over night.

    The second day I tried to start it but it wouldn't start so I pulled the spark plug and it looked carbon fouled to me. After I bead blasted it, it fired up. My guess is as long as the engine is hot, the plug will fire but not when cold?

    I tried starting it this morning before leaving for work (~25F) and it tried to start once but couldn't get it going.

    I can't figure out why removing the idle mixture screw has no effect and if the engine is running too rich, why. Unless it has something to do with the float level.

    I just got to verify the distance between the mounting holes is 48 mm and the venturi is 19mm before ordering a new one. At $14 + free shipping from a US supplier, it's almost not worth messing with.
    Last edited: Feb 11, 2017
  4. kev the builder

    kev the builder Loyal Comrade

    The quality of the Chinese made bikes and quads /4 wheelers seems to range from ok to dire most seem to border on dire you can take a m6 bolt out but it won't ago back in as the hole will be more like m5.5 I've had quite a few pit bikes and quads they're cheap to buy but come with problems usually from poor build quality and carb problems the float level is often to blame but finding the right heights not easy as there's little info on them,lots of engines/carbs don't have names on them most smaller cc ones are Honda 90 copies the larger Honda cb125/200 copies the internals are different and differ from one make to another,have you checked the valve clearances?this can make a big difference
  5. turbofiat124

    turbofiat124 Premium Member Forum Donor

    I have not checked the valve clearance or the float level. I haven't found a really good shop manual on this thing yet. I don't even know who made it!

    Another baffling thing is when you buy a replacement carburetor for these things, it usually fits anything from a 50 to 150 cc engine. I find it hard to believe the same carburetor would fit different displacement engines without needing re-jetting.

    When I went from a 1100cc engine to a 1500cc engine on my Yugo, I used the same 28/28 Weber carburetor. I increased the secondary main to compensate for the turbo but didn't think rejetting the primary main was a concern.

    When the temperature was in the 90s, the car run fine but below 60F, it would start to chug and go on under cruise. In freezing weather it would backfire. All because of a lean condition. I guess the colder air was denser so the problem didn't crop up until the temperature started to drop.

    I stepped up from a 100 to a 125 main primary jet and now the car runs fine below freezing.
  6. kev the builder

    kev the builder Loyal Comrade

    the one size fits all approach to carbs seems to be common on chinese bikes they may run but theres no way will it be close to correct thats why i try to use the opriginal if poss,non standerd engines realy need setting up on a rolling road i spent years doing plug chops and seat of the pants tuning, its expensive on the rolling road but gets good quick results without damaging the engine,but you need a good operator,in freezing or near freezing weather carbed engines with sports style air filters ice up,the moisture in the cold air freezes in the venturi like a golf ball causing the engine to slow down a bit like running out of fuel but still ticks over,the answer is to stop the engine and put your foot on the throttle for 4/5 mins this lets the warm air in the engine melt the ice,is this like what you get?
  7. turbofiat124

    turbofiat124 Premium Member Forum Donor

    Carb icing with the Yugo? No it seems the jetting was the problem all along. I don't think this car will never experience carb icing because turbo pre-heats the air. Even when it's not spooled up.

    My 81 Prelude would freeze up in the winter and my dad's Ford Bronco II would do the same thing. Both would do it when there was melting snow on the ground. Just slightly above freezing and real foggy. It never seems to happen when it's well below freezing and no snow on the ground. I guess because the air is too dry. It seems the temperature it's most prone to happen is between 33F and 45F and the humidity above 30%.

    One time I Googled "carb icing" and the weird thing was I couldn't find any information on it related to automobiles. It was all related to airplanes!

    Yeah you'll be driving down the road and without realizing it, your having to press the accelerator down further to maintain 55 mph. Before you know it, the accelerator is to the floor and your top speed is down to 35 mph. Pull off to the side of the road and let it sit or idle for a few minutes and drive another 20 miles until it happens again.

    With the Prelude I was running one of those chrome open breathers. One day I was going to tech school when this happened. The funny thing was I made it almost 25 miles on the interstate at speeds above 65 mph before it iced over. Luckily by the time the carb pretty much iced over, I was about 1/4 mile from school doing a maximum of 10 mph full throttle! I put the original air cleaner back on and never had any more problems that winter. So I only ran the chrome breather in warm weather.

    My Father's Bronco II would also do this but with the factory air cleaner. I could not convince my father it had a problem. He drove it to work and couldn't get above 40 mph. But when I drove it to school a few times, it would ice over every time. Finally one day he went somewhere and got it above 55 mph for an extended period of time and it iced over on him!

    I used to think those heat risers were installed to prevent this but from my understanding they only divert hot air off the exhaust manifold until the engine warms up (like around 155 F). Maybe an emission thing to help the engine run better until it warms up.

    Once it reaches that temperature, it pulls in cold air. Once the heat up, they don't close back off until long after you shut the car off. I used to think they operated like a thermostat in the cooling system to maintain the incoming air temperature.
  8. kev the builder

    kev the builder Loyal Comrade

    Carb icing has disappeared from modern cars which use fuel injection,it's just us old car users who get it,if you don't wait long enough for it to fully melt it does it again,as you said it's not a problem when it's really cold as the air is drier in the UK it always seems to be damp unless it's raining,you could do worse than have a dyno session,it gives you an idea of how much power the engine actually makes
  9. Keri

    Keri Leader

    The Chinese will build anything you specify. Since most Americans seem to base their purchases entirely on price, you can expect truly awful quality and many missing parts for the low, low price demanded by Americans. Especially and particularly on stuff made for Wal-Mart.

    Remember that the Chinese also build extremely high quality goods for those that are willing to pay for them. Like most Apple products.

    Their missiles and infrastructure are also taken far more seriously, and are improving very rapidly. You won't find shortcuts or missing loctite on those!

    The carburetor will likely be a clone of a Keihin or Mikuni. Mixture screws do not have to be tapered to function. A ball end or blunted taper will work as well.

    Sounds like you missed something or damaged something in the carb. A more careful examination is called for, but a $14 replacement is less than the price of gaskets for many carburetors, and certainly less than the time and effort you've spent so far.
  10. kev the builder

    kev the builder Loyal Comrade

    heres my latest toy,this is why it took 3 months for me torebuild my trabi engine as while i was waiting for people to get back to me with prices/availability and working i built this,rode it to the mot station monday it was minus 2degrees c and white over it was bloody cold but nice to ride all i need is some warmer dry weather maybe about june then trabi exhaust 005.JPG
  11. turbofiat124

    turbofiat124 Premium Member Forum Donor

    Sweet! But you forgot to metion what it is! Looks kind of like a Tomos with a "Chopper" seat.

    Here's my Tomos TX-50:

    http://s222.photobucket.com/user/turbofiat/library/Tomos TX50?sort=6&page=1

    Once again an unwanted item I patched up and got running. I've had this thing for about 10 years. I think most of these were sold in the US, Canada and Eastern European countries. It uses the same A35 engine, transmission and brakes found on other Tomos mopeds.


    1) fuel system was packed full of rust from the fuel tank to the carburetor. In this case I was able to take the carburetor apart and clean it and it's been fine ever since. I tried patching the bottom of the fuel tank with fiberglass and it held for awhile but eventually had to buy another tank. I've heard E10 is bad about eating fiberglass tanks out of boats, that maybe why so I only run 100% pure gas in my 2 stroke stuff.
    2) All cables were seized
    3) Rear shock was worn out.
    4) Crankcase seal was worn causing engine to suck in automatic transmission fluid and smoke really bad.
    5) Rear fender was missing (they all are because they break easy)

    Modifications include:

    1) Handlebar risers made from water pipe, two tees and a union and longer bolts to clear my knees
    2) Local guy who deals with old BSAs, Triumphs made me a longer throttle cable. I made the brake cables from a bicycle brake cable kit.
    3) Heavier shock to support my 160 lbs @ss.
    4) Voltage regulator/rectifier for headlamp although I've never actually ridden this bike a night.

    I rigged up my cellphone to the handlebar to see how fast it would go. I thought it went 30 mph but at the top of my driveway my phone says I'm doing 17 mph. I would probably go faster on flat land. I guess when your on something this small it just feels like your going faster than you actually are.

    Loads of fun.

    My wife thinks I'm nuts for liking mini-bikes and go-karts. Well when I was a kid my parents wouldn't let me have one so I guess that's why I like them. Mom was afraid I'd get hurt on one and I think my father was just too cheap to buy me one! I told him, "Dad you had a BSA before I was born, why can't I have at least a mini-bike". Well you know how that goes. He says, "yeah I almost lost my leg on that thing".

    I did have a go-kart for awhile but sold it for an Atari 2600. Boy what a mistake. But I still have the Atari!
  12. turbofiat124

    turbofiat124 Premium Member Forum Donor

    Like I said, cleaning, rebuilding carburetors seem to be hit or miss. I'm starting to wonder if when I heated the jets with that propane torch and that black funk oozed out, it was lead solder and I inadvertently enlarged the jets. It wasn't shiny but sort of balled up like hot solder. Maybe these jets are filled with lead solder then drilled out after the fact. But kind of sounds like the float level maybe off. Trouble is, I have not been able to find any specs on what the correct float level is supposed to be. I ran into the same issue with my Trabant carburetor and it was float level related. It got 14 mpg and fouled the plugs.

    But with this carburetor, for $14, I'm not going to fool with it anymore.

    Before heading off to work, I pulled the spark plug and sure enough it was carbon fouled .

    Speaking of Chinese made crap. My parents have this old Microwave they bought in 1976 from Monkey Wards. I think they paid $700 for it. You could buy a descent used car for that price. I'm really surprised my dad let loose $700 for an appliance.

    I'm guessing it was made by Raytheon in the USA when they held the patent on it. That thing still works! Although it hasn't really been used in ages. It's in the kitchen upstairs. But I think it was used for at least 20 years before my parents "moved" downstairs. Point being, I've replaced about 3 or 4 microwaves in the past 15 years because they crap out. But they are cheap to replace! Just a hassle.

    I've got a deep freezer my grandparents bought in 1964 that still works.
  13. kev the builder

    kev the builder Loyal Comrade

    my bike a 1979 honda cx 500 i seem to like the older bikes ive just sold two newer bikes one was a 1993 and the other a 2012 far to new and the other far to fast for me,your tomos looks nothing like the ones we have in the uk they are step thros,some carbs have drillings capped off with lead/solder you may have melted a cap and opened up a drilling in which case your $14 carb looks a better bet,my wife says she doesn think im mad she knows i am, i have a liking for the more unusual cars and bikes like you i wasnt allowed them as a kid so im making up for it now as a big kid
  14. turbofiat124

    turbofiat124 Premium Member Forum Donor

    I've also got a Kinetic TFR moped but this thing has been kicking my A trying to get it running. I'm just about to give up on it. These may have made it to the UK as the Kinetic Luna. The drive train is a copy of a Vespa CIAO which was sold as Piaggo Ciao here (or may have been the opposite). They were made in India and the frames were their design.


    This thing is a pig. Unlike the Tomos mopeds which use a 2 speed automatic, this one doesn't have the variator transmission that came on some Ciaos. I guess it was made for flat land. Any incline bogs it down. They you have to push a 100 lb bike up the hill because it's geared too high to pedal. Worse than trying to peddle a BMX bike. Not quite suited for the terrain of East Tennessee.

    The headlamp housing was busted so I used an auxiliary light (no high beam), made a bracket for the front turn signals and relocated the horn.

    So why can't I get it going?

    I was on a little trip one day and made a stop and when I pulled out and made it 5 feet the engine locked up.
    Got home and got the engine freed up but something was still putting it in a bind. Initially I thought it had something to do with the starter clutch. I could turn the engine over by hand but not using my foot. Then discovered the crank had up and down play in it. Split the engine and discovered that one of the crankshaft bearings had disintegrated and one of the balls got wedged between the counterweight on the crank and engine block. This explained why the engine locked up and why the crank had play in it.

    I tried spinning the engine over with a cordless drill and measures something around 125 lbs of compression. But you can't spin an moped engine backwards to get it started!

    Once I replaced the bearings, the engine would only run at WOT but not very well and not very long. Like I have an air leak. The compression dropped to 90 lbs. I discovered the gasket they sent me that goes between the cylinder and the bottom end was leaking fuel and loosing compression (or so I think).

    Got frustrated and parked it for 2 years.

    Decided last summer to try it again. Pulled the engine off and replaced the leaking gasket.

    Engine still won't start.

    I decided to order new rings (actually broke one trying to measure it, I guess because it was brittle from heat). Discovered the cylinder is not true and needs to be bored out. I tried honing it out but it has a scar down the side of the wall so I think it needs to be bored slightly. Weird that the cylinder head also has a small scar in it in the same location.

    Hopefully the rings I bought will work after the cylinder is bored out a bit. I just need to take it to someone who can do it.

    I also decided to see if maybe when I removed the carburetor I dislodged some junk and may have clogged up one of the jets. I couldn't find anything.

    As of right now the engine and carburetor are in pieces and once again got pissed off at it, I've pushed it aside for another year.

    Then I discovered that unlike South Carolina and some other states, Tennessee requires anything with an engine to be registered. Except for bicycles with engine kits. My guess is bicycles have no VINs and titles so there is no way the state can force you to register something that didn't come with a VIN from the factory.

    I have no title to this moped and I doubt it was ever registered in the first place. One idea was to pull the VIN off an old Suzuki 550 GT motorcycle I have out back and register it as a Suzuki. Illegal of course. But because the Suzuki is a 76 model, I don't need any documentation for it and I can get an antique licence plate like I have on my cars and not have to pay to register it after that. I think I have to get insurance for it. So it's probably not worth it considering I only had intentions of riding it down main street to pick up some ciggys or goto the bank.

    I think I'd be better off building a motorized bicycle instead. I've got a Mongoose Mountain bike with an aluminum frame that would make a nice candidate. That way I can ride it whenever I want and not have to worry about registration or insurance. But you do have to have a headlamp if riding a bicycle after dark.


    Here's the timeline of this Kinetic project:

    http://s222.photobucket.com/user/turbofiat/library/Kinetic moped?sort=2&page=1
  15. kev the builder

    kev the builder Loyal Comrade

    sounds like your better off letting your ped go,or if it realy p**s you off buying some marsh mallows and a gallon of gas and toasting them on it as you burn it,i threatened to do this to a particulary troublesome fantic motorbike i had it sort of co operated enough for me to sell it to a fantic fanatic,theres a buyer for everything it just takes some finding,i would be making a caferacer out the old 550
  16. turbofiat124

    turbofiat124 Premium Member Forum Donor

    The two 550 GTs I have are parts bikes. I thought it might be cool if I could make one engine out of one and use it in something (go kart maybe?). I need to try to sell those things for whatever I can get out of them. They were given to me.
  17. turbofiat124

    turbofiat124 Premium Member Forum Donor

    Speaking of cheap chinese knockoff carburetors, here's a 30mm unit for $17 free shipping. Kind of weird its for a 250 cc engine but it bigger than the 28 mm carburetor on a Trabbi. If it could be identified as to what it was copied after, I could get the appropriate jets and compare to what others are using on their Mukinis. I think Keri has one on her car. I haven't heard her talk about lately. How's it coming along? Still using it?


  18. kev the builder

    kev the builder Loyal Comrade

    koso are mikuni copies they also have a large range of jets available apparently theyre supposed to be good according to my local pit bike shop so i may be trying one on the trabi when ive finished running it in
  19. Steve

    Steve Loyal Comrade

    Ah, the venerable CX500 maggot. I rode hundreds of thousands of miles on a posse of those in the 80's and 90's as a dispatch rider in London. (A job more dangerous than the SAS). Reliable steed except for the alternator going tits up a lot cos it runs in oil and also the ceramic washer behind the water pump leaked cooling water inconveniently into the engine oil. Got fed up after a while with these flaws, so went onto Kwaka GT550s and the occasional BMW boxer. All shaft drives of course. Chain drives can't hack it dispatching.
  20. kev the builder

    kev the builder Loyal Comrade

    Yes the maggots have a few faults they soon showed up when they got despatched I've had the engine out 5 times to sort a starter clutch,then an oil leak,then an ignition pick up,then a gear selector spring it was all ok till I took it out to paint the frame,that's why you shouldn't take things apart if they aren't broken

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