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Discussion Starter · #1 · (Edited)
What’s up guys? I just snagged this MTA3 with a 40mm piston for $50 and it runs strong, but with issues. As you can see, it’s missing a ton of parts. It leaks from the float bowl and the overflow tube. It is a Huazhong 13mm. From what I’m reading, you guys upgrade these to a 15mm? Can you recommend a better carb or place to get the float bowl ring/gasket? Can I use a carb that uses the primer bulb instead of the float bowl?

The rear wheel also started binding after a short ride and the chain is way too tight. I’m not sure if it’s the bearings as well or if the chain tension was always like that, but the wheel is difficult to turn. Where can I get replacement bearings, chain and hardware for mounting the rear wheel because it looks jerry rigged as hell?

I’m also looking to replace the fairings to match my older 01 ZX6R Ninja in red. I’ve found them on eBay for $100 shipped but they’re listed as “used” but they’re new “with scratches.” Can you recommend a vendor for all new fairings?

Lastly, can you recommend some common beginner upgrades? I’m fairly new to pocket bikes, but I know a bit because I have a Baja 5B SS that I’ve worked out. Thanks a lot and I’m looking forward to contributing to the forums. Photos attached below.

EDIT 05-02-21: I’ve discovered it is actually an MTA3 with a 40mm/47cc piston/cylinder according to the block engraving starting with “40-6QW” and the sticker on the pull start housing stating the model and engine family number of “6ZSSX0.05TSM.” Good to know the 44mm big bore kit is an upgrade.

UPDATE 05/06/21:
Bookmarking this awesome site for my eventual exhaust;
http://pocketbikesunlimited.com/47STAGE3.html

Current Spending & Parts (Includes Tax and Shipping)

CHASSIS:
Full MTA2 Fairing Kit $98.00
Universal Fairing Screw Kit 6mm x 20mm $10.61

MTA2 Windshield $2.95 + Shipping
Anodized Red and Silver Aluminum Foot Pegs $14.50
Chain Tensioner (Pair) $4.99 + Shipping
Seat Pad $9.95 (Returned- one came w/ fairings)
Possible Parts To Buy:
Hydraulic F/R Brakes $49.99
Chain Guard $16.99
Anodized Red Triple Tree $15.72
Double Foot Pegs $20.00
Wheel Bearings (Pair) $6.49 + Shipping
Kawasaki ZX6R Ninja Decals x 6 $16.50

04/27/21 Looking for or making a Windshield Support

ENGINE:
47cc-49cc Rocket Key Timing Advance Mod $10.64
Performance 47cc, 49cc Carbon Fiber Reed $10.00
44mm Big Bore Kit With 19mm Float Carb/58mm Air Filter $51.99
Anodized Blue 1/4" Glass & Alloy Fuel Filter $8.39
Full Circle Crank $19.99
.66mm-.72mm Jet Kit for 13mm Carb $12.00
1/4" ID x 3/8" OD Red Fuel Line $8.69

159872
 

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Hey and welcome. I see you have the cool 5 spoke wheels. Good start.
As for the carb you could fix it and taper bore it. You could also use the pumper carb (primer), or a walbro clone (which has the best tunability). The last two need a intake change and different fuel lines.
As for your fairings, ebay is pretty much your only answer, as is with most of the parts you asked about, Amazon, and a few pocket bike specific sites still exist.
Quick mods are Rocket key (advance timing), carb upgrade (or modified stock), modify the stock exhaust by making the chamber longer in the middle and shorter before the chamber, fibre reed, and bump compression by deleting your base gasket and using yamabond or something similar.
Many more mods you can do, depends on how far down the rabbit hole you want to go. Lol
 

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My recommendation is don't hesitate to buy the parts if you find the parts those bikes are no longer manufactured and parts sources are drying up quick especially with spring and summer on us.

GGet all of the body work and stuff done first there are engine parts a plenty.
 

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Yeah, the body panels are hard to come by. Get them as fast as you can. I usually just use what came with it.
Mods, rocket key, bump compression, fiberglass reed, 1/4” fuel line and filter. Quickest to a bit more power
 

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Bearings are cheap, but you need the numbers off the race. My last crank bearings C3, 23,000 rpm got them off Amazon.
Get some rust buster oil and take the rear wheel off. You will know right away if the bearings are shot. Remove them and make sure the bearing spacer tube is between the wheel bearings inside the rim, or when you tighten the rear axle it will lock then up.
 

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Discussion Starter · #6 · (Edited)
Thanks for all the replies guys. I'm super hyped to be part of the community and contribute. So far, I have bought, full fairings in red, a windshield, hardware, a stock 13mm carb (how are these so cheap?) with the missing velocity stack, air filter, fuel line/filter, aluminum foot pegs and just ordered a rocket key. (Edit- To hell with it all, I added a big bore kit and CF reed as well! :))

It's missing chain adjusters, the chain guard, and the rear wheel mounting looks super rigged up as you can see with hardware store washers (likely because there are no chain adjusters on it), so I want to replace the wheel bearings and get the correct hardware setup back there.

As far as "taper boring" the new carb, do you mean port matching? I can just use a Dremel to do that and then wetsand/polish it right? Any recommended videos or channels for the process? Should I use threadlocker red or blue on the carb to intake bolts?

A few more questions::

1. My chain measures 41", but I see most chains are sold by how many links it has. Without the frustration of counting links, what chain should I be looking for? Should I get a premade on e or a length with a master link? From what I have read it is a 25 or 25H. What is the difference? Also,

2. I meant the rear wheel bearings rather than crank bearings. Are they a standard size?

3. Is the Dellorto carb/Blata 2.5 intake mod worthwhile? I can't seem to find the intake anywhere.

4. Is there anything in this big bore kit I just bought that I should upgrade? Like the roller bearing?



s-l500 (1).jpg s-l500.jpg s-l500.png 61Cnv-lW8pL._AC_SX679_.jpg s-l500 (2).jpg 31bPn6GdBvL._AC_.jpg 61P-+OIsMhL._AC_SL1001_.jpg s-l500 (3).jpg
 

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Oh no, another Addicted pocket bike rider, lol. I was so bad I had to seek help, lol. With a $12 Walbro clone WT603 from a chainsaw and $18 Cag alum pumper carb manifold, $9 for billet V-stack, the any 44mm ID air cleaner. Davesmotors.com has scooter stuff, RC stuff, and 2 stroke carbs, real walbro carbs, V-stacks and all that good stuff.
Going in the right direction, don't try to get to crazy at first with hp engines, it will come in time. See what i can find.
Any of these pumper carbs will fit your engine. On eBay you can get a 15mm pumper carb for $10 and black plastic intake manifold $9, it all bolts right up.
 

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Discussion Starter · #11 · (Edited)
I did not polish the carburetor
What is that bit called? I would try a conical sharpening stone on my die grinder. I bet it would smooth the powerband with a good sand and polish on the port. The smoother, the better. Would this VS match up with or at least be larger than the 19mm intake on the BB kit carb?

Edit- The BB Kit comes with a 58mm air filter and this stack is probably for a 44mm. Is there an adapter or something that is used or is there a bigger diameter VS for the 19mm carb?

Edit 2: It looks like the 58mm carb does not even use a VS? Added second pic for reference.

Last question, do I need to change my throttle cable setup for this type of carb or does the stock one work? Is the fuel line the same diameter as stock? I don;t want to miss anything and have to wait longer for parts to come in.

61B6Ki0FqDL._AC_SL1005_.jpg 61ltx2Wtc6L._AC_SL1000_.jpg
 

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I agree those slide carbs suck mine cracked and fell off before I could even really test it other members have had to chang jets for weeks trying to get them right it really is best to do a stock modified or get a pumper carburetor
 

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Discussion Starter · #15 · (Edited)
I agree those slide carbs suck mine cracked and fell off before I could even really test it other members have had to chang jets for weeks trying to get them right it really is best to do a stock modified or get a pumper carburetor
Ah so that is what the BB kit carb is? A slide carb vs the 13mm stock being a rotary? How can you tell from the outside? I am familiar with the mechanisms from RC nitro engines. Rotary carbs have a "rougher" intake path than a slide carb, assuming that is what the stock carb is.. Granted a 1/10-1/8 scale RC carb is no bigger than an inch, but it makes a huge difference with flow and throttle response/idle. I think I need to do some self-education on how these carbs fundamentally operate.

If you had to buy jets for the 19mm slide that came with the kit, where would you get them?
 

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Ah so that is what the BB kit carb is? A slide carb vs the 13mm stock being a rotary? How can you tell from the outside? I am familiar with the mechanisms from RC nitro engines. Rotary carbs have a "rougher" intake path than a slide carb, assuming that is what the stock carb is.. Granted a 1/10-1/8 scale RC carb is no bigger than an inch, but it makes a huge difference with flow and throttle response/idle. I think I need to do some self-education on how these carbs fundamentally operate.

If you had to buy jets for the 19mm slide that came with the kit, where would you get them?
It's not like an RC carburetor at all it is a sloppy piece of crap!!!

The different slides you need for the low speed idle air/fuel are non-existent the only way to get them is from the OEM manufacturer Dellorto and cost more then the entire engine itself and no guarantee that they will properly fit the clone.

The high-speed jets are available I hope you like changing them every time the weather conditions change...

The way the carburetor mounts to the intake manifold is stupid to say the least it is as a slide on style thing with a rubber hose gasket thing and a slot cut in the carburetors casting that pinches the aluminum tight against the manifold you can only flex the aluminum a few times before it cracks causing a huge vacuum leak or it just loosens up from vibration and causes a vacuum leak and is why half of the people that put those carburetors on their engines they can't get them run and have cut out at high rpm yes gooping silicone around it works but why should you have to do that...

It's why modifying the stock carburetor or using a pumper chainsaw style carburetor is definitely the way to go.

If you have already purchased one send it back for a refund.
If you like fiddling around with crap that other people have wasted there time with and failed then I guess have at it lol I'll bet you nobody comes in this thread and says they have that carburetor and it's the best thing that they've ever had they will come in and say oh the carburetor works okay if you do a bunch of hokie stuff and get it to seal to the intake manifold...
 

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The worst part is getting the throttle cable into the slide and spring. You might need a longer throttle cable, with more free cable than the Cag. When I bought one way back it came with the right length cable. Once you get one thing fixed, something else goes wrong.
 

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Yes the cable is a big problem. They are a hassle, (race carb) the stock is a round slide carb, like a Mikuni but very generic, less adjustability. But modify a stock carb is easy, will suit your needs and pleanty of parts and some adjustments. The pumper carbs are great, easy adjustability overall. But a little upfront cash for the carb and new intake.
 

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Discussion Starter · #19 ·
It's not like an RC carburetor at all it is a sloppy piece of crap!!!

The different slides you need for the low speed idle air/fuel are non-existent the only way to get them is from the OEM manufacturer Dellorto and cost more then the entire engine itself and no guarantee that they will properly fit the clone.

The high-speed jets are available I hope you like changing them every time the weather conditions change...

The way the carburetor mounts to the intake manifold is stupid to say the least it is as a slide on style thing with a rubber hose gasket thing and a slot cut in the carburetors casting that pinches the aluminum tight against the manifold you can only flex the aluminum a few times before it cracks causing a huge vacuum leak or it just loosens up from vibration and causes a vacuum leak and is why half of the people that put those carburetors on their engines they can't get them run and have cut out at high rpm yes gooping silicone around it works but why should you have to do that...

It's why modifying the stock carburetor or using a pumper chainsaw style carburetor is definitely the way to go.

If you have already purchased one send it back for a refund.
If you like fiddling around with crap that other people have wasted there time with and failed then I guess have at it lol I'll bet you nobody comes in this thread and says they have that carburetor and it's the best thing that they've ever had they will come in and say oh the carburetor works okay if you do a bunch of hokie stuff and get it to seal to the intake manifold...
I guess it's a good thing the stock carb is less than $20. I may go ahead and order the 13mm stock carb to mod as well and just flip the 19mm back on eBay for $15. That or go with the Dellorto and Blata 2.5 intake. Does the Big Bore kit require a larger intake carb (19mm came with it) or will it produce the roughly the same flow/power with a modded 13mm/Dellorto/Blata setup?
 

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When I do a two-piece cylinder I do a lot of modifications to the stock carburetor
1. Petcock delete/high fuel mod
2. Drill and slightly enlarge the fuel path in the carburetor that feeds the bowl. (Be careful not to drill or nudge into the brass overflow valve)
3. Dremel out the float bowl ( a few milliliters extra is it big help for fuel starvation)
4. Adjust the float height I want the fuel to stop filling the bowl at the last possible second before overflowing I adjust this with water and usually involves taking the bowl area apart at least four or five times and retweaking the fork.
5. Taper bore the carburetor intake ( effectively increase air intake velocity)
6. Sharpen the needle just a little bit ( not too much this will actually affect low speed idle as well and make it slightly less stable to enhance top rpm horsepower)
7. Raise the needle all the way up ( they're going to need more fuel with all that air )

First start up notes
Start out with the stock jet increased air velocity and crankcase velocity sometimes the stock jet actually works out perfectly to make a stoichiometric air/fuel mix.

The choke may not work so good if the taper boar is too large try a very tiny amount of starting fluid on cold days.

.........

The 15 mm pumper carb is the way to go if you want a bolt and go carburetor
...........

19 mm carburetor is actually too big for these engines over carburetion tends to make them sluggish and very tricky to tune.
 
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