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Broke a rear wheel, so I...,...,...

8K views 79 replies 5 participants last post by  CAM2 
#1 ·
What's happening, y'all? I know I've been MIA for a short while (since the TNT135). Like I said, I'll be around though. I have acquired what I believe is a new-old stock 49cc 2 stroke pocket bike from eBay. I was seriously only on there looking for a rear wheel (here comes the story).
So I was out at the school playground/parkinglot (my own little, personal neighborhood pocket bike track!) riding the 1st pocket bike I bought (junk 4 stroke from MPR). I was there for quite a while & decided it's time to call it a day, I was getting tired. Anyway, riding back home my leg started cramping up, as usual I just kind of straightened it out but this time it made it worse instead of helping. So my dumb@ss tried to slightly stand up on the footpegs (lol)...,...,...bad idea! The front started violently shaking & I couldn't set back down fast enough to let it straighten itself out. So of course this little bike comes out from under me. Wasn't that big of a deal really, but it is slightly embarrassing to crash a pocket bike going in a straight line (LOFL)! I went to ride it the next day & the tire is flat. I put air in but hear it coming back out somewhere, long story short, wheel cracked where the spoke meets the "tub".
I ran across a dude on eBay with like 8 or 10 49cc, 2 stroke bikes for like $250 & free shipping. I messaged him to make sure it was actually a 2 stroke bike & not just the picture of one. It showed up & its most definitely a brand new 2 stroke pocket bike. The plus side is I've got a new rear wheel to mount my PMT back up to (LOL).
I'll get some pictures tomorrow when I take it out to the garage & get the fairings off to check everything over. I've got to pick up a velocity stack & an air filter (already have a 15mm carb on the bench), I may be able to score one from a guy I know, I just have to call him & possibly go out and pick it up.
Anyway, if one of you dudes are wanting an extra 2 stroke pocket bike there's definitely some floating around on eBay. Just thought I'd say so.
I'll update with pictures soon

Randall
 
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#3 ·
Yes, the wheel was damaged when I crashed it last time. That particular pocketbike came with tube/tires installed. I put new valve stems & PMTs on it.
The spoke has a hairline crack where it meets the “tub” of the wheel.
I think it could be run with a tube installed, but I’m not going to do that, it’s a safety issue for sure. No one wants to be riding something when a rear wheel lets go, especially when I knew it was like that.
Now I need to find a wheel that’s not $70+ to replace it with. That’s almost half the cost of the bike by the time it’s shipped & a new tire installed. Same reason I was like “well....I’ll just buy this entire bike”
 
#4 · (Edited)
That's why we used to just chuck them in the shed and buy another....If you tried building a cag from the frame up it would cost ya 2-3x the cost of buying another whole bike....

Im surprised you didn't crack or bend the cheap rim edges just by changing the tires..The aluminum is ultra soft yet brittle...…..

When I used to build bicycles with alky powered chainsaw engines the rear spokes could only handle so much pressure before they tore out and the rim collapsed under power....It definitely was a wild ride when it happened....There weren't too many bikes with heavy duty rims/tires to utilize back then either....LOL

There was a member who bought one of those 2 stroker GP-RSR's from ebay...Im pretty sure I mentioned it in your MPR thread....He received a 2 stroker with reduction transmission and it went a topspeed of 20mph just like the 4 stroker......….It just has better/easier ways to make it faster.....

Good Luck
 
#6 ·
You might check out, www. scooterparts4less .com, he had some pretty good deals before on whole rims with tire mounted with China slicks. He has reg., soft, and ultra soft tires too which I have on my 50cc C1.
 
#7 · (Edited)
Scooterparts4less is pretty much out of business...……...I went on their site not too long ago and when you click on the pics to order the pages either say "forbidden domain" or "404 not found"..…

Best way would be to put a wanted ad on craigslist....When I do I get pics of very tempting things to buy aswell....LOL.
 
#8 ·
Got the PMTs swapped over to the new bike today. Took it apart (somewhat) to make sure things were all good (chain got an oil bath, had to straighten forks in the triples, greased axles, swapped front wheel, changed rear tire to PMT, drilled a few holes in stock air box & got rid of some extra plastic from casting) As promised, pictures coming.
The bike is most definitely not “new-old stock”. There’s a nameplate on the side that has a build date of 2019.
I fired the bike up, started easily & it’s pretty loud (lol). I let it run in the driveway for about 10 minutes after adjusting idle a little.
It’’s supposed to be dry & around 40-45 the rest of the week, so guess what this guy is doing.?!?.!?.! 🤙🏻🏁🏍
 

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#9 · (Edited)
Very nice looking bike....As for the actual year of manufacture I don't think its a 2019 model......Nameplates can be made then riveted on....Theres many truckbox loads of bikes sitting at California loading docks that could still be bought and sold aslong as its not sold in a state that outlaws the sale of 2 stroke modeled engines...

The GP-RSR's w/2 stroke engines and reduction transmissions they sell on ebay are 2012 models....Judging by the tubing,paintjob,plastic gastank instead of steel and light scale rust on the TF-8mm chain tells me its a 2009/2010 model replated as 2019..They also rivet the floatbowl on too after 2010 instead of using screws......…...

After 2010 they put spark arrestors inside them that kill power......You can tell if you have a spark arrestor by feeling with a long thin rod through the exhaust pipe exit...Steel gastanks started in 2011 too...…..



If it is a 2009 model with no EPA restrictors youll see speeds of 27-28mph after proper break-in...

Youll love the powerband a lot better than the 4 stroke joke hands down and youll be wanting more uumph out of it especially from a dead standstill and out of the corners.....

For that you have the WYK pumper race carb setup , rocket key,hp flywheel mod and clutch mod w/hp clutchsprings...............

Have fun....
 
#21 ·
I watched those videos & I can see what you mean about the pipe holding the engine back. Exception, something's going on with the video that's supposed to be "stinger removed"...,...,...It says on the screen "adult content, must be logged in to view". IDK what that's all about, just thought I'd let you know.
IDK what to do about the pipe, closest things I can find is stock & I'm definitely not wasting money on that one when this stock pipe broke & I haven't even ridden the bike yet. Of course I could always cut the stocker off after the header & just make something up...even if it's wrong, LOL! I'd love to weld one up myself. I seriously need to get one of my brothers to give me a crash course in welding. I'm pretty darn sure I could do it, I've just never had the opportunity to try my hand at it.
There are a couple of used pipes floating around for an X1 - X2. Will one of those fit on the MTA2 I've got?
I did order one of those manifolds with pulse port, gaskets, walbro style carburetor (looks like a WT813), 2 sets of FG reeds (having spares is always nice), a velocity stack & filter for it. I ordered a nice looking pipe from "mini bike parts now", but they didn't actually have it, they pretty much immediately refunded my money.
 
#22 · (Edited)
In the vid that's what I used.....I welded the X1 rev pipe onto the j-bend.....

On this engine is the j-bend with melded rev pipe from that bike with the expansion chamber lopped off...I turned the 40cc engine into a nitrous experiment and put it on my Supermoto cag...



The chopped off expansion chamber was used on the pipe below that's mounted on the Evil Wasp Cag..

When I made the double chamber rev pipe for the trophy cag I put a fully modded 44mm engine in the 2011 frame...…..Ive done endless comparisons and modifications its mind boggling how Ive done more than 120 pocketbike cylinders with engines built all sorts of different ways when I think back or look in the build journals.....LOL>>LOL.

It was great having my youngest brother live local to me back then too...He was my side-by-side comparison test driver on many of the builds...…...Some I built like a lot of the members with their reed mods etc then I compared it against something more refined but lower level with flywheel,rocket key,reeds, carb aswell as clutch switch arounds......

The engine was heavily modified,blueprinted ,balanced aswell as polished....

Try it again...IDK why it says adult content....LOL

trophy cag modded exhaust 2 by Dizzy Gillespie, on Flickr

If you just do mild mods the rev pipe will work killer...

I used the piece of rev pipe for my 15:1 alky cag exhaust and it worked out killer aswell...in the vid you can see it blast right out...



033 by Dizzy Gillespie, on Flickr
 
#23 · (Edited)
I think I found out why thevideo said adult content....In the settings theres a spot where you rate the vid as "safe" , "moderate" or "restricted"....

It was set to moderate....

Heres a vid of the same blue cag but with some frame mods as the thing even with the corked-up exhaust managed to pump up enough power to pull itself out from under me causing the body to become pretty busted up....LOL

If you look at the Evil Wasp Cag vid you can see where I reinforced the tail on that one with aluminum flashing and fiberglass resin as that tail became awefully busted-up aswell prompting me to do a 4" stretch and a lil frame reinforcing..

When I go to pullstart it I step on the flatspot of the kickstand with my left foot,I use my right leg as a brace , I grip the throttle pretty good and even with that watch how the rearwheel still wants to jump up

Even with a 1pc cylinder I got the compression to around 11.5:1 by grinding down the base and raising the ports to compensate..…

With the dual chamber rev pipe the exhaust tone is a lot tamer but the revs that belted out of it was pretty sweet...Throttle response was pretty crispy too......

trophy cag modded exhaust 3rp by Dizzy Gillespie, on Flickr
 

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#28 · (Edited)
You know you can braze the pipe also, even with a propane torch and brazing rod and flux. I use my tanks and torch. Go look at RCfish post he made a whole pipe from little pieces. To add a big belly to a stock pipe I buy Ford pickup size diesel exhaust pipe extension and cut 4 to 5" of it.
 
#29 ·
That's good to know. I'm going to take it that brazing is similar to soldering just a lot hotter. I've seen it done, but like welding, I've never actually done it.

I've got another problem now. I went out to do throttle cable & fuel lines & didn't make it past the throttle cable. Where the cable comes out of the bracket (IDK what that threaded fitting is called), it's way too sharp of a bend to operate smoothly. I couldn't leave it like that because I'll end up with a broken cable. I'm kind of not sure what to do about this one. The bracket is way too thick to bend/twist it enough to make it good.
 
#33 ·
dont even waste your time with flux core its the worst possible way to learn how to weld get oxy-acl or a stick welder you can get a used miller stick welder for the price of a junk harbor fright wire welder trust me sometimes when i get out the harbor fright welder i think to my self i would be better off just brazeing it those buget welders dont have good transformers and dont produce a stable arc makeing it impossible to run a nice bead.
 
#34 · (Edited)
First off rosin core welders are beginner friendly..Would you rather burn up a $125.00 or a 600.00 welder learning??

Then you have to buy a bottle of gas and sometimes a regulator too then learn how to regulate the gas etc......

Those cheap harbor freight welders even come with video instructions....


All's you have to remember to do is clean the metal good and while laying a bead stop every two to three inches to clean up the burnt rosin that flashes on the metal from the welding process..

I use wire wheels on a drill...
 
#35 · (Edited)
Well I guess others have had better luck than I did... the one I bought from Harbor Freight wouldn't even feed the wire consistently i took it back.

my expectations might have been to high as well your not not going to be able to lay down phat beads for days like i can with a Miller or Lincoln

it might have also been because I got the cheapest one that they have.

Definitely get one that has an argon hook up.

i have a harbor freight stick welder right now its ok but it defentley is lacking in the power department and i have to dive in to get penetration its onley 110volts probably the reason why and I wouldn't expect Harbor Freight to put copper wound Transformers into those things anyway...
 
#37 · (Edited)
https://makemoneywelding.com/discov...ding-joints-are-extremely-important-to-learn/

https://makemoneywelding.com/how-to-use-a-no-gas-mig-welder/

Maybe you need a higher power service...Those trailer parks only belt out like 100 amps per padsite due to most trailers being manufactured from the late 60's to the late 70's having aluminum clad wiring and not needing much power seeings some of its supplemented by propane or natural gas for the heating and the stove….

Youre like 25 amps too lite on the juice also to mention you cant use an extension cord longer than 5ft before it starts browning out the juice...

My homes have 200amps of service and my shops have 3 phase...….On my cheap migwelders I have to add like a 50-75ft extension cord just to make the power low enough to weld mild steel on the low setting...

Ive had two of those cheap Harbor Freight welders..One I still have and had for about two years now..

The original one I bought I chucked and it still worked too but was beat up badly and the sheath for the gun n lines was too kinked-up from doing like tons of welds and being moved around over a span of like 8-9 years plus when the speed controller blew out I just put the low side wire on the higher side seeings the high side was actually middle and the middle on the highest side then the dial worked in reverse but feed still surged from the beat-up handle with feed line.......

All welds in pics are done with old blue....





If you notice in this picture below you can see the Milwaukee drill with wire wheel I use to remove the rosin slag aswell as a Mapp gas torch which I use to preheat the metal a tad to about 200-300 degrees to get the weld to bite into the metal and flow sweetly...

 
#36 ·
My best choice would be a TIG welder and SS pipe although you can use steel too. I just love to TIG weld, got a lot of time on welders to get my Diesel Tech Certificate in college. I called the petal, gas pedal, and the teacher is looking weird at me, lol. I just fix the throttle arm and swivel on the Walbro HDA223B 19mm Walbro on the billet Cag yesterday. Get use to it, there is always something to fix.
 
#40 ·
I didn't know about having to stop and remove the flux I was welding my Thrush muffler on my work van I figured I could just get the Harbor Freight welder and then I would have it around here for other projects instead of using the stick welder I did just look up on YouTube and saw that people are using a hand clamp on the feed to make it stop slipping and the speed more consistent so that probably would have helped me out a lot right there changing out the janky Factory ground clamp probably would have helped as well I did have it plugged into my good shop cord with good plugs but it didn't seem to have the power and I did watch some YouTube videos of people that looks like it works mine didn't work like that unfortunately 😞
 
#41 ·
I've had an old Millermatic 35 (aka The Nuclear Mig) for years that's got 6 taps on the front of it. I dunno about amps at each tap, but I've never needed the top two! With some .035 wire you could probably weld half inch plate.


That being said my biggest problem is seeing and following the gap once the arc starts. Quite often I'll put a tack at the other end cuz the light will reflect off of the bump and that'll give me a target. I'm "shootin' in the dark" and because of that things do get wobbly sometimes. And I get mad ... lol. This is purely a cosmetic issue tho. Back in my stockcar days I used to test my welds on concrete walls. They're fine. I just want them to look pretty.


Sometimes I wonder about the my auto-dark helmet from Harbor Freight. Maybe a better helmet would help. Who knows?



On thinner sheet metals my 1st requirement is .023 wire. That's a huge help. Other than that I use a start and stop technique in that I weld as far as I dare and then freeze. When the red glow from the hot metal goes away I'll pull the trigger and repeat. It's a nuisance but it beats blowin' holes.
 
#42 ·
As long as the welds are strong who cares. Get a spray can of 1500F. black exhaust paint, or? Most of my small bikes you can not see the exhaust, its under the gas tank and seat cover.
 
#43 · (Edited)
So I went and got myself a piece of aluminum flat stock today and made my own throttle cable holder. Actually I made 3 of them. The first 2 were close but didn’t actually work, 3rd time was a charm. I didn’t take a picture of it earlier, but I’ll take one & post it. Not bad for some dude in his garage with a hack saw, drill bits, bench grinder & some sand paper.
I now have the carburetor mounted and in working order, small win.
Next up is the exhaust...just so happens that the neighbor has a flux core welder he said I could borrow. Lol...I have to put in some practice stuff before I jump into my pipe though...
Sorry for the not so great pictures. I should have taken photos of the piece I made before I installed it.
 

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#44 · (Edited)
So I went and got myself a piece of aluminum flat stock today and made my own throttle cable holder. Actually I made 3 of them. The first 2 were close but didn’t actually work, 3rd time was a charm. I didn’t take a picture of it earlier, but I’ll take one & post it. Not bad for some dude in his garage with a hack saw, drill bits, bench grinder & some sand paper.
I now have the carburetor mounted and in working order, small win.
Next up is the exhaust...just so happens that the neighbor has a flux core welder he said I could borrow. Lol...I have to put in some practice stuff before I jump into my pipe though...
Sounds great....Looks great too!.....I don't knock the tact and tools as that's how I tackle a bunch of this stuff myself.....

Good to know the neighbor is cool and willing to let you borrow his welder....

Its not really hard at all....You just need the wire wheels that can be mounted in a drillchuck to keep the metal clean and remove the welding slag..

When welding an exhaust expansion chamber do a series of many tack welds to secure it then stitch it together 2- 2.5" at a time with a 10-15 minute cooldown time for the welder in which you use that time to de-slag the weld and pre-prep the welding area...

When you do the 2-2.5" stitching you just go forwards 3/16" and do a series or whoops and swoops with a lil back n forth action to produce a nice even solid non-porous weld bead....

A grinder or 80 grit cookie wheels can be used to pretty the welds up too...….

Once you successfully pull one project off you'll be buying a welder and doing more projects like the inner creativity locked with-in just explodes outwards...I just have that feeling....LOL

This is my 83 YZ80 I converted to alky and put an expansion chamber from a Banshee350 quad on it to handle the flow...…...I had to cut and reclock the expansion chamber to get it to work.....



Cag dual chamber revpipe in its infantcy………

 
#51 · (Edited)
Alright folks,
I got everything put back together a little while ago (didn't do anything to the exhaust, just wanted to make it run) & went to start the bike.
I set the H/L screws both to 1.5 turns out, idle screw touching the throttle plate, so I gave it a twist (nothing wrong with an initial high idle). Went to start the thing...,...,...nothing.
So when I pull the throttle, it starts fine, it runs great! The thing will not sit there and idle at all though, I have to be pulling throttle for it to stay running. When I was pulling the throttle to what would be a low idle, theres a significant amount of space between the idle screw and the throttle plate. Did I get a carburetor that is messed up right out of the box (like low circuit not pushing fuel)? I don't believe I did anything wrong, seems like the carburetor isn't functioning properly.?.?.?.?
Should have just chalked up the coin for an actual Walbro, I think.
Side note, anytime I’ve run a pumper carb on a 2 stroke (GoPeds/GoPed Super Go Quad), I’ve always bought Walbro and never had a problem with them. This is the first time I bought some junk copy of a Walbro & I seriously believe that’s what the problem is.
 
#52 ·
the LSN screw is hidden in the top of the carby inside the brass thing that holds the throttle arm on you can turn it with a small flat bladed jeweler's screwdriver/eyeglass repair screwdriver sometimes they glue it put a small drop of brake cleaner inside the hole and letting it sit there for about an hour will loosen the glue.

Picture coming soon...
 
#53 ·
Maybe I should have said so in the first place...,...,...this is a copy of a Walbro WT 813. It doesn’t have the needle you’re describing. It has a H/L screw on the side and underneath that is the idle screw to push the throttle plate out a touch.
So while I know exactly what you’re describing, this isn’t that particular type of carburetor.
I’m seriously just going to order a Walbro WT-813 & call it a day. I seriously believe that this will be resolved by simply replacing it with an actual Walbro.

It is very disappointing for sure. It’s been below freezing with ice & junk here all week. Today it’s actually pretty darn nice out & dry & this thing wants to act up.
 
#55 ·
This one isn’t erratic, you let go of the throttle it dies.
I put my finger in the way of the plate completely closing & then it would chill out and idle. That’s why I think the carburetor is messed up somehow. It’s like it’s not pumping fuel through that 1st hole & it is pumping through the 2nd/3rd holes.
 
#58 ·
Did you adj. the idle screw both the 192 and 813 have one that opens up the rear throttle plate for more RPMs?? The 813 has a accell pump, when you open the throttle it squirts gas into the bore. Maybe the carb is not working right.
The best gas cap vent is a brake caliper bleed screw, the bottom holes is on the side and you can run your gas return line to the nipple. You thread the cap to the screw threads and use sealer when you thread it in.
 

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#59 ·
Yes sir, I adjusted the idle screw also. It never made a bit of difference. This is why I was thinking that the low side of the carburetor isn’t working properly for some reason.
I went out and messed around with it some more today to no avail.
Didn’t I see one of your posts somewhere on the site with an 813 set up on a reed plate/intake manifold/WT813/velocity stack/filter?
I’m asking because it’s one of the reasons besides the good adjustability that I picked this particular carburetor for the engine...I thought you guys were successfully using them.
Once again, I could be mistaken.
I hope I’m not mistaken because here’s a Walbro WT-813 on the way right now.
Thanks for the cap vent tip too, I appreciate it.
Thanks EPR
 
#60 ·
The bleed screw mod works great. A WT-603 16mm carb is what most Cag engine use carb along with the 15mm. For my twin drag engines I got 2 HDA48 cause the have no return gas fitting. Many choices for carbs.
 

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#61 ·
Ok, before I start, I need to remind all of you that I'm 42 going on 13.
Here's what I did...,...,...of course after putting in some work on this bike, I was super excited to get out and go ride the thing. The filter I got from DDM was covered in this weird yellow/clear, really thick oil & a very excessive amount of it...like the bag was seriously about 1/4 full of this crap. When I originally took it out of the package I only wiped off the excess so I could handle the thing without getting oil all over everything & myself. I never actually cleaned the foam filter out.
So I wake up this morning & the first thought I had was "I never cleaned that filter out & it's probably starving the engine for air" (great first thought of the day, right.?.?.?).
I cleaned this thing out, dried & then blew it out with the compressor, reinstall & I've got a running piece of machinery now.

So way to go me for being overly excited & missing a very important step (air) of cleaning out my air filter. I appreciate all of the replies & tips. I'm sorry that I was here "chiming in" with a problem when this was my own fault.

Guess who's getting the minimoto out when it warms up a little later?!?!?!?!?!?

Thanks again, Y'all
 
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