49cc Saga Retro Rebuild

[epitome]

Hey guys!



New user here, starting a rebuild project on a 49cc 139QMB Retro Saga. My wife and I picked it up a couple weekends ago for $550 CAD and the previous owner said it wasn't running. He said something vague about a broken spark plug and admitted he isn't much of a mechanic. That's an understatement.


This past Saturday we started disassembly. Lots of things weren't tightened down, including body panels and the new spark plug that was barely in the hole. When we got the engine open... well... let's say he must've had it taken apart at some point and didn't know what "timing" meant.  Check out the pics. That jagged piece of metal sticking out of the top of the piston wasn't formerly part of said piston. It wiggles slightly when you pull on it. I'm guessing it was once part of the valve with the missing head.

Thankfully the connecting rod is still spinning freely on the wrist pin, and the cylinder wall shows zero signs of damage. I still need to check if the connecting rod is bent, and of course we're going to drain the oil and check for metal bits. I'm hopeful the crank case isn't wrecked as well.

My original plan was to take it up to 80cc and add a few other cheap upgrades. This pretty much makes it required.
And my wife likes painting projects, so we're going to turn this from red/cream to Chevy Belair blue/green and cream.

I haven't done much engine work in 20+ years since high school mechanics (grade 10 power mechanics and 11/12 regular mechanics) but I've been watching a bunch of YouTube. Rolling Wrench, 49ccScoot and RouseGarage have been great. I have a few questions as I plan my parts purchases and painting.

1. What should I look out for as I keep investigating this engine failure? I'd hate to get it back together and have something I missed kill the scooter all over again.
2. I'm planning on getting an 80cc big bore, dipstick breather tube, jetting the carb and changing the air intake. Maybe CDI and exhaust too. What do you think?
3. I'm basically at sea level where I live. If I do all of the items in #3, what idle and main jets should I start with when tuning?
4. Do you have experience painting the body panels on this scooter? What primer and paint should I buy for it?

Looking forward to having you along for the ride. Thanks guys!

[aeroxbud]

Welcome to the forum.
Looks like a good excuse to upgrade the parts for sure.
Here is a good build thread about the GY6 50cc. 49ccscoot.proboards.com/thread/6365/project-taotao-stroke-experiences-upgrades

[epitome]

BBK arrived in the mail a few days ago, and I'm hoping to have time to start installing it in a couple weeks. All-in-one kit from GooFit. I've also ordered my helmet and I'm super excited to get it. Speed and Strength - Tough As Nails (orange) from FortNine.

I think my biggest challenge will be sorting out the wiring. There was an anti-theft box on the scooter that I've removed, and the previous owner had taken apart a bunch of the wiring and not put it all back together. I also need to source some body panel screws and the like for the same reason. There seems to be a Saga dealer in Canada I should be able to order from.

[tortoise2]

Sept 17, 2020 13:03:02 GMT -5 epitome said:

There was an anti-theft box on the scooter that I've removed

May need to install a jumper?

[epitome]

Thanks man, that might just be what I'm looking for!

[epitome]

I ended up buying a replacement security system online. The wiring and plugs matched exactly, so for the price I figured it was worth it. Now I have a problem remounting my carb, but that's in a different thread. It's only taken me a year to get this far, what's another week?

[epitome]

Now I'm having to replace the fairing turn signals. The previous owner must've had some kind off accident, because they're both so badly damaged that replacing the bulbs in making them fall apart. One of them was 'repaired' with aluminum foil and glue to get it back on the fairing. Here's an image of what I'm trying to find, along with it's other-handed counterpart. I'm kinda stumped though. I can only find the parts on a German site that doesn't ship to Canada. Even if I could convince them, it would cost a small fortune for what should be a fairly inexpensive part. Does anyone know where else I could find these parts? Online this scooter seems to show up as a Benzhou YY50QT-15. Mine is labelled a Saga Retro, but it seems to be hard to find ANY parts under that name.

[epitome]

Well, thanks to the purchase of some calipers, and my friend introducing me to tinkercad.com, it looks like I'll be making those replacements with a 3D printer he has. Just the rear part of the assembly, mind you. Took me about 3 hours to create the model. But the test print I brought home today is nearly perfect. I've made some slight adjustments and should have the final prints in the next couple of days. I'll have to prime/paint them chrome, but considering that the site in Germany never replied to my email, this is a pretty good alternative. I'll be sure to post the plans in the 3D printer part of the forum for anyone else who might need them in the future.

Also, I have most of the scooter reassembled, but the new battery needs a charge. I tried starting it with the kick starter and couldn't, and found that I'd forgotten to close the carb drain screw completely. Once the battery is charged I'll try again, but I'd wager I still have some tweaking to do before this thing runs.