HI folks, I have an opportunity to buy a GB125 for cheap. It starts, but doesn't run. It also has a trashed final drive. "Trashed" as in grinding noises and metal in the FD oil. I've never dug into a scooter final drive before, but I've watched a few videos. I assume I will have to replace everything that turns or rotates in the final drive. I haven't had any luck finding an online fiche. Any idea how much $$ I'm looking at to replace all the bearings and gears? Any special tools required? Thanks,
You might be better off sourcing an insurance totalled Buddy and just doing an engine/driveline transplant. They're out there!
I thought about that. I saw one on eBay for $900. Thta's way too much for this project. I'm hoping to spend $100 or so on parts. I'm not interested if I can't do it for that.
OK, I found an online fiche. Looks like about $200 worth of parts. Interesting. Looks like I'll get to use my bearing puller. Anyone know if the gears need to be pressed?
May want to try modernbuddy.com forums. Also, the parts may be swappable with aftermarket GY6 bits which could save some money as well.
The basic aircooled platform of scooter engine from 125cc to 150cc(Buddy 170cc is now even bigger). There are different versions of the GY6 so parts have to be confirmed before purchasing and swapping since there are several derivatives.
Be careful; on real Honda scooters, if the needle bearings are trashed, you need to replace half the engine case (the needle bearings are not replaceable). Call that a "worst-case" scenario!
Try www.scooterwest.com or www.scooterworks.com. Scooter Works is the same company that distributes the Buddy 125. These are the best locations I have found and use them on my Buddy 125. Interesting, never heard a drive train being toast. My has been a real work house for over 14,000 miles.
Thanks again. I kinda got the it was run without rear drive oil, or it was never checked. The whole thing is fishy, but I can live with fishy for super-cheap.
I've seen a few scooters with final drive failures. A lot of them had crappy bearings put in at the factory, and there are some that have obviously been under water at some point. One thing you want to make sure of before ordering parts is that when the rear end self distructed the bearings and gears didn't take chunks of engine case with them. That's expensive. Also, sometimes people think the final drive is toast and when you open it up you find out that a clutch shoe broke or the variator froze on the crankshaft. When you pull the bearings, note the sizes and try to replace them with German or Japanese bearings. We use a brand called Nachi and have had very good luck with them. Freeze the bearings and they will slide right in where they should.
If the transmission ate the end of the crankshaft you may need a $900 transplant motor. Go for it and tell us the result!
My understanding is that the GY6 is only found in Chinese scooters, and only 150cc. The Buddy is built by PGO in Taiwan, and is likely to be completely different. If the damage was cause by running it without final drive oil, it may not be so complicated after all. Probably does not involve the engine or even the variator. Most everyone on the Zuma forum recommend UNDERFILLING the final drive on Zumas and Vinos. I slightly overfill mine. It is vented so it won't blow a seal. And I have never had any oil blown out the vent.
Often repeated, especially on the internet, but nobody has ever come up with anything from Honda referring to a GY6, or parts fiches or service manuals about this motor. AFAIK, Honda produces service manuals and parts fiches for pretty much everything they make. The first examples of the 50cc version I have seen came on the Kymco Filly. That is the only non-Chinese one I have seen that uses a 669 belt, and it has a design flaw, corrected in later Kymco versions but still in the Chinese versions, that is the primary reason you don't see many high mileage Chinese scooters that have not had the top end replaced. When China banned two strokes on their own roads, the 150cc GY6 was rushed into production, and there is an additional design flaw in the version the Chinese chose to copy which causes abnormally high crankcase pressure to build up.
The final drive and engine are completely separated, sealed oil containing entities on most twist n go's so the top end defect would have little effect on trashing the rear drive.
So is the GY6 a Kymco design, made into a 150cc by the Chinese? Aside from the crankcase venting problem (which the earlier Honda GET engines used in the Metropolitan and Ruckus also had) what is the other flaw in the GY6? Do current Chinese GY6 scooters still have these problems?
The 150 was also being made by the Taiwanese, but it was not quite perfected when the Chinese decided to "borrow" it. The other problem is the design of the camtower on the 50cc head. It is still being used on the Chinese product today.
