CT125 Conversion in Vietnam - Need Your Expertise!

[BunRieu]

Hey everyone,

Im after some advice on converting a Honda scooter to a CT125.

So, I'm currently living it up in Vietnam, and I've got my eye on a Honda CT125. The trouble is, they are not sold here by Honda. I could import a brand new one from Thailand, but that's gonna cost me $10,000ish USD all said and done, and that's just way too much.

I like the idea of a smaller Honda engine that just about any mechanic here can fix, no matter how remote I get. Scooters do the job, but they're not great on rough roads, they're a real pain for off-road, and honestly, they just feel cramped. The CT125 looks just perfect for Vietnamese roads and the riding that i'm used to.

I've found this little mechanic shop in Saigon that imports CT125 parts and converts locally sold scooters sold here.

Honda Grom:

Honda Future 125:

Honda "Super Dream" 110 in progress:


I took the two bikes above for a spin around the block and they ride beautifully.

Talking to the guy who runs the place in the worlds worst Vietnamese, from what I could gather, he's got two main ways of doing the conversion:

1. He imports the frame, suspension, tank, fairings, lights, and all that jazz, then slaps on a local engine.
2. He imports just the fairings, suspension, tank, lights, handlebars and stuff, then fits them onto a locally sourced frame and engine but has to modify the frame quite a bit.

Option 1 is quite a bit more expensive.

I'm really thinking about getting him to build one for me, but I'm a bit worried about possible mechanical or engineering problems as these are obviously not the engine the frame was designed for.

So here's where I could use some advice: What are the potential downsides to either of these conversion methods?

I do like the idea of going with a Grom engine to get a manual clutch ( although the newer 5-speed Grom engine might be too pricey)

I'm not too worried about the legal stuff – I've been dealing with Vietnamese police for years. I just want to make sure I'm not going to end up with a bike that falls apart on me.

Any advice or ideas you guys could throw my way would be awesome!

 

[dmonkey]

Personally if given those options I would go with the CT125 frame. It is changed from the Super Cub frame with added gussets and a longer sub frame in the rear that make it hardier for off-road riding and carrying cargo on the rear rack. These same changes are likely improvements over the Supra 125 or Wave 125 frame as well, also more suspension travel. If you start with the CT125 frame you will know the bike has the CT125's geometry. That will help to make sure any other parts and accessories for the CT125 are more likely to fit without requiring extensive modification. I would try to stick with the Honda 125cc or 110cc engine for reliability, with the 125cc strongly preferred for the extra 1.7 hp or so.
An area you may want to ask more questions about is what options the builder offers for the electrical and fuel systems.

See here for mention of the chassis changes from the Super Cub:

2022 Honda Trail 125 Features and Benefits

2022 Honda Trail 125 Features and Benefits

hondanews.com

 

[Tiger]

option 1 looks better imho

 

[oldskool]

What about an older 110 or 90, are they available there. Seems like you could fit the new 125 engine in with less trouble than reworking a different bike

 

[m in sc]

I have to agree, id find an older bike and tart it up with some fresh parts. Im sure you could get a 190 motor (clone hond amotor or smaller cc) and stuff it in there. The bikes above remind me of fiero based Ferraris from the 80s.

 

[BunRieu]

What about an older 110 or 90, are they available there. Seems like you could fit the new 125 engine in with less trouble than reworking a different bike

I have to agree, id find an older bike and tart it up with some fresh parts. Im sure you could get a 190 motor (clone hond amotor or smaller cc) and stuff it in there. The bikes above remind me of fiero based Ferraris from the 80s.

It's kinda wild but the older 110s and 90s never hit the market here either, especially since the original Super Cub is still a common sight. The older Trail would be just about the perfect ride for these Vietnamese backroads. And it's clear there's a demand for the new Trail, given that this local mechanic has gone all-in on conversions.

I'm starting to lean more towards Option 1, no matter what. It's significantly cheaper to import the original frame as a part and just source an engine here, than to import the whole bike through official channels. Appreciate all the feedback, from everyone above.

Now, my next mission is to find a Grom to take apart. They're not super common here, but I do spot them from time to time. Worst-case scenario, there are plenty of Waves / Future 125s around.

 

[Tchap]

I’m wondering if you could maybe just hop over to Thailand for to purchase a bike there?

 

[BunRieu]

Just wanted to share an update on my CT125 conversion journey for those who might be curious or find this process as interesting as I do.

So, I ended up buying a brand new 125 Future from the Honda dealership (which, as far as I can tell, is basically identical to the newer 125 Waves sold in other places - only the 110 Wave is available here). This saved me a heap of time on sourcing an engine and handling paperwork that I honestly just didn't have.

I've decided to roll with the first option I mentioned earlier, which means I'll only be using the engine from the Future.

Once I dropped off the Future at the mechanic's place, it was pulled apart faster than you can say "Honda."



Then came the OEM parts from Thailand. How they get here so quickly is a mystery to me.

now, the new bike assembly is well underway.

I'll drop another update when the build is complete, but in the meantime, there are a few things I'd love to get your thoughts on:

1. As I understand it, I won't have ABS if I want the bike pronto (my time in Saigon is pretty limited). Is it worth waiting for?
2. Anyone know the key differences between the Wave/Future version of this engine and the CT? Could the gearing be different, given that it's primarily for road use?
3. Any fun ideas on what to do with a perfectly good Honda Future that's down an engine? Sure, I could sell it for parts, but i'm likely to just keep it in storage for now. You never know, I might stumble upon a Grom engine in time, and wouldn't it be cool to reunite the Future with its original engine? Then, I could live the dream of having a manual CT125.

Just thought this update might be an interesting read for the forum. It's bonkers to me that building this CT/Future mashup and buying the better part of two complete bikes is both quicker and more cost-effective than getting a CT125 through official import channels.

 

[dmonkey]

That's a fast and exciting update!

1. IMO, no. Just practice progressive braking so your muscle memory keeps you from grabbing a hand full of front brake.
2. Probably very few engine differences other than exterior cosmetics since they're both the semi-automatic transmission. The PGM-FI system very likely has a different tune. Transmission gearing looks the same (assuming they're both the same as the 2021 model years), sprockets are a different ratio:
* 2021 Honda Trail 125 page numbered 100
* 2021 Honda Future 125 page numbered 88
3. Just a few ideas: decorate the bike and use it as art, build it into a controller for motorcycle racing video games or a place to sit and watch MotoGP if you're into that, throw any odd engine or electric motor into it, build a large pull behind trailer using the rear section.

 

[Shoot870p]

Looking forward to the next update. You really got the ball rolling in a hurry!

 

[BunRieu]

Finally got the (mostly) done deal back to my home base. 'Mostly' being the operative word because we're still waiting on a couple of bits from Thailand. That said, I'm stoked about how the bike feels and handles.

Things hit a bit of a slow patch since my last update, thanks to some parts taking the scenic route from Thailand. We're still on standby for the skid plate, speedometer, and foot pegs. So in the end, maybe not quicker than importing through official channels but still less than half the price.

As for where we're at right now, it's almost all OEM parts for the build with a few exceptions. Of course, the engine. Then there are the slightly more off-road-ready tires I opted for right out of the gate, rather than importing the stock ones. They also dded a slight elevation to the mudguard, chucked in a mid-rack, and installed a USB charger for good measure.

The cheapo temporary speedometer I've got hooked up now is ugly, but it's surprisingly functional. Everything you'd find on the original is in place – fuel and indicator lights, high/low beam notification – and it even shows the current gear and comes with a clock. The only downside is that the tachometer goes haywire and maxes out as soon as I start moving. It's a bit of a letdown, otherwise, I might've been tempted to stick with it long term. The control switch isn't original either, and I've got no clue where it came from, but it's a nifty piece of kit. A button press pops the seat open, no more fiddling with the key and the lock under the seat.

As for the Honda Future that graciously donated its engine, it's getting a Wave 110 engine transplanted in. I'm keeping it as a spare runaround for when friends and family pop by. A shoutout to dmonkey here for the suggestions on this. Extensive and super helpful.

 

[Shoot870p]

Sounds good to me! Glad it is working out for you. That’s a great plan for the donor cycle for sure.

 

[dmonkey]

Just saw the Small Bike Stuff RTW series episode on this build. Glad to see how nice it turned out for a "bitsa bike"!

 

[BunRieu]

Just saw the Small Bike Stuff RTW series episode on this build. Glad to see how nice it turned out for a "bitsa bike"!

Thanks. I'm really happy with the bike; easily one of the best I've ever owned. I'm planning a trip to Thailand soon to avoid Tet. While there, I'll pick up a new speedometer and a few other accessories for my bike.