KEEP IT HONDA: CT70 / Grom by Therapy Garage

Honda CT70 Scrambler

A Grom-Powered CT70, ready for town and trails…

The Honda CT70 — aka the “Trail 70” — debuted in 1969, featuring a pressed-steel “T-bone” frame, folding handlebars, and a 72cc OHV four-stroke engine good for a top speed of 43 mph in stock trim. It was street-legal, weighed just 143 pounds, and could fit in the trunk of a car with the bars and pegs folded down. In rural areas, the little Honda minibike was sometimes seen as an alternative to the horse, used by ranchers, hikers, and the US Forest Service:

“The CT70/Trail 70 was wildly popular in the US during the 1970’s. The mid-west and other farm and ranch areas of the US gave huge sales of the models to Honda Motorcycles.” –Trail70.com

Honda CT70 Scrambler

Enter Toby Reed of Therapy Garage, who’s no stranger to minis, having grown up riding his grandmother’s Yamaha JT2 Mini Enduro, constantly cleaning the carbs to keep the bike running and making some modifications of his own:

“I would put a little clip on the fuel line to lean out the mixture and squeeze an extra mph or two out of it.”

Both of his grandfathers were mechanics, but it was only years later, after starting his family, that Toby discovered that this garage time was a kind of therapy. Hence the name Therapy Garage, founded in Oceanside, CA, in 2015, and now based in Traverse City, MI, carrying on the family legacy.

“I use the tools that I inherited from my grandfathers every day.”

Honda CT70 Scrambler

Soon after the Michigan move, Toby was contacted by a customer who had two museum-quality CT70s, as well as a pair of brand-new 2017 Honda Groms, complete with electric start, fuel injection, modern suspension, LED lighting, etc.

“But the Groms seriously fell short to the vintage style of the classic CT70s. His vision was a bike that had it all and we were up for the challenge! (Twice.)”

The first step was the engine.  While there’s a wealth of aftermarket Chinese parts for the CT series, “Keep it Honda” was a mantra of the project.

“A full engine swap from a Honda was the only option for this client. And to the best of our knowledge, it has never been done.”

Honda CT70 Scrambler

They managed to swap the Grom engine into the CT70’s T-bone frame, complete with custom reinforced mounting points, offset sprocket for chain alignment, and an in-tank EFI fuel pump.

“It’s crazy to turn the key on this bike and hear the fuel pump hum.”

That was all last summer.  This summer, they took everything a step farther, swapping in the Grom’s suspension, including the swingarm, monoshock, inverted forks, and front brakes. The result is one of the baddest minis we’ve ever seen, a modernized Trail 70 that we’d love to rip around town or assault the local trails. Below, we get the full story on the build from Toby himself.

Honda Trail 70 / Grom Scrambler: Builder Interview

• Please tell us a bit about yourself, your history with motorcycles, and your workshop.

I had a little Yamaha JT2 Mini Enduro as a kid. It was my Grandma’s. The inside of the tank was rusty so I was tearing apart the carb every week or so until I discovered in-line fuel filters. My grandpas were both mechanics but it definitely skipped a generation in my family (sorry Dad). I loved messing with that little bike as a kid. I would put a little clip on the fuel line to lean out the mixture and squeeze an extra mph or two out of it. In high school and college I rode a modern bike and didn’t wrench much. But after I started my family I found that garage time was my Therapy. Therapy Garage was founded in Oceanside, CA in 2015. In 2017 the Therapy Garage was moved to Traverse City, MI. Our shop here is very humble. I use the tools that I inherited from my grandfathers every day.

• What’s the make, model, and year of the bike?

The make, model, and year of this bike get a little blurry. Really, it depends on who is asking. I can tell you that it is a Honda through and through. If the cop who pulls you over for doing a wheelie as you pull onto the highway and speed away at 60mph asks… “It’s a vintage CT70. No need for a plate on this old mini bike, Officer.”

• Why was this bike built?

We were contacted shortly after relocating to Michigan by a customer in the Metro Detroit area who had seen our builds on Instagram. He wanted a more reliable CT70. He had two of them that were near museum quality, but was always fed up with unreliable carbs when he wanted to take a little rip around the neighborhood. His story reminded me of that Mini Enduro I had as a kid that would only run on full choke. So he had purchased two brand new 2017 Honda Groms. He was stoked on the electric start, fuel injection, modern suspension, LED lighting, etc. But the Groms seriously fell short to the vintage style of the classic CT70s. His vision was a bike that had it all and we were up for the challenge! (Twice.)

Honda CT70 Scrambler

• What was the design concept and what influenced the build?

There is a huge subculture of custom mini bikes, monkey bikes, scooters, DAX bikes, etc. There are also a ton of aftermarket parts available to customize your CT70. Most of these parts come from China and aren’t of the highest quality. “Keep it Honda” was the tone of the dialogue with the client from day 1. There are big bore kits available to juice up a CT70. But we wanted more than that. A full engine swap from a Honda was the only option for this client. And to the best of our knowledge, it has never been done. As far as the color scheme goes, we kept sending pictures back and forth that seemed to revolve around a red/white/blue theme. In a very intentional attempt to keep from going full Evel Knievel we agreed on a Martini Racing color scheme. Right now it is in it’s “less is more” stage. There very well may be some custom pinstriping down the road.

Honda CT70 Scrambler

• What custom work was done to the bike?

The first stage of customization on this build was fitting the engine into the frame. None of the engine mounting points line up and the frame itself needs to be cut to fit the contours of the engine casings. All of the new mounting points are then reinforced and spaced accordingly. From there, every system needed to be reengineered. A custom offset front sprocket was needed to align the chain.

Honda CT70 Scrambler

The Grom swingarm and monoshock needed to be mounted at the correct geometry and in a way that was strong and safe. The triple tree, steering bearings, neck of the frame, all had to be modified, fitted, TIG welded, etc. in order to use the inverted shocks from the Grom. The rear brakes utilize a Honda XR dirt bike master cylinder with a custom fabricated brake lever. We had to fit the CT70 foot pegs and engine guard to the Grom engine in a way the allowed for oil changes and also play nicely with the rear brake lever and the exhaust. And, as with all of our builds, the seat is custom fabricated, quilted, and upholstered in house.

Honda CT70 Scrambler

• How would you classify this bike?

By definition, this bike is very restomod. However, the seat is brat and the tires are scrambler. It breaks the mold. It will be exciting to see how it is received online. I am optimistic it will make it’s rounds on instagram.

Honda CT70 Scrambler

• Was there anything done during this build that you are particularly proud of?

We spent way too much time researching in-line fuel pumps and flow regulators to get the fuel to the throttle body and play nicely with the ECM. Real estate was going to be a huge limiting factor in any option we found. So we sourced a steel tank for the CT70 and grafted in the mounting plate from the Grom fuel tank to the CT70 tank. It was then pressure tested and sealed. The EFI fuel pump now fits like a glove into the CT70 tank beside the custom filler neck under the seat. It’s crazy to turn the key on this bike and hear the fuel pump hum.

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4 Comments

  1. Frank Falcon

    I bet the boys at honda wish they had thought of it first. Mr. Honda would have a big grin on his face if he could see what you have accomplished. Maybe there is a market for some kind of kit? They didn’t have such cool bikes when I was a kid, just homemade mini bikes with lawn mower engines, yea “The good ole days” not the “Cool faster than crap-ola days”. I hate to think what it would cost to build starting from scratch $$$$$$ it’s only money lol! I like it and am a bit jealous.

  2. Such a rad little build. While it has a pretty different overall flavor to it, this build instantly reminded me of another Grom-powered Trail 70 project that a car designer named Murray Pratt whipped up a few years ago called the “Squeeze Box.”

    • bikebound

      Just looked up the “Squeeze Box” build — that thing is rad, especially that rear suspension linkage!

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