RETROL R29 4.2CC Miniature V-Twin Engine Motor OHV for Mini Chopper Bike Motorcycle

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$100 OFF Coupon Code : 100 , Only $799.99 ,Save $100

Color: Silver

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R29 4.2CC  Miniature V-Twin Engine Motor OHV  for Mini Chopper Bike Motorcycle

in stock. the order will be sent out within 1 working day.

.Based on the V-twin double-cylinder Knucklehead motorcycle engine in the 1970s, the miniature gasoline mini knuckle head engine model embodies the spirit of different ages in a wonderful way.
.Designed with classic body lines and cold-cooling structure, the retro machine restores a host of authentic engine details, including a new carburetor and lift throttle.
.Each part of the engine was carefully designed, processed as well as made of brass and stainless steel, working in conjunction with a wooden base for easy display&control and stable operation.
.Built with start and ignition equipment, the engine is ready to run and friendly to novice model enthusiasts. When running, you will satisfy and marvel at its operation.
.As a coveted collection, the engine model is worth showing and playing, suitable for personal use and a high-end gift to friends and families at major festivals.
.Notes: 1. If the engine is failure to start normally under the normal ignition and cylinder compression, it is likely that the carburetor needle will need to be adjusted.
2. After tightening the main oil needle on the carburetor, loosen 1/4 turn and start the flywheel to make the mixture ratio of gasoline and air reach the normal working mixture ratio after several times.
3. Turn off the power switch when the machine stops.


.Material: Brass + Stainless Steel
.Item No: R29
.Color: Silver
.Scale: 1/5
.Form: Ready to Run
.Type: Double-Cylinder Four-Stroke Gasoline Engine
.Displacement: 4.2CC
.Cylinder Diameter: 13mm
.Stroke: 16mm
.Cooling Mode: Air Cooling
.Starting Mode: Manual/Electronic Drill Starting
.Ignition Method: Electronic Igniter
.Spark Plug Type: 1/4-32 Thread ME8 Spark Plug
.Lubrication Method: Mix/Splash Lubrication (Gasoline/Engine Oil =25/1)
.Fuel Type: 95# Gasoline
.Engine Oil Type: 2T Engine Oil
.Starting Power: 4.5V AA Batteries*3 (Not Included)
.Engine Dimensions: 120*80*110mm
.Wooden Base Dimensions: 150*120*30mm
.Product Dimensions: 15 x 12 x 14cm
.Product Weight: 1650g
.Package Dimensions: 20 x 20 x 20cm
.Package Weight: 1850g
.Packing: Carton Box
.Ages: 14+

Customer Reviews

Based on 5 reviews
Frank Schiavo
awesome knuckle head mini

I am a Harley builder and love this motor.

Jon Cook
R29 Knucklehead 😁

What an outstanding miniature engine!

I ordered my R29 Knucklehead immediately after it went on sale, and was thrilled when I got my notification that it had shipped from Stirlingkit!

This is my 5th engine that I have bought from Stirlingkit, and always look forward to what they will be releasing next.
My R29 arrived three days after it left Stirlingkit‘s warehouse, using DHL express shipping.
It arrived safely and in perfect condition, as all my engines and parts have arrived.
Stirlingkit‘s packaging method is outstanding, and the special presentation box they had made for the Knucklehead, really stands out and was totally worth waiting for. It’s a beautiful sturdy black box, with a picture of the engine embossed on the top section with the new Retrol brand logo.

The instruction manual that comes with the R29 Knucklehead contains a lot of engine information; such as specifications, setup & how to operate the engine.
The engine is completely ready to run. Install 3 AA batteries and add fuel.
For fuel, I chose ethanol free w’ added 2 stroke oil as recommended. I wanted to try starting my engine directly out of the box, using the preset carburetor setting.

My R29 started immediately using the included drill adapter, and idled perfectly stable.

This engine sounds incredible!
It has a very crisp exhaust note, and runs all through the RPM range beautifully. Although the fuel tank is small, it will run a surprisingly long time off a single tank of fuel.

The details of the R29 engine are spectacular. Retrol has put a lot of effort into even the smallest details, such as the tiny hardware, simulated oil pump & top-end oiler line, and beautiful CNC made jugs & heads.

I have now ran around 10 full tanks of fuel through my R29, and the engine continues to run better and better with each tank.

What I was most impressed with was the ease of starting. No need to use the drill starter after the engine gets a little time on it, one or two flips of the flywheel is all it takes to bring the engine to life now.

Stirlingkit has released yet another miniature scale engine to be extremely proud of, and the R29 will be another engine loved by their customers. Huge applause Stirlingkit 💕👏

William Swink
knuckle head

it was purchased as a gift to my best friend.

Randy Vickery
Great little engine

The engine started with very little adjustments needed to the carburetor. Fun to play with. It worked better using the pull rope to start it than the adapter with a cordless drill. Detail on motor is incredible.

Gil Garceau
Knucklehead V-Twin R29 by Retrol (Micorocosm)

It is a very nice recreation of the iconic Knucklehead V-Twin Harley Davidson engine. I have started it about 40 times so far and have found it quite reliable and easy to start by hand with a simple twist of the flywheel between my thumb and forefinger.

You can purchase here and get the discount from this link or use the discount code REDRYDER for any and all of the products on Stirlingkit.
Link to Knucklehead R29:
Link to V-Twin Vtwin engines:

Have a great year!

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