Swapping a Honda 110 engine into a Rokon Trail-Breaker
If that Power Bee is about half dead and you'd like to swap in another engine, maybe something a little more quiet, this might interest you. While Rokon/Honda 90/110 engine swaps aren't uncommon there are a couple problems. First is the engine case on the Honda is in the way making it difficult to run the chain directly from the engine sprocket to the miter box sprocket. This has led to all sorts of work-arounds like tilting the engine, moving the engine forward in the frame, using a jackshaft, moving the rear miterbox, or even extending the bike a few inches. Here are some examples:
It is possible to grind down the engine case for chain clearance, here are before and after pictures of this:
Another issue is finding a Honda engine to swap in. You dont want a beat-up old piece of junk that is hard starting or on its last leg.
Here is an option. There is a Chinese copy of the Honda 110 available built by a company called Jainshe. These engines run about $550 (depending on exchange rate) and you can get more details on these engines here. These come with a 4 speed transmission and even an electric starter. Tell them it is for a Rokon engine swap and they will throw in a free ignition coil.
As for the swap, it really isn't all that difficult but requires basic welding and fabrication skills. Might be a good excuse for you to finally get that MIG welder you have been wanting. The instructions here aren't specific at all because you really need to eyeball everything and work it to your particluar installation, but it can be installed without modifying the main frame tubes. The swap is really nothing more than cutting out the old engine and transmission mounts, setting the new engine in the frame and welding in new mounts. The hardest part is making an intake manifold and exhaust. If you can do without the electric starter you might be able to use a stock Honda 110 intake manifold. Just be aware, this swap requires some work and fabrication. When you are finished you will have a nice, reliable, quiet Rokon with shift-on-the-fly 4 speed, kick and electric start, and Honda replacement parts fit this engine.
One thing that will be very useful to you is this wiring diagram. Check this as you do your wiring, and please forward any corrections or additions. As part of the installation you will need to get a Honda 110 coil as the engine doesnt come with one. If any of you want to write a "how to" on this engine swap I will post it here.
Check the pictures below, get a case of beer and lock yourself in the garage for the weekend.
For a look at another Rokon with a Jianshe "Honda" 110 engine, check here. Note on this one the electric starter has been removed and the carb is located in a different position, where the starter is normally located.