1972 SL100 Lifan 200CC 163FML Engine Swap and 12V Upgrade


Active Member
You may be good with that i was wrong and the onevon my bike
Was a 17 toot
I now have a 15 and 14

Boat builder

New Member
What Jetting did you put in it? I just put on in my 1978 Honda Xl125, I still have to build an exhaust and finish making a new wiring harness for mine.


Bikes: 2014 Honda CB500F, 1972 Honda SL100
I'm just using the jetting that came in the included carb for now. Don't know what that is. Once it's rideable, I'll report on the jetting. Seems okay at the moment. As you can see in the video, it starts easily ands revs freely, but that can change with a load on it.


Bikes: 2014 Honda CB500F, 1972 Honda SL100
Battery/electrics box fabrication has begun.

The box will be positioned to clear the new air filter, which is a 42mm foam eBay item.

I also ordered a new Chinese clutch cable to fit the engine. It's the same overall length of the original cable, but has a longer unsheathed length.

Original cable:

New cable:

Seems to work well.

While replacing the tail light with a 12v 1157 bulb, I noticed the last time the bike was tagged was a month before my wife was born, ha ha.

Next, I'll fab brackets to hang the battery box and weld the assembly together. After that, I'll replace the rear sprocket, rear tire and rear brake shoes.

At that point, a little jerry-rigging should make a test-ride possible.


Bikes: 2014 Honda CB500F, 1972 Honda SL100
Battery box fab continues.

I've used two bolts tacked to the bottom to mount the regulator/rectifier.

Brackets were made for the CDI and starter solenoid.

I marked the positions of the brackets in place, then tacked them on.

I just need to mark and drill the rear mounting points for the box. Unfortunately, my hobo freight step drill broke. So until I get a new one or maybe splurge on a real Unibit, I started on the rear wheel tasks.

A quick test fit of the new sprocket confirms it is correct. The bore of the new sprocket is a bit tight, however. I suspect it's due to the thick, black powder coat. I'll sand that down for a smoother fit to allow for side play from the chain.

With the old tire off, I find the usual surface rust on the rim. These old chromed-steel rims are so beefy, though, I'm never very concerned.

That's all for now. After cleanup, the rear will get a new sprocket, new shoes, and a fresh tire.



Bikes: 2014 Honda CB500F, 1972 Honda SL100
Thanks Alex jb, I appreciate that. I do a fair amount of aluminum sheet metal fab for my job as an aircraft mechanic. I was also really fortunate to be taught welding by an excellent welder at my previous job. I'm still nowhere near as good as he, but I do okay.

Cxman, that's my faithful mutt Hank, who is far more photogenic than myself. :)

Sent from my iPhone using DO THE TON


Bikes: 2014 Honda CB500F, 1972 Honda SL100
So, it's been a balmy 25 degrees or so here this past week. Cleaning rear wheel parts in water and Simple Green in my unheated shop space was as appealing as eating dust bunnies.

As such, I decided to work other angles. First, I decided to finish battery box fab work.

What can I say. Harbor Freight was having a New Years sale. Though, when are they not having a sale?

I used hardware store rubber grommets and some aluminum spacers to make rubber mounts for the battery box. Results are only ok. Would order beefier grommets in the future.

See the mount below.

With that done, I decided to indulge in some lathe work, and make some knurled nuts to hold down the seat. The seat simply has two studs protruding on the bottom rear. These go through tabs on the frame. The knurled nuts go on the studs to fasten it down.

I loaded up some 1/2" 6061 aluminum and faced the end.

Laid out some lines.

Turned it down to leave a raised area for knurling.

Knurled the raised end.

Drilled to #8 for M6x1.0 tap.

Chamfered the hole and tapped it.

Parted it off, then cleaned up the other end and drilled it up a bit larger half way for lightening and visual interest.

Rinse, repeat, and presto!

In place on the bike.

Weather is supposed to climb into the scorching 40's next week. So, with any luck, I'll get the rear end buttoned up soon.

Until next time!


Bikes: 2014 Honda CB500F, 1972 Honda SL100
So. Time for an update!

The last few weeks here brought many things, including 12" of snow. In Portland, Oregon, that means utter chaos. As a result, shipments of crucial motorcycle parts and materials clearly of great importance to the American people (like me) were delayed. But, the snow has gone and we're back up and running.

I began cleaning the rear wheel. Rust was brushed from the rim.

While cleaning the hub and spokes, I noticed more than one loose spoke. Hmm...

I soaked all the nipples in WD40 for a couple hours and checked them for freedom. About seven nipples were seized. Several others were stiff. And one broke upon turning the nipple. Sweet.

I ordered spokes and set the wheel aside. Wiring then began.

I split open the harness provided with the engine and began to rearrange it to fit the SL100 both dimensionally and functionally. I plan to add turn signals, so that was also a consideration.

At this point, I realized I needed additional wire. The Lifan engine, being a Honda clone, conveniently uses the same wire color code as Honda. I want to do this properly, so I ordered wire in the correct color combinations.

Eventually, the snow began to clear and the goodies came rolling in.

This is an NOS aftermarket muffler I bought off eBay. I will be replacing the included hardware to spruce it up a pinch. Seemed a little more fun than the ubiquitous Chinese pit bike muffler.

Mandrel bends to start exhaust fabrication.

A sheet of 1/8" neoprene to line the battery box.


The new spokes also came in. In my next post, I'll finish the rear wheel, install the drive chain and make the battery box liner.

Boat builder

New Member
That thing is looking great! What diameter tubing are you building your exhaust out of? I just finished building mine out of 1-1/2", which was oversize. I had to machine a custom flange to weld the exhaust to. Finished that a few days ago and I took my xl125 with the 163 engine in it for its first real ride today. Road it 40 miles around town and took it up into the mountains. It runs pretty good, but I'm getting a lot of popping from decelerating. Its a really fun engine, and had quite a bit of power.

I have the same carb, but under the name K&F PZ30. I ordered a a keihin jet kit that should work with this carb and will try and figure out the best combo, I'll let you know when I get it tuned better.

Keep up the good work!



Bikes: 2014 Honda CB500F, 1972 Honda SL100
Thanks Boat builder! That xl125 looks fun. I actually just test rode my setup two days ago. I used the original exhaust in a temporary configuration. Engine ran well, but I only did a couple laps around the block.

I'm going to use 1 1/4" tubing for the exhaust. I was thinking 1 1/2" also, but I measured the port at about 1 1/8". As such, I am using 1 1/4" by 16 gauge tubing, which puts the inner diameter at around 1 1/8". I also will be turning out a flange on my lathe for it.

Hashing out the wiring harness now. Looking forward to some real riding!

Boat builder

New Member
Any Updates Forklift. I have close to 700 miles on my bike right now. So far so good, It took me awhile to figure out my sprocket combo and I am about to upgrade to the VM28 carb per cxman's advice (Now that the shock of spending all the money fixing the bike has worn off). Hopefully you figured out the wiring diagram, it took me way longer than it should to get me wired after I made a new harness. Still forgot to wire up the horn but I should do it soon.



Bikes: 2014 Honda CB500F, 1972 Honda SL100
Yes, I really need to update. I got pretty busy with non-motorcycle life activities, but I've been working steadily on the SL100 all the while. I'll try to post something longer tomorrow. The bikes current state is pictured below.



Bikes: 2014 Honda CB500F, 1972 Honda SL100
So, first, let me agree with der_nanno. That XL is a sweet little bike, Boat Builder. Second, I apologize for my lack of posts. I've been busy...

It may seem as though the above pictures are unrelated, but not so! All of the pictured items contributed to delayed progress on my little green alley-bike.

That said, progress has indeed been made. I shall now elaborate.


Bikes: 2014 Honda CB500F, 1972 Honda SL100
I did, in fact, finish the rear wheel.

I have no photos of the spoke replacements, but it was pretty straightforward. If you've never trued a spoked wheel, it's an interesting experience. Because I have a dial indicator, I was able to get total runout all around to less than .5mm radially and .2mm axially. Not going to get any better from an old welded steel rim.

One thing to note, I was unable to use the EBC grooved brake shoes I bought on the rear drum brake due to a difference in the way the springs were mounted on the shoes. The shoes on the bike were in good enough shape to re-use, luckily.

Next up, I'll post about the wiring harness rebuild that ended up happening. I decided to use Deutsch connectors, so stay tuned!

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