This is a frame job!

It's been over a year since I parked the Cub. When we last saw her, I'd taken her for one last ride for the season and nearly lost the swingarm bolt in the process... Then a year of nearly continuous business travel intervened, my flight time, some other totally legitimate excuses... I've replaced the nut to the swingarm bolt since then, and I've decided to take care of a little frame repair that I've been trying to ignore for a while now.

In a nutshell: The engine is designed with two bosses that function as mounts- run a long bolt through each boss and two lugs per mounting point and you've got your engine solidly connected to the frame. My engine bosses are in good shape, and the top mount lugs on my frame are still solid. The rear mount lugs are... less so. See below, for example:

Fig. 1 - Oh great

Fig. 2 - Ugh, that one too

See where the frame makes a C shape? It should make an O shape. In fact, that engine mount boss should be totally concealed. 

I've known about this for a while, and just put off doing it because 

1. The loads are low
2. The engine's not rocking around when it's installed
3. I've been impatient to ride

Low loads or not, I do eventually need to fix the frame. It can't be good to ride around on half an engine mounting setup.

My plan is to make some little steel lugs that fit into the existing formed section of the frame back there- basically tiny "D" shapes out of 1/8" flat stock. I'll line them up and shape them in-situ on the engine, clamp everything in place, then tack them on with the engine in place. Once they're tacked, I'll drop the engine off and finish the welds. These are pretty concealed areas, so just a shot of primer to protect the metal would be fine- no need to spend the money on matching the color until I want to redo the whole frame. Goal? Next weekend. Until then, it'll be lunch breaks and sneaking off on the weekend.

Since my last post (which was quite a while ago, granted) I talked to an electrical engineer friend of mine about the engine and electrical system, and he suggested that before I spend the money on a whole new powerplant, I should try replacing the battery with a capacitor... I think perhaps there might be some electrical system experiiments in my future. Not like I don't have experience with that recently...

The Proprietor

Cub 2.0 - Introduction

It's been over two years since the last post, wherein we discussed a few little creature comforts which I'd added to Cub (like a brake light). It's been about that long since I did anything worth mentioning with her, actually... I rode around a little bit at the end of last summer, but lost my swingarm nut and nearly died... and bought a plane in the intervening time anyway, which took up a bunch of time and money... and this year has been essentially one long business trip, so I haven't even seen my poor Honda in months. Or my wife, for that matter.

I've had some time to think about it a bit, though, and I've come to some important realizations:

1. I love motorcycles, and it's a real shame I don't have one reliable enough for regular use.
2. Cub is a really special bike- fun, simple, and full of character.
3. The engine is small, but will keep on ticking with shockingly sloppy repairs.
4. That said, her electrical system sucks, which is causing the reliability problems I alluded to in item 1.
5. A bike like that deserves to be ridden everywhere.

I do love my Cub, and it would be really nice to be able to justify taking the time to clean her up enough to install that beautiful new seat my brother-in-law gave us as a wedding gift (so that Audrey can ride her around as well). But here's the question: do I really want to spend the time and energy to properly repair a half-century-old engine that can do... maybe the speed limit on a 35 mph road? Not really.

Enter Lifan. There are swarms and swarms of Cubs and Passports in various shapes and sizes all over the place, and Lifan has a whole line of theoretically drop-in replacement engines for them. The displacements vary, of course. There's a 49cc, like the stock motor... and that's nice, but I still keep coming back to my same problem of not having enough power to keep up with traffic on the roads just outside the city limits. 

I'd rather put their 90cc engine in instead. For one thing, it's about the same cost as a 49cc. For another, the 90cc Passports were awesome bikes. For a third, 90cc is a respectable size for a city commuter/occasional Home Depot runner with a single rider, and has enough power to take a second person to the coffee shop without too much smoke. Mileage shouldn't be too bad, either- 90cc is still going to be way north of 60mpg, and the benefits in terms of oil consumption and leakage would be definitely worth considering.

So Cub gets a new engine. We get a more reliable, more capable motorcycle. The garage gets cleaned out once I don't need to keep a box full of spare parts around just-in-case.

-The Proprietor

Witnessing the power of this fully armed and operational motorcycle

Of course, when I say "power..." And, for that matter, "armed" or "fully... operational," what I really mean is "I've ridden to work more than once and I'm not dead, and Cub is in the same number of pieces as when I started." Let's make sure we set some appropriate standards for success, here.

I've added a few parts since last post:

1. I installed the air hose, which dramatically changed the engine noise. With the air hose in place, and thus the air filter, the engine sounds a lot deeper than you'd expect from a 49cc. Granted., appropriate standards again- it sounds like a single cylinder small displacement, but it sounds like a small displacement that's as large or larger than the smallest gas lawn mower offered at Home Depot. No, really- I checked.
2. I replaced the speedometer cable, which means I don't have to ride around with a handheld GPS zip-tied to the handlebars anymore. Since the top speed is so low, you could argue that the important improvement here is aesthetic... and, since it reads a little low, I did end up putting a sticker on to remind me to add a couple MPH, which looks a bit out of place. Still, I have a reading, and that's progress
3. I installed a brake light lens, and I've got bulbs in the headlamp and tail lamp. So far only the brake light works, unfortunately, but I'm working on that a bit.
4. I added a heavy spring to the rear brake pedal for return force. This has the unfortunate side effect of blocking the brake light switch, though- I also have a bad feeling that the spring and bracket combination I installed is going to harm the structure in the long run, so that'll change fairly soon.

I've still got to sort out the lights, and I'm having problems with the fasteners for various bits of trim and equipment of the "all non-standard sizes" variety... it's a bit frustrating, but I think I'll start looking for part numbers instead of just sizes that fit. I've also got a pretty nasty smoke cloud on cold starts, and an oil leak that makes me blush a little when we talk about the EPA at work... It's on my list, of course. I'm planning a full engine overhaul over the winter- new piston rings, new gaskets, proper valve seating, honing, etc. For now, though, I'm going to focus my attention on side cover knobs and mirrors- I think that having most of the Cub aesthetic will be nice, and being able to see the cars passing me while I slowly creep up to the speed limit will improve safety dramatically...


I have to say, some of the things on my list aren't exactly small, but overall I'd assess Cub as being in decent shape. I'm pretty proud of her- not exactly built for performance, but definitely fun to ride. And, of course, I can accurately claim that I've resurrected a vehicle from the dead- which is instant gearhead credit. I may even get enough done in the next year to justify entering Lost in the '50s next summer, despite the actual model year. How cool would that be?

-The Proprietor

Clutch- a friction opera

Perhaps "opera" isn't the right word exactly- but that makes it sound more exciting.

So first of all- a 49cc motorcycle doesn't need a title or registration in the state of Idaho... so I've been riding around for the last couple days worry-free. Nice to know, and it means that Audrey can (and has) steal Cub from me to ride herself. Not that I blame her. It fits her, and she looks better on it than I do.

We left off with Cub running, but not able to idle in gear. I suspected a clutch issue (that was pretty obvious), so I dug out the clutch from Spare. I stripped and reassembled it, and learned a lot in the process. It's a centrifugal plate-type wet clutch, which is sort of the logical step between a simple chainsaw clutch and a traditional manually actuated motorcycle multi-plate wet clutch. The clutch housing is attached to a grooved heavy plate by means of screws and springs... well, here, look at this:

So the drive shaft basically comes in and spins the heavy plate and the clutch housing. A set of plates locked to the housing spin along with it. Sandwiched between those plates are a set of friction plates, which spin freely inside the housing but are locked to a central core. The core becomes the output gear, which sends power to the transmission. Between the first set of housing plates and the heavy plate are the rollers, which are really just little tube sections. They fit into angled grooves in the heavy plate- see them up there in the figure? So as the engine runs the heavy plate, clutch housing, and housing plates turn with it. The rollers stay in the deep part of their grooves, forced there by the angle of the grooves and the pressure of the springs. As the engine spins up, the rollers' inertia shoves them outward, into the point that the heavy plate grooves make with the first housing plate. That forces the housing plates and the center plates together, and friction causes them to spin together. That spins the core, which spins the output gear. It's a bit more complex than the simple centrifugal clutches you get on go karts and weed eaters, but it also provides a bit more finesse starting from a standstill.

I found that when I disassembled the spare clutch, there are stop screws which keep the springs a bit pre-loaded, and if those are removed the heavy plate basically just shoves the rollers into the friction plates and jams the clutch engaged. I assumed that this was the problem with the clutch on Cub, as well, so I was surprised to find the screws installed correctly. When I pulled the clutch off and broke it down, I found that someone else had gotten into the clutch at some point- but they'd put the rollers back in perpendicularly. They didn't fit into their grooves, which was actually what was forcing the clutch to stay engaged. I put them back in oriented correctly, and the next morning had a motorcycle that would start smoothly from a standstill. It's the little things in life, right?

That was my Saturday night. Yesterday I had to revive the battery, because it had become sulfated from sitting discharged, and it had discharged because the charging circuit wasn't hooked up. So today, I rode Cub to work (which was monumental on its own) and inserted a connector to tie the battery into the charging circuit. When I rode home and put a voltmeter on the battery, it was reading 6.3V- plenty of juice. 

It's really exciting to have actually taken it somewhere for the purpose of providing transportation, rather than just on a test ride. And yet more exciting that the components are coming back online. Next goal is to get the headlight and taillight working (and the neutral light and speedo light as well). And mirrors. And side cover knobs. And... that whole list of things from the other day. Fun stuff.

-The Proprietor

Needs and wants (parts)

I've spent some time examining what I need to do to get Cub street legal, and what I want to do to get her looking the way she deserves to. It's not quite a Venn diagram, but there is some overlap. So, in no particular order, the needs for legality:

1. Brake light (including a red filter)
2. Brake pedal spring bracket (to establish more positive brake pedal return force)
3. Headlight
4. Speedometer cable (possibly a new speedometer, but I know that the cable is damaged, so we'll start there)

I took care of part of numbers 1 and 3 today, by going to buy bulbs. Now it's just a matter of determining why the lamps don't light when I turn them on... At least it's an easy system to ring out. The spring bracket is a part I can fabricate myself with some scrap steel- not worried about that. That just leaves the speedo cable- I know they're out there, hopefully for cheap. We'll see.

I should also call the DMV and inquire about what I'll need to provide to get a title (or whatever) and a registration, then go find an insurance policy that makes sense. That shouldn't be too expensive, given how small Cub is, and how cheap they were originally (incidentally, looking at my serial number narrows the build date down to the first quarter of '66, making her 46 a couple of months ago). Still, the only reason I want or need insurance in the next month is so I can do my operational testing on a street where I have room to run up, and those are usually not full of potential claims.

So it's a pretty clear path forward to registration, I think (but no real hurry). After covering the essentials, my list of wants is much longer...

1. New leg shield- current part has a piece missing
2. New head lamp ring, without pitting and a bad coat of silver paint
3. Knobs for the side plastic covers- I can hack it together with bolts, but that'll get old fast
4. Permanent connection for battery charging circuit (not that alligator clips aren't useful)
5. New rubber packing between center and left engine case pieces (I actually have this, but it requires complete disassembly to install)
6. More appropriate air hose for the size of my carburetor
7. Piston rings? Smoky exhaust- likely oil consumption
8. New throttle cable
9. Chain guards
10. Winker relay (unless I have one hidden in there somewhere, which is a possibility)
11. Battery with posts to attach starter motor circuit
12. Rubbers for foot pegs
13. Mirrors (might actually be a street legal thing)
14. Neutral lamp bulb and speedo lamp bulb
15. Actual red filter for brake light (if I end up making one with clear red tape)
16. Cool decal for the side plastics - I should really have a Ride-By-Night logo
17. Cool key chain - perhaps the old Honda motorcycle logo?

There are a few things to do as well- right now I'm focused primarily on inventory. Later this week I'll put together an action list, I think. And continue to enjoy my success, of course.

-The Proprietor

Change in priorities

Yesterday I'd pulled the head off my cylinder to clean the valves, with a plan to clean and lap them. One of the nice things about having such a small engine, of course, is that you can do that by hand. This morning I took a wire brush and cleaned the carbon deposits off, then lapped the valve seats with a bit of extra white toothpaste (the whitening means a higher silica content- bad for enamel, good for old valves). After re-installing the cylinder, and in the process discovering that A) I need a torque wrench and B) it's a damn lucky thing I have a box of spare engine parts with extra cylinder studs lying around in the garage....

This happened:

The kicking you see me doing to get the bike going at first belies a clutch problem- she won't idle in gear, so I have to get some movement going manually first... but the engine runs and the drivetrain does work. Two years, and a couple weeks of dedicated evenings got the job done. I'm ecstatic- it means now I can justify taking time to work on cosmetics, minor parts, etc. Hence the title, as a matter of fact- now my priority isn't getting the engine to run at all, but getting it to run like a Cub should.

More to come- I'm working up a list of things I need and things I want to be ready to take her on real roads, and I'm starting to source where I can get the mirrors, speedo cable, etc I'll need.

Good day today.

-The Proprietor

Two weeks

In two weeks, I've made more progress on the Cub than in two years of owning it. Seriously... Which is fine. She's never taken up space that wasn't available, really, and I've never regretted buying her. Before Audrey and I left Atlanta, I'd tried to hook the battery up to see if the electrical system worked, and after grounding the battery to one of the terminals of the starter solenoid, diagnosed an electrical problem. Some of you should be scratching your heads... I know. Looking back, of course that wasn't going to work- the battery wasn't ever really grounded... I finally got around to printing off a proper wiring diagram for that model of Cub and took another crack at it two weekends ago, with this as the result:

Sure, not too exciting in terms of noise and spectacle, but I'd hooked up a new battery correctly, and was using the button to make it work- pretty exciting to me.

The next logical step, of course, was to try to start the engine. Less success here, unfortunately. I was able to verify that I was getting good spark consistently, and better spark after a bit of contact cleaner. A buddy of mine helped me adjust the timing to about where it should be, with no luck. I replaced the old gas with fresh premium, with no luck. After making other adjustments elsewhere (and noting along the way that I needed to replace the head cover gasket), I took the exhaust back off the bike and kicked the engine over. Here, I found that the fuel/air mixture was spraying from the exhaust port of the cylinder. Last night I took the head off, removed the valves, and found some carbon deposits on the exhaust valve... I'm not sure if it's in the right place to affect the seal, but it's worth a cleaning anyway. I'm also planning to check the tappet clearance once I reinstall the head (got some feeler gauges the other day). If it's not the seal itself, perhaps the rocker is just holding it a little bit open.

My plan at this point is to focus entirely on getting the engine running- that's the key goal. I've got a repair to the engine mounting holes I need to do, a lot of cleaning, and more than a few components to track down before I'm ready to call the project complete, but once the engine is running, the bike should be rideable, and I'll be able to take the cosmetic and detail repairs in whatever order I like. 

I'm pretty optimistic about getting this bike running in the next few days. I've learned a lot about engines, and it's been a lot of fun (I think I'd just procrastinated so long it was just ingrained before- funny what a small success will do for work ethic). Besides, I'm an engineer, and I want to build a plane- this is turning out to be good practice for that. I'll post a set of pictures tomorrow, and (maybe with some luck) a video of the engine running.

-The Proprietor