79 Puch Free Spirit Project

[RebelRider.Mike]

I did it again! This time the piston ring broke while I was trying to install the piston.

I really thought I was home free once I got them on the piston ok. What is it with these things?

Well, I also bought another set of rings for my old piston just in case. The old piston takes 2mm rings while the new piston takes 1.5mm. Maybe that made the difference, because those went on the old piston just fine, and I installed the piston without incident. I've also had the old 2mm rings off and back on the old piston ring several times without any trouble.


Before installing them, I measured the ring gap to compare with the old rings:

The 0.203mm gauge was pretty tight, but it fit. That's a larger measurement than on that spreadsheet I found earlier, but it is tighter than the old rings.

I got it all put back together and properly torqued, and did a compression test. 101 psi. That's 6 psi less than with the old rings!? I must have a gasket leak, even though I can't seem to find it. I don't know what else it could be.

In the mean time, I found some Magura brake light switches on eBay.

These are used, but they have metal housings and threads. My current ones are all plastic.

[RebelRider.Mike]

Got tired of working on the old top end, so here's a new one:

A 70cc K-Star kit all cleaned up and ready to paint.


I'm liking this VHT stuff. Most spray paints I've used tend to spit and leave bare spots. Unless I put it on thick enough that it runs. This stuff may only be the primer, but it went on smooth and evenly. I'm eager to find out how the actual paint does.

[RebelRider.Mike]

They turned out pretty good, I think:

[John]

VHT hi-temp paints I use all the time on my motors that I restore. Goes on perfect every time and dries quickly.

[mopedlar]

FYI....not all brake switches are the same. Some activate the brake light when the button is depressed, and some activate the brake light when the button is not depressed. If you swap them out and the brake lights are always on without pulling the brake levers, then you have the wrong switches.

[RebelRider.Mike]

That was my experience with VHT also. It was a bit of a challenge to get the paint in between the cooling fins though! But that's just the nature of cooling fins, I think.

I figured it was a bit of a risk buying those brake switches, but I think I lucked out. The continuity breaks when the button is depressed, just like the old ones. And they threaded right on to the lever assemblies. I think the big difference is that my original switches were generic, while these replacements are name brand. I didn't know that when I bought them though. I just figured it would be nice having spares for only a few bucks.

It was suggested to me that the old cylinder should be deglazed, and the new rings should be allowed to break in before I worry about compression. As a mechanical noob, I hadn't thought of that. Well, I now have two complete top ends, and a second E50 engine with no top end, so my old stock parts won't go to waste...

[RebelRider.Mike]

Not much progress on the moped lately. I've been building a Halloween costume for my boy. I did get a couple new mirrors though:

And just for fun, I polished up my intake manifold:

I like shiny things!

[RebelRider.Mike]

In addition to the freewheel and speedometer rebuilds:
http://www.mopedriders.org/viewtopic.php?t=14010
http://www.mopedriders.org/viewtopic.php?t=14014
I also got the new K-star top end kit installed on the engine.


I got an initial compression reading of 149psi! I haven't even worn the parts in yet. I'm hoping to take it on a test ride in the next couple of days.

[RebelRider.Mike]

I had my first startup test for the moped's new top-end kit.

It was a little hard to start, and didn't want to idle. I had to turn the idle screw way in to get it to idle like "normal".
The exhaust seemed clear until the engine warmed up. Then it turned white. That probably means something, but I forget what.
Also, at full throttle, the sound of the engine gets deeper, and there is a lot less power. Maybe a larger jet is in order.
The engine seems to vibrate more than it used to. And there might be a "knocking" sound somewhere. I'm not sure.

The way its set up now, is it has a 14mm Bing carb with a #68 jet (normal for a Free Spirit). I've put a high-flow air filter on it. I've not modified the bottom end of the engine yet. Stock crank, no port matching yet. The exhaust is a stock "cigar" pipe. It has no restricter tubes, and a hollow baffle. (I've heard that Maxi exhaust baffles come stuffed with fiberglass?)

Anyway, I have some research to do, but it did start, and has lots of compression. The new top end hasn't been worn in yet, so that may be a factor. It seems to have the most power at 1/4 throttle.

Here is a video I took of the event. I've eddited it for length:
https://www.youtube.com/watch?v=u2q84JErYxM
https://www.youtube.com/watch?v=u2q84JErYxM
http://youtu.be/u2q84JErYxM
http://youtu.be/u2q84JErYxM

(I don't remember how to embed YouTube in this forum.)

[RebelRider.Mike]

I decided to put a volt meter on the moped just to show off its 12V capability. And also, gauges look cool.


Once I got the gauge, I realized it is meant for a dashboard; like in a car.
Found a mounting kit and added a few spare parts of my own to make it go on a handlebar.


I built my own wiring, and replaced the clear incandescent bulb with a green LED. I'm also trying out an o-ring to help keep moisture out of the cup.


I'm really glad I kept the Cat-Eye battery box as a junction box. It sure is handy for wiring things up near the headlight.


Also, I'm thinking that the new 70cc kit may be starved for fuel. I've replaced the old #68 jet for a #70. We'll see if that makes a difference.


My 5mm bit driver didn't fit in the carb to get the tube out, so I did some custom grinding.


I'm hoping to do a test run tomorrow.

[RebelRider.Mike]

Huge breakthrough today!

I've been reading a book on 2-stroke engines that I found on Amazon.
http://www.amazon.com/gp/product/0071625399/ref=oh_details_o02_s00_i03?ie=UTF8&psc=1

It turns out my little Bing carb has an adjustable jet needle. Its been on the recommended first notch setting, and I decided to try moving the clip to the second notch, raising the needle just a bit.

What a difference! Between 1/4 and 3/4 throttle, I have a lot more acceleration and power. Full throttle is better, but still not there yet. I managed to get the moped just over 30mph on a flat road. (Up from 26) Also, I can now go up the hill I've been testing on with only a little deceleration.

The spark plug is still very clean, so I've ordered a couple larger jet sizes to try out. That should hopefully, help out at full throttle.

[John]

Normal position for the needle is in the middle, someone had been tweaking it before you trying to get possibly a bog out of the bike. good work on your project..

[RebelRider.Mike]

I'll keep experimenting with my jet size and needle position. I've also discovered that the atomizer comes in different sizes too. (If you can find them.)

For now though, I got some new pedal crank arms in the mail!


They're longer and wider than the old arms. And one of my old arms is bent anyway. Makes my foot position feel awkward. These new ones also have a thicker crank end. The right one fits fine, but the left was too thick and wouldn't slide in far enough to get the pin in. I ended up shortening the tube on the frame by 10 mm, and now it fits perfectly!


The old nylon bushing didn't hold up well to removal. But it will work temporarily until I get a new one.

As long as I had the back end apart, I decided to clean up the chains, sprockets, and back wheel. I've been using an improper lubricant for the chains, and its turned into grime and has gotten everywhere. I'll be switching to a proper motorcycle chain oil during reassembly, but first the old junk has got to come off.


With the chains off, the back wheel rotates quite freely. As long as I've got stuff apart though, I might as well get all the wheel parts cleaned up too.


The brake shoes look like they have lots of life left in them, but they are quite old. And I'm not sure they're wearing properly. Maybe they just need some brake cleaner.

[John]

If they have lots of brake shoe material left then scuff them with emery cloth and clean up the brake housing at the same time with emery to remove any rust or glazing on them, good to go. No moped has decent drum brakes, have a good pair of flat boots to drag your feet at times.

[RebelRider.Mike]

Ok, I will do that.

I finally got all the parts I've been working with cleaned up and ready to assemble.


Even though the wheel turned easily and quietly, the bearing grease was still really dry and crusty looking. I got all that removed from the bearing cups.

I just need to clean up the brake drum and the wheel will be good to go.