Motobecane Mobylette rebuild

I looked over the carb again earlier this week and I found a passage that I didn’t get cleaned. I was all excited thinking that as soon as I cleaned that up the thing will run like a champ. Well, no go.

So, I sent out an email to Responsible Jon in Seattle. He has a 30 mph carb that will bolt up to this intake. It’s super cool of him to sell it to me for a good price. He has been always been helpful…even back a few years ago when I went to my first rally and didn’t know a damn thing about mopeds. If you haven’t checked out his blog, definitely do. He has all kinds of updates on lots of different bikes. LINK

If this carb doesn’t work, I’ll likely switch it out for a dellorto. I really don’t want to do that if I don’t have to though. This bike is going to get kitted in the future and it would be a waste to buy a dellorto only for a short period of time before everything gets upgraded again.

I’m anxious to get this bike wrapped up…

Well, sort of. I got it to start, but it doesn’t want to run without the choke being on. I’ll probably go through the carb again to make sure I didn’t miss anything. I’ll also check it out for air leaks. Those can cause similar symptoms.

My switch from MoPedLar arrived yesterday. The knob fit perfectly. It was nice to not have to do any wiring, so nice in fact that I decided to spend some time trying to start it. I went to the gas station and got some new fuel. I poured it in and turned the petcock on. I then pedaled like crazy. Nothing.

I can tell that the engine does have compression. It isn’t great, like a new engine or kitted bike, but it is there. I think it has fuel. I’ll have to verify tonight that it is actually making it to the carb, but I’m pretty confident that it is. The only other remaining item is spark. That’s where the troubleshooting comes in. I guess I’ll keep you guys updated.

On Friday I picked up the hardware I needed for the side covers. I put those one and swept the garage floor as best as I could…that floor just gets nasty in the winter. Anyway, here are a bunch of finished pictures. Provided it runs, it’s going to be a really nice bike.

I’ll make sure to get a video of it once I get it started.

After talking to MoPedLar yesterday, who has been cool enough to hook me up with the switch I need, I realized the two dangling wires that I showed in an earlier post are likely for the horn that is missing. I checked the wire colors and they almost match the wiring schematic I have. The colors are just really faded. So, once I receive that switch, I’ll install it, put some fuel in the bike, and see if it fires. I could hard wire the bike like I have done on some of my other projects, but I’d rather not unless there is a problem.

I spent some time last night cleaning up the side covers and figuring out what hardware I need to mount them. I think the bike would look a lot better if they were repainted and new decals were applied, but I don’t want to take that on right now. They look good enough. I’ll get some pictures posted this weekend of the whole bike after I put them on. It looks a lot better now that everything is cleaned up.

I got my custom piston stop finished yesterday. It’s an old spark plug with the ceramic part cut out and a nut welded in. It works great and has adjustable depth.

Having that finished allowed me to pull the flywheel. I knew it had left handed threads, but I started second to guess it when I was leaning on my 1/2″ breaker bar and it still wouldn’t free up. After a couple more pushes it did finally give it up, but damn, no wonder why people screw these up.

Before

After

Since I’ll be working on the wiring next, I could really use a lever for the kill switch. Anyone have one?

Last night I put the carb back together and reinstalled it in the bike. For the life of me I cannot figure out how the choke cable works. I bought a new one and attempted to install it, but it just doesn’t make sense to me. Within the carb, it seems like the bottom part of the choke is fixed and the top part is springy, but I have no idea how the cable is supposed to do anything with that when the sleeve is either in a fixed cup or a fixed elbow. Part of my problem is that it didn’t work when I got it and I’ve never had a chance to see a Moby up close and personal until this one.

So, I ended up putting the carb in without the choke cable; I’ve heard it doesn’t do much on these Gurtner carbs anyway. I also added new fuel line and a new fuel filter. I used black line and a clear filter from treat. I like that combination. I should take a picture of it.

Right now I am trying to rework my piston stop. I made one using an old spark plug. It worked well on my Puch, but it doesn’t reach the piston on the Moby. I need to get that going in order to remove the flywheel. It seems to be stuck on there pretty good.

The next step will be looking into the wiring.

I cleaned up the front fender and front wheel today; although no pictures.

I also tackled the pipe. Like everything else, it was pretty damn grimy.

After 45 minutes of scraping and scrubbing, I ended up with this.

The pipe turned out pretty good though. There are a few minor dents, but overall it’s nice.

I’m not sure why I didn’t put new nuts on the end of the pipe. I have them. I just didn’t do it. I’ll be sure to take care of that tomorrow.

I picked up my new 6″ buffing wheel from sears yesterday. I decided to try it out on the headlight. It was pretty rough.

Here’s the wheel and the compound.

I’m not sure how I feel about the wheel. I does a decent job of bringing out the shine, but I think I can do just as well with the 00 steel wool. I wasn’t able to get inside the ring with the wheel, so I had to use the steel wool. I think it turned out just as nice. I guess it doesn’t require quite as much physical labor though.

Check out how nasty the center stand was.

It’s much better now, but it took me quite a while. I don’t it would get any cleaner without sandblasting it and then painting it…and I’m not willing to do that just yet.

I pulled off the carb and intake. The intake wasn’t too bad, but the carb was nasty. It had all kinds of grime on the the outside and a bunch of VERY old fuel on the inside.

I’m happy with how it turned out, but I might have a problem. I’m not sure how the choke is supposed to work and I’m pretty sure the cable is stuck in there. Anyone know how to get it out?!

I haven’t looked over the wiring yet, but this probably isn’t right.

Second question…anyone know how to get the flywheel off. I haven’t really looked at that either, but all I see is the 3/8″ square drive in the front. Is that just a cover?