A Weekend of Maintenance

This weekend I had the chance to truly get my hands dirty while working on my scooter. I had set a long list of things that I wanted to get done since a good friend of mine was allowing me to use her garage to do the work and I had put off a few things since I am no longer allowed to use my parking place to do such things.

To start off I will go over the things that I needed to fix on my bike… or to be more precise the thing I needed to fix on my bike. In the mornings or when the bike was sitting for longer than a couple hours I was having a very hard time getting the bike to stay running after starting. It would fire up first try but then would sputter out very shortly after that. After a bit of research I had come to the conclusion that it was ether my valve gaps were messed up or my carburetor‘s auto enricher (I call it a choke but I think it works a bit different than that) was messed up. This problem has been causing me a lot of trouble and the colder it got outside it seemed to make it worse and unlike many of the other problems that I have had in the past it was getting worse instead of better over time. It was robbing power from my already not super powerful scooter until the engine was warm and I couldn’t get the engine warm because I couldn’t idle it because it was stalling every 30 seconds.

So to start off the weekend I had to get everything ready to go. I had already purchased a new carburetor and free flow air filter. I wanted to up jet the carburetor as well which was an adventure in its self. I called my normal scooter dealer and they didn’t have any in stock, called a motorcycle dealer and they thought they had something but ended up not having the right size, they gave me 2 more places to call… no luck. I started trying to find a scooter shop that may have the part I needed. I even resorted to calling Vespa… never again because they are rude. Finally I was able to find a place that had it available and I was all set along with a better quality spark plug. Next was getting a new feeler gauge that is small enough for the gap on my engine, and a new quart of oil which neither was very hard to get a hold of. So now that all the parts and tools are ready to go so all that was left was the work to be done on the bike.

I woke up on Sunday morning to find out it was 32 degrees Fahrenheit outside… I don’t do freezing friends. So I got a bit of a later start than I was planning but I doubt I would have been much use after riding in the super cold so instead I waited to ride over to my new found garage in sunlight with an extra 10 degrees which was still a less than enjoyable journey. After thawing out it was time to get started.

Every good mechanical job on a scooter starts by partially disassembling the scooter. In a car you have a hood that allows you access to all of the engine components, this is not true on a scooter which some parts are always accessible but most of the engine is hidden under the plastic fairings. I had pulled some of the plastics off in the past but this time Pepe was almost completely naked. Once I had the plastics off I was able to get started with my long list of things that needed to be done.

This list included:

  • Checking and setting the valve gap
  • Changing the carburetor out for a new one with an 85 main jet
  • Changing out the air filter to a free flow air filter instead of the stock air filter
  • Changing out the original spark plug with a higher quality one
  • Last but not least changing the oil.

Valve Gap

This is something that after reading quite a few posts on one of the forums that I frequently use (scootdawg.proboards.com) that is a constant problem with the Chinese GY6 engines. From the sounds of it this is also something that needs to be adjusted multiple times throughout the life of the scooter as well. To adjust the valves first you need to remove the valve cover of the engine. This is done by removing the 4 bolts that surround the head and pulling the valve cover off. The first time I did this I had to tap the valve cover to get it to release but this last time I didn’t have any trouble pulling it off. Once the valve cover is removed you will see the top end of your engine. Inside you will see a few things: The valves on the top and bottom and to your right you will see the timing chain and gear. There are 3 holes in the timing gear: 2 parallel holes and one larger hole in between them. You need to line up the parallel holes on the side of the engine case by turning the timing gear to what is known as top dead center (You can see this in the photo here).

You accomplish this by using a wrench in the fan to turn the engine over. Once the engine is set to top dead center you can use your feeler gauge to check the gap between the valves. When I went to check mine I couldn’t even slip the .003” gauge into the slot so my gap was way too tight. I was shooting for .004” so I started by loosening the lock nut on the valve with my wrench and then I could adjust the valve height with needle nose bringing it down to the gauge then backing off slightly before locking it back down, then rechecking to make sure that a larger gauge would not slip in. Once this was done I closed everything back up and fired up the engine to see if it would stay started cold and low and behold it did. So this was in my opinion the single item that actually fixed the major problem I have been having with my scoot.


Replacing the Carburetor, Air Filter and Spark Plug

One of the main reasons I wanted to switch to a new carburetor was that the stock carburetor was not adjustable at all. Even though it was working it just seemed to me that being able to adjust the carburetor would be better in the long run. I also wanted to change the main jet as well which was much easier to do without the carburetor being installed in the bike.

To change the main jet you need to flip the carburetor over so that the float bowl is facing up. Then you can unscrew the 3 (sometimes 4) screws from the bottom of the bowl and pull the bowl off the carburetor. Then in the middle of the floats you should see a brass screw with a hole in the middle of it. Using a flat head screw driver you should be able to back that screw out and replace it with the new jet. Once you have everything done inside you can close it back up making sure the gasket didn’t get moved or fall off during the change.

Now it is time to attach the new carburetor and in order to do that I needed to take off the old one. I have never done this before and really have to admit I was flying blind. I was able to see where the different tubes and wires needed to be attached but I had no idea about what order to do thing in. So I started with the gas line. I had read somewhere that I needed to clamp that off while I was working on the scoot which made sense to me. I didn’t have a clamp so in a moment of genius or luck I thought of using a hair tie to fold the fuel line in half and secure it with the hair tie. With the fuel line out of the way I moved onto the throttle cable. On either side of the tube there are nuts that clamp the loosening the back nut will give you a bit of wiggle room with the front nut which then can be loosened past a divot in the threads that looks like you should be able to pull the throttle tube out of but that didn’t work for me. I had to unscrew it all the way back and then I was able to work it all the way down. That freed the cable to be able to unlatch the dongle that holds the throttle cable in place on the carburetor. This is where I started to have fun. I didn’t drain the float bowl so now every time I moved the carburetor around it was pouring gas all over the place. Lesson learned: Drain the carburetor before moving it around. The rest of the process was pretty easy, just unclamping and disconnecting each of the lines and wires to make sure I knew where they would hook up on the new carburetor, and then reassembling the new carburetor in the old ones place.

At this point I also opted to remove the stock air box since I had up jetted the carburetor I thought I would end up with enough of an air/fuel mix to be able to handle more air into the system. There are 2 mounting bolts that screw into the bottom of the air box that comes right out and then the air box is free to be taken off. Once the air box was off I was able to install the free flow air filter in its place which just attaches with a cable clamp.

Once that was all put back together I also put the new spark plug in place. I then started it up and after getting enough gas into the new carburetor it fired right up. I’m going to skip the part about how to adjust the air/fuel mixture on the carburetor since I’m not really sure exactly how to do it and that will leave something for a later date. The first thing I noticed was with the new free flow air filter the bike was much louder. After double checking everything I put the seat back on and went for a test ride.

The test ride showed a couple things: First it had much more get up than it did before between 0 and 25 mph. and second it started to choke a bit when it got over 35 mph. This was no good; even though I liked the added acceleration I wasn’t willing to sacrifice performance on the midrange to get it. I took Pepe back to the garage and mounted the stock air box back on and took it for another test ride. Looks like Pepe doesn’t like free breathing and much more prefers to be a bit restricted. Everything seemed to be running very well and I was very happy with the way Pepe is running now due to the adjustments and upgrades.

Oil Change

I have changed the oil in a scooter many times before but every time I changed the oil I had drained the oil out of the filter cap instead of from the oil drain bolt which I never knew existed before this oil change. Can I just say it was 10 times easier to drain the oil this way rather than changing it threw the oil filter cap.


It was a very successful weekend of wrenching on the scooter.  I learned a lot about how to do things with my engine and gained a lot of confidence when it comes to pulling things apart and putting them back together. I think this is my favorite part of owning a scooter. There is something very rewarding about starting with a project and ending up with a better situation than you started with.  Sorry if I was a bit long winded today guys but thanks so much for reading and I hope you enjoyed it. As well as a big thank you to SB for letting me use her garage. Be safe out there friends.


2 Responses to “A Weekend of Maintenance”

  1. Good deal there then, great pics, still waiting for my scoot to get shipped to me 😦

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