Injector Fuel Additive Gone Wrong

July 6th 2025

I recently (week ago) got a 2008 Burgman Executive with around 34k km. This is a 650cc "luxury" scooter meant for road trips and being almost like a replacement for a car.

It was in generally good condition, except the fuel economy. The fuel economy was ~18km/l (42mpg); and that was with me driving like a grandma. I wasn't very happy with that as people on Fuelly were getting around 20km/L.

The thing still had a ton of power (got it to max speed once), so I didn't think it was compression or valves.

So I started leaning towards the spark plugs, intake air, or the injectors. Spark plugs were old, but 34k km shouldn't have gotten them this bad. The intake filter wasn't the cleanest but it wasn't too bad. So I thought I would try to clean the injectors.

In my infinite wisdom I decided to try to treat a fuel tank with "STP Super Concentrated Fuel Injector Cleaner, 155-mL". The bottle treats 79L of fuel. The fuel tank on the Burgman is 15L, so I went to the store and put the entire bottle in, LOL.

Well needless to say that was a very bad idea.

Within maybe 50km it started to chug like it was a horse at low speed. There would be times were I would try accelerating and it would give me like 25% of the power for a few seconds, and then snap back to 100% power. When the engine gets hot it would start acting even worse, like it was right about to stall completely. Other times it would vibrate like hell and sound really bad. The fuel economy dropped to 16km/L (37mpg).

I thought at first maybe it was knocking, so I added some 97 octane. That didn't help.

Then I had the hunch that basically I was sometimes running on one cylinder at low RPM. Maybe the injector cleaner dislodged something in the barely legal fuel line and it got stuck in one of the injectors.

Now, at one point I had a similar thing going on with my car, Gutless. Gutless had a really bad engine shake and a misfire on the #3 cylinder. After so much troubleshooting I cleaned the injectors in a poor-mans way. I wrapped duct tape between the input of the injector and the red straw from a carb-cleaner can. And then I used two wires and a car battery to actuate the fuel injector. After two painstaking attempts I eventually got them clear enough to get rid of the massive knock. Not wanting to repeat the headache, I decided to grab a cheap chinese kit that basically makes it easy to connect the can of cleaner to the injector, and an adapter to the battery.

Anyways, the plan was to apply this piece of kit to the fuel injectors to see if that was the issue.

First problem was to get rid of all of the fairings. For this I referred to the service manual (readily available with a quick google search on some Russian websites ;) ). Basically, follow every step to get the "front box" off the bike. Unfortunately, this involves removing the plastics from the handlebar, the piece underneath it, the entire front part of the bike (including the headlights), the maintenance hatch, and even the ignition key-thing.

I also don't have a garage, and I decided to do this repair in the street. Even though it's a gray area. Bylaw says that you can only do "minor repairs". Considering I thought I would be done within an hour or two, I guess that counts as minor.

For removing this front piece on the bike I would strongly recommend a technical butter knife.

Just before removing the "front box" you need to remove the ignition (or at least remove the screws so that you can move it out of the way). For this you'll need a Security T30 Torx Bit. This bit is a regular T30, but it has a hole in the middle. I found this collection of bits from Canadian Tire to work perfectly. For reference, the service manual specifies "09930-11930: Torx bit JT30H and 09930-11940: Bit holder".

Eventually I got to where the fuel rail and two fuel injectors are. I was quite worried that I would have to completely remove the throttle body. The service manual wasn't entirely clear about if I actually had to do that to get to the injectors.

Fortunately, I found a bit of a shortcut. Without removing the throttle body, the two bolts holding the fuel rail are hard to get to because part of the frame is in the way. If you use a 1.5 inch long Phillips head and some vice grips and effort, you can get the bolts off and torque them down after again!

Anyways, after this part it was pretty easy. I first removed the three electrical connectors nearby. Then, I removed the fuel line from the fuel rail. There was about 250mL of fuel in the line. I gently pried the fuel rail up, and then without twisting, removed the fuel injectors. Then I hooked them up to the battery (check polarity), and stuck the other end in the white piece that came with the kit. Then, one hand pushes the white piece + injector onto a can of carburetor cleaner, while the other connects the positive lead to the battery.

Thankfully, my hunch was right! One of the fuel injectors worked way worse than the other. But after maybe a good 30+seconds of actuation they both worked well!

All-in-all it took me 1 hour to get the fairings off, about 30 min to remove the injectors and clean them, and about another hour of getting the fairings back on.

After the cleaning the rumble went away, the bike had way more power at low rpm, and the fuel economy jumped almost instantly to 20km/L on the dot (47 mpg). Probably even higher if I took it on the highway.