Modern Vespa

This is a quite a tale, are you sitting comfortably? Then we will begin:

Relatives 2006 GTS250 was parked up working perfectly 2 weeks ago under a large carport protected from the elements.

Due to take it on a 3hr ride we attempt to start it.

It turns over but does not fire.

Check Engine Stop switch - but of course it wouldn't turn over with it off anyway.

Check petrol (gas), can hear some sloshing around - indicated half a tank but fill it up any way.

Remove sparkplug - plenty of spark.

Remove air filter - curious hole 1 inch by ½ inch at intake with some black around the edges (mmm first clue - though we don't realise it at the time.)

Spray Ether based starting spray can stuff in the air intake - nothing.

Remove spark plug and spray a bit in the combustion chamber - small rumble on starting.

Remove air filter pipe to ECU - is something stuck inside like the foam piece? No its not.

Undo Fuel line to injector - turn it over - plenty of fuel.

Remove fuel injector (accidentally break brittle electric plug) - steal fuel injector of another relatives GTS250 nearby (mmm have to explain that one to them later).

Could it be that the ECU is not sending signal to injector?

Fuel injector is spraying fuel out nicely - put new fuel injector in - turn it over - nothing.

Battery goes flat - could it be that ? Get 40Amp charger out and put it on. - turns over no start.

Pull out injector a bit turn it over - it sort of starts - switch it off quick.

Mmm it will run with injector half out but not in. Would seem it is starved of oxygen but the ECU is just a throttle body with a butterfly valve - and it's not blocked???

Okay think a bit - maybe the exhaust valve is stuck shut and gasses can't get OUT of the combustion chamber. This is going to be fun as getting to exhaust valve is not easy.

Back is hurting from leaning into engine bay / laying on the ground.

Okay lets do it - take off exhaust to get to header to at least see if valve is shut.

Kick over engine with header and LAMBDA sensor still attached - IT STARTS .........
Mmm is the sensor being tricked with no exhaust on as its now getting a mix of exhaust and open air?

Look at exhaust - looks fine - try blowing into it - no air will go in by mouth either end. Start air compressor - still can't get air in.

Take exhaust off other GTS250 and fit it - bike runes FINE...

Go back to original exhaust consider cutting it open resigned to the buying a new one.

Bash it very hard against pine cattle race post - mmm what coming out of the end? Bits of mud and spiders? No wait they are European Wasp larvae (an introduced pest here) that make nests in holes made up of spit and dirt.

They have completely blocked the exhaust in 2 weeks!

Pump water in the exhaust and clear it - take other exhaust off fit original - bike runs perfectly.

4.5 hours to diagnose and fix the problem (and new injector and air filter foam required to fit to other GTS). Oh and the black hole in the foam air filter? Must have been the engine blowing black through it on the first attempt to start it.

In 40 years of fixing engines / vehicles of all kinds never came across this!

Still just shows you a process of elimination will generally find the reason.

Thanks for reading.

Paul S

Thanks for the story. We have something similar where I am that are called Mud Daubers. Build nests in small places with mud. To get the air filter cover off a used 2006 GTS 250, I had to clean the mud nests out of all the recessed screw holes. Not as frustrating as your experience but thank you for sharing.

I would have guessed mice. I have had problems with mice over the years, once in my Kawa GPZ , when starting the bike all kind of junk would shoot out the tail pipes, mostly nest material.
In my muffler on a different motorcycle it was full of sunflower seeds. I feed the birds in the winter, and there was about a pound of black seeds inside, the bike smelled like chinese take away for a few weeks. Luckily it did not hurt my engine. I since cap the tail pipes of my machines, even my leaf blower tube, I would start it and a mousse would blow right out the tube.
I found out in my experiences with mice problems in engines, that they like to eat the coating of the coil wires, I had that happened in my snow blower and lawn tractor. So if you park your scooter in the basement or garage or even outside in the winter mice will get in where it's warm and nest so cover the tail pipe and feed the birds away from it.

Maybe they thought your GTS was family.

I guess you should plug the exhaust pipe and maybe the air intake with a ball of steel wool when you park the scooter for any length of time. You can get stainless steel scrub pads at a hardware store that will work well and they don't rust. Just don't forget you did it.

Big Daddy gets points for the family comment !

My Vespa gets used enough to blow them out but the othe one doesn't so blocking the pipe is not a bad idea, just got to remember it's there I suppose or it may end up like the potato up the car exhaust trick.....

Paul S

most of them have a hole at the end of the plug that you can just run a string though and toss it over the handlebar or something near the ignition to remind you

https://www.amazon.com/DEALIKEE-1-07-Motorcycle-Streamer-Silencer/dp/B0777P4Y97/ref=sr_1_6?ie=UTF8&qid=1548102169&sr=8-6&keywords=scooter%2Bexhaust%2Bplug&th=1

"It was big, said 'Vespa' on the side, looked like a cool place to nest..."

Well I guessed.

While working in Indonesia a mate had a old Chinese 50cc two-stroke scooter as a village runabout. I wouldn't start. I poked around with it and noticed there was nothing coming out of the exhaust when cranking. I removed the exhaust and low and behold it fired right up.

Yes mud wasp built a nest tin the end of the muffler.

wow. So wasp hives they are pretty hard too unlike bee hives.
Great story and process of elimination.
I wonder is using water to clean the exhaust a good idea in general.

So Wasps nesting in the Wasp's zorst...

Must be a regional issue. Mechanic I worked with in Dallas on mine that was like the 2nd or 3rd thing he checked on non starters. Would put his hand on the exhaust and see if it was "popping" air on his hand. Dirt Dobbers and Mice was his reasoning.

We have two kinds of pests here. The ones you experienced and the ones that weave something like cotton. Both are the usual culprits on clogged exhausts...

I disassembled an air-cooled VW motor in a dunebuggy many years back, and found that a small bird traveled all the way through the header past the exhaust valve, and into the cylinder. Of course, this was after trying to run the motor...

Hey Paul..

I'm from Vic too and I've had the same thing happen! And yep, it drove me nuts. The wasps blocked the 1 inch exhaust in less than a week.

If I leave the scoot for more than a few days during summer, I stick a stick up the exhaust before I try and start it.

Sounds like you need to bung up the exhaust with something when you are not using it.

Mud daubers are notorious for stopping up 2-cycle small engine mufflers as the diameters are so small it's in their genetic size range to store spiders they stockpile. The engine will not run when they've done their magic and over the years seems to be worse than I once experienced. Like many pests they seem, at times, to be winning? I know to look there first when winters over.
My main nemesis is rodents, house mice and deer mice, rats in barns and chipmunks. They run in cycles, more snakes, then more rodents, then back again...
I never have plugged exhausts with PTW's, it's chewing wires and nest building that's the problem. Certain brand vehicles they get up in the air ducts, some as far as the cabin air filters.