CARB HELP! ET2 Problems turned me into a baby-gearhead
Post Reply    Forum -> General Discussion
Author Message
2003 Vespa ET2
Joined: 09 May 2019
Posts: 2
Location: Boston
Tue May 14, 2019 2:18 pm quote
I have read so many forum pages on here over the last few weeks. I've read through manuals, and poured over exploded diagrams for days. I have literally woken up at 3 am and not been able to get back to sleep for thinking about fuel lines. More than once. I def don't know much- but its much more than I did! At this time last month I could barely SPELL carburetor for the love of cheese, let alone having taken it out and apart over ten times now. I've gotten to know it so well, we're moving in together and getting a houseplant.

I have learned a TON! I'm no clueless girlie when I talk to my mechanic now. Awwwyeaaa! Engines are interesting as hell! So I've found a new hobby/obsession with a dash of empowerment- Awesome!


This is bc my 2003 ET2 won't start. Button NOR kick start. I bought her on craigslist :'( she ran beautifully for 2 days then *blowing raspberry sound* NUTHIN.

I've gone thru the 2-stroke page, the won't start page and maaany others multiple times.

Here's where I am at this point:
1. Replaced spark plug/ checked for spark? YES sparks
2. Replaced the battery
3. Fuses OK
4. gas tank @ 3/4
5. oil full
6. air filter OK
7. cleaned fuel/vacuum line
8. @#$%ing fuel tap replaced
9. carb disassembled, cleaned
10. Jets clear
11. good lord what else??? who knows I'm probably forgetting something.

Some LOVELY mechanics at Best of Boston in Roslindale (if ur local, go see them for your car things, they actually don't even do small engines but worked together looking at it with me for 2 hours just for the fun of it!)

Long afternoon getting our hands very dirty and sucking on vacuum tubes like some real crazies, we tested every component and found that fuel is not getting sucked into the carb.


I've bought a big can of Gunk Carburetor & Parts Cleaner and am just hanging on a prayer that an overnight soak will do some fairy god mother stuff and solve the mystery before I have to replace this carb only to maybe find that doesn't help either- idk. GULP!

Forgive this long post, i figured as much info as possible would be best?
#1- Before i dunk this dirty hoe into the magical dip and hold a seance for my scoot, there is a little plastic cap jammed in there below the oil valve. As I understand it I have to remove all plastics? how do I get that guy outta there?
Also- how about the brass bits? What's the plan for them?

#2- If this doesn't work and I haven't gouged my own eyes out as a result, does anything else come to mind for anyone about what THE HECK is goin on in there??


My lil dog is giving me dirty looks. He LOVES to cruise in my backpack.

How do I get this guy out?

Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2010 Can Am Spyder RT-S, 2012 Honda NC700 DCT
Joined: 02 Mar 2013
Posts: 5031
Location: Madison, Wisconsin
Tue May 14, 2019 2:23 pm quote
I'm going to go out on a limb here and suggest you replace your vacuum lines.

There's this picture, strewn all over this site, of some vacuum hose that just fell apart, into PIECES. PIECES I say.

Anyway, that's where I'm gonna start.

'Cuz you said, no gas was getting to the carb. The vacuum line is important in this process.

And that other reason.
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1996 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1382
Location: Veria, Greece
Tue May 14, 2019 2:28 pm quote
If fuel / vacuum lines are OK, no vacuum could mean, broken reed petals, air leak, bad seals, worn piston / rings. Start from the reed petals which is easy...

Unscrew the manifold...

Take out the reed valve and check the petals...

Granturismo 218
Joined: 04 Feb 2013
Posts: 5058
Location: South Carolina
Tue May 14, 2019 2:45 pm quote
Will it run with starter fluid?
If not, check the compression.
If it does, back to the carb, lines, etc.
LXV 150 Midnight Blue (SOLD)
Joined: 06 Dec 2010
Posts: 2545
Location: Bangkok
Tue May 14, 2019 4:09 pm quote
When you crank it with the starter can you feel air coming out of the exhaust?

Take the spark plug out put your finger over the hole and press the starter can you keep your finger there?

Were you riding when it stopped? Made raspberry noises and then slowly died?
Joined: 22 Oct 2011
Posts: 3808
Location: Tega Cay, SC
Tue May 14, 2019 4:12 pm quote
Do not take that part out of the carby. The only thing you need to check would be the float, float needle, gaskets and jets. If is back on the bike, check for spark again. Got spark? Then you are a third of the way there. As mentioned, spray some instant start in the carb mouth ( filter off) and should at least pop. That happens, then you can look to fuel delivery , vacuum lines, petcock, fuel line. Got fuel to the carb by putting applying vacuum to the vacuum line and observing fuel flow? Then, you can move on to the carb.
GTS 250ie Super, BV250, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 324
Location: Winston-Salem, NC
Tue May 14, 2019 5:08 pm quote
As Motovista asked, will it start with starter fluid? It will only run for a few seconds while it uses it up. Reading your post it sounds like you found your problem, the petcock or the hoses are bad. Put good hoses on then try sucking or simply putting vacuum to the vacuum line. I hate the taste of gas so I use a mustard bottle to provide the vacuum. If new hoses solve the problem then clean the jets and passages in your carb, there are plenty of YouTube videos. If no fuel from the petcock then that's your problem, has them very affordably. I am working on an ET4 of the same vintage and it had a bad petcock. If it doesn't start with starter fluid then there is something else wrong. Start by seeing if it starts then work on getting fuel to the carb and cleaning the jets.

There may be other things but lets start here before someone has you replacing the crank. Report back to us what you find. Always start with the simple stuff because that usually all it is.
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 38
Location: Cambridge, MA
Wed May 15, 2019 7:43 am quote
when you say it wont start can you be a lil more specific? does it not turn over? does it turn over and over but nothing? ran so we know it can run ... if its not turning over just follow these steps for electric start

1 - be sure key is all the way clockwise in the on position - you should see the oil light light up
2 - be sure kill switch is not on - turn it on and off a few times to be sure its making good contact
3- be sure you are holding a brake when you attempt to start (try one then the other just to be sure)
4 - If its not turning over, listen for a click when you press the start button..

for kick starting you just need to do 1 and 2

if all the above are working and you are hearing a click (relay) then your starter might be bad

if its turning over and over and over but not starting:

1 - fuel...we need to be sure its getting can check by simply opening the carb float drain screw and see if the bowl drains out
2 - spark - i would try a new spark plug just to be sure...take out your old one and look at it..if the tip is all wet from fuel it wont start
3 - air - be sure your airbox is hooked up properly and not sure no little critters crawled in and made a nest (seriously this is an issue)

if you can make a little video that might help us .... let me know how you do..i have a 2003 et2 as well...
2003 Vespa ET2
Joined: 09 May 2019
Posts: 2
Location: Boston
Wed May 15, 2019 1:13 pm quote
UPDATE: My responses- you are all so wonderful and helpful!!
@madison sully
Lines are ok, but they're old so might as well swap em out anyway, can't hurt

Oohh interesting! This is the first I've heard this idea. Manifolds and reed petals and such - huzzah! I have afternoon plans now! Will update!

Haven't tried starter fluid yet either. Will try it!

My mechanic friend tested the exhaust, now that i think of it, i don't remember noting the outcome. I will test the spark hole idea.

Oh... so the raspberry sound was me being dramatic and adding my own sounds effects. I was making a giant fart sound in my mind when i wrote the post. Frustrationnnnn

But no i wasn't riding it when it wouldn't start.

Will def try some starter fluid

Mustard bottle?? You're BRILLIANT! Y didn't i think of that?

So when i had the help of my new mechanic friends they used the same lines and simulated the vacuum by sucking at the thing while i tried the button start. Eventually it would turn over when he did this. So once i can get the fuel where it's supposed to be all is well in the world! I just gotta get it there.

Petcock is aka the fuel tap right? This lil fella? (Pictured below)
I already replaced that guy already, which now i actually don't think i needed to do after all but o well. Not too $$ for that one.

It gets raring itself up but won't turn over. You know, like rarrr raarr rerrr and on like that forever with no kkeckkVROOM in sight.

I'll go take a video in this brief rain respite.
For now looks like the plan is to get new fuel lines, check it those reed petals (what an adorable name) and try the starter fluid.

YOU ARE ALL AMAZING! ! Ty ty ty ty


2003 ET2 (SOLD); 2004 GT200
Joined: 22 Oct 2016
Posts: 237
Location: Atlanta, GA
Wed May 15, 2019 1:45 pm quote
Fingers crossed the new lines and/or reed petals do the trick! While getting to the petals, make sure to check the intake manifold. I had to replace mine as it found to be cracked shortly after I got it.

As an aside, if the petcock (aka fuel tap) you replaced is in fact functional, definitely hold on to it. I ran through three of them on my ET2. It's always good to have a spare.
1980 P200E in progress, 2005 Stella 2T
Joined: 20 Jul 2018
Posts: 336
Location: Staten Island, NY
Wed May 15, 2019 2:07 pm quote
Full speed ahead. Love it! Keep going, you'll sort it out.
Joined: 22 Oct 2011
Posts: 3808
Location: Tega Cay, SC
Wed May 15, 2019 3:24 pm quote
And if I may politely suggest that next time you have a problem, present it here first. If you go tearing into the scoot, you may make a problem worse. Fuel and vacuum lines are fairly cheap and easy to change out. The petcock may or may not have been at fault. And for some bizarre reason, many people are always ready to blame any problem on the carburetor. These engines are fairly simple and can give you many years of service. The trick is to do the proper maintenance and don't tinker with a good running scoot. ET2s are a lot of fun, ride safe and often.
BV 350
Joined: 22 Nov 2016
Posts: 248
Location: Nebraska
Wed May 15, 2019 4:51 pm quote
Maybe think about picking up a bottle of fuel system cleaner at your local auto parts store and adding the appropriate amount to the next couple of tanks of gas, after you get it running.

Sounds very much like you have the problem isolated as a fuel system issue, and are on your way to a solution.

Occasionally I find a broken key on a flywheel, which allows the flywheel to rotate on the crankshaft and change the ignition timing, often to the point that it won't run. Still has fine spark, though. So sometimes worth checking ignition timing as part of the diagnostic. Still have a timing light for that.
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 38
Location: Cambridge, MA
Thu May 16, 2019 6:32 am quote
Tierney is spot on...its better to try to troubleshoot one thing at a time... we can help

usually the problem isnt something as complex as you might think...often i have had to learn that hard lesson...if it was running fine before its usually something simple...often used bikes have loose hoses and nuts and bolts and you wind up spending the 1st few weeks just tightening everything down...dont get discouraged...its still much cheaper than a new bike....and a 2003 et2 has the hiper2 motor which is arguably one of the best 2stroke 50cc motors manufactured...the emissions are as low as a 4 stroke

back to your issue at hand... I'm also thinking that this is fuel related...i doubt theres an issue with any of your lines or a faulty carb ...i bet its related to your fuel vacuum...or simply the idle jet is clogged....

Can you snap a pic of the carb all mounted in the bike? I want to look at how the hoses go..sometimes a hose can be kinked...hoses - i mean the fuel in and vacuum ...

idle jet - this can be clogged real easily...take the carb off..take the bowl off...(let us know if its dry or if fuel poured out)..there are two jets that you can is big - thats the main..the one beside it is the idle jet... unscrew them both with a flat head screw driver...hold them up to the light and be sure you can see clearly thru them...i use a nylon bristle from a dustbrush and i ream that idle jet with the bristle...spray both jets thoroughly with a can of carb cleaner....before you reassemble, hold the carb so its sitting upright..flick the float up gently and be sure it can go up and down without sticking...put your jets back in (let me know the size that scribed on the main jet (bigger one) if you can)...put the carb back
Granturismo 218
Joined: 04 Feb 2013
Posts: 5058
Location: South Carolina
Thu May 16, 2019 7:02 am quote
Re: Maybe
Jimding wrote:
Maybe think about picking up a bottle of fuel system cleaner at your local auto parts store and adding the appropriate amount to the next couple of tanks of gas, after you get it running.
It's a two stroke. A lot of the mechanic in a bottle stuff makes it burn hotter and melts the piston and rings.

Step one, try to make it start with starter fluid.

If it does, go through the fuel system. If not, check the compression. IF the compression is low, you can replace everything in the fuel system and it's still not going to run.

Jixaw has a very good idea. Take a couple of photos of the carb and the fuel tap with everything hooked up.
After you do try to start it for a long time, pull the spark plug and see if it's wet. That will tell you if gas is getting in. What brand is the spark plug and what number is on it?
Team Scooter Trash for Petfinder Foundation   vespa scooterwest scooter west Motorsport Scooters   Scooter Parts Company
Post Reply    Forum -> General Discussion
[ Time: 0.6607s ][ Queries: 25 (0.1433s) ][ Debug on ]