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@marc avatar
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Molto Verboso
06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Molto Verboso
@marc avatar
06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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as usual, karma has had it's swift revenge on my bragadiccio on how clever I am changing my sparkplug.
I hopped on my scoot to ride home from work tonight and opened it up around a corner and got a whole bunch of misfiring, surging and backfiring.
As long as I kept the throttle below half it ran fine, but as soon as I hit it (and as I understand it, the main jet kicks in) it ran like a three legged goat.
First thing I thought was the main jet was partially blocked.
I pulled the carb, without disconnecting anything, removed the float bowl, there was a tiny bit of black muck in the bottom of the bowl.
I removed the main jet, looked clean, removed the atomiser, looked clean, pulled the needle and diaphragm (sp?) from the top, blasted everything liberally with carb cleaner (I have some for my Lambretta :? )and put it all back together.
Now it's even worse....
I kept the hose from the aircleaner off to try and feed carb cleaner into it while it ran, I did get it started, was able to rev it quite a bit, but it started bogging badly and finally died.
I pulled the fuel line off the petcock, under the gas tank but it wasn't dripping fuel, so I re-attached the hose and tried to start it again, no luck.
I noticed there was a lot of gas leaking back out, or, more like pooling in the air intake body, where the hose from the airfilter attaches.
why is gas leaking up there?
Is it the float valve needle or do I need a new gastap?
I've read of similar behaviour before that was caused by a worn out gastap, it's a vacuum affected diaphragm, I believe, but there was no gas leaking out of it when I removed the fuel line.
sorry about the novel here, just trying to give all info in case something rings a bell with someone.
I have 13000 miles on it btw.
any and all suggestions and heckling gladly appreciated ,
cheers,
marc
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Vespa ET-4, Aprilia SR-50 Factory, Bajaj Chetak
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I don't recommend running the ET4 without all the air intake hoses and filters in place. Runs very poorly in my experience. All is designed to work in harmony!

It's easy enough to test the gas tap: disconnect at the carb and put something there to catch fuel, then disconnect the vacuum line at the intake manifold and apply vacuum (suck on the end). If fuel comes out, you're OK. If not then you need a new tap. According to my local shop, the gas taps generally fail "open", BTW.

You can also suck a lot of gas into the system by overfilling the tank (lots of threads in this forum about that) - it gets into the charcoal cannister.

At 13K miles, it certainly wouldn't hurt to get a carb rebuild kit and replace gaskets, o-rings, etc.
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Molto Verboso
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Molto Verboso
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fuel tap check
is done by removing the fuel line at the carb, a bad fuel tap will not shoot gas out when you try to start the engine, or if the fuel just comes spilling out without starting then the tap could possible be bad. have a small recepticle nearby to catch the gas, wear goggles and extinguish your hookah while doing this. are you useing good gas? 91 octane? I try to stay away from gas stations that sell "thrifty"gas, the worst gas i ever got was in barstow calif. at "Terrible Herbst" gas. I was filling up my dirtbike, there was little aomeba's and bric a brac in the gas. i had one of those desert tanks that was semi clear and you can see this stuff floating around. hope this helps
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Molto Verboso
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Quote:
I have just changed my spark plug the 'easy way' for the first time in five years of ownership.
I almost cried it was so much easier, 20 minutes instead of four hours.
The trick is to put the scoot on the center stand, tie a rope or hook a tie down to the rear rack and attach to a handy ceiling rafter and undo the lower shock mount bolt.
Lift the rear of the scoot using the rope and the engine will rotate backwards on the front engine mount giving you ample access to get at the plug, (in comparison to 'normal')
Hey Marc,

I've been thinking about the way you said you change the plug. You jack the body of the scoot along with the fuel tank and hoses. maybe you got gas in the overflow and ET/GT/LX Hard Starting, Rough Idle, or Stalling may help out ?

Good Luck,
Tim

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06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Molto Verboso
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thanks for the tips, guys.
I was under the impression the tap failed 'open' as well, but when I removed the fuel line from the bottom of the tap it was not dripping....
what seemed most unusual to me was the amount of gas pooling in the front intake part of the carb.
maybe I have a stuck float valve.....?
I had put around 50 miles on it since the plug change, and I did the same thing last week and then couldn't find the spare plug I thought I had and couldn't get one locally so I had to put the old one back in, no problems then, so changing the plug is probably not the cause, the motor doesn't tip back that far I wouldn't think.
I have 1/2 a tank of weasel piss in it, got stuck and failed my number one rule of always putting Chevron 91 in it, so I'm thinking now I have dirty gas.
Looks like a carb rebuild kit and a new gas tap for good measure, I have heard of them fail much sooner than 13000, more like 8000 miles and the fact it's not dripping might not be an indicator that it's alright, the symptoms are very similar to gas tap failures I've read of in the past.
I'll pull the carb again tonight and check the float valve, drain the tank and cross my fingers.
I haven't had time to read the links you gave me Tim, I'll get to that today.
cheers,
marc
p.s. love the pic 'I'm watching you'
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Molto Verboso
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Quote:
I pulled the fuel line off the petcock, under the gas tank but it wasn't dripping fuel, so I re-attached the hose and tried to start it again, no luck
You don't have a petcock to shut the fuel off. when you pull the fuel line off the tank it should not drip. It needs the vacuum (engine running) to get the fuel flowing. I learned this the hard way when I needed to change my fuel line. Pull that evap hose before you try anything else. It takes 2 seconds and may save you a lot of trouble.

Tim
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You're going to find this hard to believe Marc, if a new problem crops up, just after you've performed some maintenance, the root-cause is usually found in the area of your maintenance.
Your petcock is fine. You carburetor is fine too, assuming it wasn't damaged by inspection. Your spark plug is most-likely misfiring. You possibly didn't fit your spark plug cap on securely, or you may have dislodged the high tension wire from the spark plug cap, or the CDI.
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@marc avatar
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Molto Verboso
06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Hey cool, this is getting good!
I'll pull the evap hose, I'll check the plug, maybe the cap has popped.
These are things that I would not have thought of trying right away, although it was cold and dark by the time I got home last night and I had had a hell of a Monday already Crying or Very sad emoticon .
When I had a 190 kit put in, at 4000 miles I had trouble with the main jet being drilled out too large oversize and had a huge hiccup right at half throttle and real shitty top end performance.
The symptoms I have now, although completely different, start at half throttle and my conditioned response was that it has something to do with fuel delivery out of the float chamber....
btw what kind of carb is that on your et, Tim?
Mines a Walbro and doesn't look anything like that.
thanks again fella's
you rock!
marc
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Not my carb
That was not my carb. I got the picture from ET/GT/LX Hard Starting, Rough Idle, or Stalling . My ET4 is going out to have the 190 kit put on soon. I have the Sito Plus pipe on now and I'm getting a real dead spot or hessitation. What do you have for a pipe ? What size jet did you use ?

Tim
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As Gary had mentioned check your spark plug cap and spark plug. I have seen them installed incorrectly and when you are riding above a certain speed or corner the cap will get loose and misfire. Also you might want to check the connectors at the H.T. coil and wiggle them around, but be careful though a lot of current goes through that coil.


Sean
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@marc avatar
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Molto Verboso
06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Thanks Tim and Sean,
I'll get the wife to hold the HT lead while I kick it over?
Thinking about it in hindsight, it could well be a bad spark....
I'll hold off ordering any parts until I check it all out tonight.
I had a Sito Plus when my engine was stock and didn't get any hesitation,
I believe the stock main jet is a #85, mine got taken out to a #90 and was horrible, when I hit it it just stopped for a split second, enough to make me feel I was going over the handlebars, then picked up but was a slug, just like a stock engine, not a 190.
I eventually was advised to put in a #87.5 by Steve at Scooterwest, solved the problem immediately, although some guy's say not to rejet at all, just leave it alone.
I now run a Ti Force pipe, not much noticable gain over the Sito to be truthful, sounds like a Ducati though!
Oh one other thing, after a couple thousand miles on the 190 I put in the Malossi Multivar, I was a little sceptical about it when I had the engine done but it really makes a difference and is worth the extra.
cheers again,
this is all good fuel for thought (pardon the pun)
marc
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Molto Verboso
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Ok got home and attacked the plug leads.

Everything there is fine, tried to start and it fired up right away.
Still, at half throttle it bogs and dies.

The trouble with working for a living and having two toddlers and a worn out wife waiting when I get home the last thing I can do is get all deep throat with my carb in the evening....

I'll be thumbing a lift to work for the rest of the week and I'll get at it on Saturday.

I'll pre-emptively order a fuel tap and a carb kit, can't hurt.

Any other tips or experience most welcome,
thanks again everyone.
marc
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Check to see that the air intake boot is completely fastened, and sealed, starting at the air-box down to the carburetor.
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Molto Verboso
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Any luck this weekend ?
Just curious how things worked out for you. Are you up and running again ? I'm still waiting for a test ride on mine. We got snow this morning so it may be a while. Thanks for your advice on my ET4 hesitation problem.

Tim
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@marc avatar
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Molto Verboso
06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Location: Monterey Ca.
 
Molto Verboso
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06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Location: Monterey Ca.
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Hey Tim,
didn't get a chance at it yesterday, wife had to work a full day and it was daddy day care around here.
My three year old and 1 1/2 year old always want to 'help' daddy with the scooter and with small parts around it's can be an excersise in 'calm but firm' parenting.....
not worth it.
I found a hotwheels car jammed in the front fork of my lambretta once, grinding itself down on the sidewall of the front tire every time I braked, thought it was the front brake shoes until I removed the wheel to have a look and out drops a '69 Dodge Challenger
I'll be at it today, I'll post results with what I find.
Did you move the clip on the main jet needle?
cheers,
marc
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@marc avatar
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Molto Verboso
06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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Molto Verboso
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06 GTS250. 00 Yamaha Vino airsal 70cc. 01 ET4 (wrecked). 67 Lambretta Vega125. 48 Beam Doodlebug Super. 1915 Board Track replica 80cc
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so I undid the vacuum line and the fuel line.
gave the vacuum hose a suck and got a big nasty mouthful of gas.
my new tap arrived friday so it was a reasonably painless job to replace (after undoing the crashbar and pillion pegs).
problem solved.
I think it may have been on the way out for quite some time, I found I had to move the main needle down a notch to fix a newly acquired flatspot.
Next up I'll adjust the valve clearances, but it's Oh-beer-thirty here in Ca. right now and the sun is shining after a very wet saturday.
happy trails
marc
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Molto Verboso
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Congrats on your fix

Tim
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