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@davemcr avatar
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LX 50 4T 2v
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@davemcr avatar
LX 50 4T 2v
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Location: New Hampshire
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Hi Again Everyone. Just posted my "Hello I'm a Noob" post and I thank you in advance for all the welcomes! Most everyone said "Get out and ride" and I'd love to do that but I have a problem that I cannot seem to nail down. Here's the general history and here is what I have done so far. Looking for some insight as to what to look for next.

My wife bought this LX 4 50 in 2010 . Had very low miles (about 200) and came from a friend who didn't feel safe in the road. My wife works only about 3 miles from home and enjoyed riding this back and forth in the summer. One problem; there is a pretty steep hill for about 1/2 mile and she felt that she was getting ridden into the ditch by impatient car drivers as she could barely hold 30MPH on the hill (That is the speed limit incidentally, but as you have to take off from a standing start at traffic light, seems real slow). Over the winter of 2010/2011 I installed the Malossi 78cc Cylinder kit with Power Cam and Malossi Multivar kit and added a new drive belt. That worked like a champ and she had faster acceleration and added easy 5mph for that hill and generally was running on the flat 45-50MPH. Then winter hit and we put it away for season.
Summer 2012 arrived and with it starting problems. My Mrs got stranded a couple of times and I had to go pick her and the bike up. Probably gummed up carb I thought. As I was traveling a lot for business I dropped off at local Vespa dealer (also Aprilla, Ducati and some more). I was extremely disappointed by their lack of professionalism and seeming lack of knowledge about the Vespa. They said that they were busy and it would take maybe 3 weeks. It took twice that; it took 6 weeks and they informed me that it was an electrical component and now it was fixed. For the life of me I cannot remember the component that they say they changed, but it ran me $300. So now getting later in the summer and the machine is running again although my wife tells me that it was definitely getting slower and lacking the power it had after the upgrade. Then she got stranded again. This time missing an appointment. She lost all confidence in the scoot and didn't ride again. (I am now certain that it was a crumbling vacuum line). At the time I was so pissed with the local Vespa dealer about the 6 weeks (and that they told me that the new issue had nothing to do with what they had fixed) that I decided that I would fix it over the winter. Well I never did. Ended up draining the gas and using in a photo shoot. Then it just stayed at the office as a prop/decoration - that was summer of 2013. Fast forward to today.

1. Kept the battery on a tender - now holding charge at 11.8v (no issues turning over and starting with that power).
2. Removed carbs dissasembled and cleaned. (several times in basket style can) and blowed out all holes etc with compressor.
3. Replaced both Fuel and vacuum lines - checked for good throughput by sucking on vacuum tube - all good.
4. Checked condition of spark plug (looks normal) and re-gapped to be sure. Also grounded to engine and checked for "good spark" visually. Looked solid and blue.
5. Washed, dried and reinstalled air filter.

So the good news is that she starts easily - by battery or by kickstarter. Idles fine. On stand back wheel barley rotates under idle. Rev her up and the wheel starts to spin pretty hard and release throttle and she backs down smoothly to idle showing no signs of wanting to bog or stall etc. Only problem is cannot get any vroom...... max speed I can get her to is 10-12 mph.

What the heck? What do you guys think I should check for next? She has only 375 miles from new and maybe 120 of those with the Malossi cylinder.

Have not changed oil yet, but planning to do that. The gas gauge does not work and shows empty even when full (probably gummed up sender unit - maybe will drop tank and clean air replace, but want to get running properly before I invest the time). I did also replace the clock battery (what a pain for such a small task). Since doing that, the gas warning light that was on constantly before is now still on but extremely dim and the check engine oil light which was not on is on solid and constant. Thinking that it might be a bad connection at plug and so will open up front and make sure connections are god and tight and add some WD40. I don't think that this has anything to do with the power issue??

Thanks for reading my long winded history, but always thinking that more info is better in a case like this right?

Thanks again for any input!!
Dave.
@andythebuilder avatar
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250 gts, nitroed zip 69cc " the teenager", 200 now 300 lc zip "all grown up"
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@andythebuilder avatar
250 gts, nitroed zip 69cc " the teenager", 200 now 300 lc zip "all grown up"
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rodents
Hi all,
Whilst at my friends motorcycle workshop a guy came in with a simlar problem that it would not rev up and go beyond 10mph, it ran perfect when put away for winter,
My friend took a hold of the scooter, and on its stand cocked it to one side so the wheel was well above the floor and just held the throttle open, there was an almighty thunder crack sound plenty of smoke and a mouse complete with its nest shot out of the exhaust like an exorcet missile.
So check the airfilter and exhaust for a blockage.
Cheers Andy.
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@davemcr avatar
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LX 50 4T 2v
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UTC quote
Re: rodents
andythebuilder wrote:
Hi all,
Whilst at my friends motorcycle workshop a guy came in with a simlar problem that it would not rev up and go beyond 10mph, it ran perfect when put away for winter,
My friend took a hold of the scooter, and on its stand cocked it to one side so the wheel was well above the floor and just held the throttle open, there was an almighty thunder crack sound plenty of smoke and a mouse complete with its nest shot out of the exhaust like an exorcet missile.
So check the airfilter and exhaust for a blockage.
Cheers Andy.
Thanks Andy!! I had already checked the main air box/filter, cleaned and replaced so I know that's fine. I did see mention in the manual that there was a secondary air filter on the exhaust side. I will take the exhaust off and check that as well as the pipe itself. Thanks for the input. I do not have a problem with revving. It seems normal to me, but not sure how to check that in reality.

Dave.
@andythebuilder avatar
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250 gts, nitroed zip 69cc " the teenager", 200 now 300 lc zip "all grown up"
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UTC quote
reving ok
Hi mate,
If its reving fine just loss of take off and speed then it WILL be vatiator or pulley related, the rear pully assembly if not lubed correctly can rust slightly in the slider tube, this then causes the two pulley halves to stay together and not release, which causes the gearing to remain fixed and not change up.
Cheers Andy
@dooglas avatar
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@dooglas avatar
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First thing I would check are carb jets. If the idle jet is okay, but the main jet is clogged - you will not be able to get the engine much above idle. Often hard to tell if there is an obstruction in one of the jets. I just replace them when I disassemble and clean a carb.
@judy avatar
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@judy avatar
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Sounds like they did a bad install. Check your rubber diaphragm on the carb. If it's not seated perfect ypou won't get above 30 on a 150, so 10 sounds right on a 50cc. The fuel gauges on the LX series (early models) don't work right at all. If you change the fuel sender you can get them to work. However the yellow fuel light that tell you when the fuel level is low works very well. When mine come on solid i have almost a gallon left. When it comes on solid do a see how much gas you put in it. I did this a few ties and then do it sporadically to see if it remains the same and it has. Sorry about your problems. I found a great moped shop who can work on mine. Delaer sucks. Good luck and hope this helps.
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Dooglas wrote:
First thing I would check are carb jets. If the idle jet is okay, but the main jet is clogged - you will not be able to get the engine much above idle. Often hard to tell if there is an obstruction in one of the jets. I just replace them when I disassemble and clean a carb.
You could always spend $20 and get a set of Jet Drill bits.
http://www.ebay.com/itm/like/161720379861?lpid=82&chn=ps&ul_noapp=true
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Lets review
So this is becoming a frustration that is making me crazy....

OK, so here are the suggestions;

1. Pulley Issue: I checked the Variator rollers/guides etc and everything is to spec.
2. I did a "squeeze test" of the rear pulley/clutch bell. I found that I could squeeze the plates together although a couple of times it appeared to stick. I dod not take apart as I did not have a tool to hold the clutch bell and loosen the nut.

3. Carb jets. I have removed the carb maybe 5 or 6 times and repeatedly cleaned with carb cleaner and compressed air. I am 99% confident that the carb is working correctly - not 100% but pretty close.

4. Carb upper diaphragm not seated properly or damaged. I was very careful in handling this diaphragm - is there a way to check it?

So leaves me with 3 potential issues.

Rear driven pulley/clutch assembly. I will fashion a tool to check this next.
Carb - jets or diaphragm. There does not seem to be any issue with revving the engine. It also starts easier than I ever remember. Revs up and back down easily. Maybe the rev up is a little "slow". As I do not remember this from when it was running it is hard to say. Could it also be the accelerator pump diaphragm?

Apart from a cheap Chinese carb for $25, is there a Carb rebuild kit that includes the diaphragms for the CVK 18mm? I have not been able to locate.

Thanks again for any insight.
Dave.
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Re: Lets review
DaveMcR wrote:
So this is becoming a frustration that is making me crazy....

OK, so here are the suggestions;

1. Pulley Issue: I checked the Variator rollers/guides etc and everything is to spec.
2. I did a "squeeze test" of the rear pulley/clutch bell. I found that I could squeeze the plates together although a couple of times it appeared to stick. I dod not take apart as I did not have a tool to hold the clutch bell and loosen the nut.

3. Carb jets. I have removed the carb maybe 5 or 6 times and repeatedly cleaned with carb cleaner and compressed air. I am 99% confident that the carb is working correctly - not 100% but pretty close.

Dave.
Air will not clean your jets, you need jet drill set. They are very cheap to buy.
@madison_sully avatar
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@madison_sully avatar
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UTC quote
I'd picture a broken contra spring in the clutch causing such symptom. Engine revs fine, runs fine, variator checks good, but no power transfer to the rear wheel. This being due to the clutch not grabbing hold of the belt. So the belt sort of slides between the driven pulley halves.

When you took the clutch out, how difficult was it to squeeze the clutch apart? It should be difficult; I can do it bare handed, but then, I can do the clutch on my MP3 500 bare handed (with a glove on top to give some padding from the fins).
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@davemcr avatar
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LX 50 4T 2v
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@davemcr avatar
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Location: New Hampshire
UTC quote
judy wrote:
Sounds like they did a bad install. Check your rubber diaphragm on the carb. If it's not seated perfect ypou won't get above 30 on a 150, so 10 sounds right on a 50cc. The fuel gauges on the LX series (early models) don't work right at all. If you change the fuel sender you can get them to work. However the yellow fuel light that tell you when the fuel level is low works very well. When mine come on solid i have almost a gallon left. When it comes on solid do a see how much gas you put in it. I did this a few ties and then do it sporadically to see if it remains the same and it has. Sorry about your problems. I found a great moped shop who can work on mine. Delaer sucks. Good luck and hope this helps.
Checked the carb diaphragm and that was a good tip! Not seated just quite right and once i reset I got up to 35mph. Thanks!
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UTC quote
Re: Lets review
WEB-Tech wrote:
Air will not clean your jets, you need jet drill set. They are very cheap to buy.
OK. Bought a similar kit from Amazon and cleaned again. I have a couple of things though.

1. This machine has a Malossi 78cc kit, Power Cam and Malossi Variator. I have read that the carb should be up jetted to a 78. Will this increase top speed? Right now it sits at 35mph on the flat. I seem to recall that it was at least 10mph faster before.
2. The idle speed seems a little high to me, how do you adjust idle on the CVK 18mm carb? (There does not seem to be a idle adjust screw on the carb body).

Thanks Dave.
@dooglas avatar
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@dooglas avatar
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UTC quote
WEB-Tech wrote:
You could always spend $20 and get a set of Jet Drill bits.
Yes, you could. Or for the same $20 you could buy a whole bag full of new jets.
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