Scooter doesn't respond according to throttling

[morphex]

May 1, 2022 15:08:52 GMT -5 ghostaroni said:

I have the original from 2003 bando vs belt in there right now, and it is doing just fine;
So I don't think its an aligment or mounting problem.

Heres a pic of the naraku,
The outside peeled off somehow;
But the rest of the belt you can see is brand new.
I could even go with a longer belt than the 788;
I think the polini evo belts do it.








Edit:
I got my scoot to work but getting things off for tuning is quite the hassle now.

I will eventually need a new crank.

I would report it to the seller, and ask what they can do to help you. I'd imagine this is the thing the manufacturer wants to know, and they would also be able to tell why it happened.

[morphex]

May 1, 2022 19:23:06 GMT -5 Zino said:

Carb cleaning is probably needed bad .
Used scooters are notorious for poor carb cleaning.
Many of of us have picked up non running scoots in the spring for pennies and cleaned the carb drained the old bad gas and flipped them for a few bucks .
The jets are easy to plug up.

Carb cleaning is not a tough job take alot of pictures /plenty of you tube videos to follow
I have boiled the brass jets in vinegar to clean them up and a small wire to clean the jets and passages  and compressed air 

I run a fuel stabilizer(sea foam) over the winter in my full Gas Tank.

I added dry gas this morning, and things were good.  Only problem was starting up the scooter after a 10 minute rest, after a 10-km ride, which went steep uphill for a good bit, and then downhill.

Interestingly, shaking it once or twice side to side made it start, and it started and kept what seemed like a low RPM.

I've bought fuel-system cleaner, and I'm adding that later, but I thought I'd let the dry gas work its magic first.

This scooter has a separate oil (injector) tank, would it do any good for the carbs to add a dash of oil directly into the fuel tank?

[morphex]

May 1, 2022 19:40:42 GMT -5 Zino said:

When your scooter fixes itself after sitting it has cooled down .
If it has problems after going up hill then engines has been working harder.

Another problem are for 2 strokes is air leaks .
What color is your current spark plug greyish white ,brown or black?

You can check for exhaust leaks when the scooter is running take a wet rag and plug the exhaust .
If it kills quick you are good if it keeps running that is a problem .

You also can look for air manifold leaks .
When the scooter is funning You can take wd 40 /carb cleaner and spray around the seams of the carburetor and manifold if the rpms change you have a air leak there .

use this diagram to get clues from your sparkplug

OK. I'm trying the simple additive and no-touching the engine approach for now, to see if that works.  Otherwise I might void my arguments towards the seller and/or give myself headaches.

Longer term I'll look at this, I want to change the spark plugs and gear for example.

[morphex]

Gear OIL.

[Zino]

I never add oil to my gas .
On any of my stock scooters or my kitted and piped scoots
That is what the stock oil pump is for .

Adding oil to the gas tank leans out your fuel mixture and can cause you to seize .
Make sure your fuel system cleaner is safe for 2 strokes so you dont blow it up.

There is not a fuel cleaner out there that you put in the gas that can clean as well as a full tear down and cleaning of the carb .

[morphex]

May 3, 2022 18:22:24 GMT -5 Zino said:

I never add oil to my gas .
On any of my stock scooters or my kitted and piped scoots
That is what the stock oil pump is for .

Adding oil to the gas tank leans out your fuel mixture and can cause you to seize .
Make sure your fuel system cleaner is safe for 2 strokes so you dont blow it up.

There is not a fuel cleaner out there that you put in the gas that can clean as well as a full tear down and cleaning of the carb .

I can believe that. However, I bought a bottle which is enough for about 70 litres of gas, so I'll be able to "take it to the cleaners" multiple times.

The engine runs OK now it sounds like, the only problem is that it is more difficult to start now than it was when I bought it. But that might be down to lower ambient temperature. Giving the gas throttle two small twists fixes that as well and it starts right away.

But there has been a change in performance since I bought it, and I haven't done anything, so yes, I am postponing doing anything mechanical until I feel fairly confident that the scooter wasn't broken when I bought it. The seller also failed to mention that the scooter had a broken foot on the main stand.

Cleaning the carb doesn't sound like a very difficult thing either, but I guess I should read up and think about it, so I can adjust it at the same time. Safely.

The fuel additive cleaner says safe for any gas (petrol) or ethanol engine. That must also include 2-stroke, such as scooters, chainsaws etc.

[morphex]

This is the cleaner (should be in English):

www.biltema.no/en-no/car-care/additives/fuel-additives/petrol-additive-2000032151

[morphex]

Hi.

I have a follow-up on this. It started loosing power again, this time going uphill.

The previous time it had been standing still for a day or two, was cold and fairly quickly developed a problem.

This time, I drove it for a couple of kms, went to a store, drove it a km to another store, then a km back to the first store, and then a couple of kms back to my home.

So it was warm this time around, and there is a steep hill just before I get home, and this is where it lost power.

I did the same drill as last time, added some fluid to remove condensation, but it was hard to even start, and it could run a little, weakly, and stop.

I got it up most of the hill, then it stopped. Then I pushed it the last bit, and let it be for a little while.

Then, starting it up, it instantly responded to the throttle and was quick again.

So it is a coming and going thing, and it doesn't seem like whether the engine is cold or not has anything to do with it.

[Zino]

Your scooter stopped going up hill .
Which is another way of saying under heavy load .

Did the engine quit like you hit a kill switch ?
And when you started it up a again after a few minutes it had the normal power .

This sounds like you seized it and then when it cooled down it worked .

All of your symptoms from your posts say clean the carb or rejet the carb.

rejetting carb
Your current main jet may need to go up a size or 2 to give you more cooling fuel mixture under heavy load .
So what size jet and type is in there
Get some jets 3-10% % bigger .
Run the biggest one that performs best for wide open throttle.


pilot jet setting
After the scooter is well warmed up Blip the throttle if the scooter rpm stays high or races up you are on the lean side this has to be fixed .
The screw needs to be richened up .

If the rpm after blipping the throttle drop back down to normal idle speed you are good .
If you blip the throttle and it drops rpms below normal idle speed struggle for a bit then comes up to normal idle speed you are rich this is ok .

If you have and adjustable needle
raising the clip richens the needle
Run the richest setting that performs best at half throttle.

You probably dont need to replace your pilot jet but I would boil it for 1/2 hour in a pot of vinegar to clean it up .
Pilot jets on old carbs get gummed up .
I then would take a fine piece of wire and run it through all the holes before reassembly

Both jets are easy access from the bottom of the fuel bowl in th carburetor the real big brass colored one will be the main jet and the small one the pilot jet .

here is brents more thorough guide for jetting .
www.49ccscoot.com/faq/carbtune.html

[morphex]

OK.

There is one thing I don't understand though. Why do the symptoms come and go?

When I bought the scooter, it had about 10000km on it. Then I drove it, without any problems whatsoever, home, for 30 kms in one day, then I used it a bit on and off, and after having driven less than 100km in one week after I purchased it, it started having problems.

And the first time, it was after it had been idle for a day or two, and it happened more or less straight after I started it up and started driving.

And then it ran fine after that, took it on a longer 20+- km trip, up and down some very long and steep hills.

So it can have problems when the engine is hot, and when its cold. It can have problems on a level road, and up a steep hill.

I can't follow the logic here, if it is the carbs, wouldn't the problems be happening under similar conditions? Are there parts that can get lodged?

I noticed the scooter getting 50 km/h on a longer level stretch before it had problems up the hill last time, and normally the speedometer shows around 46-47 max on a level stretch; does that indicate that it is getting flooded?

[Zino]

Do you have a airbox or open filter
A open filter is even more finicky

A dirty carb can jus t run in the edge of being ok and just a slight hill slight change in humidity or tempature or running against the wind can send your temps into a danger

If you clean and reject your carb you have a safer and better performing tune than now

[Zino]

What does your current spark plug look like ?
Please post a picture 
Looking top down and from the side .


Have you made any adjustment to carb ?
What other changes besides the fuel additive  and dry gas have you tried ?

[morphex]

Hi.

OK, so it seems the carbs could be the problem, judging from what I read here, and how the engine works, and the symptoms.

I used dry gas first, then drove it for a while, then the fuel additive to clean the carbs, gas lines etc. - then I noticed that the scooter was a bit "wet behind", and purchased an additive for the oil, to make the seals expand.

Today I added a dash of fuel system cleaner again. I starts when I give full throttle and use the kickstart. It idles reasonably well, I can hear slight variations in the RPM without moving the gas throttle.

After 3-4 minutes of idling with slight variations in the RPM, I hold either or both of the brakes and throttle the gas. It responds, but after a while, it dies down, and stops giving power. IIRC, it finally just stops.

I'm trying to avoid opening up the scooter for now, I really don't have the time or energy, and it also becomes a question of what I did to the scooter if it goes to small claims court.

See also attached image of the rear end.

[Zino]

with that picture we may have found a fix for you

If that is gas mixture coming out of your airbox .
Leaking down from the top of the air box to the transmission case .

In that volume of wetness you do not have a good seal on your airbox and are pulling in extra air into your scoot .
Your gasket maybe shot .
That extra air would cause your scoot to run erratic at idle (up and down slightly)it would over heat your scoot under heavy load or when the heather changes .

What oil are you adding the sealant too the 2 stroke oil that mixes with your gas 
That wont work. Because it burns up 

Or the Gear oil in the transmission case ?

[morphex]

Aha, OK.

Well that makes sense, the ad said that the air filter has been recently cleaned, and the scooter hasn't been used much the last few years. That might mean that the owner had some problems that he also associated with the air filter.

And it might that the gasket is shot or that the filter was improperly cleaned or that it was remounted improperly.

I'm using oil additive that mixes in the oil tank that goes into the combustion chamber yeah.