need help kymco super 8 will not go faster than 10 mph

[chris75]

ive just had my kymco super 8 50cc in for repairs riding back from shop everything was fine next day it run fine for a short distance then lost power and wont go faster than 10mph any ideas as to what could be causing this please as i really dont want to be spending any more money of fixing it if i could do it myself also when you first ride it its fine from cold but when the engine warms up is when it loses power tia

[mrbios]

Sounds like a problem with the main jet and / or vacuum leaks.  What work was done in the shop?  Is this a two-stroke engine?  If yes then look at the reed valve - if that gets messed up you loose power and is the exhaust on tight or leaking?

[chris75]

hi thanks for your reply its a 4 stroke and when i had it in for repair it was basically for brakes a bit of a service and new tyres if its the jets as im no machanic i guess it would be better me putting it back in to be done
 

[mrbios]

I suggest the following:
1. since your scooter probably sits alot like many scooters you should purchase and add fuel stabilizer to your gas tank at the next fill up.  It costs around $4 and will treat ~ 20 gallons of fuel and keep it stable for a year to avoid clogging the jets on the carburetor. 

2. The main jet may have gotten clogged buy a chunk of old gas that can jell up.  It is the easiest jet to clean.  To save money you could attempt a basic limited cleaning by loosening the carb boots, rotating the carb and draining and removing the bottom cover then carefully spray a little carb cleaner on the jets and poke a tiny wire through the holes to clean things out.

3. good luck and if you get it working update this thread with the solution.

The videos below take you through the basics and cleaning procedures on a grandvista 250 - all carbs on small engines are basically similar.



Carburetor Cleaning Part I   
Carburetor Cleaning Part II   
Carburetor Cleaning Part III   

[chris75]

thanks for the advice i put the bike back in for repair and its not the carb even the mechanic has struggled to find the fault just when they think they have sorted it it loses power again

[mrbios]

thanks for the advice i put the bike back in for repair and its not the carb even the mechanic has struggled to find the fault just when they think they have sorted it it loses power again

That's too bad.  It sounds really frustrating.  My next line of attack would be further investigation:

1. Has your scooter ever worked correctly since you owned it? 

2. How long have you owned it?

3. Does it sit unused for long periods of time or have you used it on a regular basis?

4. How old is the gas?  If it is old you could drain it and reuse it in the lawn mower or an older vehicle -  mix with fresh gas at the gas station.

5. Take the scooter for a ride, run it at full throttle at 10mph or whatever it will do for about 5 minutes or so.  When you get home remove and inspect the spark plug and take / post a picture.  If the plug is black and fowled up you probably have a spark / electrical issue.  If it is a fuel deliver problem - possibly arising from a bad  / clogged fuel pump the spark plug will tend to be light brown or white from a very lean (and hot) burn.  You might need to remove some plastic first so it is easy to access the plug. 

[chris75]

thanks for the advise it turned out to be something to do with the carb as i have a similar bike i just changed them and it works fine now the machanic cant be very good as his boss was off ill when he came back he told him change the carb
anyway Thanks for the advice

[Mr. Paul]

Glad you got it running Chris.