I recently purchased a 50cc chinese 2 stroke scooter. It had been sitting around a towing and salvage yard for about 2 years. The scooter started and I rode it home about 1 km. I replaced the fuel and spark plug but now the scooter starts, runs for about 20 seconds then loses power and cuts out. I have checked the carb and it seems ok. I can't find any vacuum leaks and don't believe it is electrical.
Did you remove the jets or just spray cleaner in the carb . I would change the fuel lines as well since gas with ethanol in it will slowly dissolve cheap rubber hoses and have tiny particles that clog up the carb . When scooters sit up for a long time the carb will get gummed up so remove the bowl to remove the jets and use any carb cleaner . A larger main jet most of the time will help performance as the 49cc are so restricted by moped rules and emissions . Check the vacuum lines as they will crack or collapse and most change them out from the start with automotive fuel line from any auto parts store . I would drain out the oil tank too and put in any premium synthetic 2T oil in it . The weedeater grade will smoke more , perform less and more likely to foul out the sparkplug . Look at old plug and ride the scooter down the road at WOT for a bit and inspect the spakplug after it cools to see if its lean with this chart www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html . How high can it hit on the centerstand . Note only let it hit its max for under a second as running it on the CS that high may cause damage or injury if the tire touches the ground and jumps off the CS .
How many miles are on it ? Here is some derestriction tips www.scootnfast.com/scooter/Tuning_mods/De-Restricting.htm . Check the intake manifold for holes or cracks as they will get them as they are rubber instead of metal . Does the exhaust pipe have any dents or holes ? I had a rock bust a hole in the pipe I had on a Honda CR125 and it really messed up how it ran and killed my top end . Tried JBweld but it blew out from my racing engine I built so I had to buy a new pipe . The exhaust plays a more important role in how the engine performs on a 2T than a 4T .
Belts will stretch when worn and should be replaced before they break . Remove the variator weights and weigh them . Most tuners run with 4 or 5 gram rollers . I had 6 gram , tried 4 and mixed them up to equal 5 grams .
Does it have the airbox ? Cleaned the airfilter ?
Done a compression test ? Harbor Freight sells a compression testing kit for 20 dollars . You may need new rings or opt to put on a new piston and rings if it has damage from a soft seize etc .
Post by josesantiago20 on Jun 10, 2012 8:49:14 GMT -5
how do you get compression to come back to the scooter cuz Im also having another problem with the engine it's having problems with getting up to top speed an climbing up into higher gear and only does it when it feels like it this is how it goes . i start it up in the morning to go to work and at first it feels like its in low gear an the RPM'S are high an the scooter will take off in seconds an make it to top speed but from the moment i take off an make it to top speed after about a mile the scooter engine will jerk me like as if someone slammed the brakes then the scooter starts to slow down an doesnt pick up speed again its 6gram roller weights in it ive tried heavy ones an changing the cluch spring to 2500 RPM but everything just got worst . ive even checked the valves an adjusted them but stayed the same . i dont know if its the compression but ever since i took it to a bike shop an they messed with my cluch an variator everything got messed up