Modern Buddy

First of all let me apologize if these are stupid questions. This is my forst time wrenching on any scooter. I'm well experiences in working on cars and sportbikes, but I've never worked on a scooter before.

My son recently purchased a used 2008 Buddy 150. It appears to be in decent condition (about 7K miles on it), starts easily and idles well.

He reported that when on the road, it will initially accelerate well, until between 3 and 40MPH, then lose power under full throttle. If he backs off on the throttle and gently coaxes it, it will eventually get to ~50MPH, which is probably a decent speed for a scooter that size. A total guess on my part.

I had limited time to look at it, but I figured that an easy thing to check would be the air filter. If severely dirty/clogged that could account for the hesitation under heavy load at high RPMs.

When I started taking the screws off of the air filter cover, engine oil started leaking out onto the ground (and me). When I got the cover completely off, the interior of the housing and the air filter itself was soaked with engine oil.

Not having a replacement handy, I cleaned the filter as best I could with solvent (brake cleaner actually), let it dry completely and reinstalled it.

I then checked the engine oil level. According to the dipstick on the filler cap, the level was far too high. THe indicated level was at least 1" to 1.5" above the "full" mark.

Since I didn't have any of the correct engine oil on hand, I carefully darined the oil until I got it down to the correct level.

He reports that it now accelerates nicely, without the dead spot and hesitation.

My question is, what else should I check? WHat are the other regular maintenance and wear items I need to replace or inspect?

I've ordered engine oil, a oil filter, final drive oil, a new spark plug and a new air filter.

As I said, I'm a newbie mechanic when it comes to scooters. Given the 7K mileage should I proceed to inspect the CVT belt as well? Anything else?

Thanks in advance for any and all help and suggestions.

It could be the stator. Check the spark. Is it strong and steady?

At 7,000 you're due for a belt, valve adjustment, roller check etc. Unless you know the maintenance history of this scooter, you are best off assuming none of this has been done. You're issue could be a combination of deferred maintenance items. Wouldn't hurt to run a couple of ounces of Seafoam through the fuel system next fill up. That scooter with a 200 lb rider should be able to hit 60mph fairly easy.
Your list is fairly complete. If mine, I would flush and fill the brake fluid, and replace the fuel filter.

When the oil is overfilled, the engine will essentially choke on it and shoot it through the breather and into the airbox. That was the problem.

Someone may have changed the oil without changing the filter. They drained the oil and refilled the total capacity, not accounting for the old oil still in the filter. I could see that happening since getting the filter off of the 150 is not the easiest thing I've ever done.

Everything you did was correct in solving the problem, so other than checking the sparkplug for oil contamination, you should be good to go. If you want to be really thorough, you can check to make sure the carb isn't gunked up with oil within the venturi and slide. An overfull crankcase will not affect the CVT components.
Good job!

Thanks for all the tips and advice everyone.

Once the parts I've ordered come in I'm going to replace the spark plug, and give the carb a good cleaning.

It's running fine now but I'm also going to replace the CVT belt, inspect the rollers and replace if needed, inspect the clutch, change the engine and drive oil and just generally give it a good once-over. Replacing the front and rear tires as well.

I've ordered most of the parts online, but there is a dealer in the area that can supply me with anything I didn't know or think to order.

I'll report back when I've done it all.