Modern Buddy

I cant find this exact issue but have found some similar. I have an 07 Buddy 125 that refuses to go over 20MPH, but seems to accelerate fine on the stand. The carb has been cleaned and I have double checked the diaphragm and have also replaced, but no luck. I have checked for leaks, cleaned filters, replaced fuel filter, Fuel petcock, clean gas in tank.

Have you tried cleaning out the CVT, especially the variator? Make sure to inspect the rollers to make sure they are still round.




There is always a chance it is still the diaphragm, those things can be a real pain in the butt.

You should post more info when you are asking for this type of help. How many miles on the scooter? Was it running fine, and then started acting up? What is the maintenance history? A lot of good mechanics on this site, very few mind readers. Triple check the diaphragm. Take some plumbers grease and lightly coat your thumb with it. Drag your thumb all the way around the lip on the carb to put a very light coat of grease in the groove. Work the diaphragm back in, and re-install the cap. That diaphragm can look perfect, but still leak air.

Sorry for the lack of details, lost in the moment. I will check the CVT today and if that look fine check the diagram again as described. Buddy has about 725 miles on it, and sat for many years. Ran fine in 2010 when daughter was going to college, then sat until 2018 when I started working on it. I have completely rebuild the carb and also have a spare, drained and flushed all the fluids. Once I was able to get it running again it had the 20MPH problem.

Unless you poked a guitar string through all the jets or used an ultrasonic cleaner, I would suspect a carb problem.

With that low of miles, don't waste your time opening the CVT. Unless it's been sitting in river water, no way is that your problem. Re-check the diaphragm with a bit of grease. Where in Denver are you?

I checked out the CVT and it is clean, the rollers do have very slight flat spots. Not noticeable to looking at them, but you can feel it.

I plane to put the other carb on and see what happens

Thank you everyone for the input. Replacing the carbs just made it worse, so I went back to troubleshooting diaphragm being seated properly. These things are a pain. I finally used some silicone clear window sealer, jut a tiny bit on the back side of the diaphragm where it seats on the carb. I used a spare dewalt battery to hold it in place for about 5 minutes and put back together. This seemed to help the diaphragm stay in the grooves while I could get it all together and now it goes 50+ again.