Modern Buddy

Hello All,

I have checked around this site to see if there is already a thread about this but I can not seem to find one(maybe searching the wrong terms).

I have a buddy 50(2010), with just over 6200 miles in it. It's my daily driver. Recently I have been having issues with the scooter maintaining acceleration.

What I mean by that is the when I get on the scooter from a cold start I have normal smooth acceleration and can get up to about 45mph, but once the scooter has been running for a while I will start to lose acceleration either when starting from a full stop or from deceleration and trying to accelerate again. Sometimes I can only hit about 20-25mph at WOT. If I pull over and turn off the scooter and let it sit for a few seconds then turn it back on sometime the problem stops but only for a bit, then comes back. Let it sit for a few hours and it's good for about half of my commute but then has the same problem. I should note that I do a lot of WOT on my commute. My commute is also about 10 miles each way, light traffic(for philly).

Things I have done to remedy this problem:

1. I use sea foam, gets much better gas milage(80 or so mpg, up from 55-60), but still have the problem(I have been using sea foam for over 500 miles).
2. Disassembled and cleaned the carb. with carb cleaner(seemed to help, for a few days but now the problem is back).
3. cleaned the air filter(no change)
4. installed Dr. pulley sliders(8.5G) (no change)
5. Check to see if I vapor lock by removing the gas cap when the problem happens(I do not).
6. Changed the spark plug.
7. Adjusted idle, which was set to low.


I should also note that temperature and humidity seem to play a role but not a great one(I live in philadelphia and drive all year round). My girlfriend has 2009 buddy 50, 4500 or so miles on it, maintained the same way ridden the same way and it is totally fine, it seemed to start to exhibit the problem but sea foam cleared it right up. I had to stop riding my scooter for a while and use hers and her scooter has none of the problems mine has(I rode over 1500 miles this year on it so I would assume that the problem would show up it is was my riding style).

Questions :

1. Could the gate belt need replacing, and as it heats up from use expanded a little and then "slips"
2. I have notice the transmission cover gets quite hot(i can still touch it but it's quite warm) after a 30 minutes ride is this normal.
3. Could this be the clutch need replacing/adjusting? I have not done any maintenance on the clutch at all.
4. When cleaning the carb I did not remove the plastic house around the float, could this be a float problem? If so why does it only seem to show up after prolonged use.

Thanks for any answers! I really want to fix this as I need my scooter to get to work every day, plus I just love riding it!

I'm not really knowledgeable on TNG scooters or 2Ts, but a problem that can present itself as the engine warms up is if your fuel/air ratio is too rich. When the scooter is cold, it's like having the choke on and it runs well, but starts to run poorly at normal temps. Did you check the spark plug to see if you were running rich? Just something simple to check before you start buying more expensive parts, jets are only like $4-6 a pop. FYI, outside temp and humidity can minutely affect your A/F ratio. Colder or dryer air is more dense, requiring more fuel to reach stoich (optimum ratio, 14.7:1 for non-eth gas, 14.13:1 for E10, air:fuel), warmer or humid air is less dense, requiring less fuel for stoich.

I can't comment on everything but will say:
- 8.5g sliders is heavy. This might ultimately help top speed but will make the scooter sluggish. 6.5g might be a more normal choice.
- cleaning the carb by spraying the innards with carb cleaner might not be enough. There are small passages that a carb cleaner blast may not touch.
- I agree, temperature and humidity are very noticeable on these small engines.
- If the carb cleaner seemed to help for a few days but then things got bad again, there may still be gunk in there.

So, I wonder if another, more in depth, carb cleaning is in order.

Firstly thanks for the replies. I am going into work later today after a good carb. cleaning. Yesterday in about 90% humidity and +90 degree temps. made my ride home horrible. I will reply back if I have any success, or failures.

Did not change anything. In fact I can barely get over 15 mph. Could this be a roller problem? if I use a slider instead of a roller should I lower the weight? I got 8.5G sliders as that is the stock weight of the rollers.

Things I did today:

1. cleaned the carb, and soaked the Jet in carb cleaner.
2. Cleaned the inside of the Left side cover of dust.
3. Reinserted the sliders and cleaned out any dust build up
4. removed the clutch cover cleaned the dust and build up out(there was a lot).
5. warmed up the scooter, and readjusted the idle.

I should not again that it's about 90 degrees and about 80% humidity. How does one change the air/fuel ratio? is that just the jet?

I should also note that my air box does have fuel in it, but the filter is not saturated.

Does the engine sound like it's revving up to the same level as before?

Have you checked that the choke valve fully opens when the choke is off? I don't know why I didn't think of it early, it was a common problem on Stellas.

Before you start replacing jets, check your spark plug, use a fresh plug to get an accurate reading. This is the only way to test the A/F, other than going to a dyno and hooking it up to an exhaust tester. http://www.dansmc.com/spark_plugs/spark ... talog.html

Also give your carb a good cleaning. Get a carb cleaner kit, they look like a one gallon paint can filled with carb cleaner and a basket so you can soak the carb. Get a carb jet cleaning tool, it's a selection of small wires for poking through the jets. Hit up the air jets, they will be on the intake side of the carb inside the air intake hose, and are little brass circles with holes in them. Check for any restriction in the air intake, including the filter again. Any restriction in the air intake will cause a higher vacuum in the carb, causing a rich A/F.

If this doesn't work, then proceed to rejetting. In a carb, there is two jet "stacks", the idle, which is generally one piece, and the main, which is made up of several parts. The jet needle, located in the throttle slide, inserts itself into the main jet stack, and acts as a valve, controlling the amount of fuel released by the main jet. There is a clip on the jet needle, that can change it's position. Moving the clip up a notch moves the needle down, leaning out the A/F, moving the clip down moves the needle up, enriching the A/F. Changing out the idle jet will affect the air/fuel ratio (A/F) from idle to 1/4 throttle. The main jet will affect A/F from 1/4 to WOT, but have the largest impact from 3/4 to WOT. The larger the number jet, the larger the hole in the jet and the richer the A/F. Changing the needle clip position will affect 1/4-3/4 throttle A/F the most.
http://www.jetsrus.com/FAQs/FAQ_rejetti ... _rejet.htm
http://www.keihincarbs.com/tips/gate.html[/img]

Something you have not tried yet and will cause a big impact on a little 50cc. Try sanding your clutch shoes. They have a tendency to become glazed which will affect acceleration. If they continue to be a problem a new clutch may be needed.