Help Diagnose and Do My Own Tuneup

bigshinybutton · Post by **bigshinybutton** » Sun Aug 09, 2015 3:13 pm

So my Buddy 125 has the following symptoms:

Periodically stalls at stop (low idle)
Multiple muffler Pops during deceleration.
Fuel Vapor smell when off and sitting.

She's due for a tuneup (1900 miles) but I thought I would do it myself and solve these problems rather than take the bus back from the shop.

Anybody have documentation or step by step or suggestions on what to do to fix issues?

THANK YOU!!!!

lefthandedrighty · Post by **lefthandedrighty** » Mon Aug 10, 2015 2:09 am

well, those things might all be related

some of those things could happen from running too rich

the fuel smell could be from un-burned fuel sitting in the exhaust

which could also explain the popping from the pipe too, the vapor is igniting in there

maybe the plug is in bad shape and is causing the fuel to not ignite completely

either that, or somehow your jetting went bad or the carb needs to be tuned and/or cleaned

Dooglas · Post by **Dooglas** » Mon Aug 10, 2015 5:32 am

lefthandedrighty wrote:maybe the plug is in bad shape and is causing the fuel to not ignite completely
either that, or somehow your jetting went bad or the carb needs to be tuned and/or cleaned

We are talking about an 8 year old scooter. Yes, check the plug. Replace if needed. Try a carb cleaner such as Seafoam. If that doesn't do the job, time for a carb cleaning.

bigshinybutton · Post by **bigshinybutton** » Mon Aug 10, 2015 1:39 pm

Interestingly, the problem started after I changed to a new plug.

Yesterday, I adjusted the idle and both problems went away.

I also removed the air cleaner, which was a bit dirty, and blew it out.

The fuel filter smelled like fuel but didn't have noticeable liquid (which it probably would not since it would vaporize, correct?

I will pull the plug and take a shot of it.

How do you check the mixture?

babblefish · Post by **babblefish** » Mon Aug 10, 2015 8:01 pm

What sparkplug did you use? Should be a C7 (if NGK, a C7HSA).
It is normal for the air filter to smell like gas. A small amount gets backflushed into the filter box when the engine is running.
The idle mixture screw (also known as a pilot air screw) on the carburetor may need a bit of adjustment. It is located on the left side of the carb, near the bottom, and on the engine end (where it mounts to the intake manifold). You can find YouTube videos on how to do this. There two types of idle mixture screws, 1) adjusts amount of air in the mixture, 2) adjusts the amount of fuel in the mixture. Yours is #2, adjusts the amount of fuel. So turning it in (CW) leans the mixture and out (CCW) richens the mixture. The factory setting for a 125cc engine is 2.25 turns out from closed. One caution, be very careful when comletely closing this screw. Do NOT tighten it closed, turn until you feel it just seating or else you will damage the screw and it's seating surface.

good luck and have fun.