Scooter Exhaust Leak Help

[MrKymco]

(i posted this at another forum, thought I should bring it here)  

Hey guys

My scoot is running fine, running great. Idle is good, performance good. Never stalls, dies, or quits. So this "sound" it's making, which is sort of a "gurgle thump thump," I figure is an exhaust leak, and a neighbor friend says the same.

Kymco Agility 125, much like any other gy6 125 with all the CARB stuff on it. My question is where should I check FIRST, and what is the most likely culprit? I have deduced the sound is not coming from the engine itself, but in and around the exhaust area, right side of the bike. No smoking or burning of oil, or performance issues whatsoever. So, I am going to take out my pet carrier and see whats up.

However while I know to check the header pipe at the manifold (forgive me if i get things wrong i am a newb) for a blown gasket, what if that is ok? Then where do I check, or what should I check FIRST instead?

Advice from anyone is fine. Doesn't have to be a Kymco or Agility owner as I figure this is fairly straightforward stuff. Also I assume before I loosen the header bolts or w/e to loosen the muffler mount bolts first, correct? That way the pipe will drop down easier. And maybe use a prop up thing for the muffler so it doesn't fall?

What else, guys? And thanks!  

[axy]

(i posted this at another forum, thought I should bring it here)  

Hey guys

My scoot is running fine, running great. Idle is good, performance good. Never stalls, dies, or quits. So this "sound" it's making, which is sort of a "gurgle thump thump," I figure is an exhaust leak, and a neighbor friend says the same.

Kymco Agility 125, much like any other gy6 125 with all the CARB stuff on it. My question is where should I check FIRST, and what is the most likely culprit? The only symptom I can give you is the night the scoot got louder I was riding at around 2/3 throttle and when gunning it for more throttle (WOT) it would bog down and hesitate. It did this around four times and went back to normal. Then a few minutes later while at a stop I noticed the scoot was louder and rougher sounding then usual, as if it were a small diesel engine. This was over a month ago.

I have deduced the sound is not coming from the engine itself, but in and around the exhaust area, right side of the bike. No smoking or burning of oil, or performance issues whatsoever. So, I am going to take out my pet carrier and see whats up.

However while I know to check the header pipe at the manifold (forgive me if i get things wrong i am a newb) for a blown gasket, what if that is ok? Then where do I check, or what should I check FIRST instead?

Advice from anyone is fine. Doesn't have to be a Kymco or Agility owner as I figure this is fairly straightforward stuff. Also I assume before I loosen the header bolts or w/e to loosen the muffler mount bolts first, correct? That way the pipe will drop down easier. And maybe use a prop up thing for the muffler so it doesn't fall?

What else, guys? And thanks!  

How many kms does your scoot have?
It could be that exhaust can is burnt inside so you hear strange noises. However, it would be highly unlikely if you have <40.000 kms.

If everything is in place, and bolts on the header are tight, and there are no cracks, I would head for service manual and check the part that refers to secondary exhaust re-circulation. All Kymcos have them, and they are forgotten often and never checked. There is also secondary air filter on A125, I think. I would check that first because gurgle-thump sound points to that direction, especially bogging at high revs.

[MrKymco]

thanks, axy

i am looking into this on Tuesday. the scoot has just 4000km so i doubt it would be the first thing you mentioned

i checked the bolts at the manifold and they are tight. but can't the gasket be blown out, anyway? or degraded or whatever it is that happens? the leak sounds local to that area, so shouldn't i take the pipe down to inspect the gasket?

i have also read if cold air is sucked into the engine because of the leak the valves can warp if affected. how likely is this to happen?

i will make sure to look further into the service manual for the secondary system you speak of, also.

i will update this thread as i progress

[Kevin]

Hey MrKymco,

Any news on your resolution?

I just cracked my secondary air inlet tube today and was nosing around to see how bad an idea it is for me to drive it for a few days until I get the replacement. I saw your note about sucking in cold air and warping valves, and thought I would bounce this thread back up.

Thanks!
--Kevin