Black Smoke Fart - 110cc Mini Beast

[TurboT]

Ok Forum,

Since there seems to be a lull in topics to discuss, I thought it a good time to fire out a little happening on my daughter's quad for discussion.

First a little background:
This little unit has run like a top with minimal problems since I brought it into our family back in March. Over the past two months of summer, it was out of my care and in the hands of my nephew, who I've knicknamed the "quad wrecker" since he's managed to bust the frame on his Mini Hummer TWICE. Not to mention having back axle problems on it before that. Since he broke his, we had agreed to leave it with him to ride since we wouldn't be using ours much. (due to some other circumstances) I ended up leaving it there too long (my fault) and it came back with a back axle problem and a little issue that crept up a couple times, most recently this weekend while I started it for a warm up.

If any of you have seen a mini beast, you know the exhaust comes in three pieces in the box. One is the main pipe that comes off the exhaust port of the head, one is a right tailpipe which connects to the main pipe via slide on/then clamp, and the other is the left tailpipe which connects to the other tailpipe via the same method.

I've put together two mini beasts and have had another forum member here complain of the same thing, that the exhaust leaks at the connection point from the main pipe to the right tailpipe. Seems to only be when cold, which I'm pretty sure corrects itself as the pipe heats it expands and squeezes itself tighter, effectively sealing.

On the weekend, to run some gas through the quad, I picked up the back wheels and gave it some throttle to allow it to spin the wheels and get some revs in. (With the CVT tranny no other way to do this as holding the brake just doesn't allow it to rev) As I came off the throttle the bike farted, and black smoke puffed out the leaky exhaust connection. It was a bit of a backfire but nothing major. I guess what's confusing me is the fact the black smoke fired out this connection piece, but heading the opposite way of exhaust flow, essentially towards the motor and handlebars. One would think with the pressure and air flow heading rear wards, the smoke would have travelled in that direction and out the tailpipes.

So the question, what would cause this to happen? Incorrect carb settings? Back pressure in exhaust? Plug in the exhaust system somewhere? Black smoke to me means carbon or richness. Admittedly the quad runs a bit rich, but nothing I've felt to be a major concern. I can't imagine excessive carbon build up on valves so soon..

I haven't had time to investigate, but always welcome thoughts.

Thanks!!

-T.

[Weldangrind]

If it's running rich as you say, I'll bet that the leaky joint has been a collection spot for carbon. The exhaust direction was likely reversion, due to sudden closure of the throttle. The reversion found the leak at the joint and forced out a cloud of carbon, IMHO. The noise was due to the leak, similar to how exhaust headers tick when they leak.

The first remedy would be to dismantle and clean the joint and figure out how to clamp it more tightly, followed by raising the needle under the slider (dropping the clip).

The second would be to enjoy a cold malt beverage until the issue doesn't bother you anymore.

[PCD]

Nuke it from orbit...it's the only way to be sure.

Since there seems to be a lull in topics to discuss

Sorry, I had to go to work :P

Seriously though, the 'pete" fix would be a strip of that muffler bandage crap wrapped around the smaller diameter, then slide the other piece on. The red muffler bandage crap will bond the two pieces together semi permanently, but worry about that next time you take the exhaust apart.

i've even used that muffler cement crap to seal the rotted seams on an otherwise perfectly good muffler, but once it sets, its not coming off without a major fight.

I also think W&G is correct. On both counts.

[TurboT]

Well considering I've been bidding on a perf exhaust for it for 2 months I'd rather not semi-permanently stick it on. The exhaust it a bit of a process to get on, so I can't imagine what it would be like to take off if it was glued on.

Even the second mini beast I did, I was aware of the potential leak, and tried to clamp that sucker on there tighter and in a different spot, and it still leaked.

The explanation makes sense. I was wondering what was up with that, but if it's slowly been caking itself with dust that would make sense.

Since I'm really not that ambitious, I like option 2, while awaiting performance exhaust.

I might move the needle clip up one notch when putting new exhaust on. Wish the Mini Beast was as simple to get to the carb as the big beast, but I guess I can't have everything.

[PCD]

Originally Posted by TurboT

Well considering I've been bidding on a perf exhaust for it for 2 months I'd rather not semi-permanently stick it on. The exhaust it a bit of a process to get on, so I can't imagine what it would be like to take off if it was glued on.

Even the second mini beast I did, I was aware of the potential leak, and tried to clamp that sucker on there tighter and in a different spot, and it still leaked.

The explanation makes sense. I was wondering what was up with that, but if it's slowly been caking itself with dust that would make sense.

Since I'm really not that ambitious, I like option 2, while awaiting performance exhaust.

I might move the needle clip up one notch when putting new exhaust on. Wish the Mini Beast was as simple to get to the carb as the big beast, but I guess I can't have everything.

Yeah, remember I have not put a mini beast together yet like you have, so I can believe its a bit aggrivating.

Maybe the perf exhaust is just new cans and you wont have to fool with the y pipe at all, but I never get lucky like that

MIKUNI ARRIVED TODAY for the mini ATV. Has a built in shut off valve and hardware for mounting a choke cable exactly the same as our larger beasts.
Now how do I find a universal choke handlebar lever with a 2 foot cable :(

Racing CDI came too...will try it first since it looks like 50 times less work than the carb.

[TurboT]

Originally Posted by PCD

Yeah, remember I have not put a mini beast together yet like you have, so I can believe its a bit aggrivating.

Maybe the perf exhaust is just new cans and you wont have to fool with the y pipe at all, but I never get lucky like that

MIKUNI ARRIVED TODAY for the mini ATV. Has a built in shut off valve and hardware for mounting a choke cable exactly the same as our larger beasts.
Now how do I find a universal choke handlebar lever with a 2 foot cable :(

Racing CDI came too...will try it first since it looks like 50 times less work than the carb.

Exhaust is probably the most annoying part of the mini beast assembly really.

The CDI is a snap, worst part for me was because I wanted to re-use the rubber holder piece and the new CDI is bigger, so it was a tight fit. Maybe I was just crazy, but I do think it ran better with it..

A carb re and re on that little unit to me would be a bastard... but I have monster hands so that doesn't help me. I can barely get my hands in there to play with the manual choke lever.

Not sure where to direct you on a choke lever, hadn't thought about that.. could you take the manual lever off the old one and get it on the Mikuni somehow, to avoid that problem??

[Cal25]

Not sure if the exaust is the same on the ATV's as on my dual sport. The pipe on the dual sport goes back and slides inside of the back end of the pipe with the muffler. The muffler side of the connection is slit and clamps over the head pipe.

I learned a tip on here to seal the leak it had from day 1. Hi Temp RTV sealant applied to both ends and put together. Allowed a day to dry and it has stayed quiet and leak free.

[TurboT]

Originally Posted by Cal25

Not sure if the exaust is the same on the ATV's as on my dual sport. The pipe on the dual sport goes back and slides inside of the back end of the pipe with the muffler. The muffler side of the connection is slit and clamps over the head pipe.

I learned a tip on here to seal the leak it had from day 1. Hi Temp RTV sealant applied to both ends and put together. Allowed a day to dry and it has stayed quiet and leak free.

Hey that sounds very similar. If/when I get a performance exhaust I will try this method out.

[PCD]

Originally Posted by TurboT

Not sure where to direct you on a choke lever, hadn't thought about that.. could you take the manual lever off the old one and get it on the Mikuni somehow, to avoid that problem??

Let me explain better, sorry for the confusion.

the stock carb has a manual choke lever, the same black plastic piece we all know and love, but it does not have the additional arm that holds the metal part of a cable end housing, with screw, ala our beasts. The black lever however has the correct slots molded in to it to hold the end of the cable itself.

Mikuni: has the same black choke lever, with the same capability to hold the end of the cable, BUT it ALSO has that arm with a screw to accept the end of a cable housing. The cable is held via a small clamp with a screw at the top of the arm.

Now the arm I'm talking about is the same one that is stock on our beasts. It is held on with a single screw and holds the cable housing tightly in a vertical position so when you actuate the choke lever on the bars (if you have one) the cable housing remains stationary and omly the cable itself moves.

The mini came with no bar mounted choke, so there is no cable or bar mounted choke lever to adapt at this point. I would need to go buy a universal (shudder) bar mounted choke lever with a VERY short cable, probably 24" or 30" maximum.

I am not near my bikes or a quick pic would do the trick.

Pete

[MICRider]

Yup, the exhaust on the Mini Beast was the hardest part of assembly. I didn't order the brakes of dual exhaust on the Mini and they sent them both... I had to remove the headpipe off of the engine to fit everything together, then starting at the head pipe, tightened everything up. Lol, was a head scratcher though, I pulled the back shock off first to realize that it didn't help at all It is a poor design though, the slots don't even come close to being covered by the pipes, so a small amount of leakage is inevitable. I still love it though and think it looks cooler than my full sized Beast!

Regards,
Stew

[TurboT]

Originally Posted by MICRider

Yup, the exhaust on the Mini Beast was the hardest part of assembly. I didn't order the brakes of dual exhaust on the Mini and they sent them both... I had to remove the headpipe off of the engine to fit everything together, then starting at the head pipe, tightened everything up. Lol, was a head scratcher though, I pulled the back shock off first to realize that it didn't help at all It is a poor design though, the slots don't even come close to being covered by the pipes, so a small amount of leakage is inevitable. I still love it though and think it looks cooler than my full sized Beast!

Regards,
Stew

The Mini Beast defintely has a cool look, and they're fun to burn around on even for us big guys. I actually like the Mini Hummer's too, and was more comfortable on the one I had a chance to zip around on. I was almost tempted to by myself one, in black, just for the hell of it... but that was a while ago.. and now I have the big ugly Beast.

I found you had to take the back shock off to install the exhaust. It just made it so you could work the pipes around the frame and get it in the right spot. Didn't know that on the first one I did, there was some blue air around me that night.