Exhaust Banana chamber

Neo_Epoch

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Aug 14, 2017
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Hey, I had added a basic banana chamber to my 66/80 China chunk. Can't seem to get the motor running correctly with it. Had it running 'ok' for a little while, now it just seems like it will fire up after it sits for a while. Running stock cdi with ngk b5hs and ngk wire/boot, added oz 12v magneto, nt speed carb is on it. Plug is gapped at .020, middle slot on needle (5 slot needle), cut open the punisher symbol looking black air filter cover for more air flow, current fuel is 28:1 and will go to 32:1 at next fillup.

Tried different needle settings, didn't seem to make much of a difference.

Gonna try putting the stock muffler back on today to see if it will run correctly. Banana pipe pictured is the exact chamber in question.
 

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Street Ryderz

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Hey, I had added a basic banana chamber to my 66/80 China chunk. Can't seem to get the motor running correctly with it. Had it running 'ok' for a little while, now it just seems like it will fire up after it sits for a while. Running stock cdi with ngk b5hs and ngk wire/boot, added oz 12v magneto, nt speed carb is on it. Plug is gapped at .020, middle slot on needle (5 slot needle), cut open the punisher symbol looking black air filter cover for more air flow, current fuel is 28:1 and will go to 32:1 at next fillup.

Tried different needle settings, didn't seem to make much of a difference.

Gonna try putting the stock muffler back on today to see if it will run correctly. Banana pipe pictured is the exact chamber in question.
Those banana pipes are garbage not much better than a stock pipe,I cut one open awhile back because somthing was rattling around inside it ...? this is what I found.
 

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crassius

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Jul 23, 2012
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that's right - first step with new part that seems to fail is put back old part to check
 

gary55

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What do you mean "it will fire up after it sits for a while". Do you mean after you ride it you have to let it cool down before it will start again? The plug you are using is to hot you should be using a 6 or 7, and the gap should be around .030. Can you be a little clearer what the problem is?
 

Neo_Epoch

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Street Ryderz - yea, I had seen your thread about the banana being sh1t, glad I only paid $15 for it. After seeing your thread, it made little sense to me why there would be baffles in the chamber.

Gary55 - I fired it up and had it running at idle, took it around the block for a quick ride, had it idleing for a while so that i could set the idle screw, screw was set fine, had it idling for a little while longer and then the engine cut off on its own. Tried to fire it up again and it wouldn't run. Let it sit for maybe a good 10 minutes, tried to fire it up to run again and it sputtered here and there, but wouldn't stay running.

If the plug is too hot, it would make sense then, if it sits, it cools. I get paid again tomorrow and will go for a b6hs. As far as the gap; I had the gap set at .028 and after researching here and there, saw a plethora of info about what gap to set. The original setup seemed to run smoother with it set at .020 so I'll reset the gap at .030 and put the old exhaust back together before work today (got busy with kids yesterday for halloween).

Another thing I had noticed, the studs that hold the plates together on the oz mag were protruding about an 1/8 of an inch on the flat side. I was thinking that this wasn't normal, but didn't want to grind them down until I figured out how it ran as is.

I have a new b8hs that came with my plug boot and wire "upgrade", would that be too cold of a plug for the motor? I live in Philadelphia, Pennsylvania and the weather has just recently been getting down into the mid to low 40's
 
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gary55

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Street Ryderz - yea, I had seen your thread about the banana being sh1t, glad I only paid $15 for it. After seeing your thread, it made little sense to me why there would be baffles in the chamber.

Gary55 - I fired it up and had it running at idle, took it around the block for a quick ride, had it idleing for a while so that i could set the idle screw, screw was set fine, had it idling for a little while longer and then the engine cut off on its own. Tried to fire it up again and it wouldn't run. Let it sit for maybe a good 10 minutes, tried to fire it up to run again and it sputtered here and there, but wouldn't stay running.

If the plug is too hot, it would make sense then, if it sits, it cools. I get paid again tomorrow and will go for a b6hs. As far as the gap; I had the gap set at .028 and after researching here and there, saw a plethora of info about what gap to set. The original setup seemed to run smoother with it set at .020 so I'll reset the gap at .030 and put the old exhaust back together before work today (got busy with kids yesterday for halloween).

Another thing I had noticed, the studs that hold the plates together on the oz mag were protruding about an 1/8 of an inch on the flat side. I was thinking that this wasn't normal, but didn't want to grind them down until I figured out how it ran as is.

I have a new b8hs that came with my plug boot and wire "upgrade", would that be too cold of a plug for the motor? I live in Philadelphia, Pennsylvania and the weather has just recently been getting down into the mid to low 40's
It sounds like a bad CDI. I have had them act exactly as you are describing. You may also want to check the mag., but I really doubt that it is the problem with it going in and out of operation. You are probably right on the b6 for the cold months, Philly gets chilly. If you haven't checked a mag before here is how it looks. Meter set at 20k. Between .032 to .040 is good enough. I agree with putting the old muffler back on, but I wouldn't think it would be the cause of your problems. More likely just a coincidence that the cdi took a crap around the same time of the swap out.View media item 61073
 

Neo_Epoch

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CDI is new as of last week. I originally thought that was the problem when it wouldn't start from rain riding before deciding to get a new magneto. If it doesn't fire up and run after muffler swap, I'll throw the old CDI back in to see if there's a difference. I know that new CDI's can come malfunctioning from the box. I'll see if I can't find my old meter to test the coil.
 

gary55

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CDI is new as of last week. I originally thought that was the problem when it wouldn't start from rain riding before deciding to get a new magneto. If it doesn't fire up and run after muffler swap, I'll throw the old CDI back in to see if there's a difference. I know that new CDI's can come malfunctioning from the box. I'll see if I can't find my old meter to test the coil.
Look forward to hearing how this turns out. My bets are on the cdi. Just a while back I had several brand new ones act like yours is. The bad part was I used one of the new ones that was also bad to replace the one on the bike. This had me searching everywhere else for the problem, and scratching my head trying to figure out what I was overlooking. Finally I took the cdi off my bike that I knew was working good and tried it, problem solved.
 

Neo_Epoch

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So, as per swapping the new to old exhaust, I ended up stripping the threads going into the cylinder body for the exhaust manifold. I did have it running for a short time until the stud popped out.

Any simple ideas as to how to remedy this issue, before I order another cylinder body?
 

Street Ryderz

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So, as per swapping the new to old exhaust, I ended up stripping the threads going into the cylinder body for the exhaust manifold. I did have it running for a short time until the stud popped out.

Any simple ideas as to how to remedy this issue, before I order another cylinder body?
A 6mm helicoil works well and does not require the engine to be disassembled to do it.
 
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