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Tooling/welding/machining question

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TwoSmokeDS

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Hi. What is a good way to cap a short 1/2" metal tube that is sticking out of the cylinder head. This tube (#1) is for the AIC system on a chinese scooter.

I'm permanently removing the long tube with fingers on one end (#3) and the dookhicky (#2). So I need to cap the end of the tube (#1).

The open end of tube (#1) in photo below is press fitted into the cylinder; so removal of this tube may be nearly impossible.

A copper bushing (#4) keeps the connection air tight.

Some people on scooter forum buy a copper cap from Home Depot, and then cut fingers on it like the original long tube (#3). They put the cap over the bushing and just clamp it down with the hose clamp (#7). But that looks dodgy to me because I generally don't trust hose clamp. And losing the bushing (#4) would be a bad idea, since this is a chinese scooter, replacement parts are not available.

Can I weld this 1/2" tube closed? Will the heat damage the cylinder head or the engine?

To mechanic geniuses in here. Any idea?

ScreenShot002.jpg
 
I imagine you could cut it with a tubing cutter, and then flare it and us a flare fitting and plug.
 
I don't think there's enough room to flare it. The tube only sticks out about 1/2".

Here's what the setup looks like in real life (photo ripped off from the internet). You can see the hose clamp next to the exhaust exit. Typical china horizontal engine.

symba_spark_plug_access_and_emission_control_pipe_zps81545378.jpg
 
TwoSmokeDS said:
okay. I knew there are smart people in here. But where do I find a plug that would fit. Seems like I would need one that fit precisely.

Here's what the setup looks like in real life (photo ripped off from the internet). You can see the hose clamp next to the exhaust exit. Typical china horizontal engine.

symba_spark_plug_access_and_emission_control_pipe_zps81545378.jpg
Click to expand...

Most good hardware store that carry plumbing flare connections. They are getting harder to find since the industry is moving more to compression fittings. Make sure it is half inch or get best measurment since that part is most likely metric.
 
For a chinese scooter I would do the quick, cheap and easy method. Cut a thin plate from aluminum or steel and drill two holes in it. Install between #3 and #2 to block off your doohickey. Put a little high temp silicone seal on non gasket side or cut your own gasket to keep it airtight. Leave everything else in place as it wont hurt anything. And if you ever wanted to revert back to stock just loosen two bolts and remove the plate.

_
 
SilverBullet said:
For a chinese scooter I would do the quick, cheap and easy method. Cut a thin plate from aluminum or steel and drill two holes in it. Install between #3 and #2 to block off your doohickey. Put a little high temp silicone seal on non gasket side or cut your own gasket to keep it airtight. Leave everything else in place as it wont hurt anything. And if you ever wanted to revert back to stock just loosen two bolts and remove the plate.

_
Click to expand...

This.....^

Just make a small block off plate. Can be done with a drill, hacksaw and file.

Or cut the tube off 1.5" from the head, clamp it shut in a vice and weld the end
 
Last edited:
SilverBullet said:
For a chinese scooter I would do the quick, cheap and easy method. Cut a thin plate from aluminum or steel and drill two holes in it. Install between #3 and #2 to block off your doohickey. Put a little high temp silicone seal on non gasket side or cut your own gasket to keep it airtight. Leave everything else in place as it wont hurt anything. And if you ever wanted to revert back to stock just loosen two bolts and remove the plate.

_
Click to expand...
better choice... I was following OPs lead:doh:
 
Head looks suspiciously similar to something that runs around my yard on occasion. What is the purpose of the mod? Link to Chinese scooter forum?

Thanks...
 
AustinRT said:
Head looks suspiciously similar to something that runs around my yard on occasion. What is the purpose of the mod? Link to Chinese scooter forum?
Click to expand...

It is just a typical Honda-clone horizontal engines found in millions of pit bikes around the country. Your pit bike probably doesn't have this black hose. It seems only street legal USA bikes have this plumbing. The mod doesn't do anything to performance. It just clears up the clutter around the engine. The system uses a lot of rubber hoses and rely on vacuum, and being of China origin, the quality of the hoses and gaskets are suspect. So, this mod will increase reliability.
 
TwoSmokeDS said:
It is just a typical Honda-clone horizontal engines found in millions of pit bikes around the country. I guess pit bikes don't have this black hose; it seems only street legal bikes have them. The mod doesn't do anything to performance. It just clears up the clutter around the engine.



What is a good gasket material? Would the carboard box from breakfast cereal work?
Click to expand...
Got a piece of inner tube?
 
TwoSmokeDS said:
Hi. What is a good way to cap a short 1/2" metal tube that is sticking out of the cylinder head. This tube (#1) is for the AIC system on a chinese scooter.

I'm permanently removing the long tube with fingers on one end (#3) and the dookhicky (#2). So I need to cap the end of the tube (#1).

The tube (#1) looks to be press fitted into the cylinder; so removal of this tube may be nearly impossible.

A copper bushing (#4) keeps the connection air tight.

Some people on scooter forum buy a copper cap from Home Depot, and then cut fingers on it like the original long tube (#3). They put the cap over the bushing and just clamp it down with the hose clamp (#7). But that looks dodgy to me because I generally don't trust hose clamp. And losing the bushing (#4) would be a bad idea, since this is a chinese scooter, replacement parts are not available.

Can I weld this 1/2" tube closed? Will the heat damage the cylinder head or the engine?

To mechanic geniuses in here. Any idea?

ScreenShot002.jpg
Click to expand...

I would get a copper cap that fits over tube and put JB weld in cap then let it set-uo 24 hours then slide hose over it for looks. Yoy can always drill out later if needed. Sometimes I have someone hold wet vac close to parts I am drilling for a clean bore.
 
fclay said:
I would get a copper cap that fits over tube and put JB weld in cap then let it set-uo 24 hours then slide hose over it for looks. Yoy can always drill out later if needed. Sometimes I have someone hold wet vac close to parts I am drilling for a clean bore.
Click to expand...

JBW can only handle a constant temperature of 500 deg F.
 
Drilling and tapping is also an option. If #1 is thick enough, just put a bolt in it. If it's thin wall, run drill through it to take the whole thing out. Then tap and bolt the head.

If you want to be real smart about it, get an aluminum bolt that protrudes into the exhaust manifold. Then take off the exhaust and cut/shape the end of the bolt so it's flush with the port surface.
 
that is a pulsed air induction system, as the exhaust pulse goes out the exhaust port it draws fresh air into the exhaust system where it can combine with unburned hydrocarbons and react consuming them. the end result is cleaner exhaust. draw backs is popping back on deceleration and ugly clunky stuff. a lot of bikes use this system. the cleanest most effective way of getting around it is to get rid of everything. #1 should twist right out with a pair of vise grips.
in the hole it comes out of there will be a smaller hole that leads to the exhaust port. this can be drilled and tapped and a set screw screwed in sealing it off.
 
I plugged the tube using a plate a la Silverbullet. That leaves a lot of useless plumbing in place. And the hose clamp method of securing the tubing is a janky design. It's not tight. The hose clamp is just there for looks. The brackets of the plumbing is what's holding everything up.

One day, I will get rid of the remaining plumbing by drilling and tapping the head a la focus_fren and Mokaezi.
 
Moekazi said:
If you want to be real smart about it, get an aluminum bolt that protrudes into the exhaust manifold. Then take off the exhaust and cut/shape the end of the bolt so it's flush with the port surface
Click to expand...

Why aluminum?

focus frenzy said:
in the hole it comes out of there will be a smaller hole that leads to the exhaust port. this can be drilled and tapped and a set screw screwed in sealing it off.
Click to expand...



If I make sure the exhaust valve is closed, can I drill and tap the hole without risking metal shaving damaging the engine? When I start the bike up, the exhaust should blow the metal shavings out, right?
 
Just cut and fold it over in a double crimp. All of 5 seconds. It is how we block off catalytic converters that have extra secondary air injection tubes coming off of them. Look at the bottom of a toothpaste/rtv tube if you're unsure what I mean.

edit: sorry, didn't see you had already rectified the situation.
 
TwoSmokeDS said:
Why aluminum?
Click to expand...

Why are you still asking about this? You have already got a half dozen acceptable and easy five minutes fixes for this. Pick one and just do it instead of continuing to post about it. But also the real answer is do nothing. No reason to be blocking this off anyway, especially on a low performance Chinese scooter where all the plumbing is hidden from view by tupperware anyway.

_
 
SilverBullet said:
Why are you still asking about this? You have already got a half dozen acceptable and easy five minutes fixes for this. Pick one and just do it instead of continuing to post about it. But also the real answer is do nothing. No reason to be blocking this off anyway, especially on a low performance Chinese scooter where all the plumbing is hidden from view by tupperware anyway.

_
Click to expand...

Because it's too hot to ride outside and I'm sitting here with nothing to do. :lol2:
 
Because it will save .07 grams. You don't want a heavy scooter, do you? Seriously though, aluminum because it will expand/contract with the head better.

The AIC should be on the opposite side of the valve head and near the port opening. Because the engine is sideways, the material will fall out the exhaust port. It's also likely lower than the valve. You can do preventative stuff for extra insurance.
 
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