Piping exhaust outside.

Jack Nielsen /

Dec 27, 2019 03:36PM

Hello everyone and I hope you all had a Merry Christmas or a wonderful Hanukkah.

My question for today is running a moped inside and piping the exhaust out side.

I built a test stand to run a couple of hobbit motors and would like to test them in my workshop. When the first one started up for all of 2 seconds all the smoke detectors in the shop and house went off.

Just wondering if anyone ever had experience in piping the exhaust outside and not killing themselves with carbon monoxide. I have see this done in commercial auto shops with a big hose that fits over the tailpipe.

Or should I just wait for warmer weather?

Thanks and have a a happy and Safe New Year.

Jack

I

Re: Piping exhaust outside.

P D /

pdcomm

Dec 27, 2019 03:57PM

Hose is exactly how I kept my shop air 'cleaner' .

You can get dryer vent hose pretty cheap , almost anywhere .

Fix a box computer cooling fan ( they run off 12 volt and are about 4 inches in size ) on the end , with a type of funnel .

Hang or stand that close to the exhaust exit of the bike/motor and the other end out the window or other exit . Maybe install a dryer vent somewhere in a wall .

Re: Piping exhaust outside.

Aaron Blair /

aaronb

Dec 27, 2019 11:05PM

I used a bathroom exhaust fan in a wooden frame holding it vertical. Wired in a switch in a conduit box mounted on the side.

Otherwise same idea as pd.

Re: Piping exhaust outside.

Rebel Moby /

rebelmoby

Dec 28, 2019 09:41AM

Get a short length of 2 inches flexy exhause pipe and a length of 2 inches straight exhause pipe and a couple of clamps. If you are going to run up the engine you might as well run it up until it is heat soaked, dryer hose will become melty and add to the toxic fume issue as well as being a bit too big.

Re: Piping exhaust outside.

P D /

pdcomm

Dec 28, 2019 10:16AM

> Rebel Moby Wrote:

> -------------------------------------------------------

> dryer hose will become melty and add to the toxic fume issue

Hmm , it never did for me .

Probably because there's enough air being sucked into the hose along side the exhaust .

My setup sits behind the exhaust and not attached to it .

Re: Piping exhaust outside.

Brad William /

wsemajb

Dec 28, 2019 06:53PM

For tuning's sake you probably don't want to mess with any big changes in atmospheric pressure at the end of the exhaust. A two stroke is going to be more sensitive to this than a four. So just extending the pipe out the window with a hose connected to the exhaust is going to add back-pressure.

When I've run a two stroke indoors I've set a good sized cardboard box, opened at one end, that end facing the exhaust, plug a shop vac hose into the other end of the box, and run a hose from the shop vac's exhaust out a window. 100 percent effective without altering the tuning of the pipe.

Re: Piping exhaust outside.

Jack Nielsen /

troutman OP

Dec 28, 2019 09:39PM

Brad:I like this idea best of all. Will try it tomorrow when the wife is away. Jack

Re: Piping exhaust outside.

Rebel Moby /

rebelmoby

Dec 30, 2019 09:44AM

Dumping a exit that is less than 1 inch into a pipe that is 2 inch will not measurably change the "atmospheric pressure at the end of the exhaust" as much as a device creating a partial vacuum in a collector box.... just saying...

> Brad William Wrote:

> -------------------------------------------------------

> For tuning's sake you probably don't want to mess with any big changes

> in atmospheric pressure at the end of the exhaust. A two stroke is

> going to be more sensitive to this than a four. So just extending the

> pipe out the window with a hose connected to the exhaust is going to add

> back-pressure.

>

> When I've run a two stroke indoors I've set a good sized cardboard box,

> , opened at one end, that end facing the exhaust, plug a shop vac hose

> into the other end of the box, and run a hose from the shop vac's

> exhaust out a window. 100 percent effective without altering the tuning

> of the pipe.

Re: Piping exhaust outside.

Brad William /

wsemajb

Dec 30, 2019 12:32PM

Do not put the exhaust into the box. Just aim the exhaust at the opened side any where from 1 to 3 ft away. The box i used was approx 2ft sq.

Re: Piping exhaust outside.

P D /

pdcomm

Dec 30, 2019 12:43PM

> Brad William Wrote:

> -------------------------------------------------------

> Do not put the exhaust into the box. Just aim the exhaust at the opened

> side any where from 1 to 3 ft away. The box i used was approx 2ft sq.

You're doing the same thing as I am , only I use a funnel a bit closer .

MOPED ARMY

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