Problems at higher rpm's running in barrel?

M

merc20076

Petty Officer 2nd Class
Joined
Sep 9, 2009
Messages
156
I am currently fixing 2 out of 3 outboards that I have purchased for not much, they have good compression, good spark.

The 6 HP just have a new carb kit including a new float, and a new water pump impeller. Runs better now at lower rpm than before. But since all the lake are frozen, I can't go try the motor on a lake with so I have to run them in a big garbage can of about 25 gallons. It picks up a high rpm but it slows down not long after while in gear. Is this normal? The 7.5 HP Johnson is doing the same to.
 
S

Silver Heels

Petty Officer 2nd Class
Joined
Apr 28, 2008
Messages
125
Re: Problems at higher rpm's running in barrel?

Just a thought...sometimes while running in a barrel, particularily while running in a garage, the exhaust will choke the motor. I have watched mechanics use a fan to allow the outboard to breathe fresh air while working out of the wind and in a barrel.
 
samo_ott

samo_ott

Vice Admiral
Joined
Jun 18, 2006
Messages
5,125
Re: Problems at higher rpm's running in barrel?

Running in a barrel is not the greatest. If you put it in gear you usually use most of the water and it definitely goes below the water pump. You cant fully test until you can get them on the water.
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: Problems at higher rpm's running in barrel?

Running in a barrel is ok for just seeing if it runs and pumps. That is, with the hood off and at idle speeds. Anything else is folly.
 
M

merc20076

Petty Officer 2nd Class
Joined
Sep 9, 2009
Messages
156
Re: Problems at higher rpm's running in barrel?

In fact yes when I did put back the cowl on, it didn't idle long and had to ajust again the low speed valve and it was harder. When I run it faster it runs better to with no cowl. Is this caused by the back pressure of the exhaust ? Is it possible to ajust the low speed?

I think I'll have to suspend this project t'ill April to test them at WOT.

But at least I do know that those motors can't run on ear muffs and even if they could I would ruin them if I would go at WOT in gear + all the noise ;)
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: Problems at higher rpm's running in barrel?

Smoke in the barrel from the exhaust gets sucked into the hood. Just like people, it has to breathe clean air to run, not smoke. Removing the hood allows it to suck clean air from outside the barrel.

Also, water turbulence kills any chance of having a normal load on the motor at high RPMS.
 
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