Can someone explain why loopers need fuel enrichment before you let off the throttle

[imq707s]

Can someone explain to me why fuel enrichment is needed on OMC's to keep from melting pistons before you let off the gas after a high speed run. I though I remember B.Mac saying something about the gearcase on an OMC vs. a Merc (the OMC won't freewheel like the Merc.) Do all OMC motors need this feature, or just all out race motors? I've got an 89 GT200 Looper, and I'm wondering if I should be hitting the choke before I let off of the gas after I've made a pass at around 6200 rpms. How long do I need to hold down the choke? What about if I just gradually let off of the gas? Is it only a problem if you completely let off the throttle?

Any info you guys could give me would be great. :D

[RRRevinrude]

this is more of a concern at higher rpms...when you close the buttterflies-you are cutting off the fuel to the cylinders and they tend to "go lean" on deceleration.....shouldn't be to big of a problem at 6200......................................greg

[baja200merk]

b mac explained this to me once and this is wat i got out of it...

the omc gear cases dont free wheel which causes the motor to keep spinning fast after you drop off the gas.... so cutting the fuel off while spinning the engine at 6200rpms is very risky...

from wat i understand the enricher is 12.00 insurance....
just dont let off the gas too quick not that you would want to while running a padded hull...

if i gave a crap about my 5cyl 6100rpm looper i would put one in but if i m running around on 5 cyls i have more to worry about than a lean condition...

hope it helps....

[rmh77]

I cant explain it but we came up with a solution for it!:D

[B.Leonard]

It's a cover-up for poor fuel metering under certain circumstances most likely not needed if the motor is stock configuration. Although many people use it on any 2 stroke outboard after a mod motor has just made a long run as a way of cooling the pistons down before backing down into a possibly leaner area of the carbs.

What I'd like to know is... did OMC use that restrictor plate (call it a baffle or whatever you want to call it but it's nothing but a choke) as a cover up for this problem or just to reduce the power of these motors by a large amount? I hear some GT/XP models didn't have them though.

-BL

[B.Mac]

Originally posted by RRRevinrude
this is more of a concern at higher
rpms

I wouldn't be concerned about backing off of WOT at 6200 unless you're WOT runs are extended.

Gutting this airbox has required a huge leap in main jet size but man, what a difference............ all that beautiful porting only to be restricted at the gate. Why would OMC install such an engineering marvel? Disclaimer: Gutting this airbox has required a huge leap in main jet size.....
B.MAC:D