OS Plugs for Performance on Outboard 21's ??

[Gaztech]

OS plugs #8,A5, whatever don't seem to be popular running plugs... Have talked to the Boyz at the lake and they just don't run them... What's the problem here. Do they flameout, burnout,too hot or cold.Bring me up to speed on what plug has been good to you.. Been running 30 to 50% Nitro, and 18 to 23% oil.

Thanx Gaz the Greenhorn

 

[Eric Bourlet]

All I can tell you is that when I changed my OS outboard over to K&B 1L from the OS plug that came with it I gained 4 MPH. I think the OS plug is just too cold.

 

[piper_chuck]

The OS #8 is designed for low nitro, such as is used for sport airplanes.

 

[VansRacing]

K&B-1L is the plug to use.

-Carl,

 

[BigRed]

Keep in mind that there are long reach plugs... I know that there is a OS8 long plug... not sure about the OS 5..... The oS 8 is cold... Long plugs will take up more space inside the chamber causing higher compression...

K&B-1L and Mcoy 59 plugs seem to be very popular... I tried the OS8, Mccoy59 and K&B1L using 30% car fuel and the K&B gave me a little more power still while using lower nitro...

 

[piper_chuck]

Keep in mind that there are long reach plugs... I know that there is a OS8 long plug... not sure about the OS 5..... The oS 8 is cold... Long plugs will take up more space inside the chamber causing higher compression...

K&B-1L and Mcoy 59 plugs seem to be very popular... I tried the OS8, Mccoy59 and K&B1L using 30% car fuel and the K&B gave me a little more power still while using lower nitro...

The OS #8 is a medium-hot plug, not cold. It's in the same range as the others you listed.

 

[Jerry Wyss]

"Long plugs will take up more space inside the chamber causing higher compression..."

I think most of these marine engines are set-up for long reach plugs, I know

your heads are. When a Record Holder tells you that a K&B1L plug gave him

4mph over a OS8, Believe Him! nuff said.

 

[aussieboater]

What about the R5 is it long reach and would it be to cold

Brad

 

[Gaztech]

Gentlemen thanx for the update and the time to reply............... GAz

 

[Gaztech]

I used the long plugs and was surprised to see 3 or 4 thread in to the combustion chamber on both the OS 21 outboard and the K&B 3.5 outboard.. Both these engines take long plugs although OS sends a short #8 plug... Now what's with that.. No problems with pre-ignition on the threads.. ?? Thanx Gaz <_<

 

[Grimracer]

The OS plugs are a med lenght.. yup.. thats right.. they have there own lenght.. its not short and its not long.

I use a long plugs in all my OS motors.. Odonnell Reds

Grimracer