O.S. 21, or K&B .21 Pro?

[L Akre]

In stock condition, which performs better, the K&B .21 Pro, or the O.S. 21 outboard. I'm aware of the quality of each, but don't know how well each runs.

Les

 

[Mike Hughes]

OS 21 XM

 

[MalaysianFlyer]

This may help in making up your mind

http://www.intlwaters.com/index.php?showtopic=12914&st=45#

Scroll down to post number 56

 

[Eric Bourlet]

In stock condition, which performs better, the K&B .21 Pro, or the O.S. 21 outboard. I'm aware of the quality of each, but don't know how well each runs.

Les

OS .21 XM hands down

 

[VansRacing]

O/S 21 XM

This engine holds two IMPBA records for the class (2-lap & SAW) and also the stock 3.5cc SAW record in NAMBA.

 

[waterbug]

:huh: !!

Yep !! I'm the oddball ......

I'm running the K&B's on my Lynx's and have a OS, Mike Hughes extended mount with the mount drilled for a OS pattern to swap one day. But have taken it upon myself to run the K&B's ; Gerahty SX, Bulifant SS, and Clegg W/C.....

So far, I'm impressed with the performance !! It's just a matter of set up and finding the right prop and tweaks.....

I have only run the 8907 W/C, so far and it's going to get faster as soon as I order my props .. There is a lot of speed still there to be had with the K&B.... 50's in Heat Racing Trim is possible !!!

It's best to go with OS 21 XM.......right now K&B's need mods $$ just like OS, but OS not as many....

You must be able to drive and finish as I learned this year...

Butch

 

[Eric Bourlet]

O/S 21 XM

This engine holds two IMPBA records for the class (2-lap & SAW) and also the 2-lap record in NAMBA.

You forgot the Lynx /OS also holds the NAMBA competition record.

 

[Mike Hughes]

Yeah Eric and it was stock to boot. No mods needed.

Mike

 

[Duck899]

Mike or Eric, Do you guys open up the exhaust outlets on the OS to the same size as the K&B? Or, do you run them as they come out of the box? I always thought the K&B SS was stronger, pure stock for stock.....Are the OS exhaust outlets bigger than they used to be? Everyone here runs the stock K&B SS and I believe Les is looking at the OS over the K&B. I ran an OS back in the late 90's and thought it was down slightly on the K&B although the quality of the OS was far superiour, not to mention how easy it is to put a pipe on the OS.

Thanks......

 

[Mike Hughes]

Take it out of the box. Remove the headshim and bolt to a Lynx. Have Mark Anderson build you a prop. Run about a gallon of fuel through it and then hold on. This is the mods that I did to my OS to make it scream.

Mike

 

[Eric Bourlet]

Take it out of the box. Remove the headshim and bolt to a Lynx. Have Mark Anderson build you a prop. Run about a gallon of fuel through it and then hold on. This is the mods that I did to my OS to make it scream.

Mike

Rob, Back before people understood what it takes to make the OS work they were reaming out the exhaust. We made a special rule in District 8 to allow this but it was not legal at a national level. As it turns out that was killing the performance of the OS . Just do what Mike says. (oh man did I really say that?) . Get the deck clearance down every one we have seen were so well made that all you had to do was remove the head shim. Be gentle on the motor take your time breaking it in and do not lean burn it . The trick is to not load the OS and let it rev and conserve momentum when you get it up . You will love that little thing it is a real nice motor and a K&B killer on the right boat.

 

[L Akre]

Thanks to everyone that took the time out to reply. You all confirmed what I thought may be true.

I'll be buying an O.S. 21xm for my TS2.

Les

Take it out of the box. Remove the headshim and bolt to a Lynx. Have Mark Anderson build you a prop. Run about a gallon of fuel through it and then hold on. This is the mods that I did to my OS to make it scream.

Mike

Rob, Back before people understood what it takes to make the OS work they were reaming out the exaust. We made a special rule in District 8 to allow this but it was not legal at a national level. As it turns out that was killing the performance of the OS . Just do what Mike says. (oh man did I realy say that?) . Get the deck clearance down every one we have seen were so well made that all you had to do was remove the head shim. Be gentle on the motor take your time breaking it in and do not lean burn it . The trick is to not load the OS and let it rev and conserve momentum when you get it up . You will love that little thing it is a real nice motor and a K&B killer on the right boat.