OS 21 -vs- CMB Greenhead

[mikehoffman]

Was wanting some input on engine choice for my new LYNX was wondering what experience you guys have had with either engine, I have had neither, I have always ran K&B 7.5 engines never 3.5, this will be for a racing application or I may just sell the whole thing and go back to 7.5 boats.

Thanks,

Mike.

 

[bzubee]

O.S. you should be able to hit 50mph real easy.

 

[moparbarn]

is this for 'mod' or 'sport/stock' racing? os would be the only legal option for 'sport/stock'. also parts availability. the os is a one stop deal. an os supplier can get you what you need. on the cmb, you need to make the complete unit from parts by different manufacturers. something to consider....... on a pure go fast basis, the cmb would be my choice. for day to day ease of running & tuning, go with the os.

 

[GRoth265]

Just remember the Lynx was designed around the OS lower unit. So whatever power head you run it really needs to be on a OS lower unit. A stock OS set up right is a screamer on this boat and can run with a piped motor. Greg

 

[mikehoffman]

What is the right setup Greg??? Help me out.

Mike.

 

[poolschool]

Just remember the Lynx was designed around the OS lower unit. So whatever power head you run it really needs to be on a OS lower unit. Greg

Fair enough, BUT, where do you source PTO's/adaptors for any powerhead to OS leg???

Gino

 

[Tim_Duggan]

Gino,

With a little lathe / mill time, you can modify the OS PTO to fit into the new powerhead.

I have a feeling you will see this modification in action at MBCofNSW soon...

 

[poolschool]

Hmmm, I see said the blind man - are there any "ready made" units around???

 

[Tim_Duggan]

Gino,

There are a few people who could do it for you for a small fee.

 

[topfuel443]

for a small fee.

LOL... ~James

 

[tnrcboatracer]

Just remember the Lynx was designed around the OS lower unit. So whatever power head you run it really needs to be on a OS lower unit. A stock OS set up right is a screamer on this boat and can run with a piped motor. Greg

To quote the setup manual:

"The Lynx was designed and tested using the O.S. and the Lawless lower units. Your prop hub-face* should be 6.0” +/- 1/8 from the transom (no matter what lower unit or adjustable engine mount you choose). This distance allows for easy race trim. This is a critical dimension. If you neglect this detail, you will never see the full performance potential of your Lynx.

*Prop hub-face: The front face of your prop hub. The joint between the propeller and the propeller dog (cog) is used as a generic reference point for prop placement."

The manual also describes how to use a K&B lower unit, but a fabricated spacer to get the correct prop face position is required.

I can provide a PDF copy of the current manual for anyone in need of one. I'm still working on pics, though.

 

[GRoth265]

O.K. if your going to run stock get in touch with Mark Sholund He has the numbers on a prop that works well. Tell him you wan't one like he does for me. Run at least 60% and loose the head shim in the motor. Put the boat on a setup board and start with the bottom of the prop shaft even with the top of the board at 0 dergrees angle. Move the motor up or down in 1/32" increments till the boat is loose. final trim should be with lead. Mine has 2 1/2 oz. just in front of the radio box. I could maybe tell you a little more but my buddies would have to kill me. PTO's like said earlier are kind of a custom thing I use my lathe with a milling attatchment to make what I need but sorry no time to make them for sale.Grg

 

[socco72]

my lynx with stock os .21xm

O.K. if your going to run stock get in touch with Mark Sholund He has the numbers on a prop that works well. Tell him you wan't one like he does for me. Run at least 60% and loose the head shim in the motor. Put the boat on a setup board and start with the bottom of the prop shaft even with the top of the board at 0 dergrees angle. Move the motor up or down in 1/32" increments till the boat is loose. final trim should be with lead. Mine has 2 1/2 oz. just in front of the radio box. I could maybe tell you a little more but my buddies would have to kill me. PTO's like said earlier are kind of a custom thing I use my lathe with a milling attatchment to make what I need but sorry no time to make them for sale.Grg

I race with greg and his boats are fast, thanks greg here is a short vid of my lynx last weekend its screaming now