Go Back  RCU Forums > RC Boats > Speed - RC Nitro Boats
Reload this Page >

fine tunning K&B outboard high RPM

Notices
Speed - RC Nitro Boats For all your rc nitro fuel burning boating needs.

fine tunning K&B outboard high RPM

Old 10-10-2005, 01:39 PM
  #1  
mosh
Junior Member
Thread Starter
 
Join Date: Oct 2005
Location: Tallahassee, FL
Posts: 20
Likes: 0
Received 0 Likes on 0 Posts
Default fine tunning K&B outboard high RPM

Ok you guys have to be sick of my questions. I've bought a few books on nitro but their all old. What or how is the best way to fine tune my boat for speed and HIGH RPM. I want to beable to throw a big rooster tail but also go fast. I have a newer K&B 3.5 outboard motor, right now I'm running 40% nitro and I was thinking about running 50% and a hoter glow plug. Oh and I'm using a Octura 440 prop on my 30inch tunnel hull. I just ordered a bullet lower unit and a cooper tuned pipe.
Old 10-10-2005, 04:43 PM
  #2  
ob nut
My Feedback: (1)
 
ob nut's Avatar
 
Join Date: Mar 2005
Location: Cincinnati, Oh
Posts: 1,350
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

If speed is what you are after, the "tall roostertail" won't be there. Check out a vid of a 30" WOF, MAC .21, Lawless lower, Garcia pipe and a S215 - [link=http://www.rcflix.com/photopost/data/506/612Queen_City_Race_Heat_5_2.mpg]Vid[/link] There's more speed to be had, just working on it. If you can, get 60% or higher nitro for the motor. Plug would be either a K&B L1 or MC9. The x440 prop is now on my boat, which is close to the S215.

As stated before - needle tuning. After starting the motor, blip the throttle wide open from idle. What does it do?

Revs sky high - too lean
Bogs a bit, clears out - in the ball park
Bogs, never clears up - too rich

K&B 3.5 needle should be around 3 1/2 turns out. Turn it about 1/8 of a turn each time. It'll most likely end up around 3 turns out.
Old 10-10-2005, 04:49 PM
  #3  
mosh
Junior Member
Thread Starter
 
Join Date: Oct 2005
Location: Tallahassee, FL
Posts: 20
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

I couldn't pull up the link you left.
Old 10-10-2005, 05:07 PM
  #4  
ob nut
My Feedback: (1)
 
ob nut's Avatar
 
Join Date: Mar 2005
Location: Cincinnati, Oh
Posts: 1,350
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

Try it again, when it was first posted out, link wasn't right. If not, check out the links on this [link=http://home.earthlink.net/~ob_nut2/id15.html]3.5 Tunnels[/link]
Old 10-10-2005, 05:29 PM
  #5  
mosh
Junior Member
Thread Starter
 
Join Date: Oct 2005
Location: Tallahassee, FL
Posts: 20
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

Got it. well besides speed how could I make it through a big rooster tail?
Old 10-11-2005, 08:10 AM
  #6  
ob nut
My Feedback: (1)
 
ob nut's Avatar
 
Join Date: Mar 2005
Location: Cincinnati, Oh
Posts: 1,350
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

ORIGINAL: mosh
Got it. well besides speed how could I make it through a big rooster tail?
Are you talking about another boats roost? If so, then pray or stay away from it. Some people have put air filters used for cars/trucks on their motors. Don't know how much that would help. Filters won't stop water 100%.
Old 10-11-2005, 08:57 AM
  #7  
Ron Olson
My Feedback: (1)
 
Ron Olson's Avatar
 
Join Date: May 2002
Location: Kalamazoo, MI
Posts: 18,688
Likes: 0
Received 20 Likes on 17 Posts
Default RE: fine tunning K&B outboard high RPM

I think the word that he wants is throw, not through.
The cavitation plate is what is keeping the engine from tossing a big 'tail. A roostertail isn't everything. If you've ever seen a FAST boat run, their roostertail comes out flat. A high roostertail comes from a prop that is too high. Compare it to smoking your tires, it looks cool but you're not going anywhere.
Old 10-11-2005, 10:17 AM
  #8  
piper_chuck
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,044
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

ORIGINAL: Ron Olson
Compare it to smoking your tires, it looks cool...
It does?
Old 06-08-2006, 07:20 PM
  #9  
jetpack
My Feedback: (1)
 
jetpack's Avatar
 
Join Date: Oct 2002
Location: Hobart, IN
Posts: 2,477
Likes: 0
Received 2 Likes on 2 Posts
Default RE: fine tunning K&B outboard high RPM

What are todays options for outboard pipe setups for KB 3.5SS?
Old 06-08-2006, 10:23 PM
  #10  
Jerry Dunlap
Senior Member
 
Join Date: May 2006
Location: Lakewood, WA
Posts: 1,356
Likes: 0
Received 0 Likes on 0 Posts
Default RE: fine tunning K&B outboard high RPM

For information on the Silver Bullit 3.5 Pipe, go to htbboats.com

JD
AquaCraft Models

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.