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

Nitro Engine Comparison

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

Nitro Engine Comparison

Old 04-19-2005, 11:05 AM
  #1  
jhanlon12
Junior Member
Thread Starter
 
Join Date: Apr 2005
Location: Akron, OH
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default Nitro Engine Comparison

I have a question. What is a better engine in terms of speed and/or reliability? K&B 3.5 OB or the OS Max 21 OB? Thanks in advance for your responses.
Old 04-19-2005, 06:25 PM
  #2  
eas___1990
Senior Member
 
Join Date: Aug 2004
Location: jeffersoncity, MO
Posts: 780
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Nitro Engine Comparison

idk i personally like os and always here good things about there engine so that would be my first buy between them
Old 04-19-2005, 06:47 PM
  #3  
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: Nitro Engine Comparison

I've always had good reliability with my K&B aero and boat engines, including my outboards. I can't speak to the OS, I've never had their outboard. I did notice that the K&B outboards are quite a bit lighter and the specs show the same HP. I also found it interesting that K&B offers a warranty, but OS does not. If you are just getting it for fun, I'd go with the K&B. It's a great engine. If you're going to race, check to see what the people in your area are running.
Old 04-19-2005, 08:19 PM
  #4  
jhanlon12
Junior Member
Thread Starter
 
Join Date: Apr 2005
Location: Akron, OH
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Nitro Engine Comparison

Thanks Piper and EAS. I just bought the boat on Ebay and it had the K&B OB engine already on it, but had heard about a deal on the OS Max 21.
Old 04-19-2005, 08:49 PM
  #5  
eas___1990
Senior Member
 
Join Date: Aug 2004
Location: jeffersoncity, MO
Posts: 780
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Nitro Engine Comparison

ya piper is right it doesnt have a warrenty which is very helpful if the thing breaks down or somthing.Plus if it is lighter and has the same horse power it could prolly be used for both just put a tuned pipe on it if possible if it is needed for racing
Old 04-19-2005, 10:35 PM
  #6  
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: Nitro Engine Comparison

If one thing that the K&B is, it's reliable. The carb is forgiving and they love the nitro. From what I've seen of the OS's, they aren't bad either. I know of one guy, Randall Thomas from Canada who can start his OS with a flip of his fingers.
Old 04-20-2005, 05:42 AM
  #7  
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: Nitro Engine Comparison

ORIGINAL: jhanlon12

Thanks Piper and EAS. I just bought the boat on Ebay and it had the K&B OB engine already on it, but had heard about a deal on the OS Max 21.
Oh, if you've already got the K&B on it, go ahead and run it. I would strip down the lower unit first to check the shaft and prop bearing before running.
Old 04-20-2005, 09:21 PM
  #8  
jhanlon12
Junior Member
Thread Starter
 
Join Date: Apr 2005
Location: Akron, OH
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Nitro Engine Comparison

Piper. I'm not a longtime RC Boat person yet. What should I be looking for when I disassemble the lower unit? How do I know if something needs replaced? Also do you have to use cable grease on the outboard units?
Old 04-20-2005, 09:40 PM
  #9  
eas___1990
Senior Member
 
Join Date: Aug 2004
Location: jeffersoncity, MO
Posts: 780
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Nitro Engine Comparison

im just curius but how would a person go about starting an outboard



[sm=pirate.gif]
Old 04-20-2005, 10:37 PM
  #10  
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: Nitro Engine Comparison

When taking apart a lower unit, look for wear on the drive dog bushing, breaks in the wires of the flex cable and anything else that doesn't look right. While you've got the powerhead off, take a look at the power take-off bearings (backplate) for any damage to the bearings and/or cage.

eas, the K&B, OS and some other outboards with the exception of the Thunder Tiger run in the opposite direction. We use an airplane electric starter with the wires reversed and start them like the planes with a nose-cone rubber insert.
Old 04-20-2005, 10:38 PM
  #11  
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: Nitro Engine Comparison

There are only a few parts in the lower unit that wear out, the flex shaft, the teflon flex shaft housing, and the prop shaft assembly (the part you bolt the prop onto. I suggest always keeping a spare flex shaft on hand, it's easy to change and not having a spare will end your day early. You actually can remove the flex shaft by unscrewing the prop shaft assembly. Be careful with the threads, it turns the opposite way you would expect, and you want to be sure you don't cross thread it when you put it back in. While the prop shaft assembly is out, confirm it turns easily and that it doesn't have excessive play. Check the flex shaft to make sure the winds look even and that there are no kinks. If it looks like it's starting to go, replace it. I usually pull the shaft at the end of the day, give it a quick cleaning with a rag or paper towel, grease it up (I use boat trailer bearing grease because it's waterproof) and put it back in. Occasionally I'll remove the lower unit and pull it apart to check the teflon housing. If you've got a water cooled version, this is a good time to check the water pickup and line that connects to the head. When reassembling, clean the screw and bolt threads and use a little removable loctite (I use blue). I also keep a few spare prop nuts with me, just in case I lose one. That's all I remember, if I missed anything, or others do things differently, hopefully they will speak up.
Old 04-20-2005, 10:40 PM
  #12  
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: Nitro Engine Comparison

ORIGINAL: Ron Olson
eas, the K&B, OS and some other outboards with the exception of the Thunder Tiger run in the opposite direction. We use an airplane electric starter with the wires reversed and start them like the planes with a nose-cone rubber insert.
And it's a good idea to build a stand that has something to immobilize the lower unit while starting. This reduces the strain on the steering servo and cables.
Old 04-20-2005, 11:09 PM
  #13  
jhanlon12
Junior Member
Thread Starter
 
Join Date: Apr 2005
Location: Akron, OH
Posts: 24
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Nitro Engine Comparison

Thanks for all the great suggestions! This forum is a great place. I'm glad I found it and that everyone is so eager to help out!
Old 04-21-2005, 05:55 AM
  #14  
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: Nitro Engine Comparison

Best of luck. The K&B outboard was my first "real" boat engine. In fact, the first one I bought is still in my shop, but only for another week, I sold the boat and motor to a friend, I deliver it to him next weekend. Before that I ran Cox .049s with home made cooling clamps and airplane engines on home made swamp boats.
Old 04-21-2005, 07:17 AM
  #15  
Square Nozzle
My Feedback: (1)
 
Join Date: May 2003
Location: Vernon, CT
Posts: 1,953
Likes: 0
Received 1 Like on 1 Post
Default RE: Nitro Engine Comparison

Home made cool clamps - AH the memories.
Old 04-21-2005, 11:43 AM
  #16  
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: Nitro Engine Comparison

Yup. I wish I had taken pictures of more of my adventures.

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 - Manage Preferences - 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.