SPORT 20 Outboard motor question

Intlwaters

Help Support Intlwaters:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Kris Flynn

Well-Known Member
Joined
Mar 11, 2002
Messages
4,335
short and simple.

Is the OS RG liner leagal or not to use in IMPBA for SPORT 20 class?

As I understood the rules it was any OS parts from an OS motor can be used? ie "special" non OS liners and cranks were now illeagal. Been a while since I actually read them though to be honest.

In the end, either result is fine, just want clarification please from someone in the know, not just assuming as I was lol

Cheers
Kris
 
It must "Appear" stock. Can't see the liner from outside the case. :) That's my take on it anyway. But who am I...
 
That’s my take as well, we have always allowed that sleeve in D13 sport class.
 
It's sport tunnel all mods inside the engine OS OEM parts.Stock on the outside.The brass lining is a OS OEM part.IMPBA SCREWED THiS CLASS.iT WAS STOCK CLASS BACK IN THE DAYS AND SOMEONE HAD IT CHANGE IT.NO name here.

Dave
 
Lol Dave...do not care for the politics, but those of us who run SPORT 20 OB, it works great...we afopted similar rules to Impba for oir Australian class.

Anyway, thats what I thought gents, anything goes inside. Just heard it might have been changed recently where only OS parts or parts off MARINE motors were allowed. Which would be hard to tech, which is why the original/current rules work so well...if it looks stock, then it is ok.
 
How ever you do it a STOCK OS ran 70mph in Huntsville just sayin

Yep, but did you read how many motors they tested parts from to get all the numbers where they wanted them? 20 cases i think i read. I reckon its awesome if someone has that dedication ($ or friends lol), for SAW though.

Anyway, both NAMBA and IMPBA rules work well in their intended applications :)
 
It's sport tunnel all mods inside the engine OS OEM parts.Stock on the outside.The brass lining is a OS OEM part.IMPBA SCREWED THiS CLASS.iT WAS STOCK CLASS BACK IN THE DAYS AND SOMEONE HAD IT CHANGE IT.NO name here.

Dave

Back in the day the Sport .21 tunnel class was "never" was or intended to be a "stock" class in IMPBA.....Tommy Lee and myself , at the request of Dick Tyndall wrote the current Sport .21 rules in 1995[I think}.....We wrote the Sport .21 rules "intentionally" to remove the motor teardowns used in NAMBA 3.5 OPC Tunnel racing....
That is what precipitated the Go - No Go gage for only the carb and exhaust for inspections.....If you can't get the fuel in and the exhaust out motor mods are pretty much a waste of time....
Over the years that has been proven....The 70 MPH pass that Tommy and David was made with a "NAMBA LEGAL" O.S. .21 outboard.... There are no tool marks inside that engine....period....David has just learned how to put a motor together...
The 70 MPH pass was the whole package ......boat , motor , prop , set -up , weather and driving it through the lights.....the stars all lined up that day and shazaam 70 was the result.....The motor was probably less than 50% of that result....
The inspection gage size numbers were chosen to be inclusive of all [3] 3.5 outboards produced at that time [1995] K&B , O.S. , and Thunder Tiger ......
At that time we wrote the rules there were probably only 8 people in the world of RC boat racing that really knew exactly what a "stock" K&B 3.5 outboard was....K&B made no less than 10 different rods , 10 P&S's , 2 lower units , 3 flywheels , 2 carbs ,2 prop bearings , 2 crankshafts , 2 head buttons , paper gaskets...aluminum gaskets.....etc etc etc ....you see the problem here????...NAMBA teardowns and inspections were a nightmare....
As far as I know there are only 2 of us still alive that know what K&B parts went into a "Stock" K&B motor....
Question.....Why would anybody want to screw with the Sport .21 rules???? The Sport .21 class has proven itself to be probably one of the most successful classes in IMPBA....Even with $550.00 motors it is still thriving....
Don't try to legislate your inability to compete because you cannot learn to make a boat go fast....that is not a rule problem.....get off the damned keyboard and go testing....
To answer Kris's question....Put in a RG sleeve.....if the motor is not coming apart it is a moot point.....
 
Last edited:
70 mph with an out of the box O/S outboard is very doable. I made a 72 mph fast pass with the old water cooled O/S engine (with the small muffler) and booked an average speed of 70.665 mph record back in 2008. So I don't question the engine they used. The new air cooled O/S outboard engine should easily run 75 mph on the right boat.
 
Yep, but did you read how many motors they tested parts from to get all the numbers where they wanted them? 20 cases i think i read. I reckon its awesome if someone has that dedication ($ or friends lol), for SAW though.

Anyway, both NAMBA and IMPBA rules work well in their intended applications :)
FYI it was a motor he bought from someone on here new and broke it in at the lake. No magic bullet saw it with me own eyes
 
Just to be even more clear, I do not doubt the motor used to go 70mph wad NAMBA leagal.

Defiantely a great result from a great team...all the planets need to align to make it happen thats for sure.
 
IMPBA SCREWED THiS CLASS.iT WAS STOCK CLASS BACK IN THE DAYS AND SOMEONE HAD IT CHANGE IT.NO name here.

Dave
Dave Roach-you are flat out WRONG on this. What Rod said was correct. The sport 21 rules were proposed to the board at the 1995 IMPBA INTERNATS and was put into effect for the following year and nothing has been changed since that time.
 
70 mph with an out of the box O/S outboard is very doable. I made a 72 mph fast pass with the old water cooled O/S engine (with the small muffler) and booked an average speed of 70.665 mph record back in 2008. So I don't question the engine they used. The new air cooled O/S outboard engine should easily run 75 mph on the right boat.
Carl failed to mention this was an O.B. Hydro record, not a tunnel. That record is now 76.556mph with a JAE hydro an a nova rossi engine.
 
Just to be even more clear, I do not doubt the motor used to go 70mph wad NAMBA leagal.

Defiantely a great result from a great team...all the planets need to align to make it happen thats for sure.
Thanks Kris-you are right-everything had to be perfect for that run (69+mph not 70. Just want to get the facts straight). I told David that this may never happen again and if it doesn't I am okay with that. However with that said, we did make a pass at 70.4mph at the Turkey TT's so maybe it is possible to get the record up there. Time will tell.
 
My point was....that a sport/stock/pipeless/out of box/ NAMBA legal what ever you want to call it engine is capable of these speeds and yes that record is much higher now but my record was made with a pipeless/muffled old style water cooled O/S engine and the current record was set with a Modified Nova Rossi.

My point was in your favor as I was simply saying that speeds like that can be done. GEEZZ
-You might want to look at the current rules.
 
Mr.Lee
Let me say this.When I started in 1985 B-TUNNEL WAS a STOCK CLASS you couldn't do any thing inside or outside the engine you had to run it the way it come from the factory.In 1995 they came long and change the rules to B-SPORT TUNNEL and you can do what ever you what to do inside the engine.
 
" any part from a manufacturer’s outboard may be replaced with any other outboard part for the same size outboard from the same manufacturer"

Hello Kris, I am sure you have read this part of the rule before. The problem with the RG sleeve would be if there was a protest. I am not sure what would be covered under a protest. Its my understanding that an IMPBA motor has to meet displacement, carb bore, and exhaust opening. So does that mean its the only things that can be protested :confused:? During the engine tech, when the head is pulled to check bore, the person doing the tech should notice the sleeve and DQ the motor. The same would go for a record trial. Personally I would love to run a chrome sleeve, they seem to hold a fit a lot longer.
 
" any part from a manufacturer’s outboard may be replaced with any other outboard part for the same size outboard from the same manufacturer"

Hello Kris, I am sure you have read this part of the rule before. The problem with the RG sleeve would be if there was a protest. I am not sure what would be covered under a protest. Its my understanding that an IMPBA motor has to meet displacement, carb bore, and exhaust opening. So does that mean its the only things that can be protested :confused:? During the engine tech, when the head is pulled to check bore, the person doing the tech should notice the sleeve and DQ the motor. The same would go for a record trial. Personally I would love to run a chrome sleeve, they seem to hold a fit a lot longer.

That's the part I was referring to David...this means that RG liners are in theory Ileagal. I mean, if someone was to protest over someone using an RG liner is pretty pathetic (in oval racing). But at time trials where everything counts, then the rules really need to be met.

Dave Roach, move on mate...this is not about STOCK....someone please delete his comments which are WAY OFF TRACK

Cheers
 
Mr.Lee
Let me say this.When I started in 1985 B-TUNNEL WAS a STOCK CLASS you couldn't do any thing inside or outside the engine you had to run it the way it come from the factory.In 1995 they came long and change the rules to B-SPORT TUNNEL and you can do what ever you what to do inside the engine.

Dave, I dont think the IMPBA recognized the "Stock Class" as anything other then a filler class at that time. If you read close you will read Rod stating Dick asked him and Tommy to define a 21 tunnel class.

What came of that is the class we are talking about here.

Have a great Holiday.

Grim
 
Back
Top