Broken Rod

I am asking the question about OS VII outboard engines breaking the connecting rod i bought 2 outboards ran them pure stock until they needed bearings . one i took them apart both have the connecting broke at the bottom of the rod .

This is the crank end

After having one of the outboards rebuilt with lots of mods, i was going to install new piston and sleeve i found that rod to be broke in the same place

I bought a used water cooled outboard took it apart to install new bearings and found a different style rod and it was not broken i think it is the old style rod and does not have the oil hole in this rod

My questions are 

Does everyone have this same problem?

Can you by an after market rod ?

Greg

Maybe ask Ron Shaw as he deals in OS outboards and has parts.

Brad

nope. not one...  Have been running the motors HARD sense they were introduced and so far.. NO ISSUES!

Grim

Greg

Look on ebay for a os speed rod  part no.23755020. It will fit right in.Here is a part no.for the rod with the clips 23755024

Dave

I've never heard of a rod breaking on an O.S. 21 OB.  Not saying it doesn't happened because Greg is reporting it.   Just that I've not ever experienced it or previously heard of it.  

dave roach said:

Greg

Look on ebay for a os speed rod  part no.23755020. It will fit right in.Here is a part no.for the rod with the clips 23755024

Dave

Click to expand...

That is the rod being used on the V2. 
https://www.osengines.com/engines-boat/osmg1720/index.html

Greg
I've broken 2 in the past but we're on the top end both times.

Sent from my SM-N920V using Tapatalk

Alan Elzer said:

Greg
I've broken 2 in the past but we're on the top end both times.

Sent from my SM-N920V using Tapatalk
 

Click to expand...

ouch....That's expensive!

Here is the latest rod I found broken

i race this stock engine at the SC fall national in October 

What Fuel?  More than likely a fuel/oil issue

I broke one in the same spot several years ago on an air cooled motor. 

Fuel is Technology fuel 60%

I have had two stock rod braking in the same place.That's why i use the speed rods

Dave

Fuel is Technology fuel 60%

Dave i bought the new rod and it appears to be the same as the stock rod

I see no different in the speed rod vs the stock

Greg,  do all you guys use that same fuel?  I doubt it would be that though...its top grade stuff.

I am pretty sure that is the newer rod Greg, the old rod was square on the edges, not 'knife edged' like the new ones

Hi Kris

The fuel is the best John Otto makes it, so i dont think that is the major factor.

The square rod (old style) is the rod i haven't broke. 

My biggest concern is you dont know when the rod cracks.

Well i don't know what is the problem but thanks for the feedback

Greg

Just so you know,If you go to a national event and get torn down you will be booted if found using internal parts that do not  come in a outboard version of that motor.

B. Engine Specifications

1. Engines must be standard factory production with a minimum of 100 units available for sale to the general public. To be eligible for the International Regatta the engines must have been offered for sale to the general public not less than ninety (90) days prior to that year's International Regatta.

2. The powerhead and lower unit must be of the same manufacturer and model.

3. The engine external parts shall remain as originally manufactured, but any part from a manufacturer’s outboard may be replaced with any other outboard part for the same size outboard from the same manufacturer, the exception being that slide valve exhaust adapters may not be used with carburetor equipped engines.

4. The following exceptions will be allowed in the Sport Outboard Tunnel specifications:

a. Adhesives (loctite), set screws and jam nuts.

b. Any carb linkage arms.

c. Any motor mount.

d. Any glow plug, fuel brand and mixture.

e. Any type steering arm. LAST REVISED November 2018 H -11 Nitro Specialized Classes

f. The factory color finish may be altered or removed as an appearance alteration.

g. Any flywheel nut.

h. The lower unit below the cavitation plate may be trimmed, sharpened or polished. No material shall be added to the lower unit.

i. Adjustable mixture controls will be allowed, however the original needle valve must remain in its original position.

C. Sport tunnel engine inspection procedures The maximum carb bore and exhaust outlet bore size shall not exceed 0.320 inches. These may be checked with a 'GO, NO-GO' gage or dial calipers. Note: It will be the contestant’s responsibility to check and verify carb bore and exhaust outlet bores prior to the contest. Any infraction concerning the carb or exhaust bore sizes will result in immediate disqualification from the contest.

Hi Kris

The fuel is the best John Otto makes it, so i dont think that is the major factor.

The square rod (old style) is the rod i haven't broke. 

My biggest concern is you dont know when the rod cracks.

Well i don't know what is the problem but thanks for the feedback

Greg