easystar123

Thanks Glowgeek for your kind comments. Yes, too true, the trees are always there to be watched out for. Believe it or not there's a few things I've never done in my 60 years on this planet and playing golf is one of them. I live in a small country town with two golf courses and another just 6 miles down the road.

Glowgeek

Less time golfing, more time flying.

easystar123

Maybe one day I might hit a golf ball, but for the meantime the flying comes first. Lol

1200SportsterRider

Thanks Jim, the bearing portions of the rods are same width, the beam part is wider on the later/right. one, it's also a cruder finish.

Glowgeek

Deleted the pics with measurements. I just realized that the seller didn't know what he was selling. I supposedly bought 2 150's but the one with no label is a 180! 36mm bore.

I'll have to tear down the other engine and send new pics.

Jesse Open

Personally, I would replace that prettier, "early" connecting rod with the beefier updated rod, just as Saito did!
That oil hole is perfectly wrong, both as an oil feedpoint and the location being in a high stress location.

Glowgeek

Four nice NIB Saito singles for sale. The 150S GK has silver rocker covers and no stamp on the lug. A high compression version for certain!

https://www.rcgroups.com/forums/show...-NEW-%21%21%21

1200SportsterRider

Current offering, at 58 bucks replacing the factory rod is not happening.

The current offering is more polished than the rod on the right. The left rod is a proven component, so it's staying.

Saito 100 rod, woops, wrong 100.

Saito 82 rod
From engine to engine, almost none of the Saito rods are the same.

Glowgeek

The location is ok imo, as long as there is only one oil feed hole, deburred, and it's opposite the compressive load side of the journal. Rods rarely fail under compressive loads unless undersized. Most rod failures occur under tensile loads at TDC of the exhaust stroke.

Glowgeek

Dave, I have numbers for the 150. Will upload when this site cooperates.

Jesse Open

Yes, that part applies to the compessive vs tensile load carrying ability of the rod beam.
The con rod loading is still largest during the compressive load during the power stroke.
That oil hole is smack in the area of many rod failures.
As I said earlier , It is also smack in the wrong place for hydrodynamic oiling on the journal.

It seems Saito agreed and made appropriate changes.

Glowgeek

Here ya go, Dave. Let's compare numbers between your high compression 150 and my later version.

My piston is flat topped with valve reliefs
Back plate has one nipple boss
Height-wise, the combustion chamber goes straight across from the left and right edges of the two valves. (Not recessed)

the Wasp

My Feedback: (1)

you know, I had a Zinger 9x4. my god, it was lighter than air.

Glowgeek

What is that, one of those under engineered weak OS twin brass or aluminum rods?

Could be as you say OR.....Who's to say the bottom of the rod didn't stretch first, distorting beyond it's metalurgical elasticity, losing oil pressure, overheating and then beating the bottom of the journal off of the beam? That's the most common sequence in connecting rod big end failures according to experts in fatigue analysis. I'm not one of those experts.....I'm also not a prophet.

Jesse Open

Lonnie,
That oil hole is in the wrong place to support proper hydrodynamic oiling for the crankpin journal.
I am in agreement with the improvements Saito experts made over the early version. Also noteworthy; they did not go back to that location.
Not a prophet, I just doubt they will.

The rod is an O.S.160 Gemini bronze rod.
It and it's mate were replaced over 20 years ago with a pair of aluminum rods. Still runs fine to this day. Despite whacking the conrod, the crankpin had no signs of lube failure.Likewise the bearing surfaces of the rod. The engine was running a too small prop and the rod let go in a high speed dive.

modeltronics

My Feedback: (27)

Looking in my junk that is mostly picked up from swap meets I found a Saito 80 with a broken cam housing. This 80 is the original high compression version with the hump on the piston. This engine was a mess. I started to look to see if I had another cam housing.

I had a box of 120 parts and that cam housing is much larger.

Next I looked at a FA-50 cam housing and it looks the same as the FA-80 cam housing. I even fit the FA-80 cam in the FA50 housing with no problem.

Here is where I get confused. The FA-80 cam housing is SAI6533B. The FA-50 is SAI5033A.

What is the difference between the two cam housings?

Jesse Open

Measure the distance from the pin centerlines to the flanges on both.
IIRC they are different.

Glowgeek

Yep, probably took only a split second to frag once the big end distorted. Near instantaneous heat generated.

I often thought about how amusing it would be to underprop a medium case OS to see whether the valves float or the big end frags first. I have an OS fs70S that would serve as a good martyr.

Jesse Open

Not likely a lube failure. The RPM limit is impaired by the added mass of the bronze rod.
The bronze bearings are more tolerant of oiling issues than the aluminum versions. They are also stronger.
The forces at turn around rise sharply with the increased weight of the bronze rod. The aluminum rods often make noise quite a while before they let go.

modeltronics

My Feedback: (27)

Gary, you are correct on the cam housing. After measuring I can see the pin location is different.

Glowgeek

Pete, the 65, 80 & 91S share the same case size. I have a spare camgear housing for a 91S in good shape. What's the distance from the bottom of the camgear pin hole to the bottom of the camgear housing on your junkyard 80?

1200SportsterRider

A victim of rust.

This 56 is now a beautiful black and shiny.

modeltronics

My Feedback: (27)

Lonnie
It looks like the 91 and the 80 use the same part number cam housing. I'm interested in the spare you have.

Glowgeek

Dave, I stumbled on this thread this morning. In post #12 Jim reveals an interesting bit of info! Looks like I now have one more measurement to take!

Saito 150S & 150H whats the difference?



Deck Height on my 150 (stamped "B")

Jesse Open

What about the cylinder?