hsukaria

I sure do like the AAC liner-less cylinders that Saito has. I guess it can get pretty expensive if you have to replace the cylinder/piston combo. Are the stock piston rings as good as a Frank Bowman rings?
(maybe I'm making wrong assumptions that the engines are ringed with liner-less AAC cylinders?)

Hobbsy

My Feedback: (102)

You are right on the money, neither the cylinder nor the ring wear much. In fact you cannot feel a wear ridge in the cylinder.
The replacement for that cylinder was $114.00 3 years ago.

hsukaria

Thanks Hobbsy,
The reason I asked is because after I ran my FA82 (it ran quite well and I made sure I didn't run it lean), it seems that the static compression decreased quite a bit. So, I will first see if the valve gaps got out of whack or something chewed up in the cylinder? Maybe it is all ok, but I had trouble starting it last time.
I need to get some better weather to do more engine runs before I can get a conclusion on this.

SrTelemaster150

It's doubtful that ring/cylinder wear is the culprit. I would suspect valve seating issues 1st. Perhaps the valve is sticking slightly or a small piece of carbon is on the seating surface.

When you check the valve lash, also pull the manifolds & spray some penetrating oil on the valve heads/stems from the ports as well as the springs when the valves are closed. let it soak for a few minutes then work the valves W/your finger tips to assure free movement.

Let is soak for a while. W/the glow plug removed, depress the valves slightly & blow into the glow plug hole W/compressed air to clear the seats of any debris

Then set your valve lash.

hsukaria

Sounds like a good plan, thanks SrTelemaster150

SrTelemaster150

After talking to Frank for quite some time on the phone, I'm going to try some of his rings.

Hobbsy

My Feedback: (102)

Dans suggestion on the penetrating oil is a good one, I use PBlaster, another product that does as well is NAPA Fogging oil which is my current choice for after run oil. And its cheap. The Corrosion X I used to to use was 16 bucks a can, the NAPA Fogging oil is a 3 bucks.

SrTelemaster150

Here's the reasoning for the minimal gap.

Again from "Complete Saito Notes by Bill Robison".

Cam wear

The engine’s power is enhanced by the maximum open duration, meaning the least valve clearance we can use. This can affect the idle, but normally the effect is minor at most.

Wear? Let’s suppose you have a landing strip with a 20 foot hill right in the middle. On take off, with the plane accelerating along the ground it will roll up the hill with no problem, and if not yet to flying speed will roll smoothly down the back side. This can be likened to the tappets with minimum clearance. When you land, if you touch down on the flat before the hill you still have no problem. On the other hand, if you come in at a four foot altitude your touch down on the slope of the hill will test your landing gear at best, at ten feet altitude you will probably have to get out your glue before flying again. This is an analogue to loose valve clearance, and these early cam grinds work best with no more than ½ thousandth inch clearance.

Now let’s suppose someone has built up a four foot rise from the flat part, with a few feet of level runway between the four foot rise and the rest of the upslope of the hill. Now, if you come in with the four feet altitude you’ll touch on that short level area, and again roll gently up the hill. This is like the later cams that have a quieting ramp, and should be set at 0.04 mm clearance.

All current Saito cams have quieting ramps. Sad to say, the only way to tell the old and new grinds apart is to degree the cam lift, the ramp will show in the profile graph.

Now we’ll forget about airstrips with hills in the middle, and get to the cams and valve gear.

With the clearance set to the minimum the tappets are accelerated smoothly up the ramp, with minimum forces on the face of the tappet. With looser clearance the tappet will be hitting the side of the lobe, with much higher contact pressure. Granted, the tappet may be touching the base circle of the cam, but the clearance in the valve train still has to be taken up before the valve opens, any excess clearance will cause much higher contact pressure when the valve does start opening. This is like landing on the up slope of our hill.

End of quote.


Setting your lash @ .04mm or .00157" gives you better power W/less cam wear. No down side. A "win/win situation.

I use the .0015" gauge W/slight drag. That's what the "feel" in "feeler gauge" is all about, feeling the drag. You must be careful though as the W/the (relatively) weak spring tension of the small springs, it would be easy to push the valves off the seats W/O feeling a lot of "drag" on the guage.

When you lock down the adjustment nuts, the stud will distort ever so slightly & the valve lash will increase very slightly.

I can feel the difference before/after locking the nut down & Bill cites this scenerio in his notes. using the .0015" gauge will give you the proper lash after the locknut is tightened. If you pay close attention, you too will feel the difference.

Cougar429

My Feedback: (3)

I've used Franks rings on several engines, including during the rebuild of my 91. Every one has been first rate quality.

SrTelemaster150

My method is a "MIX" of Bill's & Dave's methods W/the elimination of (Bill's) PEAK RPM needle setting until, there is some time on the engine, pehaps 1 hour of run time.

IMO, not trying to "peak" the mixtire too soon IS a way to avoid disaster.

Where mine & Dave's methods vary is that I do not let the engine run @ a steady RPM. That is against everthing I was ever taught about breaking in an engine. Also, a flat tappet cam engine shuld not be allowed to idle until there is time on the engine. W/our engines, the blowby of high cylinder pressure is needed to force oil into the bottom end & cam housing. Even in a full sized automotive engines W'flat tappet cams, you need the increased oil circulation & "slinging" of oil from the rotating assembly to lubricate the cam/tappet interface until the sufaces are burnished. Our engine are different, but they still need the increased oil circulation from the higher cylinder pressure/blowby for the same cam/tappet lubrication until the surfaces are burnished. The higher cylinder pressure also facilitates quicker ring seating.

After a few minutes running time @ moderate RPM to normalize tempertures, while still @ the rich needle setting, I use BRIEF WOT bursts from a high idle for no longer than 2 seconds @ first avoiding high RPM. I allow the engine to return to a moderate RPM level for several seconds between WOT bursts. The ratio between the WOT & modearte RPM levels should be pronounced, but not excessive, perhaps 5:1. 2 seconds @ WOT, 10 seconds @ moderate RPM before the next acelleration. It's not "cast in stone", but hopefully you get the idea.

Make sure the prop is loading the engine enough to avoid quick engine acceleration. I like heavy nylon props for break in as they further slow the engine acceleration. As the engine runs some more, I increase the duration of the WOT bursts incrementally to no more than 5 seconds. This slowly increase the RPM that the engine achieves as it breaks in.

After an hour or so of this throttle blipping & running the engine @ various moderte RPM levels W/the rich needle settings, it is time to adjust the HSN for peak RPM & the LSN for transition.

In a way, my methods somewhat parallel Dave's timeline & RPM levels, but combine Bill's WOT method W/O the peak RPM needle settings.

SrTelemaster150

My FA300TTDP seems down a bit on power. I never ran it on glow ignition, but it only makes "factory" spec' on CDI & the starboard cylinder seems to be down on compression & needs a richer LSN setting on that carburetor for ilde & transition. Having never run it W/GI I have no benchmark to compare power oupput.

There's not enough time on the engine to suspect vave seating issues & although I haven't inspected the cam, I can't see any issues W/the cylinder/ring.

I'm going to try some of Franks rings.

As cheap as they are, & the fact that I only have 3 cylinder bore sizes to deal with, I'm thinking I might get enough for all of my Saito engines.

Did you use any Bowman rings in your Saitos & if so, what were the results as far as power gain/loss?

Cougar429

My Feedback: (3)

As I stated the Saito 91 got a Bowman Ring during overhaul when the rod finally wiped after 330 flights. Even though that was the only issue, went ahead and did bearings, ring and sealing bits at that time as it was apart for cleaning anyway. Original ring was in good shape so not much change from stock after break in, but in some engines I have seen considerable improvement even when relatively new due to the poor quality of the stock rings. Saito is not one in that category. Their stock bits are pretty good. If I had any complaint it would be the fact the 91 rod was not phosphor bronze bushed.

Hobbsy

My Feedback: (102)

Couger, I think Saitos rings get a definite boost from the very precise piston to cylinder fit. I have never replaced bearings in a Saito and only one ring, That ring was in a .90 triple that from day one had a soft cylinder. I just ordered a .90 (triple) ring and that immediately brought it up to snuff.

Where Dan and I differ on the break in thing is I wait until after the 6,000 rpm 10 minute run to do the full throttle runs for 2 to 5 seconds and not nearly at peak. Normal peak on most Saito is 1.25 to 1.75 turns out and I set it a 3 after the 6,000 rpm run.

SrTelemaster150

Hardly any of the FA engines & many of the FG engines don't have bronze big end bushings.

The high silica aluminum that the rods are made of is used in some high performace automotive bearing inserts. The high silica aluminum bearings are better for high load applications sacrificing some of the embedability & natural lubricity of the bronze.

I don't really see that as a bad thing.

I had an FA150 that probably had a 55gal drum of 15% Cool :Power through it & the rod big end & crank journal were fine. If it hadn't been stored in an unheated shed next to the St Regis River W/fuel left inmthe tank/engine, it would still be aliv e.

It now lives on as my high compression FA180HC CDI/BBC engine making 3 1/2HP on 15% nitro, 4HP on 30%.

Cougar429

My Feedback: (3)

My rod would have been fine without the overheat described the first time cowled. Other than a seized big end the rest of the motor was perfect even after what I calculate was 90+ HOURS of running! I just changed the bearings for comfort, not necessity.

FNQFLYER

Reading the run in procedures put up by you all, I think they are all very similar.  In fact I use elements of most BUT when I went to the Saito factory I came away with one gem.. The engineer I talked to said and I quote
"The engine will tell you when it is run in"  What he meant was run it rich for the first tank, as rich as you can and still have it run.  On successive tanks (usually 8 oz) progressively lean the engine while varying the RPM via the throttle, until the operational target RPM (factory recommende) is reached.  Then away you go from there.  Some of this run in is done in the air (I am building another trainer type model for this) after the initial run on the bench.  Finally each engine is different as will be the conditions you run it in will vary.  Thus I say there is no real run in time just a variable period.
A final comment.  Racing Rossi engines, take one new in box engine feed it 20% + nitro, fit a wooden prop of appropriate size, take it to max RPM and stick a metal rod into the prop arc, it stops the engine (bits of wood every where.  Then start engine with a "good prop", if it achieves desired RPM it is run in if not repeat one more time and if desired RPM is nopt achieved, select another one.  This was the instruction from the factory back in the 70's when Rossi reigned supreme

blw

My Feedback: (3)

I almost always give a new Saito a couple of near full throttle runs a few times on the first tank. I run them wide open for 5 seconds or so on the second tank, and then longer runs after that. I'm running full throttle for a minute or longer periods on the 4th tank. I think it was my 72 that ran almost all of the 4th tank wide open.

Rudolph Hart

It sounds like there are many ways to achieve the same result meaning after run-in you should get factory specs on the benchmark prop.I stick close to Daves method on the first tank @ 4000 or less and don't touch the throttle.You can rest you hand on the engine all you like,it runs cool that rich.After that i get stuck into it gently and by the fourth tank can peak it steady except for the 115 which took another tank.

Fnq the old control line boys say they used to buy three irvines at a time and do a prop shear on each,then pick the one that revved the hardest as their racing engine,don't know if they were having a lend of me or not.

Hobbsy

My Feedback: (102)

Quote
Where mine & Dave's methods vary is that I do not let the engine run @ a steady RPM. That is against everthing I was ever taught about breaking in an engine.

Dan, that is an old wives tale from the 40s or maybe even the 30s, it went out the window with V8 cylinders wearing egg shaped because they were leaning over, both lines of thinking were based on ignorance. Also, if the cams really have acceleration and deceleration ramps it is most important to have clearance the .004" offers. That explains why myself and a couple of others on here had their engines lose pm when using less than .004". My 1.25 did that.

blw

My Feedback: (3)

I run 4000 for the first 10 minutes.

Hobbsy

My Feedback: (102)

I'll be glad to be able to break in another Saito. I'd like to have another 1.00.

VictoryRoll

My Feedback: (2)

This break-in discussion is really great and I am learning quite a bit... thank you.

SrTelemaster150

So now I'm ignorant? You are a real piece of work. I've had posts deleted for less insulting language than that! Am I that big of a threat to your ego?.

It has nothing to do W/wearing the bores egg shaped & "old wives tales". It has to do with cylinder pressure forcing the rings against the cylinder walls.

For an "old wives tale" it sure has a lot of support these days.

http://www.ntnoa.org/enginebreakin.htm

http://www.popularmechanics.com/cars...k-in-a-new-car

http://www.mototuneusa.com/break_in_secrets.htm

http://novarossi.us/content/view/64/71/

http://m.theglobeandmail.com/globe-d...service=mobile


Makes one wonder if perhaps it is your theory that is based on "ignorance"?

As far as the valve lash, why do you insist that Saito's own .04mm specification is wrong as well as Bill Robison's techniques?





The proper methods haven't changed.

The rings need a high enough "Break Mean Effective Pressure" to force the rings against the cylinder walls. Not only does the RPM need to vary, it requires wide (if not wide open) throttle openings for brief periods.

The thing you do not want to do is bring RPM levels so high or for so long that eccessive heat damages the surfaces that you are being to "burnished".

Once the surfaces are "burnished" properly, friction will be reduced dramatically thus allowing full power operation.

hsukaria

What I know is based on what I read in these forums and engine manuals. I understood that ringed engines you want to break in gradually and start out very rich and gradually lean in with time. It is different for ABC/ABN/ABL engines where you need to run them at peak for short bursts and then let them cool off by shutting them down repeatedly. The ABC./ABN/ABL engines need to loosen up the pinch without excessive rubbing of the plating. Running an ABC/ABL/ABN engine rich on break-in will only prevent the pinch from expanding due to heat and that causes the plating to get worn off. But Saitos are ringed engines, so you want to break them in with a rich mixture and gradually lean in to allow the piston ring to wear to the cylinder without building excessive heat. It doesn't matter how slow you take it with a ringed engine, just sit back and relax as you run them in. You will eventually get to the peak rpm and have enough Mean Effective Pressure to push the ring against the cylinder wall.

FNQFLYER

This break in discussion is interesting. For me what works for me is what I use.  My last comment is that every one of these Saitos that I run in for someone else generally results in a convert to the Saito side.
Old Fart that is what I used to do (the Irvine thing) when I had the money and I still occassionally see it done with Rossi's today (very rarely)