SrTelemaster150

Since 5/16" is about .002" smaller than 8mm I would suspect that your 72 has an 8mm prop shaft.

It may well be that although they both have 7mm prop nut threads, they do not have the same sized shafts.

KenD

My Feedback: (65)

The FA-72 prop shaft is 8mm, the threaded portion is 7mm.

Homer712

My Feedback: (17)

Boy, this is always the place to come for answers. Thanks guys. I reamed out an APC prop to 8 mm and it slid onto the 72 nice and snug.

Ernie Misner

If I remember correctly the 72 and 82 do have 7mm threads but the prop itself sits on a larger shaft where the threads end. You just have to keep on reamin'......

Ernie Misner

mike early

The cylinder wall and the piston on my .91 are scored in one small area. Is the cylinder wall coated with some other metal? Or can I try to buff it out?

SrTelemaster150

Is it scored or does it have streaks?

If you can't feel it W/a fingernail it isn't scored.

If it is scored, it's toast.

The cylinder wall is hard crome plating over aluminum. (AAC aluminum piston/aluminum cylinder/chrome lined bore)

orthobird

My Feedback: (1)

just installed my new saito fa 100 GK on a twist 40.
what a beauty.

turned engine on, very easy.

what a beautiful sound

running 15% nitro with 19% oil

pics to come.

orthobird

My Feedback: (1)

maiden flight this monday, weather permitting.

this is my second saito engine.

mike early

It's toast. can feel it with finger. far worse than what a fingernail requires...

SeamusG

Should I be concerned ...

During the disassembly of my Saito FA-82a I removed the drive flange and tapered collet. A gentle tap of the exposed threaded shaft of the crank end on a soft composite wood surface freed the crank from the case. The main bearing came with the crank. It's very easy to seat the crank/bearing into the case and remove with my fingers. Both bearings turn smoothly and without noise.

Like I said - should Ibe concerned?

FNQFLYER

Had a YS 63 like that once (being the operative word).  The bearing spun in the case and the rest is history. If it isn't a firm to tap fit I use some locktite glue on it and then guarrenteed not to cause a problem.  When you buy the locktite also buy a bottle of debonder saves tears later on

Ernie Misner

Saito 100 on the 40 size Twist??? Far out man! .... but will it balance? Watch out for that plastic spinner on a powerful 4-stroke. Don't stand near by and wear your safety equipment. Let us know what it's like with all that power.

Ernie Misner

Rudolph Hart

You are so funny ernie,safety equipment in a fun zone??

orthobird

My Feedback: (1)

yes, still slighlty tail heavy at 4 inches aft from LE, but at 4.5 inches, it balances out.

there is a post in rc universe that i stumbled upon last night where someone did same combo.

http://www.rcuniverse.com/forum/m_60...tm.htm#6048470

mudboger07

Ineed some info from the experts, A friend has a brand new saito 125 that will not complete one flight without the valves coming out of adjustment, we have readjusted them both intake and ex, flew one flight and they are out again, we disasembled the top end cleaned and even added lock tight (blue) and still they come out of adjustment, does anyone have any ideas why this would happen?

Ken

JohnB96041

Never heard of valve getting out of adjustment that quick. Describe the "out of adjustment" in more detail. I have 3 Saito 1.25 engines. Did the breakin according to the manual, ran about a gallon of fuel through the engines while flying, adjusted the valves and have not had to do it again, so far. Three years of flying. Are you sure that you are adjusting the valves according to the manual? Did you set the lock nut after adjusting? Was the gap still what is should be after locking the lock nut? The settings can slip when tightening the locknut and it will open the gap.

mudboger07

Hey John, This is the first one we have had do this, and we both have quite a few saitos, we made sure after sdjusting the valves they were still in adjustment, we set the lock nut and rechecked. The gap was the same after setting and after seting the lock nut, sometimes it will hold for one flight but most of the time after just a few minutes it comes loose the the point there is over a 60 thousand gap I dont have the manual in front of me but if i remember correctly they set at 4 thousants. also the lock nuts are not loose or any other part of the valve train is loose, Im starting to wonder if something liek the rocker arm is bending? I do know the push rod is straight.

JohnB96041

Just a thought. If you have had the push rods out of the engine, were they put back in the same direction. I don't know is there is a difference in the ends of the push rods, but there could be. I would call HH tech support and get some help. A cracked rocker arm would really do the trick. You should be able to see if the rocker arm is bent or bending. Look for a crack on the bottom side of the rocker arm near the retaining pin.

mudboger07

Will do John, its stumped us too, both of us are really good at engines thats why were so stumped...lol we havent seen anything broke, looked bent etc. its got us totally stumped.

retransit

My Feedback: (18)

This may be a bit simplistic, but did you adjust the valves on compression stroke?

Bob

SeamusG

This is an FA-82a pic to demonstrate the difference in the push rod ends. If the rounded ends (not the pointed ends)were installed towards the rocker arms, no way would (could)they stay in the "hollow"of the rocker adjusting screw. When they become disconnected from the adjusting screw the gap jumps to 1/8" from .0025".

mudboger07

John, ya the pointed in are facing the rocker arms, thats whats wierd, like i said weve never had this kinda issue before, its probably ganna be something simple that were over looking, he just ordered all new valve train parts so well see when he gets back from joe nall.

radial1951

*
Hi Ken

Some thoughts on your problem. Let's assume:

1. At the end of the flight, the adjusting screws and lock nuts are still tight and have not moved. (You might be able to check this by degreasing the parts and trying a tiny dab of correction fluid on the screw, nut and rocker. If it sticks ok, you will see if any component has moved during the run).

2. The rockers aren't brocken, the tips of the valves and rocker tip are not suffering massive wear, and the same for the pushrods i.e. they are the same length after the run.

3. All other engine screws are tight and nothing else is apparently loose.

NOW, the problem moves down to the components activating the pushrods i.e. Tappets (Part 38) ; Cam Gear (Part 35) ; Cam Gear Shaft (Part 36).

If this problem has occurred quite a few times, any wear on those components will be more than obvious!

Regards, RossG
radial1951
______________

SeamusG

If this were early April (real early) I could understand.

I assembled my 82 yesterday. I managed to get the alignment of the black push rod tube off and at that angle it pushed the push rod sideways in the tube so when the cam lobe pushed up that particular push rod could not travel freely and was pushed off to the side.

When you say "valve train parts" that could be a fairly long list of new bits. What's being replaced?

radial1951

*
Hi Ken

If the engine is brand new, why is your friend buying new parts for it.

As JohnGilmore says, that could be a long list of expensive parts.

It does have awarranty...

Regards, RossG
radial1951
_____________