w8ye

My Feedback: (16)

Your thoughts sound good

blw

My Feedback: (3)

Dave, I thought it a good term to use. If you haven't heard of chamfer, flair or bevel will work.

min$2crash

Thanks a bunch for all of the wisdom and input, guys. I was just cleaning up and looking for the alignment hole and noticed that I probably need a cam as well. Intake has spalling on both ramps, even though the lobe's peak looks fine. Tappets still look good, though. Should tappets automatically get replaced with the cam or do they fare much better than the cam ramps? Probably 20 gallons thru this 91s- seems early to me- a cam? I broke it in new, generally run rich, run it dry after each session, use after run oil and set the tappets at least once a season with an indicator to 0.003" to avoid excessive lash.... never disassembled the engine before the bearings went last week. I'm seeing that 30 hrs on bearings is about all you get, but what do you think made the intake cam spall so young (exhaust lobe is fine)?
I'm not perfect though- I tend to go fly in the spring without putting oil down the pushrod tubes- figuring I got it good and dry of fuel and then double oiled it with pneumatic oil in the fall.

w8ye

My Feedback: (16)

On that size Saito the tappets or cam followers seem to wear pretty fast so if you are going to replace the cam because of the peening on the clearance ramps, then you should replace the cam followers also. They don't cost much.

Campgems

Wow, take a couple days away and your name goes up in lights.

On the front and back of the piston. I found that on my engine, that there was a binding that went away after turning the piston 180 on the rod. This could have been caused by the grove in the piston that the rod rides in was machined a little off center, on purpose or by acident, or more likely there was a little buildup on the wrist pin and it wouldn't let the rod slide freely,


As to my mechanical experience, I do have a lot of experience, some 50 years of it,on a wide range of machinery. However, when it comes to O.S. or Saito engines, W8ye is the man for information.Every piece of machinery I've worked on had a trick or two that made things come apart and go back together easily. These enginesare no different. Keeping in mind that they weren't hammered together at thefactory should indicate that they shouldn't be hammered together, or apart in the shop. When thingsdon'tseem right, they arn't.Quitassembley or dissembly and askquestions. That trick is out there waithing for you to find it.

Iaggree with W8YE on the lifters. I've discovered that the Saitos don't have good blow by oil circulation around the cam, so it is difficult to get fresh oil in to keep things lubed. Thereis no way to squirt some after run in to keep things lubed either. Iread somewhere recelntly that someguyswould put a couple nipples on the cam housing and run tubing from the crank casevent to one and then ventthe other side. That will allow some oil circulation to take place. If the crankcase vent is behind the cam, you may want to consider this.

O.S engines either use unshielded bearings on the main or have a bore throughthe crank and a hole to the cam gear area to allow oil to migrate there.

Don

blw

My Feedback: (3)

The lobes and followers are good places to use castor.

min$2crash

OK, thanks, all. W8ye, I'll pop for the tappets- or is it tap for the poppets? (bad pun, sorry, Brits call valves poppets)
Campgems, welcome home and thanks, I really like the idea of putting the crankcase vent into/thru the cam area because this seems like a cam died young to me. May as well use the oil one last time before dumping it out into space. Any ideas on how the after oil procedure might change with this extra lube loop? (I'm cowled in herewhen the difficulty goes up the frequency goes down, eh?)

So perhaps it was a case of bad lube, perhaps bad metal. It all looked nice and wet to me in the cam box, a little brown but not rusty.
But the cam was more than "peened", it was fully spalled on both intake ramps. I'll post a nice microscope pic in a week when the part is out. Now this engine always pushed a good bit of oil out the front bearing, which was only a concern to me in terms of cleanliness- but I think its also a sign that the oil was getting pushed forward, if not into the cam box. I figured that was because I had a fairly long (6-8") hose on the (rear) vent nipple to keep the plane clean. In its first incarnation, this engine ran upright. Now it runs cylinder pointing down to about 8 o'clock- so I'd expect oiling of the cam to be better... no?

Iknow, don't think, just install the darn parts! Boss used to say that all the time when I was a car-fixer.
Since this seems like a forum of serious Saito-heads, any suggestions for torquing the jug down besides carefully and diagonally?
Those bolts clicked "real loud" when they broke free and this is my first jug-out. That's "cable guy" for 10ftlbs, right? I have a good feel for how tight to do them, but I'm always up for suggestions or specifications if they exist. Not planning to use a torque wrench, but could easily get my hands on a small one if I knew what torque specs to use.

If I am reading you right blw, Castor oil may have been a way to avoid this intake-only cam wear? I ran a range of fuels, depending on flying style/mood, what I had on hand and what I threw in the car, but mostly, say just over half the time, YS20/20 from Powermaster, balance was Cool Power 10&15, except for the odd month where I ran 30% heli from Morgan Fuels. I believe Powermaster had some castor in their lube package (semi-synthetic) but am betting all the other (Morgan stuff) was synthetic. I keep Omega for my ABC's but didn't use it in ths engine much. Thanks once again, all y'all.

w8ye

My Feedback: (16)

Stay away from the all synthetic regular Cool Power in a Saito unless you add some castor oil to it.

The 20-20 and 30 heli are OK.

blw

My Feedback: (3)

I always torque bolts out of habit. Yours probably clicked from a lot of heating/cooling cycles and threadlock.

The late Bill Robison took pictures of Saito lobes that ran with castor and without. W8YE may have the link to that comparison. From what I remember, he had pictures of damage on engines running on all synthetic fuel.

Your engine is technically an AAC, but you should treat ABC engines about the same. IMO, there isn't much difference.

min$2crash

So I got my new bearings for the Saito 91S installed OK, but still waiting for my Cam (and lifters) from the LHS. Ordered them Tuesday- guess my goodwill for helping to support my LHS will not go unpunished....! S'ok, I got other planes for tomorrow...
Meanwhile, Campgems got a bee in my bonnet with rerouting the crankcase vent thru the cam tower- I was at the Toledo show today and picked up a couple of tubing nipples/taps with a nice beefy 10-32 thread on them. Now I have to figure out where to drill for them. Its pretty tight on the outside of the cam gear part of the box where I was picturing the install. Next and probably better is to put the taps right over the cam lobes themselves. It appears as if there may be more beef up near the top, since the cams rotate but the box's sides are vertical it must thicken or at least have more clearance there. The taps I got have 5mm of thread under the wrench hex, but the cam box is only 2mm thick at the gasket line, with barely 1mm clearance to the lobes and gear. So I need to add 2-3 mm of washers, do some messy grinding to shorten 5mm down to 2mm[X(] & reestablish the nice starting thread that're on the taps now, or find a place where the case eats up 5mm. As you can see in the attached jpeg, the vertical sides of the box, near the top, are frontrunners at this point beacuse the box wall gets thicker there. In other words, the cambox sides are vertical, but the inside wall follows the cam lobe circle, therefore the wall gets thicker by what looks like plenty. I can probably drill opposite each tappet guide, i.e. staggered axially so one tap lines up with each tappet guide, but on the thicker opposite side so that the guides are unaffected. Any thoughts or experience here? They left a lot of beef up there for the brass tubes that the tappets ride in as you can see in the pic where I traced the cam lobe swing in pencil. I think I have it in hand, and really just want to make sure before I drill and tap where indicated in the pic... and then again on the other side- its going to be hard to back out of. You guys seem to think of everything and then some- so if you don't mind, I'd appreciate your thoughts. I'll take some pics as I go for future "voyagers". Thanks, both in retrospect and in advance!!!!

w8ye

My Feedback: (16)

Don't sweat it. You can buy another cover if you have too.

min$2crash

All done! It was tight, missing the tappet tubes and still working on the beefy part of the cam tower... but here it is- pics of the cam box as modified, and one of the final assembly with new hose routing- from the original back cover nipple, to the cam box with the black hose, then outlet tube like normal from the other side of the cam box. This and no more synthetic oil and I may get the cam to last longer than the bearings! The one nipple (rear, engine left, rhs from the front) blocks a cam box screw so it has to come out for cam box removal. Boy was that some pitty metal I drilled and tapped into... big ol' blowholes here and there on both sides. That's pretty common in the thickest part of any aluminum casting, but geez was it hard to clean the tapping chips out of those porosity cavities. Just wanted to post my version for the next "voyager".
Thanks again, all. I'll report back when I run it!

PS now I'm back to normal oil draining with a single hose on the backplate..... it was a waste of time to put the nipples on the cam box.... the oil never went from the backplate to the cam box. On the other hand, now I have a GREAT place to oil up the cam when i first start it in the spring! I suppose that a check valve might help, but the whole crankcase sees fairly even pressure pulses so I doubt even that would help. Guess I need an oil pump, huh?

jworden

Sorry, the post duplicated itself.

jworden

Howdy from Tennessee! Been reading all the comments here on Seito. Have learned a lot. But, I have a problem and need help. A friend gave me a Seito 65 that has been in somebodys junk box, it appears. Very dirty and covered in dirt. I have torn the engine down and have been soaking and scrubbing everything. Using glow fuel for the soak. It is cleaning up and starting to look good. The piston and rod came out of the case in pristine condition. The valve push rods were both out of the rocker arm indent but they appear nice and straight with no damage. My problem is, the crank bearings must be full of rust and boulders. With the jug, piston and rod removed, and having soaked and flushed the crank, it hardly turns and feels about like what driving down a wash-board dirt road feels. I have tried to remove the crank shaft using heat and tapping on the shaft but don't want to get too aggressive for fear of breaking the lower case. What do I do? There has to be a way to get the shaft and bearings out. Any advise will be greatly appreciated.

w8ye

My Feedback: (16)

I take the cam box off

Then you need a puller to remove the prop drive washer. I got mine at Harbor Freight

The crank should tap out easily with a soft hammer or a block of wood

min$2crash

So I broke the 91 in yesterday- not real pleased with the cam oiling mod.
After a full tank of really rich (6 turns because I didn't change the idle needle from where its been for 8 years.... ) there was no oil going from the factory nipple up to the cam nipple- it was dry when I pulled the hose off at the cam box and "milked the hose" so to speak. Luckily I had lightly lith-greased the cam and lifters in their bores.
For the next two 12oz tanks, I put it back in normal mode, looping a tube between the two nipples I added (see 3 posts ago). I was a little surprised how little oil was coming out of that port. Good news is that it will now peak at 9400 with APC 14x7 which is where it was a month ago before the bearing 'grenaded' its cage. So I guess I'm back in business.
Bad news is that the crank vent pipe isn't putting out the normal amt of oil- never got full running two tanks- just a quarter inch at the bottom. Not certain this is abnormal- but I was watching closely because the cam box oiling didn't seem to be getting fed oil by the crank vent when I had it hooked up that way. I also noticed that my old trick of covering the crancase vent with my finger or tongue (ecch!) to find when it was done blowing out so that it would take in afterun oil was not normal either. No real flow out the crankcase tube as you hand rotate the engine. Used to suck and blow alternately due to the piston moving up and down. The new bearings have rubber covered seals up front, so I am very puzzled/concerned about where that pressure/flow is now going.... any ideas? I fear that I may have excessive blowby- but then I'd expect the crank drain to be more productive.
And, all the while, its power output is normal so the blowby can't be TOO excessive. Valves were feeler checked to 0.002" pretty close, definitely not holding a valve open or anything- I checked that the rockers had real clearance/slop after setting them to 0.002. Next thing I'll do is check lash with an indicator and then try and find the crankcase leak some other way.... maybe fill the whole crankcase up with oil and pressurize it or something. No O-ring seals on the extra two nipples just yet- but I made 100% threads because they were straight 10-32's acting as pipe threads so I needed the tight minor diameter.

Hobbsy

My Feedback: (102)

Picture #1 is normal, picture #2 is new and unrun.

blw

My Feedback: (3)

Min$2crash,

That stuck needle valve is your low speed nv, and is very important on your Saito. It controls about 85% of your available throttle.

Those nipples become clogged from time to time. Have you tried sticking a pin in it to clear it out?

min$2crash

blw: Sorry about the confusion. My Low speed needle is not 'stuck'. Its right where it ran perfectly a month ago before the rear bearing cage grenaded on me. I just left the LSN where it is, expecting to get right back there after break-in. To compensate, in light of what you have posted in the past about much of the main flow coming from the LS needle, I took it up an extra turn on the main needle to 6 turns for break in. Nice and wet, cool running there, no dark color to the exhaust oil & head touchable during break-in.
As far as those nipples clogging, I didn't know that happens- so thanks. I don't think that's happening here because I actually blew into the hose attached to the factory nipple and was surprised to get lots of flow, minimal resistance, even though the two "new" nipples were closed off (connected to each other with a short hose). I picked up some 5/32 o-rings to put under the flange of the new 10-32 cambox nipples to seal them up a bit better- hand drilling/tapping is never quite square, eh?. I also need to go back and see if the crankcase takes a lot of air in all crankshaft positions: i.e. when either one of the valves is open, the reverse blowby (from me pressurising the hose) has someplace to go. When they are closed, it may be different to blow on the hose. The more I think about it- I suspect thread leakage.
Edit: Orings installed, no change. If I blow into the crankcase hose, both with and without orings installed on the cambox nipples I added, it leaks the same no matter what crankshaft position I'm in. Conclusion: flow is going out the front bearing, even a new "double seal" one from RCbearings- those are not lip seals- but rubbercoated shields. I can actually hear what is probably the front seal lightly oilcanning when I blow air into the crankcase vent. Time to quit jackin' around and go fly! I'll fly no-cowl for a few more tanks and put a clear hose on the cam box tube. If it doesn't get oil in it soon, I'm pluggin' the holes I made w/ nylon. Heck, the cam and tappets only cost me $17 and the cam box is wetter anyway now that I'm flying with the cyl head at ~8:00.

PS now I'm back to normal oil draining with a single hose on the backplate..... it was a waste of time to put the nipples on the cam box.... the oil never went from the backplate to the cam box. On the other hand, now I have a GREAT place to oil up the cam when i first start it in the spring!

jworden

Well, I managed to get the bearings out of the FA-65 with heat and a little persuasion. Got the lower case and the jug cleaned up. Installed new bearings and reassembled the motor. It feels smooth when pulled through. Not much compression for some reason. The valves and seats looked clean during cleaning and the ring looked okay. May have to go back in and replace valves or the ring. I am not familiar with Saito 4-cycle so don't know if low compression is normal. Any thoughts?
thanks,
Jim

w8ye

My Feedback: (16)

Sounds like you removed the piston from the cylinder?
you probably disturbed the ring's seating

See if the compression comes back up after you run it?

There may be a valve too tight?

RC-Bearings

My Feedback: (1)

The sealed bearings I sell are indeed lip seals. They are not generally designed to hold back a lot of pressure but are designed to kep the lube in and dirt and liquids out.

Hobbsy

My Feedback: (102)

Jim, you've disassembled a lot more engines than I have. When I pulled the cylinder from old .80 the other day to re-paint it the ring gap was right above the front wristpin hole. I made sure it was in the same spot when I reassembled. I musta dunnit right because it still has the same no leakage compression its always had.

w8ye

My Feedback: (16)

To just change bearings, there is no need to remove the piston assembly from the cylinder.

Remove the back plate first and when you unbolt the cylinder, just raise it enough for the lip on the cylinder to clear the crankcase and then slide the rod off the crankpin.

Set the assembly aside and continue to work on the crankcase . . . . .

RC-Bearings

My Feedback: (1)

That is exactly what I do, Bill, unless I want to inspect the piston or ring. Makes it easier to get it back together right!