William Robison

My Feedback: (3)

All:

I have been finding some Saito engines that are sagging at high rpm with no fuel fault, and they aren’t overheating either. Some have gotten so bad that they just quit running. If your engine has lost 1000 rpm or so, possibly even less, your tappets may be sticking.

I’ve had three engines come that were so bad the valves wouldn’t close, they lost compression entirely and wouldn’t even start. Others I’ve seen would start and run normally unbtil the throttle was opened to full.

To check, pull the rockers leaving the push rods in place. Turn the crank to get the push rods up, then keep turning the crank. Ideally, the weight of the push rod and tappet will make the rod go back down by itself, if it doesn’t push it down manually. If it takes any more than the lightest pressure to push them back down you have the problem.

Someone is going to blame castor oil for this, but castor wont “Cook” until it gets around 600F. You can get carbon burned on an exhaust valve stem, but if the tappets got that hot the engine would already have melted.

I mainly suspect a lower quality synthetic and a lack of after run oil. vAnother possibility is a restricted case vent keeping the “Nasties” inside.

Cure is a good scrub of the guides with acetone or similar solvent, then a quick polish with a 4mm rod and a touch of Colgate tooth paste spun in the guide.

The tappets are supposed to rotate, keeping the wear evenly spaced across the face, but often they don’t leading to wear into a cylindric shape.

In normal installations it wont matter much, but as the tappet wears unevenly the valve open duration can be decreased by 10 degrees or more, if the power was marginal at the start this can lead to dissatisfaction.

So long as there is a good amount still flat on the end of the tappet it is still OK to use.

Bill.

Pictures:
1) New tappets.
2) Carbonized tappets.
3) New faces.
4) Worn faces, OK.
5) Worn out faces.

IronCross

Close counts for horse shoes and hand grenades aye.... Since your the leader of this motly group I figured we could all converge at your house for a weekend of frivolities Nothing special, a few dancing girls, a few kegs and some steaks out to do it Then at midnight we could all fire up our Saitos at the same time... This will probably get you divorced and run out of the neighborhood but hey, it is for a good cause... SAITO

William Robison

My Feedback: (3)

IC:

Sounds like a good idea. No worries on the divorce; already done, and the neighbors will join the celebration even though they will have no idea what we are celebrating.

Now all we need is the participants to put a $200 credit in my PayPal account. Got to pay for the dancing girls and the brew some way.

Haw.

Bill.

Ernie Misner

>>> At the same time, I don’t run either Cline or Iron Bay systems, I just don’t like the thought of the fuel system running 10-12 psi inside the plane – I worry about leaks. At the same time I have a dozen or so Perry pump systems working with no problem. >>>

Bill, how much pressure does the Perry pump produce???

Thanks,

Ernie

William Robison

My Feedback: (3)

Ernie:

I really don’t know what pressure the Perry pump gives, but the only part of the system that has pressure is between the pump and the carb – if that hose leaks the lost fuel is confined to the engine area. Much easier to clean than sopping fuel out of the rear of the fuselage when a tank pops and sprays the inside of the plane.

Just my preference.

Bill.

huck328

My Feedback: (4)

upssteve,

My Saito 125 on my Funtana 90 is mounted sideways (like I assume yours is) and used to make a big gassy mess around the carb constantly too. The stack and filter helped with some of the mess (and helped my fuel efficiency, thanks WR), but it still leaked when the motor was not running. I found that a Cline regulator completely solved my leaking problems. It does not allow gas to go to the carb unless the carb is actively sucking. See my picture in post 4103 above.

Not to go too far off topic, but how did the 125 fit under the hood of the X100?

huck328

upssteve

My Feedback: (11)

125 easily fits in cowl on x100 and it is sideways and it leaks inside when running. need to seal fuse hole and lean low end and add stack thanks

upssteve

My Feedback: (11)

i have a question bill... how much should i lean out the low end. motor has about 1 hour of run time 2 on ground and 2 tanks in the air. it spits so bad that it actually filled the fuselage on my new x100 with fuel . spits right in the fuel tank opening. im going to make a plug and seal the hole and just make the lines come thru the firewall . i did order the stack and got the filter. do you need anything else to put the stack on with. oring rtv etc??? let me know thanks steve

William Robison

My Feedback: (3)

Steve:

The base of the stack needs to be sealed against the flat end of the carb. Select an o-ring to fit in the relief at the intake end of the carb, that’s thick enough for the stack flange to hold it in place.

To adjust the low speed needle the very first step is to open the throttle to full, and peak the high speed needle. This is very important on the Saito carb, as the LS is in control up to about ½ throttle, and still has a lot of effect up to ¾ throttle. Maladjustment of the HS will keep the LS from being set properly.

With the HS at peak go back to idle, while holding the throttle to keep it from turning, slowly turn the idle mixture screw in – lean – and listen to the engine rpm. As the rpm rises back the throttle down to keep the idle from getting too high, 2500-3000 rpm is a good range for the moment. Remember also that the engine will have a delayed response – after turning the screw the engine may take as much as 5 to 7 seconds to respond.

When you think you’re getting close, let the engine run at idle for 20-30 seconds, then pinch the fuel hose shut. The rpm should rise just a little, then fall. If the engine dies immediately you’re too lean, if there is a large rpm increase you’re still rich.

This “Pinch” test will get you close, but is not a final setting.

After you have a good steady idle, slam the throttle wide open. If the engine answers the throttle cleanly and speeds up with no hesitation you have the LS set properly. If instead it smokes and burbles before speeding up, the LS is still rich. Too lean it will just sag, and possibly die.

It might take you several tries to get it right the first time, but setting the LS is an easily learned skill, so the next one will be done a lot faster.

Please note also, if you do this before installing the stack and filter you’ll have to do it again after you put them on.

Bill.

upssteve

My Feedback: (11)

thanks bill... one more question does the oring need to be inside the stack or outside...

tailskid

My Feedback: (34)

Had a problem with my .72 last weekend.....wouldn't stay running. Changed glow, fuel lines, etc. Turned out it was a VERY small piece of metal stuck in the slot of the spray bar!

So after 4 hours of trying, and FOD removed, she is running fine once again!

plasticjoe

My Feedback: (22)

Bill,

I am not the most mechanical person in the world. But I have been having problems with my saito .91 Last Fall there was a loss in power so I thought I would re-set the valve gap like you described here in the thread. On doing so, I noticed a pickup in power, but now it seems as if the valve gap is loosening after just a run or 2. I have some pictures of the engine , with the covers off, not sure if that helps you any but here they are. I was wondering how much you would charge to look it over and rebuild it if necessary. I bought it used, so it very may well need a rebuild. You cam PM me here if you like. Thanks in advance for your help

winger62670

where is the best place to purchase parts. I've go a FA 50 Golden Knight with a broken backplate/carb mount also a FA 45 with a broken carb.

plasticjoe

My Feedback: (22)

the server would not let me attach the files, let me try again

w8ye

My Feedback: (16)

www.horizonhobby.com

If it is not a 45S then you cannot get the carb body for the engine. Its been out of production too long

http://www.horizonhobby.com/Products...dID=SAI50GK17B

blw

My Feedback: (3)

upssteve- look at the bottom of the carb and you will see a round area for the o ring to sit. Put it there and carefully clip the stack on the carb. You can see between the clip and carb to check if the o ring is still aligned correctly. You can also look down the stack and see if it has slipped.

rlmcnii

My Feedback: (3)

plasticjoe,

Take a look at the upper ends of the pushrods where they ride in the depression at the lower end of the clearance adjusting screw. The ends of the pushrods should have a slight , but easily visible, taper that ends in a radiused point that rides in the adjustment screw. If either of the pushrods is not tapered, it is in upside down. If so, it will have probably chipped the adjustment screw and will be popping out of the depression in the screw. That results in wild valve-clearance fluctuations.

Been there, done that; also with a .91. There have been a couple of other reports about the same problem in this thread. The appearance of the pushrods can be a little deceiving in that the non-tapered end (the bottom) also is radiused, and that radius looks as if fits well in the cup in the adjustment screw. It looks good, but it will not stay in place.

[email protected]

Bill Robison,

Re: your comment on lapping cam box to adjust gear mesh.

My 30 did not come with any gasket under the cam box (I think 30s are all like that). There was no choice other than to lap to bottom of the cam box. The lapping didn't take but 2 minutes or so. It was the disassembly, proper binning all parts, and assembly that took the most time. It was well worth it, because I am happy with the engine now and this happiness came at a very low cost!

Philip

William Robison

My Feedback: (3)

Steve:

Barry (blw) answered the question about the o-ring, it should seal the gap between the flange of the stack and the body of the carb. At the same time, it should not stick into the air passage. A leak between the stack and the carb will allow some of the back spray fuel to go out the side, partially defeating the purpose of the stack and filter.

Skid:

Glad you found the problem. The solution led to satisfaction? Haw.

Joe:

The pictures aren’t telling me anything about your valve clearance problem. Good try, though.

Rimcnii made a good suggestion, we have seen some engines assembled with the push rods wrong end up, do check that.

And, as I said a few posts back, the FA-91 is one I’ve seen sticking tappets in lately. That could also be your problem. If the tappet were stuck you could set the clearance to specification, then when the engine warmed and the tappet went back down in the bore the valves would be loose. Check my earlier post about this.

Winger:

As W8YE Jim said, easiest Saito parts source is Horizon Hobby.

Philip:

The only FA-30 I’ve had my hands on is the one Hobbsy loaned me a year or so back. I really don’t remember its not having a cam box gasket, I think if it did not I would surely remember because of the oddity. I am glad you’re happy with your results – does it seem to run any differently now? Let us know.

Bill.

PS: New members:
362 gbzflyer
363 winger62670
Welcome.
wlr.

William Robison

My Feedback: (3)

Push rods for the mid block engines. The top end is the one on the right. The taper is easily seen.

Bill.

glen9032003

91 on Tiger 60, 82 on a Josh Stick, and a 72 on a Kadet senior. Never had a problem.

w8ye

My Feedback: (16)

I have three late model 30's. There is no gasket under the cam box cover.

Hobbsy

My Feedback: (102)

Someone had asked about the difference in physical size between the .30 and the .40a. I've taken a hiatus from building to place a new floor in my shop, the existing concrete is uneven and ugly. I spend a lot of time making special cuts to get my mini floor joists cut so my new floor will be level and straight. so far so good. Here is a shot of the intake pipe seal on the .40a.

TimC

After looking at the .30 gasket kit at Horizon, and checking my own .30, there doesn't seem to be a cylinder base gasket either.

w8ye

My Feedback: (16)

I've had a half dozen Saito's of different sizes apart in the last year and only one had a cylinder base gasket which I removed.