Author Topic: SAITO .72 CL: Time for breaking-in (Read 6737 times)

Claudio Chacon · « **on:** January 15, 2010, 02:24:17 PM »

Hello guys,
One of the two ships that I have under construction is about to be finished, so It's time to break-in the engine.
Since this is the first time I'm going to deal with four stroke powerplants, I've got some questions for you folks that have been there already. The subject is a Saito .72 in it's Control Line version.
Here we go:

1. Would it be OK to use 5% nitro fuel (20% synthetic oil) to break it in? (fuel is quite expensive down here, so I don't want to burn a higher nitro content fuel if it's not absolutely necessary).

2. I've been told that, during the breaking-in period, it's hard to keep the RPM's under 4000 (the user manual says not to exceed this figure) because this CL version engines tend to go lean no matter how far open is the needle:
Is this true? In that case, are there any means to solve this problem other than installing an RC carb?

3. Any other tips and remarks will be VERY welcome.

Regards and thanks in advance,
Claudio.

Alan Hahn · « **Reply #1 on:** January 15, 2010, 06:06:23 PM »

The 4000 rpm number is possible with an rc version because you can simple close the throttle.

I am sure 5% nitro is fine--especially for break-in. The extra nitro is good for power (probably not an issue for a 72) and for low idle speeds (also not an issue with CL). A lot of people use the synthetic oil because it tends not to foul the valves as much as castor does. I kind of like a little castor for the "just in case" issues when you get a lean flight.

So my guess is to simply go for it. You might be able to lower the rpm by simply doing the old "stick in the venturi" trick. Just try to block off half the venturi opening, which would simulate closing the throttle.

I also think it isn't a bad idea to pump the engine with some extra lube (after run oil would be ok I think)--both through the breather, but also into the valve covers. There should be some oil there from the factory, but I think one reason for the low rpm first runs is to make sure the normal blow-by oil from the fuel has a chance to get up and around into the engine before you open the throttle up to full power. Remember that's how a 4 stroke gets its lubrication--the oil from the fuel blows by the rings into the crankcase.

Bob Reeves · « **Reply #2 on:** January 17, 2010, 04:48:41 AM »

Alan gave you some good info.. Remove the valve covers and dribble some oil down the push rods and oil the rockers. You can use any fuel it will run on with at least 20% oil for break in just be sure to use after run oil if it's all synthetic. Besides the castor carbon issue all synthetic flows easier and will help fuel draw.

I have enough spare Carbs around I just put an RC carb on for break in. I think Allan's suggestion of closing off part of the intake is a good one. I would close off at least 3/4 and run the needle as far out as you can, the low speed initial run is very important.

My findings on the 40 and 62 CL versions has been that the hole in the spray bar was drilled too small by Saito. Never seeing a need for the 72 I have not had one in my hands but would guess it has the same issue. Take the intake apart and see if you can slip a #56 drill bit .046 in the feed hole, if not it's too small. I have a #56 drill in a pin vice and just drill them out by hand. Then make sure you don't leave any burs on the inside by carefully running a larger bit down the needle hole.

proparc · « **Reply #3 on:** January 18, 2010, 01:00:19 PM »

High Claudio,
The "big block" is really my thing. Bust a move on the RC carb if you have to to keep it under 4000 rpm. You MUST use a tach on the Saito because 7000 rpm sounds JUST LIKE 3500 rpm,(trust me, I know).

Here's the deal, first quart 2000-2500 rpm no more!!! Fuel for break-in,(I fly with this) 10% castor 10% synthetic. Do not-repeat, do not use all synthetic fuel on break-in no matter what anybody tells you. When you finish break-in,(and this is the manly part) DON'T just check your valves-readjust them.

Better still, make sure you check your valve clearance before you crank it up for the first time,(Saito screws up from time to time). Do not use the valve shim gauge that comes with your Saito. When they stamp them out at the factory, it leaves a "lip" on the edges that screws up your valve adjustment. Purchase and use a high quality set "Kastor" brand here in the states.

Do not over prop your "big block" on break-in, be nice to it. Get your break-in right and the thing will last damn near longer than you.

Claudio, when you get everything right, and you crank that nose up for your first reverse wingover-I know for me, I thought, "man, this is as good as it gets".

Claudio Chacon · « **Reply #4 on:** January 19, 2010, 08:54:55 AM »

Alan, Bob, Milton:
Thanks a lot for taking the time to respond to my questions.

Bob:
Indeed, the feed hole in the 72 CL carb is small too. The .046 drill bit doesn't slip through the tiny hole. I will enlarge it.
I know that you've modified several RC carbs to adapt the 1/4" nylon screw. I noticed the the RC carb spigot is different from the CL one (as they come from the factory): Have you done this mod to any CL carb? Have you used any of the Saito engines with a CL carb without any mods? I mean, do you think that the nylon screw modification is mandatory in a CL carb also?

Milton,
Understood. I'll use the fuel you recommend. I will look for a good quality shim gauge set here. Regarding the prop, I was thinking of a 13x6 for break-in. Is it OK?

Thanks again guys,
Claudio.

proparc · « **Reply #5 on:** January 19, 2010, 11:47:47 AM »

Quote from: Claudio Chacon on January 19, 2010, 08:54:55 AM

?

Milton,
Understood. I'll use the fuel you recommend. I will look for a good quality shim gauge set here. Regarding the prop, I was thinking of a 13x6 for break-in. Is it OK?

Thanks again guys,
Claudio.

Too big bro!! Here's the deal, diameter increases load and load, increases heat. Remember, we want to conduct our operations in a manner that reduces heat and stress and allow the engine to “seat in” gently.

As a general rule of thumb, go one size below your flying prop for break-in. I broke mine in on a 12x6 APC, (remember remove all the sharp edges!). The weight and “flywheel effect” of the APC helps to “drive” the internals of the Saito through a cycle. Even Saito recommends this.

Make sure the prop is PERFECTLY balanced. You want things as smooooth as possible on break-in.

Claudio Chacon · « **Reply #6 on:** January 19, 2010, 02:10:38 PM »

Quote from: proparc on January 19, 2010, 11:47:47 AM

Too big bro!! Here's the deal, diameter increases load and load, increases heat. Remember, we want to conduct our operations in a manner that reduces heat and stress and allow the engine to “seat in” gently.

As a general rule of thumb, go one size below your flying prop for break-in. I broke mine in on a 12x6 APC, (remember remove all the sharp edges!). The weight and “flywheel effect” of the APC helps to “drive” the internals of the Saito through a cycle. Even Saito recommends this.

Make sure the prop is PERFECTLY balanced. You want things as smooooth as possible on break-in.

Hi Milton,
Yes, my flying prop for the 72 will be a Top Flite Power Point 14x6, that's because I choose a 13x6 for break-in. But I can install a 12x6 for break-in, even a 12x5 no problem. A few more questions:
What type of carb do you fly with, RC or CL?
What is the altitude ASL of your flying site?
Which is the weight and wing area of the plane you currently fly with the 72?

Thanks,
Claudio.

Bob Reeves · « **Reply #7 on:** January 19, 2010, 03:32:06 PM »

Hi Claudio,

Hers the deal, you can either run the CL intake stock and then search for a prop that works or you can make the intake adjustable so you can fine tune it to the prop you have. I like being able to tune the intake to the prop. The easiest way on the CL intake is to install threaded blocks in/under the cowl so you can run a 1/4-20 (or metric equivalent) nylon screw down the throat of the intake.

BTW: I run a 13-7 RevUp on the 56 and a 13-6 three blade on the 62 your 14-6 should work but might try a 14-7 with the intake choked down to get the lap times down to 5.3 or so. What this does is increase the fuel draw which helps maintain more constant rpm in the corners and overhead.

OH ya.. If the 72 comes with the insert like the 56/62/40 does, leave it out if you add a choke screw.

Claudio Chacon · « **Reply #8 on:** January 19, 2010, 03:56:52 PM »

Quote from: Bob Reeves on January 19, 2010, 03:32:06 PM

Hi Claudio,

Hers the deal, you can either run the CL intake stock and then search for a prop that works or you can make the intake adjustable so you can fine tune it to the prop you have. I like being able to tune the intake to the prop. The easiest way on the CL intake is to install threaded blocks in/under the cowl so you can run a 1/4-20 (or metric equivalent) nylon screw down the throat of the intake.

BTW: I run a 13-7 RevUp on the 56 and a 13-6 three blade on the 62 your 14-6 should work but might try a 14-7 with the intake choked down to get the lap times down to 5.3 or so. What this does is increase the fuel draw which helps maintain more constant rpm in the corners and overhead.

OH ya.. If the 72 comes with the insert like the 56/62/40 does, leave it out if you add a choke screw.

Hello Bob,
I have no room in my fuse to install a threaded block, that's why I need to know how to properly modify the CL carb to adapt the nylon screw.
Yes, the 72 comes with the that insert too.

If I send you pics of the disassembled carb, can you help me through the process on how to modify it?
I've read your article posted on the Tulsa web site, but the CL carb is different, so I have some doubts and don't want to screw it up.

Thank you,
Claudio.

Bob Reeves · « **Reply #9 on:** January 19, 2010, 05:37:48 PM »

The CL carb can be modified just like the RC carb but you will need another needle assy. The remote needle valve off an early OS works great. This is the metal one mounted on a metal bracket. Also, if you have an old OS RC carb laying around you can use the needle assy off it. You have to make a new barrel for the carb, drill and tap one side for the OS needle then drill and tap the other for a 10-32 nylon screw.

This will give you a spigot venturi with the adjustment right at the spigot which I believe is a better arrangement than the stock CL intake.

proparc · « **Reply #10 on:** January 19, 2010, 06:32:09 PM »

Claudio,
It is interesting to note that you mentioned the APC 12x5 because, that is EXACTLY THEE prop I am going to use to break-in my next Saito,which will be the FA-62 CL. I personally would stick with the APC 12x6 on the "big block" to get "just a scoshe" more load. Hey, but if that is all you can get, than rock and roll. Remember, the goal here is to get the internals turning gently. And ultimately, to get out to the flying field.

And wait till you do with that 72.

Welcome to the club.

Sorry, the other questions. 725sq on the plane. The altitude varies here in Socal.

Claudio Chacon · « **Reply #11 on:** January 22, 2010, 01:56:04 PM »

Quote from: Bob Reeves on January 19, 2010, 05:37:48 PM

The CL carb can be modified just like the RC carb but you will need another needle assy. The remote needle valve off an early OS works great. This is the metal one mounted on a metal bracket. Also, if you have an old OS RC carb laying around you can use the needle assy off it. You have to make a new barrel for the carb, drill and tap one side for the OS needle then drill and tap the other for a 10-32 nylon screw.

This will give you a spigot venturi with the adjustment right at the spigot which I believe is a better arrangement than the stock CL intake.

Bob,
I've been searching for a set of pictures you posted elsewhere in this forum (or maybe it was SSW, I can't remember) which shows the mods you made to some Saito 40 carbs (the same mod you describe above, using the OS needle) but I can't find them.
Can you please post them here for me?

Thanks,
Claudio.

Bob Reeves · « **Reply #12 on:** January 23, 2010, 11:05:21 AM »

This might be it, shows several versions of the Saito 40 most of which can be copied for any of the others.

BTW: When I install the new barrel I put a small amount of JB weld around the outside to make sure I don't have an air leak around the barrel. I want the engine getting all it's air through the intake. If it ever needs to be removed the JB weld can be softened with heat.

Claudio Chacon · « **Reply #13 on:** January 24, 2010, 08:18:57 AM »

Thanks Bob, that's the pic I was looking for.

Author Topic: SAITO .72 CL: Time for breaking-in (Read 6737 times)

Claudio Chacon

SAITO .72 CL: Time for breaking-in

Alan Hahn

Re: SAITO .72 CL: Time for breaking-in

Bob Reeves

Re: SAITO .72 CL: Time for breaking-in

proparc

Re: SAITO .72 CL: Time for breaking-in

Claudio Chacon

Re: SAITO .72 CL: Time for breaking-in

proparc

Re: SAITO .72 CL: Time for breaking-in

Claudio Chacon

Re: SAITO .72 CL: Time for breaking-in

Bob Reeves

Re: SAITO .72 CL: Time for breaking-in

Claudio Chacon

Re: SAITO .72 CL: Time for breaking-in

Bob Reeves

Re: SAITO .72 CL: Time for breaking-in

proparc

Re: SAITO .72 CL: Time for breaking-in

Claudio Chacon

Re: SAITO .72 CL: Time for breaking-in

Bob Reeves

Re: SAITO .72 CL: Time for breaking-in

Claudio Chacon

Re: SAITO .72 CL: Time for breaking-in