Saito FA-82b inverted

[Tim Donald]

I'm having a problem with a new Saito FA82 idling whilst inverted.  I did the recommended run in on a test bench with the engine the right way up.  I didn't notice any idle problems but I was controlling the throttle with a pushrod by hand so didn't really do much idling.  I have now mounted the motor in a Ripmax Bolero which requires it to be inverted.  I am trying to set up the throttle linkage but the engine cuts out after a few seconds at tickover.  I have set the high speed needle to slightly below max rpm and it runs fine from mid to full throttle.  My guess is that I need to adjust the low speed needle but I'm new to 4 strokes.  The procedure in the manual is a bit vague and talks about setting 2000rpm and increasing the throttle to look for a delay in pickup to set the low needle valve but without it idling I can't do that.  Is there a  better way to set the low speed needle or any ideas what might cause the problem?  Fuel tank height is maybe slightly high but I know lots of people do run this setup without problems.  

[Jon H]

I just looked at the manual to educate myself on the specifics of the model and, frankly, the model is really poorly designed. The tank is very high and you will suffer running problems unless you lower it. Looking at the photos its no wonder you are having trouble as the blasted thing is almost in orbit.  

 

Lowering it might be a bit of a pain but it is far better to get it over with now and not have to fight the engine every time you fly it. you might need to substitute a smaller tank to fit the available space ahead of the undercarriage former though.  With the tank at the level it is you will be unable to tune the engine for its best performance as the tank is simply in the wrong place and it will always run badly. If others are flying the model without changes you can guarantee their engines are not running at anywhere near their best. I would strongly recommend modifying the model to allowed lowering of the tank so the top of the tank aligns with the needle on the carb. 

 

The alternative would be to mount the engine on its side but then you have to cut more of the cowl away. 

 

Its unfortunate that ripmax didnt bother to make sure the model was designed to work with the OS engine shown in the manual given they import both items and presumably green lit the design of the model. As the OS and Saito carb heights are about the same it would have worked perfectly if that had been checked. I suspect it was intended to be an electric model and it has been rebadged for i/c without actually checking it would work.

 

 

 

 

[Tim Donald]

Thanks Jon,  I appreciate you looking for me,  even if it's not what I wanted to hear !  I will have a look and see how easy it would be to lower the tank.  It's already taken me longer to sort out that plane then building one from scratch would have taken so a few more hours won't hurt.  I'm suprised they haven't done something about it as the model has been around for years (previously the Bossanova).  I might ask other Bolero owners what they have done about it.  I did notice that after the first run (which went ok) the engine had flooded.  I wasn't sure if that was due to siphoning or the engine being upside down.  It needed the plug removing before it would re-start.

[Jon H]

Yea the fuel will syphon out of the tank and fill up the intake elbow on the carby. The tank height thing is a common mod for Laser's due to the high carb placement but in this case it will be an issue for all engines. 

 

Im actually quite annoyed by this as you (or anyone else) are trying to follow the various instructions to get the job right. but if you follow them it will simply not work as the design is flawed and you are being instructed to do something wrong. For someone who is not that experienced this would be a nightmare as they have done everything by the book and yet have all these problems with their engine and they might even damage it if they crank the electric starter and hydraulic lock the motor. You can shear crank pins doing that. 

 

Really not impressive at all. 

[Tim Donald]

Thanks Jon.  Yes - I'm finding similar problems with lots of modern kits these days.  It's like nobody has ever built one and tried to sort out the problems before bringing them to the market.  Anyway - the Bolero looks a pain to modify and I have been speaking to another Bolero / Saito82 owner who said that he kept the tank in the original position but the Saito comes factory set very rich on the low needle.  He had to lean his quite a lot.  I'm going to try that first but if I can't get it running to a reasonable standard the tank will have to move.

[Nigel R]

I think you'll eventually find that moving the tank (or mounting the engine sideways) will be needed. Might as well get it over with before struggling with a badly adjusted motor...

 

[Jon H]

I dont take any prisoners when it comes to mods of this nature. If a knife wont do then out comes the tenon saw, hammer and chisel. Its only wood 🙂 

 

That said, your options are limited to removing the tank tray ahead of the undercarriage mount former and dropping a tank in there. I dont know how big that bay is but it looks big enough for maybe a 9oz slec tank?

[Nigel R]

A nice big hole in the firewall might help matters, if it's a tank with the usual protruding stopper arrangement.

 

Some surgery to the wing leading edge might help too... Jon has posted many examples of mods to warbird wings to drop the tank.

 

As noted, it's only wood.

[Jon H]

This is a snippet from the manual. The orange arrow is the front support former for the undercarriage so my normal wing nibble method wont work here. I would remove the red bit as that bay looks a half decent size. Its only an 82, it shouldnt need that much fuel...even if it is a saito 😉 A square slec tank would work well here if the bay is long enough

 

[Nigel R]

A model like this, flown mostly low throttle with occasional bursts of power, an 8oz tank will last for ever.