gasoline

I just bought a used saito 90t flat twin engine(twin carb).the problem i am facing is the perfomance of the engine.The engine is mount on a world model P-39 running a 13 x 6 prop (6800 rpm).I still fly it and the plane is not performing (speed) i changed to a 12 x 6 and it does improve abit.so my question is , are the engine underpower for the plane.I am running 15% cool power.I have disassemble the engine and check the timing and adjusted the tappet.Which is the most suitable prop for this engine.Is it true that a 90 twin is less powerful than a 90 single piston.

w8ye

My Feedback: (16)

A 90 single piston 4 stroke engine will turn a 14-8 about 9200 rpm or more


Enjoy,

Jim

gasoline

I think what you say is true...I have a tt91 four stroke and is running on a 13 x 6 on a super chipmunk and infact its more powerful...so can you please tell me is there really a problem with my twin

w8ye

My Feedback: (16)

I doubt if there is any big problem with it. I know that the ASP 160 twin is lucky if it has as much power as a ASP 120 single because a guy that I fly with has a 160. Twins and 4 cylinder engines are like that. They don't have as much power as a single but they sound great.

Enjoy,

Jim

gasoline

O.K....thanks for the reply....i have a question...is it ok if i run it with 25% or 30% fuel...will it damage my engine or any other problem?......currently i am running with 12 x 6 master airscrew...does changing to other prop makes any diffrent?

w8ye

My Feedback: (16)

I know the Saito singles like nitro. I would assume that the twins do also. You can get by rather well by using anything from 15% to 30%. It depends on how much money your willing to spend. There's a guy at the field that has a larger Saito twin and he runs between 15% 20% in it depending on what he found at the store and what other engines he brought along.

I had always assumed that the Saito 90T engine was originally intended for use on a Hanger 9 80" J-3 Cub type plane. It would be ideal for that plane will fly with a 52 single cylinder 4 cycle engine. I have a couple of the Magnum 61 four strokes and a Saito 56 that fall in this power catagory and they turn a 12-6 at about 10,000 on 15%.

Enjoy,

Jim

plowboy

My Feedback: (2)

This is just the discussion I've been looking for. I would love a 60 or 90 twin on the H9 80" cub, but how can you justify a 30oz twin with the same power as a 15.5 oz single. Sound would be awesome, but that's a lot of lead up front. How would it float with a heavy low-powered twin?

Jeepindog

Just don't buy the engine from whatever mfg you found that produces a 30 oz twin. The Saito FA-90TS weighs just 25 oz, while their .65 single weighs just a fraction of an oz under 20. Not much difference when you consider that any plane big enough to have that engine mounted on it will be longer and have a bigger wingspan to offset a fatty engine. Just my opinion, but I am almost done building a SIG 1/5 scale Cub with an 84 1/2" wingspan and I am mounting the FA-90TS on it for power. It should fly very scale, look really cool if I don't screw up the cowl, and the sound will be great.

Lachlan

PlaneKrazee

My Feedback: (14)

I have a Saito 90TS. It is much more powerful than the older two carb .90 engine. It turned a APC 14X6 at 9600 rpm peaked on Byron 15% nitro/20% oil. I had this engine in my Great Planes Spacewalker. It was a perfect match scale for power. Aerobatics would require a dive for speed prior to doing a cuban eight or loop. I had to use a Kline regulator to stop the left cylinder from flaming out during aerobatics.

I also have a O.S. 160 twin with the new carb. It is as strong as a Saito 150 but weighs about 9-11 oz more. If you like twins and have a plane that could use nose weight and less vibration go for it. The these twins are very, very smooth at all rpm levels.

Den B

Heres why and not under powered as some may say just too cool

Sig 1/5 scale Robart gear Saito 90ts




Den

>> editd to fix hypertext code.

cwstufft

My Feedback: (17)

I am putting the Saito 90 Twin in a Hangar-9 Cub. Any suggestions on balance? Other suggestions?

Meesh

My Feedback: (135)

I think there is something wrong with your engine. My Saito 60 Twin will turn a 12x6 APC prop at 9000 RPM on the ground with 15% Nitro. Sounds like you're running on one cylinder. Download the Twins manual from Horizons' website and follow the instructions on how to set the two carbs. It's not difficult but you have to follow their procedure to get good performance. Might not be a bad idea to leave the glow drivers connected while you're doing the initial set-up. That way you'll be sure you're not dropping a cylinder. Also, remember that these are AirBleed carbs. To lean them at idle you unscrew the adjustment (counterclockwise) to let more air into the idle circuit..

If you can't find the manual on Horizon's site E:mail me at [email protected] and I'll send you a .pdf file.

Bob

CHassan

My Feedback: (13)

[X(]
I just sold one that would turn 9500+ rpm on a 13X6 Sounds like you have something amiss there. My guess is a cold cylinder. I picked mine up used and it had a cracked intake tube. It would drop a cylinder and go from 9500rpm to 6300 or so. Fiked the intake and she would hold a steady 9500 with a nice rich mixture.

Mediaman

My Feedback: (1)

Chassan is right, I'm the new happy owner of his engine, I have the 90ts on a Christen Eagle and it can do all kinds of aerobatics, It will hover for a little while with an APC 14x6. My guess is that yours is running on one cylinder.

Question, will the engine do fine with a 14x8 or 15x4 prop?

Flyin King

The Saito FA 90T Flat Twin is designed for any .60 sized 2 stroke aircraft.It has twin carburetors and hemispherical heads. It has a max rpm of 10,000,idles at 2500rpm and is designed to operate at 9,000 rpm with a 15" X 4" propeller. It is recommended a castor oil based 15% nitro solution fuel used.
Any one wanting the original spec sheet and owners instruction sheet,provide me thier email address and i'll send.

casniffer

My Feedback: (1)

Hi,
I would appreciate a copy of the spec sheet and owners manual for the 90T.

Thanks
Steve Morin

casniffer

My Feedback: (1)

I'm a genious.
My email is:

casniffer@yahoo

Just add the .com at the end.

Thanks again.

gjeffers

go here.

http://www.horizonhobby.com/Shop/ByC...odID=SAIE090TS

Gary

William Robison

My Feedback: (3)

Benson (and others):

The Saito FA-90t and the FA-90TS are both roughly equivalent in power to the single cylinder FA-72 engine, but they weigh just about 10 ounces more.

If your 90 twin will not pull a "72" prop there is definitely a problem with its running, the problem, as stated in an earlier post, is usually one cylinder not staying lit.

Bill.

casniffer

My Feedback: (1)

Thanks for the information, guys.

CASniffer

eclecticant

My Feedback: (10)

NICE ANSWERMI JUST BAUGHT A NEW OLD STOCK TA 90 T WITH NO PAPERWORK WOULD LIKE TO TAKE YOU UP ON YOUR OFFER FOR SETUP. AND ANY OTHER TIPS PROP ETC.

THANKS IN ADVANCE



[email protected] KEN

mentorman

My Feedback: (2)

A buddy of mine got a 90t from a swap meet. We fired it up and it was weak. DFound one of thge pushrods off the rocker. Fixed it and he put it in an ultrasport. He wanted speed also and was dissapointed. He promply traded it for a 90 enya and was happy. The guy he traded it to a guy who put it in a bi plane and was happy with it. scale speeds for sure but torquey. Oh, it was the older ABC "hemi head" twin carb.

Piper_Driver

I am looking for a manual for an early FA-90T Mark 1.
this old twin has two part cylinders. I would put a production date on
it as around 1983 or so.

Any help would be greatly appreciated.

[email protected]

Sgt.Rock

Hi Flyin King,
If you are still offering, I would love to get the original spec sheet, owners instruction sheet and any other
documentation you might have available on the Saito FA-90T. The one I just aquired will only run backwards
so I'm thinking that the previous owner has the cam timing scewed up somehow.
Thank You.
My email is [email protected]

w8ye

My Feedback: (16)

Cam timing looking at back of engine of the Saito 90T which is similar to the present day 100T (note the 90TS is a different engine)

Right cylinder top dead center. Cam dot goes towards crankshaft.

Do not turn engine crankshaft!

left cam dot goes towards crankshaft also

The book says to turn crankshaft 180 degrees to top dead center on the left cylinder to set left cam but this leaves the timing of the left cylinder 90 degrees off.

Check your cam timing by observing the overlap period being centered at the alternate TDC position 360 degrees from the TDC compression stroke for each cylinder. At this point one valve will be closing and the other opening but they will both be open exactly the same amount.

The desired result will have two cylinder firing 180 degrees apart and then a coast period of 540 degrees

The 90TS is similar to the 60T with a single cam. They are timed by putting the crankshaft gear mark towards to mark on the case with the accessory cover off the rear of the engine. Then the mark on the cam gear goes towards a mark on the case also.

Here is the present day twin manual. Use the 100T for explanation of the older 90T

http://www.horizonhobby.com/ProdInfo...oke_Manual.pdf