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saito 125a fs

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john melia 115/04/2017 12:08:35
1770 forum posts
24 photos
Thanks guys the motor is already run in , by the guy i bought it off
Compression is very strong , and as you say that kick back is severe , i cant use a starter at present as i don't have a spinner , tried reversing the rubber insert on my starter to fit on the prop nut but it just chewed it up
Phil 915/04/2017 12:17:28
4231 forum posts
218 photos

buy a spinner or dome prop nut and save yourself some agro

Edited By Phil 9 on 15/04/2017 12:17:44

Martin Harris15/04/2017 13:12:42
7774 forum posts
196 photos

As I suggested earlier, the reverse flick may be your friend. If you're unfamiliar with the method it's fairly easy and a lively engine like yours should respond very well, as should any reasonably well set up one. This should work on almost any engine, 2 or 4 stroke.

In case you're not familiar, you prime the engine so that there's fuel in the cylinder, wind it backwards until you just feel compression, attach the glow (keep body parts clear of the prop arc as it isn't unknown for an engine to self start if you've left it compressed) and give it a smart flick backwards with your stick (or chicken finger with a smaller engine). If you have a spinner, you can often just give it a flick with the fingers.

The compressed fuel/air mixture in the cylinder should ignite, giving the piston plenty of impetus to complete the next cycle and continue running - the stick will slip out of the prop arc during the first compression phase...

While an electric starter is probably the safest method for the fingers, I often use this technique for smaller engines as my starter is a bit of a beast - or when I just feel like showing off!

ASH.15/04/2017 14:05:24
221 forum posts

I'm always 'showing off'..
Back flick everytime usually starts first time. Saito engines need to be nice and wet to fire up. Once you get the hang of it it's a doodle.

Edited By ASH. on 15/04/2017 14:07:04

gavinman12/09/2018 20:26:26
4 forum posts

Just brought a Saito 125a to put in a Seagull Spacewalker 120. Reading the manual it recommends a 16/8 prop but reading this thread it looks like I might be better with a smaller prop .What would be the best prop for this 125a and a Seagull Spacewalker

Denis Watkins12/09/2018 20:48:41
2988 forum posts
141 photos

Chicken and the egg Gavin, you need to fly it on a 16 x 6, and judge, do you need the ground speed on your patch or the air speed?

The 16 x 6 will allow the motor to unload while it is new, then you can decide

gavinman12/09/2018 20:56:54
4 forum posts

OK I will start with a 16x6 .I like the look of the wooden props but I think the APC 16x6 will give me better performance Are wooded props OK on a 120 size engine or should I stay with the APC

Jon - Laser Engines12/09/2018 21:12:05
3963 forum posts
153 photos

15x8 is a good place to start with a 120 class engine. Saito typically like to rev as well so run on on 14x7 or 15x6 i would suggest

Martin Harris12/09/2018 21:12:49
7774 forum posts
196 photos

Wooden props on lively 4 strokes can be a bit of a disaster waiting to happen. The lightness means that there is a reduced flywheel effect and the slightest hint of pre-ignition can jar the nut loose - exit one prop and hope that you or your clubmates aren't in its way.

There's also the possibility that the wood can compress and the nut can loosen - see the previous paragraph!

For the above reasons, wooden props are best used with drilled mountings - not (AFAIK) an option with the Saito.

ASH.12/09/2018 23:09:49
221 forum posts

Don't use a wood prop or you risk having an engine cut. It's happened to me on idle coming down in a loop. They are just too light and don't have the flywheel effect. Heavy APC's are the best for thrust and efficiency, they don't flex.

john stones 112/09/2018 23:31:26
9830 forum posts
1462 photos

Interesting point, aren't there wood props made from heavier woods ?

John Stainforth13/09/2018 00:11:26
210 forum posts
38 photos

My Saito 125's go very well with a 16x6 prop (on aerobatic/sport models).

Tim Flyer13/09/2018 09:16:42
775 forum posts
116 photos

Metal spinners help a lot with flywheel effect . Although some might argue about it I also think they provide a modest added cooling benefit.

Edited By Tim Flyer on 13/09/2018 09:17:29

bert baker13/09/2018 09:38:20
1195 forum posts
253 photos

Master screw CLASSIC series is the best I have found for my Saito 125’s

Paul Marsh13/09/2018 17:32:59
3339 forum posts
928 photos

I never use a wooden prop on four strokes - they are very dangerous! I tried one time on a 70fs, started the engine and ran it up, it back fired and the prop blew into millions of pieces! scary! Not doing that again!

Best props I found, as listed here, Master Airscrew Classic series - they have massive hubs - ideal for reaming out to 1/2 inch or 13mm which I need to do on the 160 flat twins, with the reverse nut/washer arrangement...

ASH.13/09/2018 17:45:26
221 forum posts

I have tried the MA classic props but find they flex too much and are just too noisy for my ears. They do look nice on scale models. I have done static thrust tests with a Saito 72 and found APC came out on top!

Edited By ASH. on 13/09/2018 17:49:25

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