Stassiebal Posted September 7, 2013 Share Posted September 7, 2013 Hello All. I have had this Saito FA125 four stroke for a while now, but just can't seem to get it to run smoothly. I'have run her a few times now and it spits fuel everywhere and it refuses to idle. I have had the Needle valve everywhere from 2 to 5 turns out, but it seems to have fairly little affect. I am running it on 15% fuel, and it is pulling a 15"5x8 Bolly Products Composite prop. Anyone with any tips perhaps? I am new to four strokes, so not quite sure what I am missing. Regards, Dean Edited By Stassiebal on 07/09/2013 19:01:05 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted September 7, 2013 Share Posted September 7, 2013 I've never had a Saito Dean so not best placed to comment specifically but a couple of general thoughts...... 15% nitro might be a bit much for this engine....perhaps try & cadge a bit of 5% & see how that works..... Have you run it up to full power & tuned the top end? The needle valve really only affects the mixture from about 1/3 throttle to full power...below this its the idle needle that matters. That said you need to tune the main needle for full power before you tweak the idle needle.....you also need to make sure that the engine is fully warmed up first......there is a lot of aluminium in such an engine & it needs to be at operating temperature before you try & tune it...... It will take about 5 mins running at 1/3 to half throttle to get up to temperature.....so go easy on the revs until the engine is fully warm. It makes me cringe when I see modellers start up their engines & immediately open up to full power to tune them......I'm amazed we don't hear of more cold seizures. Be kind to your engine & let it warm up first.... What plug are you using? the OS F is widely thought to be the best available for 4 strokes.. Some further thoughts......don't try & tune an engine with the glow plug energised....you won't be flying the model like that so don't set the mixture to suit those conditions...also from the video where is the tank? You should try & keep it as close to the engine as possible...a long fuel line is a recipe for unreliability. Hope that helps...Saitos are good engines so I'm sure whatever the problem is it's solveable... Quote Link to comment Share on other sites More sharing options...
Stassiebal Posted September 7, 2013 Author Share Posted September 7, 2013 Hi Steve, Thanks for the help. I have actually ran it on 5% initially and had the same issue. The manual reccommends 10%-15% and I have to admit I was a bit imaptient, my local model shop didn't have any 10% in stock so I went with 15. I am certainly wary of running the engine without warming it up first and I will make sure I follow your suggestion on that. I have not yet run the engine at full throttle. The break in reccommendation is to run it below 4000RPM for 40 minutes or so before it should be good to go, as such I have been a little reluctant to open it up. On the video I am running it with the glow plug starter attached, basically because if I don't it dies when I reduce the power. I use the plug which came with the engine when I bought it, so whatever it was that Saito supplied. The tank comes into view around the 9 second mark. It sits about 5 inches back. Do you think I need to bring it a bit closer? Thanks again for the tips... hopefully I can get it running nicely soon. D Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted September 7, 2013 Share Posted September 7, 2013 Ah...so its brand new......!! Ok...well yes it will need a bit of running in before it will idle.....40 minutes at 4,000 rpm is about right but don't just set it at that & leave it running......stop it, let it cool down & start it again & vary the revs all the time....even up to full throttle for a short time.... As the engine become run in you can lean the mixture out....when it will hold full power without slowing down for a minute or more its run it......NOW you can try & tune it... BTW a 125 is a big motor.....make sure its well strapped down & keep your fingers well away from the prop.... Quote Link to comment Share on other sites More sharing options...
Rick Tee Posted September 8, 2013 Share Posted September 8, 2013 On some Saitos the carb manifold vibrates enough to cause the head seal to leak, putting a tie wrap around it solves the problem. Make sure it goes behind the push rod tubes. Edited By Rick Tee on 08/09/2013 06:37:27 Quote Link to comment Share on other sites More sharing options...
.. Posted September 8, 2013 Share Posted September 8, 2013 Dean , If its new then it will take a few tankfulls through it till it loosens up. Follow the Saito run in procedure thats in the manual to the letter and you wont have a problem. The low end needle on Saito engines is set very rich at the factory setting for running in. When its done all the running in runs you can open it up and find the peak rpm with the main needle. I use a tacho but it can also be detected by ear, the tacho will certainly help if your new to fourstokes tho. When you get it to peak rpm richen it off a couple of clicks (500/700 or so rpm). Then you can adjust the low end needle. I have found on my Saito's that at this point the low end needle needs to go in a couple of turns to find the sweet spot but they are all different! If you go in to far then the factory set point is when the top of the needle is flush with the black plastic throttle arm. Do a pinch test (search the forum for this info) at idle to check your on the rich side on mixture and once its idleing nicely for a while open it rite up , once you get a good transition re adjust the top end and your done. **LINK** The above link should get you the footage of my newly run in Saito 82b tuned and now ready for maiden. It was ticking over at around 2100 rpm for around 3 minuets before a sharp up stick to full throttle. Hope this helps J. Edited By Justin K on 08/09/2013 10:45:23 Quote Link to comment Share on other sites More sharing options...
William Morrison Posted September 8, 2013 Share Posted September 8, 2013 Saito's need a couple of gallons through them before they begin to idle well. They will tick over very smoothly when well run in. Nothing wrong with 15% Nitro fuel, even 20% works but so is 10% Nitro. The idle fuel flow rate is dependent upon the High Speed Needle setting. I would run the engine rich for at least a gallon of fuel through it. The factory setting for the idle needle is flush with the throttle arm. After a gallon or so through it use a TACH and set the high speed needle for max RPM and then back it off 300 RPM on the rich side. That is where you are going to fly it. Then set the idle needle. Do so in 1/8th turns with the engine stopped. To dangerous to do so when the engine is running. I find the best method for getting the idle right is the acceleration test. When the engine accelerates smartly from idle to max without hesitation, you have it spot on. It is not a bad idea to use a tie wrap as described above. The Intake Manifold is held in place by the carb. The interface wtih the cylinder is just an O-ring. Saito's sometimes have very strong power pulses that can make the interface bounce, ergo the use of the tie wrap. As the engine ages this becomes less of a problem as it begins to be a really smooth operator. But it takes a bit of running to get there. After several gallons of fuel through the engine you will fiind it is a great piece of machinery. Also read the Saito web page. It is found at **LINK** There is a great deal of information on the egines posted. Quote Link to comment Share on other sites More sharing options...
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