Peter Jenkins

BEB - you are being smug not just sounding smug! Seriously though, I have spent so much money on props trying to get performance and noise in balance that the thought of lashing out on different types of silencers as well is almost driving me into the dreaded electrickery! Of course, the Saito 180 also seems to be a naturally "rough" runner according to other threads so that doesn't help either. I'll let you know what happens next, but my electric aeroplane is almost complete and that might make these problems fade away!@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Hi Ian, no, it is not running rich. The engine has been progressively leaned out from its initial running in mixture and it is now at its optimum mixture. The problem with the 180 is that it generates a lot of vibration (prop is fully balanced by the way). @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

I flew the Saito 180 again today and .... the exhaust came loose - twice. That was with plumbers tape. The manifold to head joint stayed firm though. Tightened up the exhaust the second time with a good deal more torque and it stayed put for the final flight. If it comes unscrewed again I'm going to try the 5 min epoxy route!@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Thanks YakMad. I have a Dubro mount that I am going to use for my Saito 120, but I could shift it over to the 180. I've just had the Just Engines/Weston super quiet silencer fail inside so I've gone back to the standard Saito exhaust using plumbers tape so I'll see how that goes. I used some high temperature silicone to lock the manifold to head join and that seemed well set but I had to take it off to fit the standard Saito exhaust - so at least that works.@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Steve   I finally managed to fly the Saito today. I had used Plumbers tape for the manifold to muffler join (its a Just Engins/Weston super quiet silencer for the Saito 180) and that held fine. I'd used red Loctite for the manifold to cylinder head join and while I couldn't loosen it when the engine was cool (to reposition the muffler tail pipe) it came loose during a ground run! So I nipped it up when all was hot and it was fine for the remaining flights. When I got home I undid both connections as something had come loose in the JE muffler and used the tape for both joints reverting to the standard Saito exhaust. I'll report back on the outcome. Having just re-read your post, I may have skimped on the amount of tape - I wound on two or three turns only. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Lee, you are right. Saito recommend a 14x13.5, 14x14 and 15x12 for aerobatics so I am going to try them and see if that helps. An 18x10 does seem to overload the engine although it is only just run in so things might improve with a bit more use.@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Martin and Colin - I fitted a Weston pipe made for the Saito 180 and we noise tested with just the pipe. Also leaned out the engine so that it was just a little bit rich - which pushed up the rpm significantly on an 18x8 prop. Highest recording was 92 db so a fail. Then wrapped the large cylindrical silencer in rescue tape and restarted the engine. After warming up the engine we noticed that the rescue tape had split and peeled off! Guess the 4 stroke exhaust temp was too high! Shame as it would have been good to get a second noise reading to gauge the effectiveness of rescue tape.   I am now going down the route of smaller diameter larger pitch props and I'll let you know how I get on. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Craig, I run a Xoar on my Saito 100 and have no problems with it being thrown off the engine. Xoar is made from a pretty hard wood (I believe they use off cuts from full size propellor manufacture). Some wood props are a lot softer and one I used ended up being crushed under the pressure of the retaining nut and thus becoming loose and then being thrown off. Never had this with the Xoar. As for starting with a chicken stick, I doubt that will be a problem with the Xoar as it is quite strong on its trailing edge. I've used a chicken stick but only once and it tends to leave black marks on the prop which really doesn't look nice. Why not use an electric starter or do you not use a spinner?@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Well folks, I have now received a Weston pipe purpose made for a Saito 180. It must be over 3 x as large as the Saito exhaust. Now, here's the good bit. I thought I'd be radical and do nothing other than tighten up the nuts when the engine was cold and re-tighten when the engine and silencer were hot. I've now flown the aircraft twice and there has been no repetition of either the connection to the head or the connection to the silencer coming loose. So, I shall continue to fly the combo in this state and check regularly for looseness. Thank you for all your suggestions and, yes, I will try the PTFE tape idea first if I get a further bout of this problem. By the way, I e-mailed Brian Winch on this point as well and he just tightens up the nuts when cold I quote from his mail   I am wondering how you tighten the exhaust nuts on the Saito engines as they are generally not a problem here. I do all Saito warranty work and this is not a problem reported to me nor one I have with the engines I run on test and after repairs. I always lock them up when the engine is cold - I use a standard open end spanner on the muffler body and a gas spanner (a ring spanner with a gap in the side) for the lock nut. Tighten well and hard and all should be well. Saito use a 1mm pitch thread on their exhaust systems and OS use a .75 mm thread pitch but modellers wear out the thread in OS heads a lot more than they do with Saito heads.   The only problem I have is that the Weston silencer does not have any flats on it to apply a spanner but it does provide a good size object to get a good grip on.   Thanks Martin for the revised link to Motorvation Model Engines - I just hope I won't need it! @import url(/CuteEditor_Files/public_forums.css);@import url(/CuteEditor_Files/public_forums.css);@import url(/CuteEditor_Files/public_forums.css);@import url(/CuteEditor_Files/public_forums.css);@import url(/CuteEditor_Files/public_forums.css);@import url(/CuteEditor_Files/public_forums.css);@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

BEB,   Many thanks for the explanation and the pictures. I have a pipe tunnel in the Capiche which I have currently blanked off. The Weston supplied silencer is about 4 times the volume of the Saito exhaust. I can fit the Weston silencer into the space behind the engine with the silencer just bolted to the engine exhaust pipe. It may be that the Weston silencer will stay attached better than the Saito one but I shall proceed starting with the simplest course of action and get to the more involved as and when the silencer comes loose - again! I'll keep you posted on the outcomes but there might be a slight delay as currently I am focusing on practicing for a forthcoming competition. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Alan, thanks for the tip on Loctite thread locker for 800 C. I'll try my local bearing factor to see if they have any. BEB, I've just paid £55 for a super quiet silencer to fit to an engine that costs around £500 in an airframe that cost £300 with radio that cost another - don't want to count any more. So £15 for a couple of shots of thread lock that keeps the Saito exhaust in-site for ever would not be excessive me thinks.   Anyway, I'm going to start with the no cost option that Solly proposed.   Thanks for everyone's interest and input. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Solly - thanks, great idea. I'll give it a go before I try the PTFE tape.   Alan - not sure about the JB Weld approach - have you used this on a 4 stroke for securing the exhaust manifold?

Baby wipes every time. Cheap and convenient. Mind you, I do wonder what they do to the posterior of babies if they are so good at cleaning off glow fuel exhaust! @import url(/CuteEditor_Files/public_forums.css);

OK!! I'l give the PTFE tape a try Steve.   BEB, what's your flexible pipe solution mate? I've just received a Genesis pipe from Weston via JE and I'm firstly going to try Steve's suggestion and if, but only if, that doesn't work I'd like to hear your solution. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

BEB is 30 min epoxy any better or even the good old 24 hr stuff?@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Martin   The test was conducted on our flying field with cars parked approx 50 ft away - could have had a bearing I suppose. The field is pretty open so other than the cars there are no other reflective surfaces. The ground is grass but it is rock hard at the moment - RH - not sure what it was but it was threatening rain so probably quite high. I did have a silicone tube tywrapped to the silencer but it blew off when the aircraft was in flight - I did not have a groove machined in the silencer but that sounds a good fix. I will look closely at any other airframe generated noise before the next test.   Colin - thanks for your suggestion of using Rescue Tape. When I searched Google I could only find a US supplier who wanted a huge amount for shipping. However, this evening I found a whole lot of UK suppliers so I will try and get hold of some and use it on all my silencers. Putting silicone sealant onto the cowl inside is an interesting thought. How thick does it have be spread and how clean does the cowl have to be?   @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Well, guess what? The Saito exhaust came loose despite the silicone sealer. In the course of a conversation with Weston regarding the Capiche, they said that they used 5 min epoxy on the threads of Saito exhausts, including that for the head. They assemble it wet and it never comes loose until you crack the joint with a spanner. Once undone, you can just chip off the epoxy and re-apply some more. I've not tried this yet as I am a little concerned with using epoxy but the folks at Weston apparently use this on both 4 stroke and 2 stroke exhausts!@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Well, in the end, I bought a G-Sonic 18x8 and an 18x10. Fitted the 18x10 on for the noise test and that failed with 84db with the mike facing the prop. I shall wait for the Just Engines silencer, which Weston tell me they make for JE!@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Darryl, thanks for the info. Dave Wilshere of Motors & Rotors has suggested an 18 x 8 but I've found a Xoar 18x 10 in my collection. Dave thinks that might be too much load but yours seems to be OK so I'll continue with that plan. I've also bought a Just Engines super quiet silencer specially made for the Saito 180 but as they are out of stock at present it might be a couple of weeks before it arrives. As for ease of starting, I agree with you - this Saito is one of the easiest starting engines I've ever had.   Martin, I tried a silicone tube on the end of the Saito silencer and retained it with two tywraps done up really tights. When I got the Capiche down the silicone pipe was missing! As I stated above, I'll now wait for the new JEN silencer and use an 18 x 10 prop. Let you know how I get on.     @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Andy, I have just looked at my Saito 120 and it does not have a screw on the carb with a spring around it other than the throttle barrel retention bolt that has a spring washer under it - but that is not an adjustment screw - so I am somewhat confused. I followed the link in your post and how could I not agree with the comments on Saito's web site. Again, they make no mention of setting the carb movement with a screw but refer instead to the Tx throttle stick (hence servo) to set idle RPM. They then go on to say "set the high speed mixture up first and then the low speed mixture On my Saito, you can turn the throttle arm so that the barrel is fully closed before it comes to a physical stop. (Indeed, that is how you are supposed to stop the engine in normal use.) If you cannot do that with yours then it may have been dismantled and wrongly assembled. There is no physical adjustment on the engine for idle speed - I have an old OS 30 which has an air bleed carb and that has such a screw for setting idle RPM. The Saito web site photo clearly shows the idle mixture screw (in the centre of the engine's throttle arm) and just to its right (at about 4 o'clock when looking at the engine from the left) on the throttle barrel assembly you can see a hex headed bolt that holds the throttle barrel in place to which I referred in my first sentence.   I hope this helps but if not then it would be best to get someone who is familiar with operating Saito engines to look at your engine. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Andy, a further thought has occurred to me - I'm a bit slow sometimes! You may have a damaged spray bar and the idle jet instead of being concentrically aligned with the main jet is physically contacting it and preventing the throttle being closed fully. You will need to rectify this as this is a defect and not how you set idle speed.@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Andy, there isn't, as far as I am aware, a throttle stop on the Saito controlled by the idle mixture screw. As Ken Anderson has stated earlier, the idle speed is adjusted by setting up the throttle servo to close the throttle barrel - the idle mixture screw does just that and does not affect idle speed other than the main needle controls full power speed by leaning to the optimum mixture. Hope that helps.@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Thanks Martin. I hadn't thought of doubling up on the Saito silencer front - might be an option. However, the Capiche also has a pipe tunnel so that might also be an option but I suspect that the biggest culprit is the prop and I might try an 18 x 10 or 19 x 10.@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Thanks BEB. I'll let you know how I get on. I've left my Saito 100 alone as the muffler has stayed fixed in place for some time now. However, I will be looking at muffler security after every flight from now on - that is if it doesn't come adrift in flight and lead to a dead stick!@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Martin,   Actually, no! But that's only because the Graupner G-Sonic prop was perfectly balanced and didn't need any further fettling. First time for a Graupner prop in my experience! So, yes, the prop is balanced but the engine is not one of the smoothest running engines I have had. I suppose that is the penalty for a large single cylinder 4 stroke. The problem is vibration but not from the prop. I've had this with both my Saito 100s but they now seem to have beaten into submission. I suspect that Saito uses a coarser thread than OS and that is what is at the root of this problem. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);