Maninder

By "perfectly tuned" I meant a tuned system which delivers a very large gain at one frequency (RPM) but the gain drops off rapidly away from that single RPM. A less than perfectly tuned system will deliver lower gain at the centre RPM but the gain spans over a broader range producing a wide power band.

Is that not why you would never go for a perfectly tuned setup but one that is tuned enough to deliver a power increase and lower noise but off-tune enough to provide a usable spread of power, same as any antanae design?

MVVS knew how to design good tuned pipes. I have two of these amongst my collection of engines. Although designed for their 26 IFS Petrol engne, they work equally well on any 20-30cc petrol 20-stroke. The pipe is 23 inches long. I have heard the recording of one and the sound was as pleasant to my ears as Tina Turner! I bought a Chinese "canister" from ebay for about £30 out of curiosity some years ago. Opened it up and there was nothing inside other than space. An airspray can with ends soldered on would have been just as good i.e. not effective at all.

I have a Toni Clark 2577 3-chamber silencer for the Zenoah 20/26 engines. It increases the power by 25% and reduces noise when the correct length is set for the header. Those with a sharp eye may notice that this is not a standard ZG26. It is one of Ralph Cunningham's creations. Ralph was the master of all things Zenoah in the US. He took a standard 26, removed the flywheel and in its place mounted the CH Ignitions PCB using the standard Zenoah ignition coil resulting in a lighter 26 but with the excellent CH Ignitions setup.

I wondered if a moderator would kindly add the word "Engine" after the word Petrol in the title so that it makes more sense. Thank you.

Paul - what sort of canister are you using in the video?

Try this link direbtly the you browser.

As we all know 2-stroke engines can be quite useful in large model aircraft but tend to be noisy and the noise is uncharasteristic of real airplanes. I love chainsaws but not in the air! When I was an active modeller learning to fly up to around 2010, I purchased a number of Zenoah and other 2-S engines and at the same time 2*MVVS tuned pipes designed for the MVVS 26 IFS and one of the zenoah tuned silencers designed for the Zenoah 20/26 engines. I had experienced the sound of a piped 2-S engine fitted to an LMA Greenly at our Bury St Edmunds RC Model Club and and fell in love with the low noise and the general un-objectionable character of the sound. Hence my purchase of one tuned setup for each of my 20-26cc engines. Due to work commitments the engines and the pipes were never run and have been sitting in a cupboard for the intervening years. Is anyone using tuned pipes/silencers with their 2-S petrol engines and would like to share their experiences?

You could try this site. http://www.model-plans.co.uk/KIT PLANS.htm at http://www.model-plans.co.uk/kamco.htm

In the UK V-Power Unleaded contains between 0% and 5% ethanol by volume. This is in the Shell specs for V-Power but they do not say exactly what is the actual percentage and whether it varies or on what basis. As to the use of Chinese carbs and repair kits, does no one ever wonder why it is that quite a few of the UK sellers of Chinese garden machinery provide a 2-year warranty on the machines but limit the warranty on carbs and bearings to 6 months by calling them "consumables". An example being ParkerBrand - a brand of which I have some experience. Yet the likes of Zenoah, Makita, Echo... with their Walbro or Zama carbs guarantee the whole machine including the carb for 5 years. Check out nearly new Chinese original chainsaws for sale on ebay and the reasons for them being listed as "For Parts or Spares". Ditto the number of suppliers of carbs for the GGP SV150/160/200 lawnmower engines on ebay. The float needles often fail to seal properly after 12 months and the carbs start leaking. My Briggs Quantum/IC engines on lawnmowers are still on their original carbs after 15+ years. One Quantum engine on a large walk-behind lawnmower is now 22 years old and still running as it did on day 1. All it gets is a filter and oil change every year. With Chinese original carbs performance is often rather hit and miss and longevity highly limited. This is of course just my experience and that of my local garden machinery shop where the owners have been servicing such machines for 40ish years.

I have quite a few items of garden machinery which are in regular (weekly) use during the summer months but not much during winter. My fuel of choice during the summer is Shall V-Power but towards the end of Autumn I switch to Alkyl based fuel (Aspen or equivalent) which can then sit in the machines over winter. I don't use E10 based petrol in my machines at all even though I'm quite happy to strip all types of carburettors, clean and replace the diaphragms etc. Also, when servicing Walbro/Zama or even Chinese equivalent carbs, I try to use genuine Walbro/Zama diaphragm kits as most aftermarket ones are rubbish and don't last.

Thank you for the welcome messages gentlemen. 🙂

Thanks for the welcome David. Being a bit of a nut about engines of all sorts - RC models, motorbikes, cars, even garden machinery - I used to follow the engine conversion chaps in the US modelling scene quite closely. Over there they had quite a few small engineering shops with CNC machinery wand the owners willing to convert engines for not much money as a hobby. The strimmer, chainsaw types engines were really popular a they were of very high quality, lasting many years, and made good power. Which is all engines like the Zenoah 38, 45 and 62 ever were. The cheap chinese engines killed off the business side of conversions but some still do it has a bobby. We didn't really have the equivalent workshops with CNC machines over here willing to do the work for little money. The converted four stroke petrols were really popular with the WW1 biplane contingent. Some still do the conversions - Stihl 4-Mix engines are quite popular these days especially the 62cc engine from the BR600 backpack blower. It produced the same sort of thrust as a Zenoah 62 so is capable of flying 1/3 scale biplanes and sounds just right for those models.

Hi David, yes it was. He either fitted a quiet extension to the front half of a standard 2S silencer or made one up from scratch as a complete unit for an extra £5. Mine was the latter type. I always thought that he must have been very skilled to be able to come up with soemthing so effective.

It feels like I must have been one of the few MDS owners who hit lucky. My MDS40 in a HMM Moonraker performed well but was a little noisy. I had a super-quiet silencer manufactured by a chap who used to advertise in the modelling magazines and it really quietened the engine down. With this silencer the MDS sounded like an engine with a quiet tuned pipe. It was a pretty powerful combination too. Having said that, the silencer did cost nearly the same as the MDS. Perhaps the comarades who manufactured it had been on the Vodka bottle on that particular day as it performed brilliantly. I still have it!