Mike Watters

Good idea with the revival of DSM kits. I've had a few Smart Moves, Excelsior 188 and a Joker in the past. Very nice kits. I liked the way they used obeche veneer as a substitute for plywood doublers in strengthing the fuselage nose. I heard Dave Smith sold on the business and went into being car dealer.

I've noticed on the back of a gallon of Optimix 12% glow fuel it has a expiry date of roughly one year. Even though the cap has a sealing foil. As long as the fuel is kept out of direct sunlight and cool temperatures, I didn't think glow fuel had a shelf life, or is this something new?

Very interesting Jon. Thanks for explaining the high nitro therory.

OK, thanks John.

Interesting John. I read somewhere running motors on higher nitro in hot weather made them run cooler. I can't remember if this was for 2 or 4 strokes. That's what got me thinking about using higher nitro.

Paul, no 15 - 30% nitro for the YS 4 strokes. Jon, thanks I'll go with your recommendation and stick with taking two fuels to the field. Cheers.

Quick question for the engine experts. Would running OS 4 strokes on 20% nitro be too much for these engines and lead to failure / damage. The instructions say up to 5-15% nitro. The reason why I ask is, I fly with the YS 4 strokes also, which I run on 20/20 fuel. If possible I didn't want to keep lumping two fuel bottles to the field with varying nitro content, if one fuel would run all my engines, that would make things easier. The OS 4 strokes I'm running are 26, 40 & 70 engines. Thanks

Thanks for everyone's reply. I'll look at DB Sport and Scale.

Does anyone know what grade of aluminium is a suitable replacement for Dural aluminium. I want to make a undercarriage for a Pilot kits Aeronca champion 20 I'm building from a plan only. A search on the net for Dural aluminium doesn't bring up anything. I know you can buy pre-formed aluminium undercarriages, but I want to make the correct size undercarriage than buy something, make it fit and live with.

Well I ran the YS70 up on a Graupner 11x7 (normally I use a apc 12x8). Short runs, full throttle 10 seconds, no more than 10k rpm to get the temperature up, stop and let it cool. After running 6oz of fuel, the compression is really strong. Tick over nice and reliable, like it's a new motor. So it goes to show, like Jon said you can bed in a new piston ring to a partially worn liner.

A great fuel, used it years ago, but not seen it stocked anywhere in the UK.

Thanks for everyone's replys. Since new, the engine has only run on Model Technics Yamada 20. Interesting to hear what fuel others are running their YS engines on. The 70 does have a crankshaft ring. It also has four cut outs slots machined into the top edge of the piston at the factory, like in Olaf drawing. I thought it was a bit extreme having to replace the whole head everytime you replaced a piston ring. I'll give the engine a run as you recommended.

Thanks, I'll give the engine a run and see if the problem is sorted.

I decided to give my YS70FZ a overhaul, after the engine started to surge in flight at full throttle. From experience with these engines, it's most likely a leak somewhere. I stripped the engine and noticed that the top of the piston, brand new (three flight old OS F plug) were jet black. There was a lot of carbon build up on the exhaust valve, which I know is common. I cleaned the engine and found both inlet and exhaust valves leaked. I lapped the inside cylinder valve seat and both valves were replaced with new brand new valves. No leaking. I had a new piston ring too and that was replaced, so pretty much a newer engine. The cylinder head incorporates the liner, which looked nice and shiny, almost polished with no score marks. I've been told that the new piston ring will not bed in well because it's lost most of the honing marks from manufacturer, and a new head will be required. Has anyone else had problems bedding in new rings? The engines back assembled, compression feels very good, but I've not run it yet. Cheers Mike.

ED, Try John or Paul Goodall of Barton Model Products, they may have a spare crankcase. [email protected]

Thanks to everyone for their comments. It's given me plenty to think about. Cheers Mike.

I'm laying up a OS46AX for storage, while I run in a new OS46AX for a twin project. I had a thought for long term engine storage, could you give the engine a good dose of isopropyl alcohol (IPA) in the carb, swill round the bearings and drain out the excess. Then give the engine a good oil with after run oil? Previously for long term storage I'd drain the fuel tank, run the engine dry and when I'm home give the engine a good oil with Model Technics After run oil. I've heard of others after the end of season flying, fill the tank with zero nitro fuel, run the engine for a minute to clear it out, and after run oil it. Has anyone any thoughts on the IPA idea? Thanks Mike.

Thanks again for both of your replys. There is a fading price sticker on the box for £42.95 indeed quite a mark up from the balsa kit version. Interestingly the Bowman address looks to have moved for a third time to Devon. At some point I'd like to build the kit. It would make a nice semi scale fun flyer. Cheers Mike

Thanks for your replys. Interesting to hear it was also available as a balsa fuselage version. A closer look at the bottom of the plan is dated 83. Nice to finally see the old advert for the kit.

I recently aquired a Bowman kit's Hurricane, saved by a relative from going in the bin during a house clearance. I remember Bowman kit's adverts in the 1980's RCM&E, but none showed the Hurricane. 50" span with light foam / veneered wings. Moulded glass fibre fuselage is chopped matt which is a little on the heavy side. Recommended power is a 'hot' 25 or 40 with retracts. Has anyone had one of these Hurricane's back in the day, or know if there was a kit review in any old magazines. There's nothing relating to this model on the Internet. Thanks Mike.

Looking good Andy. Are you going to glass the entire airframe, or glass the fuselage and film the wings and tail?

I didn't notice any more power. The pipe was more for muffling, very quiet.

It's 61" span and weighs 6 1/2 ibs. Originally it was powered with a YS63S and long Hatori pipe, which was a good combo. It's now 9 years old and since been replaced with a YS70FZ. As its a kit made by EZ, its quite a light construction. Balsa/ liteply airframe, depron sheeting with a coloured mylar fuel proofed finish.

Nice to see another Mystic. Your Mystic is looking good. I've been flying a EZ Mystic 90 for awhile. Superb, quite quick smooth flyer, it will hold knife edge all day long, amazing flick rolls. I'm powering mine with a YS70FZ and a short Hatori muffler. Prettner mechanical retracts. Inside the fuselage it's date stamped from the factory 8.8.92 If there's one down side, it comes in quick on landing.