ahughes

Hello,
I'm hoping someone here may know the answer regarding YS engines.
I currently have a YS FZ63S that started acting up. Inconsistent speed at full throttle, then when you throttle back it locks and stops. Has a slight clanking sound as well. I have reached out to CKAero for a service request, but they have not responded yet.
My alternate approach is to look at the new FX80S as it appears to be a drop in replacement (measurements look very similar).

My questions are as follows: I currently use a Hatori #643 header and #640 muffler. Does anyone know if this header will attach to the new FZ80S, and wheter the muffler is sufficient for the new FZ80S?

Thanks,
Andrew

jngoins

Andrew, It sound to me that the engine is going lean. Check for air leaks especially around the valve push rod covers and the high speed needle. I use a piece of large sized fuel tubing on the High Speed Needle instead of the detent clicker. That solves a common problem of leaks here. If you are looking to step up, the YS70 is a great engine and is just a punched out 63. The 80's are notorious for vibration. Lastly, why are you using a muffler. These pumped engines will run great with a straight pipe. Good Luck

ahughes

Thanks for the reply jngoins,

I ended up sending the 63 into CKAero for service. No news yet back from them.

I am actually using a Hatori pipe on it. Wanted to know if it would bolt up to the larger engines (70 or 80) so I don’t have to change any mountings.

I also appreciate the feedback on the 80 as that was my fallback plan.

Thanks,
Andrew

Four Stroker

I have had all of the variations of the small YS 53,63,70,80. They are all a bolt in replacement with the same spacing. The exhaust header thread has not changed. The muffler you have is getting small for the 70 and 80. I would suggest getting the YS F3A header and muffler from: https://www.yspower.co.jp/en/ order direct. You just send him an email under the parts tab and describe what you want. He will send you a bill and will take PayPal. Your old header if in good condition will also fit.

The new 80 is the best engine yet. Works fine for me. Has the improvements of the 70 plus a new carb that works great.

ahughes

Thanks four stroker,
I appreciate the feedback. My current pipe is like new, so I’d hate to let it go to waste. Plus it is a tight fit in the plane already. You indicated it was a little undersized for the 80, would you think I would experience just a power loss with no damaging effect?
Thanks again,
Andrew

Four Stroker

I have two of the 640 pipes. They are at least as big as the standard muffler that comes with the engines. The 80 comes with the same muffler as all the rest. So it won't cause any harm. The 80 may be 1.5 mm taller than the 63. It is a stroked 70. 53 bored to 63 bored to 70 stroked to 80. The 80 carb is better than the 70. The new regulator is mounted on the side of the carb which can also be a problem fitting to old planes.

ahughes

Thank you four stroker!

Bad Falcon

Four Stroker - This is a reach out for help. First of all, you need to know how I "inherited" this problem with my YS FZ63.

Year 2006 - I saw a friend of mine fly a Pilot Seduction Freestyle and he had a YS63 in it. The plane was fabulous but the engine was occasionally fabulous...but when it was fabulous, it was fabulous with a capital F.

Back then, (I started this hobby in 2003 with a 30 size Raptor helicopter and then transitioned into planes) I was only flying 2 strokes : TT, OS, Rossi, Webra...45 to 60 class.

I had an opportunity to visit Singapore Hobby that same year and got myself a Pilot Seduction kit too and a second hand YS63 at half price off new (I had wanted a new one but the gentleman in the shop offered me this unit which apparently was run but never flown because the original buyer couldn't get it to run consistently. It was sent back (through SH) to YS Japan and after they returned it repaired, rectified or serviced etc, the original owner had long moved on to OS and didn't want the YS any longer. Whether it was a wise decision, then and now, is a whole different conversation...let's just steer clear of that topic for now)

I started building the kit and I had only managed to finish the wings when I had to move due to work....plus life happened. The engine was left as is in the original box (un-tested) and believe it or not the engine(s) and kits(s) actually followed me to all my work locations but were NEVER unpacked.

Year 2022 - I moved to Qatar (also for work) and I happened to visit (by chance) their RC Flying site - seriously this is probably among the best dedicated RC flying site I have ever seen. So.....all that interest came back in a rush...and I unpacked my kits/engines.

I have started back on building the plane and in preparation I thought it will be best to check out the engine as well....
Last weekend I built a "running in" stand - quick conversation of an old coffee table - and bought fuel, glow, batteries and installed engine test mount to run the YS63. Fuel is 20/18 full synthetic, APC 12x7. What happened next is still a miracle to me....

I primed the engine as per the manual, plus guidance from advice, comments and post in this forum (I did a bit of reading up - I had to), put on the glow starter and turned it with a starter - the damn thing fired up at the first kick.....after 17 long years in hibernation !!! I didnt even change the plug...it's still on the standard YS plug that came when I bought it.

Now as for the engine - after the initial period of idle for 30 seconds to build tank pressure - it idles great, revs up like anything for the first 3 or 4 throttle punch ups.....then after that it kind of leans out and if I don't return it to idle, the engine will cut out. I restarted and it did exactly the same thing three times. I managed to tach it just once - tach was showing 10800 max rev.

I dont see any leaks in the line or tank, and yes the tank is pressurised and I also dont see any bubbles in the fuel line.

Reason I am writing this is because I know this engine isn't that far off from being perfect and the last thing I want to do is fiddling things I shouldn't. What do you think is causing it to lean out after 2 or 3 full throttle openings?

Thanks in advance.