Union Models

Hi, wondering if someone might be able to help.
I've been running a new YS70FZ in a pattern model.
The YS70FZ is using a Hatori 577 flexible header with a Hatori 530 tuned muffler (looks more like a tuned pipe)
The engine runs well, I'm getting 10300-2100 rpm on a APC 12x8" prop using Model Technics YS20/20 fuel.

Here's the problem I see lots of white smoke through the running of the engine, however, the oil is a very dark brown /black look instead of a nice light oil colour my other YS Engines are

As a test, I ran the engine with the standard exhaust, the engine needed to be run a bit leaner, but the oil colour was a nice clean colour.
Back to the pipe setup, a the engine needs richening and back to the black oil.

Is the flexi header too long ? Causing burnt exhaust gasses to come back into the pipe, causing the oil to burn?

BTW, I'm running the long pipe setup as it suits the old style pattern model I'm flying also it's a very quiet set up.

Thanks Mike.

Union Models

Problem sorted.. As this was a new YS70FZ I was using, the Hatori pipe and header had been used for quite along time in another model.
The problem was due to coking up in the pipe, causing some restrictions of the exhausts gases. This caused the residue oil in the pipe to cook turning the oil black.
Pipe was cleaned up with neat thinners and the problem went away.

Four Stroker

I have three 530 pipes. I have long since stopped using the flex header. If you need one I have a new one. This is a very quiet pipe. It was designed for the 53. The 70 is getting a bit large for it. It does not run well on the 80. I have switched to the 720 pipe and the YS header.

http://www.yspower.co.jp/en/engine/acce.html

The 80 is a beast. The 725 still a few at Central Hobbies would work as well.

Union Models

Four Stroker, thanks for your reply. This backs up what another flyers thoughts were, that the YS70FZ is on the limits for the Hatori 530 pipe.

I've since replaced the pipe with a Hatori 720 short cooling muffler and ridged headed, as its less restrictive.

This could also solve the problems I was experiencing with the engine over heating in vert warm weather, despite there being more than ample cooling in the cowling.

Regards Mike.

Four Stroker

Where did you get the 720 ? There are none in the USA now. A place called Probuild has them on the webpage.

Manuals and parts are available from: ys_top direct if Central does not have or stock them. I have ordered parts and it was prompt and simple.

Union Models

Probuild don't have any more of the 720 pipes, I phoned them. There will be no more Hatori pipes, I hear they are not making them anymore.

I bought my 720 pipe and header second hand from a UK aerobatic website. Might be worth trying Singapore Hobbies, they sometimes have old stock items.

Four Stroker

Well YS should get off their rumps and make a muffler for each of the headers they sell. They currently have a F3A pipe, actually two.

Long ago a 21~28 car muffler could be used. You would have to make the coupler. Hey, that's 3.5~4.6 to you.

Four Stroker

I emailed Yamada and asked what they were going to do about this problem. It would not hurt to also email him yourself. Contact on the website.