smok

Hello Dave,

I am breaking up a new YS-63FZS, it ran one or two tanks like a clockwork, prefect idle and transition, still quite rich... I use CoolPower PatternPro ( 20/20% nitro/oil ) and the high speed idle is open 2.5 turns, the low speed one turn from closed, just by the manual. I had some minor problem with the regulator, so I closed 1/2 turn from flush and it stopped leaking at times, I'll check it later...

But what really puzzles me now, is that at about 3rd tank ( 450ml, on a stand, 12x7 APC prop ) suddenly I see that I can not get it to idle anymore, once I close more than 2/3rd of the throttle, it will start to rev up when closing further, it would peak really high then I close a tad more and it will try to slow down but with a bit more closed throttle it would quickly slow down and quit. So in other words when closing from half throttle to almost closed throttle it speeds up from maybe 4k RPM up to some 8k rpm and still emits smoke and no detonations, then the throttle seems kinda work on the last 10-20% before complete closing, again no detonations but seems just like in that problem range the throttle works in reverse ??
I suspect false air maybe getting somewhere, but before checking I am interested to know if you have seen that before or do you have any suggestions what to check ?

Thank you in advance,

Smok

Dave Shadel

Go through the running instructions at www.ysperformance.com and let me know the result. I can tell you that the HS needle at 2.5 turns open is completely wrong and should be closer to 1.5 turns if it is set correctly.

smok

Hello Dave,

Thank you for your reply - yes indeed the initial 2.5 turn for high speed was too rich, I did subsequent runs at 2 turns from closed, and for low speed I tried 1 turn, 2 turns and 3 turns. But the thing is that the engine was running very well initially at any of these settings, but suddenly after 3rd or 4th tank it started this weird behavior that closing the throttle from half down to almost closed was actually increasing the RPM quite a lot, at least to 8-9k. OK, I will try once more tomorrow - do you have any ballpark suggestions for the low speed needle initial setting ? Before I had a great idle between 2 and 3 turns open for the low speed needle..

Many thanks in advance,

Smok

smok

Hello Dave,

I found something !! - one pushrod cover o-ring is partially blown out of place - the one on the top side of the intake valve pushrod - this is probably where the engine pulls air from, when closing the throttle - does that make sense ?

Also I have noticed that the throttle barrel seal is cut at the edge in one place - likely happened while the throttle barrel was installed and the seal did not completely go inside the carburetor body and a small chunk of the seal was cut off by the body edge( that is how it look like ) - but the seal in anyway only on one side of the barrel and that cut off happened during assembly, so I believe that the pushrod cover o-ring could be the culprit here ?

Also,is there any engine assembly manual available on-line ?

Dave Shadel

Sounds like you have found the problems. The same link as I gave you before has all the parts lists and drawings.

smok

Hello Dave,

Yes indeed after loosening the four screws holding the cylinder to the crankcase I was able to push the o-ring back into place and reassemble the push-rod. After that the engine was running fine back again - it was the air sucked into the crankcase that caused the problem.

But that makes me ask yet another question - it's a brand new engine and I can see that it still has the snap-on regulator mount, while in the forum I read that this has been replaced around Dec 2005 with another mount that one needs to dismount the push-rod covers to put that new one in... Can you confirm that the current design in not the snap-in ?

I am asking this since the regulator runs fine most of the time, but from times to times it would stick open and flood the carb, then I screw it down to closed and open the same amount ( 1-1.5 turns from closed ) and it works fine again. It seems quite random and to avoid it for a full tank run I need to turn the regulator down to 1/2 turn from closed, but then I am afraid of leaning it too much on transition. Also it is not consistent, but acts up so I am afraid to put it to a plane yet, I hate dead-sticks and quitting motors ( I have several other 4 strokes but that is my 1st YS ). Almost looks like someone swapped the regulator to an old one and did not fit the o-ring properly in the process...

Thank you,

Smok

smok

I have found now that the regulator opened 7/8 of a turn from closed, the high speed opened 2 turns and the low speed opened 2.5 turns give me stable idle at 2000-2200 rpm and an instant transition with a quite scary top end, all with a nice smoke and the exhaust oil color still unchanged, I will test further tomorrow with CoolPower 30 and will see how it goes. I have also replaced the fuel line from the regulator to a carb with a little thicker-walled one with smaller internal diameter and I now have less bubbles there as well. So far so good..

Smok

Dave Shadel

Keep us posted.

smok

Just wanted to give an update - I tested the engine today with Master Airscrew K series 13x6 prop and CoolPower 30% heli fuel. After some testing I arrived at the low and high speed needles 2 turns open from closed, and the regulator 3/4 turn open from closed and the engine was working great. I got peak RPMs of 11,4k, idle was stable down to 1800 rpm and an the engine has an instant transition. Many thanks Dave for answers and for this great forum which helped me with the tuning details.

cheers,

Smok

Dave Shadel

Sounds good, but 1800 rpm idle might be a little low. If you can keep it running there, the engine is exceptional. Most won't idle reliably under 2200 or so. Don't forget to reset the valves after the first gallon of fuel.

smok

Yes 1800 rpm idle was on a stand, with the engine mounted upright and with manual throttle ( just a piece of wire to the throttle, not a servo ) so I will see how it keeps the idle when mounted in a plane. Anyway 2200 would be already good. Thanks again,


Smok

Dave Shadel

Good Flying!

smok

Of course it was about breaking-in the engine, not really about breaking it up as I wrote in the first post ;-)

BTW. same thing once happened to me when I said that a motor was properly screwed - when I really meant that screws were properly tightened ;-)

Dave Shadel

That's OK, I can't speak Belgian either. Sometimes I can't even speak English!