OK... Here's the deal.. I posted some of this last year, but i need a refresher before I go about this...

I have my 110FZ mounted in a H9 Spitfire with a Keleo Scale Exhaust spinning a 14X7 3-blade prop running 20/20

ON THE GROUND...

It starts on the first flip.. Once its tuned its PERFECT.. peaked at 9200, richened to about 8900, Idles at about 1850, good transisiton, good smoke.. yada yada..

Take off and it pulls that plane straight up.. fly it for about 3 minutes and then everything goes to hell.. Mushy throttle then it dies and i dead stick it in..

On the ground.. the compression is DEFINATELY less and it WILL NOT START.. It will sometimes cough, but you can adust till you swear and throw things, and it aint gonna do nuthin but look at you and LAUGH..

the Check valves are right.. it holds good pressure (i know this because i pulled my fuel dot off while peering straight at it once.. don't do that!!)

Put it away, take it out the next day, starsts right back up and runs perfect untill you get it in the air (i've tried running the plane without the cowl.. same results)

Now.. the engine is mounted inverted and i note that it will spit fuel out when you open the throttle up.

NOW.. i'm pretty sure that this is heat related.. but... not sure WHAT its related to.. Ring.. Gasketts.. o-rings,,, Valve springs.. something cracked??????

I've got the mtor ripped off the plane and would really like to try and fix this myself.. I'm a competent mechanic, just have no experience wtih YS motors!!

If ya'll think i should, i'll just box her up and ship her out to YS in Arizona..

It sounds like you are getting it lean in the air by foaming in the fuel tank. When the cylinder gets too hot from lean, it will lose compression and not run right.

How many flights do you have on it? Those are pretty normal symptoms of a ring going, or it could be bearings starting to go, but my thought would be the ring. The engines are no that difficult to rebuild and it would be quicker to order parts and rebuild more than likely. Richard is usually very quick with repairs, but you will also learn a great deal by doing the rebuild.

Arch

My thoughts were a weak ring myself as i've had this problem on other engines....

HOWEVER........ I found my old post......

Someone commented that the fuel sptting out the carb was a sign of the regulator not seating and then asked if fuel spits out the exhaust when i crank it..

After she dies.. it does seem like theres a lot of fuel in the exhaust when you crant it.. but... with the keleo scale exhaust, its hard to tell... the scale exhaust is cool.. but makes a hell of a mess!!!!!!!!!

I would definitely start with a ring. All of the symptoms are there for a ring. I find it hard to believe that foaming in the tank is really a possibility with the quality of fuels these days. I would think if it was a regulator issue it would be there from the start, not after it is running for any length of time.

Arch

Arch....

Gonna order some parts..

Guess i need a ring... duh.. a gasket and o-ring kit.. might as well get the regulator rebuild stuff as well

Have an owners manual to it, but is there a shop pmanual with torque specs and all that jazz availalbe somewhere???

Anything else i mght need?

I don't know of any shop manual for it. Basically make sure all the case bolts are as tight as I can get them with an allen wrench, and snug on everything else. That should pretty much cover your rebuild and give you any parts you may need in the future. You might want to order bearings as well, just to have them handy as you will need them eventually.

Arch

Ditto on the ring.... that was my first guess.
Skids

I had a chart for torque specs for different sized screws, but I can't find it anymore.

For head bolts I use 10in/lb for 4-40/2.5mm and 12in/lb for 6-32/3mm. That will cover 99% of the nitro motors out there.

I found a post on MECOA's forums, all in in/lbs:
2 56 - 2.2
4 40 - 4.7
5 40 - 6.9
6 32 - 8.7
6 40 -10.9

Those numbers sound a little low to me, but it also depends on how many threads are engaged. A backplate screw would be fine at 4.7 in/lbs and would probably strip at 10. A head bolt would be way undertorqued at 4.7.

well.. I finally got the parts i needed to re-ring this thing and replace the gaskets, etc... Will do it this week. (really!!)

Was reading some other articles about props and such ..


could the 14X9 Three blade prop be part of the fault here?? Ie.. it runs at 9250 on the ground... but a three blade with a pitch of 9 its going to be stalled at that RPM.. When its in the air, and it's flying at 40 mph, its getting a bite and heating it up cause the load is actually higher that at the same trhottle setting on the ground (as airspeed increases, the effect of the propwash also lessens, allowing the prop efficiency to go up at a given RPM)


Dunno, maybe I'n thinkin too much... but, the three blade prop is also something different on my motor thats not as "common" and therefore could make some problems..

DirtTorpedo:
I am in the process of rebuilding my 110fz. My rear bearing died. I thing I am going to have to replace the piston and ring, along with gaskets and o-rings. I am having problems removing the rear bearing, or what is left of it. I have already tried heating everything up and tapping from the front with no luck.
Did you replace the bearings and if so how did you remove the one in the back?

FWIW Are you tapping the case or the bearing from the front?...Try after heating (just to the point where a drop of water will boil when applied) with a "Gloved" hand, abruptly "Slamming" the rear open end of the case squarely down on a large piece of wood (2x4?)....The bearing SHOULD fall out [sm=thumbs_up.gif]

WELLLLL......... I did some calculations on a propellar load simulator.... that 14X9 three blade on there was too big!!!!! the simulator said it was pulling 2.85 H.P. suggested 14X10 and 15X8 two blades props on the simulator pulled 2.2 h.p...

A 14X7 three blade registers about 2.15 h.p... but i don't have one!!

SOooooooooooooo.. I put a 13X8 on there which comes in at 1.9 h.p to turn it...

BINGO... got a nice long flight on her, the mid needs set, but i landed the plane with the prop still turnin and taxied her back to the pits 1st time EVER!!!!!


Then.... all hell broke loose on the second flight....... my KELEO scale exhaust decided to explode!!!!!!!! the pipe that runs from the header back to the Y pipe just broke off and exited the cowling somehow!!!!!! still landed the plane.. but, it wouldn't start up...and thats when i discovered the piece missing!!!!!

Oh well.... I'm gonna get a header from central hobbies, and put a silicone connector between it and the Y pipe (after i weld a nipple onto the Y pipe cause theres just a hole there now!!!!)

The rear bearing is shot on my 110. Where is a good place to buy replacements? Which ones? I see there are bearings ranging from $18 to $60. Any advise would be appreciated. Because I have the whole engine apart (with the exception of taking the valves out), I am planning on replacing the piston ring, all the gaskets and O rings, and the front and rear crank bearings. Anything else I should do while it's in pieces? What about the camshaft bearings?
Thanks in advance for any advise.

For bearings, I use these http://www.bocabearings.com/bearing-...s-fz-110-s-110 if the cam bearings rotate smooth/quiet, should be good/to/go....FWIW

Question from a YS newbie. Replaced the bearings, piston ring, cylinder head O ring and gaskets on my 110 fz. Everything went great expect for the fact that when setting the cam timig dots, with the crank dot at 6 oclock, the cam dot had to be either 11:55 or 12:05. I chose 11:55, and hopefully it was the right choice because OMG, the engine runs awesome now. Tached over 10,000 with 16 x 6 APC, and that was with the HS needle at almost 2 turns open. I didn't want to run the engine that fast with the new ring and bearings, so I quickly backed off the throttle. My question is, after following the tuning instructios, all three adjustments have changed. The regulator had to be leaned about 1/2 turn, the low speed needled leaned 3/4 a turn, and the high speed needle appears to have to be leaned a quarter turn although for the next 5 flights or so I thought I should keep the HS needle a little rich until the ring breaks in so I really don't know where it will end up exactly. The question is: Is it normal for the adjustments to all change like that?, or should I change the cam timing to 12:05 and see if the adjustments go back to where they were before the overhaul? I just really don't know much about these engines, and don't want to ruin it because I have the timing set wrong. First YS and 4 stroke engine for me.

Sounds like you guessed right. Usually choose lining up with the pushrods over 12:00.

FWIW....I would leave the cam timing....What nitro % are you using?....Two turns on the h/s sounds a little "Heavy", but then again with high nitro, maybe not (you did say it was a little rich)....My experience with this engine is the reg. adjustment is approx 1 full turn "Above" the housing & the h/s approx 1-3/16...1-1/4 turns open (25% nitro, 21/22% oil)....Mich. elevation...

It really varies some between engines. A full turn on the regulator from flush seems the exception rather than normal.

Good news! Then I'll levave the cam alone. Boy I didn't want to open her up again. Wildcat YS 20/20. The regulator was about 3/4 turn above the housing before the new parts went in, now close to flush, maybe a little higher. I flew the plane with the HS at 1-1/2" turns out, but before the rebuild 1-3/4 turns. BTW, I purchased the engine used and didn't touch the settings other than the HS needle. Only one flight since the rebuild, but it flew tremendous. I'll check the regulator adjustment next week. That's the hardest thing for me to get right. It's set correctly if the engine holds a steady 4000 rpm - is that right? She's' rich if the 4000 rpm drops, and lean if the rpms surge up and down at 4000. That's what I read at least. I think other than that, I'll just fly it as long as it gives a nice smooth smoke trail and idles good and continues to act and sound smooth. So far so good. Top end is too much for me anyway. Hardly ever go WOT, my flying skills can't keep up with what's happening at those speeds. Plane will come home in a bag for sure if I try to push it. Thanks for the input.

Sounds like you pretty/much got it figured/out....FWIW, for me one of the first signs of a "Lean" reg. &/or low/speed adjust., are "Dead/stick" landings...With the throttle back & the prop "Windmilling" the engine, she will lean/out & die....Again FWIW...