slskn

My Feedback: (4)

Just started my 7-77 on my Stearman this year, after adjusting the valves a month ago, wanted to see how she ran, on the second flip after choked by hand she ran like a Swiss clock, very happy, going to taker her out soon!

montt00

Thanks for the answer Tom.
I will adfjust the valves before break in.
Timo

Straightleg

Hi all!
Just a short report from my OS conversion for the 7-77.
What an improvement! It is almost like a new engine. Very good throttle response, increased power and good idle. It pulls my 9 kg SDSHOBBY GeeBee model Y in big round loops. Numbers: HK Aerostar 24x12, 5000+ on ground, 5600+ in level flight. I would not have used a smaller prop than this...

/terje

montt00

Is it an Ziroli Stearman 87 inch?
Timo

slskn

My Feedback: (4)

No, this is a Flair Stearman 89 ins., 35+ lbs. fabric covered 7-77 24x12 Falcon Prop, home made exhuast from sprinkler at home depot.
1. first start after valve adjustment http://youtu.be/qDdAN2Kw-U8
IMG_20160401_190518467_HDR.jpg (3.21 MB)
0413142042.jpg (2.06 MB)
0413140900.jpg (2.18 MB)
0412141710a.jpg (1.98 MB)
0413142043a.jpg (2.09 MB)
2. https://youtu.be/udRhKyPidM4

TimD.

My Feedback: (207)

Looks to have plenty of power. I have a Ziroli that I was considering putting a moki 180 in but the 7-77 seems to pull it around pretty good.

slskn

My Feedback: (4)

I have the 9-99 in my Ziroli Corsair, 36lbs. 26x12 prop, flies nice, but, would like to get a 180 Moki, for it just because I like the sound better, but the 9-99 flies it pretty good.
1. https://youtu.be/mKJK_3xvcz8
2. https://youtu.be/R0aBkZB7IUQ

slskn

My Feedback: (4)

https://youtu.be/a6aqOheDvOM

Ozflyboi

Hi all,
As I previously mentioned I was experiencing pushrods dislodging in flight on my 7-35 and since I investigated further I discovered that my valve clearances were incorrectly set as I used .004mm instead of .10mm (004). I confused the 004 on the feeler gauge as 1 thou (.004").

The motor is now only revving max rpm of 5500 which is less than it was performing with the tighter clearances which provided max above 6000. Also the idle characteristic is sluggish and motor is unhappy idling at low revs, than before where it was much happier.

I have read up on the effects of having too tight valve clearance as to valves burning out and now I am concerned this may have occurred to my motor as a result.

Please note the motor from new has around 1 hours run time using 10% oil 90% methanol and has remained cool with rich mixture set. I will change to 9% in the next runs.

I have been running Biela 17x8 and now 17x10 which has been loading up the engine correctly. The 17x8 was allowing motor to unload too much and over-rev.

Have any of you had any experience or photos of removing the cylinder heads from these radial motors? Is it difficult to change the valves?

I would now like to check these for any signs of wear or damage due tight clearances.

Any help or advice is appreciated.

Thanks for your guidance in advance.

Steve

Linkan2

Hi Steve
I have a UMS 7-35 has flown more than 10hrs.
always have a valve clearance of 0.1 mm (hope you know how to make the radial engine)
I have also lost pushrods but then discovered that the tappers have to be oiled.
they top tappers can go dry.
min at 7200 rpm with a 18x8.
has now ordered a carburettor from Saito 90R3.
Lars

Maxam

My Feedback: (62)

I seriously doubt you have burned the valves in one hour. These engines really wake up when a bit of nitro is used (5-10%). -tom

cymaz

I run mine on 8% nitro and 9% oil. It took a while to loosen up, now it has , it's a peach. Several hours of running in also so be patient my good fellow

Ozflyboi

I am little worried of nitro introducing rust to this motor. I have been careful to date with using blue block after each session of running. I also use Tri Flow on the rockers to keep them lubricated. I just cannot understand why this motor has lost power now with the correct valve lash. Perhaps there is less compression now?
May I ask you "cymaz" what prop are you using and what rpm' are you getting?

I've added RPM and Temp telemetry sensors to my motor so I can keep an eye on things from the transmitter. The JR 28X has a telemetry widget that logs all data which is handy.

I'd prefer to avoid running nitro is I possibly can.

slskn

My Feedback: (4)

Methanol is the ingredient that attracts moisture, not nessesarely the Nitro, also I use a chain saw lube for the chain in my rocker arm lube, has a kind of stickyness to it, and lasts a little longer.

Ozflyboi

Yes agreed that Methanol is Hygroscopic, however it is the Nitromethane that encourages rust through its Oxygen carrying properties. It is for this reason for which I avoid it. I have experienced rust in helicopter motors which use larger quantities of Nitromethane. So essentially it is the combination of the two ingredients which encourage rust at an increased rate. I have also experience corrosion from nitromethane in the form of "staining" discoloration of components in engines.

My main concern in my earlier post is the motor is running rougher since I have re-adjusted valve clearances to 0.1mm. The lowest reliable idle I can have now is 1400rpm and even then the motor is struggling to idle with the glow turned on. I am using a microsens onboard glow system with balance board in case you were wondering.
Tonight I will recheck the plugs with ignition as I have only visually check and the coils appear to be in tact but I want visual "glow" confirmation of this.

cymaz

My 7-77 was doing about 6000 on a 24x10. This is the max according to the book. I used to run a 22x10 but as the engine has run in the bigger prop was needed.
I always regularly oil both ends of the push rods and rockers. I also run the engine completely dry at the end of each day ( no matter if I'm using it the next ) and add good amount of after run, using an electric start to fling it about the crankcase.
i use a Sonic Tronics system of on board glow which has never let me down. Now I admit it hasn't been plain sailing with my engine.
However, I totally repiped and replumbed the fuel system. Added larger bore fuel tube. Put Dubro pipe barbs on all the pipes, new tank bung, o rings on the carb and heavier clunk....the works. Start from the clunk and work your way forward double check everythihng. I also found that at some point the intake tubes from the crankcase had worked loose , check those.

Ozflyboi

Thanks for your advice.

Yes I have revisited my fuel lines and clunk already. I will also take a good look at the intake pipes as you suggested. I noticed the exhaust tubes going into collector ring were leaking a little so I nipped these up.
I will let you know how I go.
The throttle range on these carbs is way up ^%*& creek. My carb arm moves quite a bit before the engine is even able to idle, meaning that is non linear. Has anyone else noticed this? Perhaps my carb has some issues I need to look into?? I have a service kit I ordered from horizon so can always rebuild if required.

cymaz

You are right about the carb trave not being linear ....forgot about that. With my Futaba 9c I dialled in + expo in.

Maxam

My Feedback: (62)

Oz, Just a thought, the RPM drop is close to the performance of loosing one cylinder. Start your engine an see if one cylinder is cold and does a glowplug need replacement of if there is a broken wire to that cylinder. -Tom

Ozflyboi

Hi Maxam and cymaz,

Okay so I have finally worked out what my problem was. This was all due to valve lash being too tight (not enough clearance).
Now that I have the clearances set correctly the motor runs oh so sweetly. I can hand start and it will low idle very slowly and smoothly.
I am also now getting peak rpm of 6400 this is with 17x10 biela prop. I have also finished the five litres of 90% Methanol /10% Synthetic oil fuel and now switched to the 9% Oil 91% methanol mix.

The motor has allot more power now and I have had three full flights on the Waco.

I am using a microsens on-board glow system which I sourced from Austria through a local distributor. I am finding the battery is depleting quickly as the unit is staying in high current (Engine Start mode). It should be exiting this mode after 90 seconds. I have programmed the unit a number of times but it appears to be bit of a hit and miss with this feature.

I have also taken taken Linkan2 advice and used chainsaw oil which is in spray pack. This seems to be working well for lubricating the rockers.

Thanks again for all your advice guys I really appreciate the feedback and responses received.

Linkan2

Hello
I also have a microsense, I have a battery 15000mAh.
I drive a lot of the battery.
Maybe you should contact Microsens for any update / warranty !!
If you do not get it work properly.

Ozflyboi

Hi Linkan2,

Last night I did some more tests on the microsens and I will explain what is happening.

I entered automatic programming mode (jumper removed) and completed the calibration starting with low idle position waiting for status light at power up then to full throttle wait for status light then moved throttle down to preset position for correct glow brightness setting. I replaced the jumper and powered off the unit.

When I turn the receiver back on again the unit initializes as per led blink. I move the throttle up to full throttle and down quickly to enter start mode which is confirmed by fast blinking red led.

Now when I move the throttle stick towards full throttle i can see that when I reach the point where I set the glow brightness it is past this point the led then changes to solid. When I lower the throttle again the led flashes again so it would seem the unit is not exiting start mode.

From what I understand the start mode shall only remain active for 90 seconds, of which it is not doing. I am unable to exit start mode. Perhaps I am doing something wrong?

Any help would be appreciated.

Thanks,
Steve

Ozflyboi

I have resolved the issue with the microsens on board glow unit.

The problem was very simply. The pin jumper which is removed to enter programming mode was in fact missing the tiny metal contacts. It would appear they had fallen out at some point meaning that the unit was operating in programming mode which I am surprised did not blow any of the glow plugs.
I have temporarily used another jumper just to prove that the unit is working correctly and I can now complete Automatic programming which allows the unit to be used as intended.

Dad_Roman

Nice. Thats a good find.

Camel

Good day to you all and thank you for all your experience. Recently decided to retro fit my old sopwith pup with a 777 and am just enjoying breaking in this lovely motor.
Can any one tell me the voltage for the plugs supplied please? I'm putting together a regulated supply and need to set the correct number many thanks Robin