asmund

Today I tached my new 75 on APC 12.25-3.75 and APC 13-6, 15% fuel. The 12.25 prop gave a steady peak at 14400 rpm`s and the 13-6 gave 11400 rpm`s. (I have no idea if this is normal, good or bad for this engine)
Someone in here claimed a while ago that his T 75 would turn 15000+ on the 12.25, now I find that a little hard to believe even though my engine has only consumed about 1 litre of fuel so far. It would of course be nice if it would loosen up more and produce 600 more rpm`s, time will tell.
I can not shut it down by closing the carb or even put my finger over it, but it will idle so low it barey ticks over, so I`m not worried by it.
One annoying thing about it is the STUPID way of fastening the muffler, it is next to impossible to get to the screw that is behind the muffler so to speak and it takes me almost 10 minutes just to screw in that screw because I can only turn it a tiny bit before I have to relocate my allen wrench. Why in gods name couldn`t they just have done it the way most other brands do!!! And I have had the muffler come off twice already even though everything is ballanced and I use loctite. Well I will degrease the threads and use a stronger locktite next time

summerwind

asmund,

i agree on the muffler mounting, but i took FlyboyDave's advice and didn't use the muffler gasket, but instead, used RTV sealant and used loctite on the threads.........never loosened up.

as for not being able to make the engine quit by blocking the air, think about it, the engine is leaking air just as some of us have already discussed. yes it idles, and will idle super low, but have you flown the plane between just less than 1/2 throttle to 1/4 throttle?...........that's where mine (but not at first though) started to act up, and got worse as it was run.

also, you do know that AMA has a rule that says you are suppose to be able to shut the engine down by using your TX, whether pulling the trim down or using the shutdown button or switch?

asmund

I didn`t use the gasket either, never do. I will try to fly around at low throttle settings a little next time the weather allows any more flying to see if mine too acts up. I`m going to tach it on some 11-7`s and 12-6 and 12-8 as soon as they arrive in my mailbox

Rcpilot

My Feedback: (78)

The carb is leaking air. You need to get it seated down in the crankcase tightly or it will leak air and never shut down.

Loosen the nut that holds the carb on. Take the carb off. Put a little engine oil or castor oil on the carb where it slides down inside the crankcase. Now put the carb back on the engine. Grip the front of the engine with your hand and put your thumb over the top of the carb. Squeeze it down on the motor to compress the O-rings and seal it up good. Now tighten the bolt to hold it in place.

You can also use Flyboy Daves method of putting a small block of wood on top of the carb and tap it down with a hammer. Works fine.

You just need to get that carb down in there TIGHT and get it seated on the O-ring or it will never seal.

I run most of my TH .75 engines with a Pro Zinger 13-5 prop. It's the perfect prop for 3D on a 5-7 pound airframe. They scream. Can't remember the RPMs. Haven't tached one in over a year. No reason too.

I wouldn't run more than a 13-6 prop on this engine. Even a 13-6 is pushing it. Too much load leads to heat build up and causes deadsticks.

The Master Airscrew 12-8 is an okay prop for sport flying.

Just depends on what you want to do with the engine.

On the muffler attachment -- just cut 1/4" (6mm) off the allen wrench. Then it fits in the tight spot and makes it easier to attach the muffler. I don't like the muffler attachment either. Small price to pay for such a nice running engine though.

summerwind

hey Rcpilet,

my carb on my Twoer .75 was fully seated, and still the engine would not shut down...............carb was bottomed out, and the carb neck has 2 O-rings.
my front bearing passed air like it was not sealed at all........still think this is a carb leak problem?

asmund

Have done all the above, but still....
No big a deal, just a little annoying

yallaair

This is probably the reason why they are so cheap. Inexpensive production gives inaccurate tolerances. Why not by engines from a maker with good reputation like MVVS or Webra?? Then you will get "quality power"!

Harry Lagman

Thanks for the tach numbers Asmund.

I have seen similar numbers to you on the APC 13 x 6.

My guess for the props on their way:

APC 11 x 7 - 13,300
APC 12 x 6 - 12,400
APC 12 x 8 - 11,300

Rcpilot

My Feedback: (78)

Sumerwind,
I wasn't addressing you in my post. If you look at the reply too: you will see that I was talking to Asmund. I thought maybe he could use some help from a guy who has had 8 of these engines and been around them more than just once. I've learned a lot of tricks on these engines. All engines have little issues that you need to get familiar with in order to get maximum enjoyment.

But, why the anger and animosity? "still think this is a carb leak problem?" There was no reason for that.

summerwind

gee, that is hardly what i call "anger and animosity?"...............................thing is, Asmund is not a beginner, nor am i, but even so, i find it hard to not get the carb into the Tower .75 and still have a leak. there are 2 o-rings, 1 at the bottom, and 1 at the top.........any engine set up like this requires very little effort to get the carb body installed without leaking.
this is also an open discussion, and i do believe you have taken my reply the wrong way, but it would help if when you join in on a public discussion as this, and feel free to let us all know who you were replying to.

Harry Lagman

Rcpilet - a couple of suggestions:

1) When addressing people, please spell their names correctly. Cut and paste can help...

2) When a problem turns out to be other than what you have suggested, don't take it personally.

Rcpilot

My Feedback: (78)

Summerwind,
All you have to do is look to the bottom of my post on the right side and it will say:

(in reply to: xxxxx)

That's how you know who a person is addressing.

I don't always scroll to the bottom of the page and hit the reply button. You can reply to any person in the discussion by hitting the reply button at the top of their post. WHO you are replying to is indicated on the bottom right side of your post.

summerwind

i see says the blind man.........you know, i never have looked at that corner of the replies........learn something new everyday eh?

youngun

This is just a reply to the thread and not to any individual.[8D]

Who does it say I have replied to?

It seems you get that "replied to" thing with any reply.

Just an observation, and not taking any sides here.

w8ye

My Feedback: (16)

It generally states the name of the person in the previous post to yours

rainedave

My Feedback: (1)

Yes, if you click the "Post Reply" button at the bottom left corner of the entire thread it registers your post as a reply to the previous post. If you click the "Reply" link at the top right corner of a specific post it will register your post as a reply to that post.[sm=bananahead.gif]

Rcpilot

My Feedback: (78)

Exactly

If you just scroll to the bottom of the page and hit the reply button, it will register your post as replying to the last one in line.

But, if you go up to the top of any post by another person, there is a reply button there too. When you click that button, it specifically indicates that you replied to that person. Not always the last poster on the topic.

This particular post indicates that I replied to rainedave because I hit the QUOTE button to reply.

yallaair

To be honest, I think Asmund is interested in getting information on "how to get maximum power out of this engine", and a benchmark what is known as "normal" power for this engine. Asmund needs more than normal power from this engine , and he usually gets some extra out of them! Of course he needs it if he is going to beat my MVVS 91 hehe

speedster 1919

My Feedback: (3)

Asmund provided your carb is cinched down tight ,your keep running is too rich LS needle. It is too early in breakin too adjust now. If you want speed the MAS 12x7 K series or the Mas 12x8 S2 series work better than the APC 12 sizes.

asmund

Yes I am a little rich on both needles since break in isn`t finished yet, but it seems as the carb is leaking, it will run for a long time with the carb blocked, but I can live with that. Looking forward for more testing but the weather doesn`t allow me to go flying around here these days

asmund

Laugh all you want, but if my only goal was to just beat you I would just slap my YS 110 or tuned 91 fx in there and hang on To get absolute maximum power out of this particular engine is what I`m after (without using a long pipe)[X(] I have flow ported the sleeve and now I need to test different plugs, fuels and possibly tach it with one or two less headshims, drill the stinger of the muffler. I find this very interesting and fun and can`t wait to get a chance to experiment more with this rather pretty engine, damn weather[:@]