What can you guys tell me about this engine, Im in the market for a new engine for my 40 size profile plane. Ive got a 55AX on the way but after doing some reading I have changed my mind about using that engine. I came across the TT 75 and Im very close to sealing the deal and buying this engine. I can get it for $180 which is a lot less than Saito's and OS. Just wondering if someone could give me some RPM number they got with different props. I plan on running a Xoar 13x4 with it. Also, I was reading the specs on Towerhobbies and it says this engine has an airbleed carb, I read in other posts this engine was a two needle carb, any clarification?

Hi!

I have the engine and I'm very pleased with it

It doesn't have an airbleed carb, its a good two needle carb.

Mine turns about 9600 a Graupner 13x6 (heavy load prop), I don't have tach so I can't track the engine regularly, only when a mate at the field with tach comes... It is a very nice built engine and the power is good, it was my first four stroke.
13x4 may be too small load for the engine, I think a 14x4 could be better.

I've also run the engine with the new graupners, the one that looks like the APC but MUCH lighter...and the 13x7 works pretty good.

I've found 2 problems with the engine:

1. A burr in the intake pipe obstructing it, but Thunder Tiger says that they've corrected it.
2. Camshaft lubrication....it has a sealed rear bearing and no oil passages to the camshaft... I almost had a Failure there, and I noticed it on time, What I did was just to make a pinhole in the seal of the bearing



Have you checked the prices on thundertiger4u?

Yes I was that they are very cheap on thundertiger4u but it tells me $50 for shipping and I live in the U.S. so Im not sure why so much, they must be overseas. Also I thought that I read elsewhere that it had a nipple on the backplate? Ill have to look into to it, how old is your engine?

it has a nipple in the backplate just like most of the 4 stroke engines...a normal breather.

my engine is about 3 months old

is the new one type, with the black head and the nice muffler

It can't be that the shipping is 50, take a look at your settings there.

You may get a good price on tower with discount codes when they are there...

The folks at http://www.thundertiger4u.com normally ship orders of $150 or more for free. They've recently redone their website, and not everything is working like it should. Some of the engines (GP-42 and GP-61) are showing up at full retail, for example.

I'd recommend that you simply e-mail them before ordering that your F-75s will be $169.99 with free ground shipping. They can fix your invoice manually before processing your order if they know that it's coming.

I've always gotten great customer service from thundertiger4u.com, and I'm confident that they'll take care of you.

I just got this motor from TT4U for $169 delivered to my door. $50 les than Tower wants for it. I just want to know how it runs. Also the nipple in the rear cover is just for a vent? The instructions do not address this. Suggestions and comments?

You have to put a fuel tubing on that nipple and route it to the bottom of the plane. It will spit oil there, and there is where most of the mess of the engine comes from.

Engine runs very well, and will run better after 2 gallons of fuel.

Just put a 13x6 prop on it and enjoy!

Thanks for the input. Tell me more about the lower end lubrication problem please.

you were right about the shipping, I double checked my info and I accidentally chose the country Georgia instead of the U.S., since i live in Georgia the state right now. Free shipping, but I went with towerhobbies because I ordered other things and it came out the exact same price in the end.

O.K the problem I had is the following:

As you know the lower end is lubricated by means of blow-by gas through piston ring gap. To get oil in the camshaft, oil muss pass through rear bearing, and since the rear bearing is sealed and there is no holes or something that allows the oil to get there...well, my camshaft was just dry. When I bought the engine, I put some oil there, and did it a couple of times, but the oil there is always expelled. After one flight some day, I felt that the engine was so rough turning by hand, that I thought that the bearings were damaged...then I took the cam cover off and found metal powder there.... took the camshaft and I found that it was bronze from the intern bushing, the cam seized the bushing there, and everything was dry there. So I cleaned up everything and put it together again, but I took the rubber seal of the rear bearing.
Started the engine, and the engine was a nice sweet engine, better than before, better idling etc... I flew the plane...and found the cowling with a big oil mess, now most of the oil was expelled through the front bearing (shielded but not sealed).

So my solution so far was making a pinhole on the rubber seal of the rear bearing, I put it back together and now everything is fine, it spits a very small amount of oil on the front bearing, but it is ok, not like before, but it tells me that everything gets the oil there.

I guess a better solution could be a shielded rear bearing and a sealed front bearing....but I didn't do that at the moment...still my solution worked for me.

The other thing was the burr in the intake pipe, just at the elbow, it was like a ring obstructing the pipe...I grinded it and the engine performed better.

My engine was funny also because it came with a muffler which had one nipple and at the opposite side had a threaded hole for another nipple... I just put another nipple on it and a piece of fuel tubing.... Once I wonder if I put the vent line to the muffler... and it worked ok...and the mess came only from the muffler.

I wrote to thunder tiger (taiwan) ....and the man didn't know about the muffler with two nipple holes...and told me that the intake pipe burr was corrected...so I hope you get a good one...
About the lubrication problems...the guy just said.... "the rear bearing muss be replaced since the seal was removed" ...and contact Thunder Tiger Europe for further problems... then I wrote again...ahh you don't understand the problem bla bla bla....but again I forwarded the email to thunder tiger europe....and guess what... NO ANSWER, from thunder tiger in Taiwan nor from Thunder Tiger Europe...

That's my story! I've already made a post about that if you search a little here on the forums

Hope this helps,

Jorge

Jorge, thank you very much. I planned on disassembling mine before running it and check everything out. I will change the bearings with a shielded rear bearing and a sealed front bearing if that is not what is in mine. I will let you know how it works.

You are welcome Barry, I'm glad I can help...

It's a shame that some silly things happen...I really like the engine, and it is very well made I think, when you dissassemble it you'll notice it... conrod is nice machined, everything is nice machined. the liner is actually is steel but nickel plated.

Check also the intake pipe for the burr...and take pictures accordingly =) I didn't !

Anyone else out there with this engine have the same problems?

I will take pictures. There are very few engines I have bought over the years that do not need some kind of modification to run right. I also, when I started model airplanes, ruined a few engines by not taking them apart and thoroughly cleaning and deburring them.

I got mine from Thunder Tiger 4U and the price was very reasonable. $169 US delivered. I noticed that Tower Hobbies was selling it for $219 and have been wonderinbg why. Maybe it is the end of the production run with the poor camshaft lubrication. Anyway, if I don't get it disassembled today it will be next week as I bought a P-51 with a YS 110s in it and I have to go to Louisiana to pick it up tomorrow.

The lubrication issue is a huge oversight on TT's part. I don't know what they are thinking. The US distributor is just as oblivious to the issue. There is a small step in the intake port in the head. This is a minor concern. The engine was clean inside. Most engines need no modification today.

Sounds like somebody is not thinking at the factory. Probably got a good deal on sealed rear bearings and stuck them in the engine, or were short sighted in trying to correct a nose bleed problem by installing a sealed bearing without a thought about the cam area. Of course, if the cam bearings are sealed that probably means they have a life time lubrication inside the seal and don't need to be lubed by the fuel. Don't know the answer but do know that it was a good catch by the end user. Not the first time such a problem has cropped up, I seem to recall the OS 70FL has a similar problem with a sealed main bearing.

Cheers,

Chip

Cam has bearings, friction bearings.

OS FL-70 had a drilled crank to allow oil into the cam area.

I got my 75S disassembled and the problem in the intake is gone on mine. Thge bearing are the same with the rear brg having a seal and the front being shielded. I am heating the case to remove the grgs and will see if the rear brg is lubed inside the seal. I am wonering how big was the hole in the seal estradajae as I am going to put one small or a couple small holes in the seal. If it is sealed on both sides of the bearing which is what i am used to then I will have to put holes in both seals. Comments and suggestions from all but mostly estradajae.

Hi Barry

Mine has only one orange seal...at the other side it doesn't have any shield or seal.

I made a hole about 1mmx1mm just where the seal touches the bearing at the center ( I don't know how to say that), just where it is soft, the seal looks like it is made from bronze or brass and only where it touches the moving part is only rubber, so I made the hole there with a knife... I made it somewhere I hadn't proper tools to make it.
I guess a 1mm hole made with a drill bit anywhere would be just fine??

ONly a very small hole is needed, since it will be under pressure at the down strokes??

I will be taking pictures and posting shortly

It would be interesting if the engine has a small passage at all to lubricate the cam??

I am curious what does estradajae stand for on English? Or does it not convert?

There is no passage at all from the crankcase to the cam shaft. Other models of TT fourstrokes, 54 and 91 I now for sure, have passages to get oil through. I just removed the seal.