Repairing a Super Tigre 75

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There is no perceptible difference between Italian and Chinese parts. They look, feel and work exactly the same. Rebuild your engine.
Ed Cregger

Hey Ed, I also have a problem with an Italian ST 45. The carb. has the old thumb screw on the low idle side. About half of the threads broke off of the skirt part therefore I don't have enough threads for a proper setting. How do I resolve this issue? New part, new carb(will it fit), or what? I tried soldering the skirt back on to no avail.

"dennyboy" wrote
You are not going to believe this one, but try it and be surprised.
Build up the area with JB Weld. There are two ways to go about it, but both assume that you are going to prepare the are to be bonded, by cleaning very well, and acetone would be the best to use after alcohol, with no oil-of course.
Also, don't use the quick JB Weld, as it is questionable about being fuel proof, so I have heard.
One way is to build up the area and then drill and tap it. That is probably the harder way, since you have to be able to drill it accurately before tapping it. One way to do that is to get it lined up in a drill press vice, with a drill into the old hole, and then don't move it as you apply the JB Weld. After it cures for 24 hours (48 is even better) then you can proceed to drilling and taping it.
Another way is to use Vaseline to lightly coat (put it on, then wipe practically all off) the screw, and put it into the hole. Then, build up some JB Weld around the outside of the body, and pay attention to how the leftover is setting. When it is almost completely hard, work the screw out carefully, put a little more Vaseline on it, and thread it back in. Wait a while, and do it again.
I did this to a Fox carb probably 10 years ago, and it is still holding like a new crankcase holding the carb.
If all else fails, you can JB Weld it in place permanently.

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What Jim said.
Great answer, Jim.
Ed Cregger

Hey Jim, I tried the JB Weld on the outside of the needle skirt and it seems to have worked. I will have to run it yet to see how it holds up. If there is a problem with it I would like to know if the new style (Chinese) lo speed needle will fit into the old style carb. barrell. Or will it require a new barrel, and if so will it fit into the old carb. Also, I have a Super Tigre 51 (Italian) that has started spitting grey matter all over my plane, I assume that means bearings or sometning needs replacing. Would it be worth the time and expense to go into it and replace parts or just buy a new ST 51 for $85?

"dennyboy" wrote
Glad the JB Weld worked. If you got the parts getting bonded good and clean, and you used enough, it is there for good. I have been flying that type of repair for well over ten years, I think, and it has never given me a hint of failing.
Don't know about the specifics, on this.
Not necessarily.
I would guess that the fuel you are burning has castor oil in it, and the gray/black goo that comes out is completely normal for fuel with castor oil, in small percentage of the oil content, or all castor oil.
That is a reason that some people do not like castor oil. The mess is unfortunate, but castor oil is the best insurance you can buy to protect an engine from a run that has been over leaned, and to protect an engine from rust and corrosion while it is sitting between flying sessions.
Fly it until it does not run anymore, or is not reliable. You will probably not have a problem, but it is hard to tell over the internet!

What Jim said is all true, I might add that a loose screw on the header or a loose muffler may cause that residue. It could be bearings, or con rod or cyl & piston, anywhere there is metal on metal. Take it apart and see if you can tell.(the metal shavings at the con rod to crank bushing on my K&B61 was a pretty good clue) In My Humble Opinion a good engine is worth putting in Boca bearings(maybe Paul McIntosh has some) but not worth replacing all parts. Check all screws and engine to engine mount first. mk

I used JB Weld several years ago to repair a broken exhaust flange on a Saito 4 cycle. It worked like a charm and held up extremely well considering the incredible heat generated right at the exhaust port. Great Stuff

"Jim" wrote
No, Great Stuff is used to fill cracks around window frames, and pipes and stuff, to prevent house air leaks.
Oh, you meant that JB is good stuff, eh? Sorry, I had to do that!
Yep, I hear one tale after another, each topping the previous one, about well that JB seems to hold.
Ya know what? I believe them all!
I have only had one failure, and it was a long shot, at best. In other words, I expected it to fail, for what I was asking it to do.
The only thing that it will fail at, occassionally, is where it is expected to take a substantial structural load.
Like your exhaust flange? If it has screws holding it, and the JB is to fill it out and seal it (and perhaps take some of the load), then it will work every time. It is rated at 500 degrees F, but I swear it will do better than that.
Hey, they even make a permanent radiator sealer product. Also, a two 5 ounce tube industrial size. I gotta get me some of that!

"MJKolodziej" > wrote
What he said!
I did not figure theis in, partly because I didn't think of it, and partly because I would have hoped that he would have seen something as obvious as this, and corrected it to see if the gray gunk stopped.
At least, that's my story, and I'm stickin' to it!
Also, if there is an area that looks like it has been polished from parts rubbing together, it will be very obvious, and very different in appearence from the surrounding metal. One area that comes to mind is on the back plate. Some minor circular polishing is normal, but much more than what would be caused from an occasional rub could indicate a serious problem, then for most any case, go for replacing the bearings to solve it.