I was reading in the 1/2A threads about some people having engines that they never could get to run.  Ive experienced this with larger motors and Im wondering what other peoples experiences are.
The glaring example in my case were 3 Thunder Tiger 15's bought new back in the late 70's when they first came out.  Never once got one of them to fire back then, best I ever got was about a 1/2 second burp and that was it.  Flipped those props untold scores of times, different glow plugs, different fuels, nothing.  Eventually sold 2 of them and kept one. Not sure why.
Last year when I got back into the hobby after about 30 years away. I got out all of my old engines and determined to run them on a make shift stand.  Everything worked and then I looked at the Thunder Tiger 15 and decided I would try it again.  Nothing different about what I was using really, just dealing with an engine that had collected dust for nearly 40 years and had never done more than gurgle a few times out of dozens of tries and many hundreds of flips.  About the 40th flip it started!!!  The darn thing actually ran!  No idea why it finally decided to fire, but it did.  I was so excited.  Since then Ive run about 15oz of fuel through it over several runs on a now proper test stand.   Recently acquired a much newer Thunder Tiger 15 RC, NIB condition, and now I want to locate a TT RC carb for the old one and have a pair that I can put on a twin of some sort.

Anyone else had issues with motors that just never cooperated?

Frank, I agree completely. Regarding this particular engine, and its two twins I let go of, I was far from sticking with a set routine. Over the 13 years I was actively flying I tried everything I could think of as well as everything anyone suggested. Nothing ever worked.  For reasons unknown to mere mortals it has suddenly decided it was time to start and run. I am not complaining a bit, I just wish I had kept the other 2 as well.

About 10-12 years ago, I bought 3 new Fox 25BB motors to use for SL combat. Broke all 3 in properly. Used bladder pressure. Over the course of 2 years, could never get them to run consistently. Tried everything: different plugs, props, fuel (various Sig 20%+ oil, mostly castor), nvas, venturis and nothing worked. Never used them in a contest. Two had the main BB cage disentegrate, one had a crank come apart, and I did not use more than 10% nitro, never went smaller than an 8-4 schimitar prop.

Finally gave up on them and stuck with LA25s. No more probs.

Ok now that we have that covered how about engines that are too easy to start. I have a OS 40 FSR that would start running if you looked at it funny. No joke that thing would start at times without the battery attached and often when turning it over by hand slowly to get that bump. Scary when you did not have the battery attached.

You must be a masochist , Gary ! .

If you gettem firing up first flick , consistantly , consider a twin .

FPs LAs or Even G-15s can do that .

Tho I dont know anything about early thunder tigers , I belive they mave improved over the years . .

Twins can be bleedy fustrating if the injuns dont tune evenly or hol settings . Half your flights can be a dead loss .

' a bit ' of NITRO , like 15 % , gets a fat rich setting & plenty of grunt , as a rule .

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If you can mount the two on the bench , and from cold , wet / prime them , and get a ' in synch ' run , inside ten flicks total ,
Theyre Probly worth persevering with .

But if they get bothersome on the bench firing both of , as you would in a plane ; or wont run the same note / rpm's Ea Time you fire them up
setting unaltered , you could just end up flicking the noses off , or spiraling it in if a engine goes off suddenly . bin there , done that .

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A Oriental Wing & moments , cranks 7 in from fuse , can build around 40 Oz with two .15s , scribled to match your chosen look .Profile .
Fox 19s / 25s can be cranky - hence the Nitro . But docile engines are almost a nicesity in a multi injuned ship .
Veco 19s often one wile fire & kick back and fwd a few seconds , normally it , after a few seconds , cranks up .
About the same time it looks like its stopped - you go to flick it - as it catches , snarls -  hits your finger - gets blood on the aeroplane .

Normally you start the outer first , so it runs out of juice first . Props tangental ( 90 deg from ea other at same compresion ) can stop the shakes .
Normally the outer vertical & the inner horizontal , on compresion . Outer injun ofset a few degrees is usually required or itll be very Light on the lines
on the outer .

We Await a video of both starting first flick simultaeneously , repeated Ten Times .