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Engine basics => Engine set up tips => Topic started by: Rob Killick on October 07, 2007, 10:53:09 PM
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Hi ,
I need some help from some SuperTiger aficionados ...
I have three ST G21/.35's .
The best of the three is a brand new (never run) G21/.35 with flat piston . # under the exhaust port motor lug reads " B29 / 8 and has a balanced crank .
The second of the three , is in good shape and like the first has a prop driver that extends back over the aluminum casting (bearing fit) . It hasn't got the wrist pin hole and screw in the rear of the case , though .
Flat top piston , liner with two odd shaped intake ports . Wrist pin with hollow brass pads .
Bronze bushed con rod . No writing undermotor lug . The crank has a circular counter weight and this confuses me somewhat .
The third engine , only the crank (balanced) and the crankcase seem to be of any use and has a flat piston ... No writing under lug .
The prop driver only extends about 3/16" past the front bearing housing .
What I'm wondering is what the second mentioned engine has a circular fly wheel ?
Would it be advantageous to swap it forthebalanced type ?
Thanks :)
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If you look closely at the crank without any balancing cuts, it's probably got a thin sleeve over the crank covering the balance cuts.
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Hi Andrew ,
Yes the flywheel has a shiney , silver band around it .
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As I remember it, some Super Tigres used a crankshaft that had a lighter material filled in on the crankshaft where the counterbalances had been machined away, and then a band installed around the whole thing. The reason for doing this I was told was to stuff the case for less case volume. Back in my early R/C days, I saw a few of the bands come off. Not a good thing.
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Hi ,
I need some help from some SuperTiger aficionados ...
I have three ST G21/.35's .
The best of the three is a brand new (never run) G21/.35 with flat piston . # under the exhaust port motor lug reads " B29 / 8 and has a balanced crank .
The second of the three , is in good shape and like the first has a prop driver that extends back over the aluminum casting (bearing fit) . It hasn't got the wrist pin hole and screw in the rear of the case , though .
Flat top piston , liner with two odd shaped intake ports . Wrist pin with hollow brass pads .
Bronze bushed con rod . No writing undermotor lug . The crank has a circular counter weight and this confuses me somewhat .
The third engine , only the crank (balanced) and the crankcase seem to be of any use and has a flat piston ... No writing under lug .
The prop driver only extends about 3/16" past the front bearing housing .
What I'm wondering is what the second mentioned engine has a circular fly wheel ?
Would it be advantageous to swap it forthebalanced type ?
Thanks :)
Hi Rob
The cranks that you are looking at that is a full circle crank is balanced ,it is just machined away inside and the band you see covering the crank is an aluminum piece, this should be removed if you use the crank. Like as was stated earlier, they have been known to fly off and damage the engines, plus the T crank has a better balanced to it.
Regards
Randt\y
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G'day Rob. All the above is good advice. The one without the wrist pin hole is younger. Guess S.T. discovered they could arrange to remove the piston/rod assy. without withdrawing the pin first. S.T. are (were?) notorious for the frequent mods. they made to their engines, often without any notification or change of designation.
I'm a little curious about No.3 - Prop driver 3/16" past the bearing? Sounds as if it might just be one of the PB (= bushing) jobs. What is written on the engine? Is it definitely G21 and 35, or is it a big V with a C inside it? If so it is a "C35" PB combat engine. There was also a baffle piston stunt motor on ths c/case. Good examples of both are very nice engines.
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As far as I can tell, the short prop driver is stock, I have a G21-35 with the same prop driver. Just chalked it up to normal ST differences and never researched it.