Jim Oliver

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Bob,

I have just acquired a Sport Jett .65 that has never been run, but is several years old. I want to use it on a Classic/Ballistic Pattern model (about 700 sq. in., about 8 pounds) with an 11x6, 11x7 or 11x8 prop. Of course. I want all the power (speed?) I can get; is there a muffler other than the stock red muffler that will allow using one of those props with higher rpm than the red muffler?

Per your experience, which of those props would you expect to give the best performance? Any other advice/comments will be appreciated.

Thanks,
Jim

bob27s

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Hi Jim

Rare find. But a good engine.

11x7 is good. Target 13500-14000 ground peak rpm with your prop selection. Back off 600 or so for flight.

Bob

Jim Oliver

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Thanks for the info-any advice on the muffler option?

Thanks,
Jim

bob27s

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Run the jett-stream that came with it.

Or you can run a full size pipe. Header for ST61 matches bolt pattern.

Jim Oliver

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Bob,

I'm posting this here so that others may benefit from it.

I got the "old" SJ .65 and an early ( I think) SJ .90 in this deal; both were said to be unrun and I believe the seller to be a very honest and honorable person. Being a bit cautious (both engines had been in a glass display case for a long time), I removed the backplate from both engines to make sure the wrist pins were free and the bearings looked OK. After removing the backplates I saw that the oil had dried out and gummed up the bearings. On the .65 there appears to be rust on the crankshaft counter weight and on the part of the shaft that is visable through the carb mounting hole.

I am going to send both engines to Dub for his inspection and probable bearing replacement. I don't want to risk having bits of rust going through the piston/liner.

BTW, the idle needle on the .65 carb isn't a screw, it's just a tiny needle valve. Must be an early design........The instructions with the .65 have a 1995 date; the .90 has a 1996 date. The .65 is S/N 09. The .90 doesn't have a S/N that I can see.

I also noticed that the older .65 and .90 have aluminum liners; my somewhat newer SJ .90 has a brass liner............

Thanks for your help.
Jim

bob27s

My Feedback: (19)

Thanks for the details Jim,

Yep, that is an old one The very original carbs had the small L-shaped adjustment on them for low speed mixture.

The engines were available as AAC and ABC. AAC saved on weight quite a bit.

Jim Oliver

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Bob,
Dub has both engines now, for replacement of rough bearings.

Jim

Jim Oliver

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Bearings have been replaced; surprizingly, Dub found the rod on the .65 cracked at the very top, 12:00 position relative to the wrist pin hole. The engine is several years old but had not been run since it left Dub's hands........strange???

Jim

bob27s

My Feedback: (19)

Unusual, yes. But he is thorough looking through engines. Glad he caught it.