Sport-Jett 60L carb blow out problem

Sport-Jett 60L carb blow out problem
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Sport-Jett 60L carb blow out problem - 10/15/2007 12:04:32 AM

Posts: 61
Joined: 11/8/2002
From: Fox Creek, AB, CANADA
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I have a problem with the carb blowing out of its mount off of of the engine. I have tightened it back in twice and now during the last 2 flights it has blown out. It has been suggested to lock tight it in, and balance the prop. I have an APC 10-06 prop on it. What would you advise me to do. By the way I have been very impressed with this engine's performance, as well as have impressed all my flying buddies. I have it on a Northstar.
Doug

RE: Sport-Jett 60L carb blow out problem - 10/15/2007 12:08:04 AM

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Joined: 8/23/2002
From: Jacksonville, FL, USA
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Sky,
What's a Northstar?
Arthur

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(in reply to Skyventures)

RE: Sport-Jett 60L carb blow out problem - 10/15/2007 12:09:31 AM

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From: Paola, KS, USA
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Maybe try an 11-6? Perhaps the 10-6 is letting the SJ60 get to an RPM range where it's difficult to balance. The SJ60LX is rated with the 10-6, perhaps it's a different animal...

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RE: Sport-Jett 60L carb blow out problem - 10/15/2007 1:58:56 AM

rmenke

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From: Merced, Ca., CA, USA
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Skyventures:

Having recently gone through this with Dub on the same engine, lets have a go (Dub spanked me) If you have put this engine in the ground at speed and puched the carb out, or back, you probably need a new case, the original being oblonged. Sent mine in to Dub for repairs as was haveing same problem as you after sticking it into the ground hard. Dub sent it back with original case and it has had no problems since. Aparently I was not getting the sinch bolt lined up correctly before tightening. I would argue with anyone about it except Dub, and the fact that its still in place after some time is proof Dub was right (again). Only thing was, I am very carefull with my engines, and almost obsessive with my Jett engines, the lesson here is "Listen when the master speaks" (Dub). By the way, go to th Jett site and read up on the props again. The 10X6 is breakin, the go-go prop 8.8 X 8.75 with minimum 18,000 rpm. Watch the rpm's, somedays 18K is no problem, actually around 19.5K, other days its 17.5K on the same prop. When Dub says not to run below 18K, follow that per gospel. Also watch prop ballance and be sure to keep a gap in the prop lug, otherwise you may get a unusual vibration that is impossible to find (Prop shaft toutcing back of the crank). Then you get air bubbles in your line from needle to carb, the source you cant find. Learned this one the very hard way. When all else fails with these engines, go back to the masters instructions, and follow them. Ahhhhh, that also includes Bob, he's got a good handle on these things, probaby from goofing as much in the past as I have. ENJOY

(in reply to Skyventures)

RE: Sport-Jett 60L carb blow out problem - 10/15/2007 5:27:21 PM

bob27s

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From: Cleveland, OH, USA
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Hi Doug.....

Loose carb huh?

Pretty rare that happens....

1) DO NOT use loctite or anything to glue the carb in unless Dub himself suggests it.

2) Regarding using a bigger prop ....

if that is a SJ-60L (regular version, lower rpm setup) you can try an 11x5 prop or 10.5x6 - and an 11x6 is fair game.
You can also try a 9x9 and 10x7 since the Northstar does not have a great deal of room for prop clearance.

If that is a SJ-60LX engine - nothing bigger than a 10x6 under any circumstances.

3) Make sure the carb is down all the way - it should be somewhat snug in the case

4) use a small socket wrench or sturdy nut driver to install the draw-bar. That nut should be very snug. If you wish to use loctite on anything, just a tiny bit on the drawbar nut (brass nut).

5) A well balanced prop is very important when you are talking 17K rpm. Shaking would be very obvious. A soft engine mount can cause the engine to shake a bit too... but those are rare. The only time I have had a carb come off of the engine due to vibration is when I actually lost a blade in flight.

6) I suggest ensuring that your prop-installation stud is NOT bottomed out in the crankshaft. You want to thread it in, back it off 2 or 3 turns. Then install the prop and prop nut. You want the drive washer, not the prop stud, to ensure a square prop installation. If you bottom out the stud, it can skew off a fraction of a degree - if the prop its tight on the stud - it will try to align to that instead, and cause the prop pitch to be unbalanced.

As Roger noted above, if you have attended to all above, and the carb is still abandoning the crankcase, it may be worth sending the engine back to Dub for a look see. Something is definately not right. If it vibrated out for some reason in the past, it is possible that it shook itself loose and wore away some of the crankcase material - which would just make things worse.

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(in reply to Skyventures)

RE: Sport-Jett 60L carb blow out problem - 10/15/2007 8:09:26 PM

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From: Fox Creek, AB, CANADA
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Thanks Fizzwater2, Roger, and Bob,
I think you gave me the clue to the answer. The engine kicked back once and the prop came loose. I probably bottomed out the prop-insallation stud. I'll follow up all of your suggestions though.
ArthurD,
A Northstar is one of the most popular float planes in our club. (MOFFA- Mostly Old Float Flyers Association). It is a "Balsa USA" kit. The Northstar I have pictured here doesn't have the Jett 60L on it yet. No one else in the club can catch it with the Jett installed on it.

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< Message edited by Skyventures -- 10/15/2007 8:22:56 PM >

(in reply to bob27s)

RE: Sport-Jett 60L carb blow out problem - 10/15/2007 8:26:05 PM

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From: Paola, KS, USA
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I can see where an 11 or 12" prop might be a problem...

There were a couple of northstars flying at our club's float fly this summer - neat planes!

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RE: Sport-Jett 60L carb blow out problem - 10/15/2007 8:47:35 PM

bob27s

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this was a fun project....
Northstar with a FIRE (rear exhaust) SJ-60L engine --- and a pipe

took some creative fuel tank to pull this off as I understand it. but it flew well.

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RE: Sport-Jett 60L carb blow out problem - 10/16/2007 12:14:47 AM

MJD

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From: Orangeville, ON, CANADA
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quote:

ORIGINAL: bob27s

this was a fun project....
Northstar with a FIRE (rear exhaust) SJ-60L engine --- and a pipe

took some creative fuel tank to pull this off as I understand it. but it flew well.

So, where's the pipe? I only see the rear exhaust outlet directly in line with the vertical stab..

Who's the dude on the left?

MJD

(in reply to bob27s)

RE: Sport-Jett 60L carb blow out problem - 10/16/2007 2:44:39 AM

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From: Fox Creek, AB, CANADA
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I said that there was no other Northstar in our club that could catch my Northsar with the SJ 60L Jett. I didn't concider Len Boisvert's Nothstar, because in my opinion it is in class of it's own.
It is , I believe 1.5 X larger scale with a PST 600R Turbine jet engine. I asked Len's permision to post this, and he said he wasn't sure that mine couldn't keep up with his.

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< Message edited by Skyventures -- 10/16/2007 2:46:02 AM >

(in reply to bob27s)

RE: Sport-Jett 60L carb blow out problem - 10/16/2007 12:42:51 PM

MJD

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From: Orangeville, ON, CANADA
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quote:

ORIGINAL: Skyventures

I said that there was no other Northstar in our club that could catch my Northsar with the SJ 60L Jett. I didn't concider Len Boisvert's Nothstar, because in my opinion it is in class of it's own.
It is , I believe 1.5 X larger scale with a PST 600R Turbine jet engine. I asked Len's permision to post this, and he said he wasn't sure that mine couldn't keep up with his.

That's crazy - I mean great! Say, where's Fox Creek - anywhere near the Lethbridge / Fort McLeod area or?

MJD

(in reply to Skyventures)

RE: Sport-Jett 60L carb blow out problem - 10/16/2007 4:46:10 PM

bob27s

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From: Cleveland, OH, USA
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quote:

ORIGINAL: MJD

quote:

ORIGINAL: bob27s

this was a fun project....
Northstar with a FIRE (rear exhaust) SJ-60L engine --- and a pipe

took some creative fuel tank to pull this off as I understand it. but it flew well.

So, where's the pipe? I only see the rear exhaust outlet directly in line with the vertical stab..

Who's the dude on the left?

MJD

Id have to look up the datasheet for the aircraft....
You can see the tail end of the pipe just aft of the fin.... tends to blend in with the curtain wall.

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RE: Sport-Jett 60L carb blow out problem - 10/16/2007 5:19:16 PM

MJD

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From: Orangeville, ON, CANADA
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quote:

ORIGINAL: bob27s

Id have to look up the datasheet for the aircraft....
You can see the tail end of the pipe just aft of the fin.... tends to blend in with the curtain wall.

Don't trouble yourself - from the picture it looked like just the exhaust adapter, but now that you pointed it out I can see the pipe there. Now I know what you meant by a tricky tank installation..

MJD

(in reply to bob27s)

RE: Sport-Jett 60L carb blow out problem - 10/16/2007 7:00:09 PM

rmenke

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From: Merced, Ca., CA, USA
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Sky:

Great stuff guy, thanks for the pics, way out there. What I was trying to get accross in props etc. for the Jett 60 applys to the 60LX, not the 60L. Don't know why I assume everyone is running the LX high rpm version of the engine. You wll never be whole and alive until you have the 60LX. Imagine the power of a 60 stuffed into a 40 sized case with the rpm output near a racing engine (very near), and also idles better than your anything else. Would say better than sex, but at my age, I just don't quire remember. First time in my life I built something faster than I wanted was 60 LX powered. The re-design runs a 12oz tank to enjoy some flight time and flys much like a Kayos until you push the left side stick up to the top. No, not as fast as a good Quickee, but if your Quickee is average, your in trouble, period. Yea, sorta love this engine and related life.

Have you noticed how good a Diplomat Bob's 27 is. Never ****es about us getting comments into his thread, but kicks a little tail if your off base, but nicely. We are out of line when we do this by protocall, but we just feel like this place is "home", all warm and cuddely. Thank you Bob.

(in reply to Skyventures)

RE: Sport-Jett 60L carb blow out problem - 10/16/2007 8:27:54 PM

bob27s

Posts: 4588
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline

quote:

ORIGINAL: rmenke

Sky:

Great stuff guy, thanks for the pics, way out there. What I was trying to get accross in props etc. for the Jett 60 applys to the 60LX, not the 60L. Don't know why I assume everyone is running the LX high rpm version of the engine. You wll never be whole and alive until you have the 60LX. Imagine the power of a 60 stuffed into a 40 sized case with the rpm output near a racing engine (very near), and also idles better than your anything else. Would say better than sex, but at my age, I just don't quire remember. First time in my life I built something faster than I wanted was 60 LX powered. The re-design runs a 12oz tank to enjoy some flight time and flys much like a Kayos until you push the left side stick up to the top. No, not as fast as a good Quickee, but if your Quickee is average, your in trouble, period. Yea, sorta love this engine and related life.

Have you noticed how good a Diplomat Bob's 27 is. Never ****es about us getting comments into his thread, but kicks a little tail if your off base, but nicely. We are out of line when we do this by protocall, but we just feel like this place is "home", all warm and cuddely. Thank you Bob.

hey... you guys are the best source of information.
There is only so much data we can collect/test/destroy/attempt on our own. Real world applications are invaluable.

All help and feedback is appreciated

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Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to rmenke)

RE: Sport-Jett 60L carb blow out problem - 10/16/2007 11:04:44 PM