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SportJett question... - 10/29/2012 3:43 AM   
1QwkSport2.5r



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From: Cottage Grove, MN, USA
Status: offline 		Greetings, Bob! I am entertaining the idea of getting a SJ .30 or .35. However the Jett website is in dire need of updating and it only shows the .25-.40L as BSE only. Can I get a cast case SJ or are they BSE only? Are the rpm figures on the site using a Jettstream muffler?

Thanks in advance for the help & info!

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RE: SportJett question... - 11/1/2012 6:45 PM   
bob27s



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Status: offline 		Hi,

Sorry for the delay, and thank you for writing.

Those are only available in BSE case as shown.

Cast case .25-35 size engines are not available. Dub has never manufactured a cast case in that size.

Similarly, the SJ-76L, and FIRE-90L engines are only availalble as BSE.

All of the specs, weights and dimensions shown are configured as you receive it with the JettStream muffler, and the prop indicated. So to your question, Yes, that is with the Jettstream muffler.

The "46" size engines as well as the side exhaust 90L are available in cast case.

Bob


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RE: SportJett question... - 11/1/2012 6:59 PM   
1QwkSport2.5r



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From: Cottage Grove, MN, USA
Status: offline 		Thanks for the information Bob. Is the pricing on the website correct?

Thanks again.

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RE: SportJett question... - 11/19/2012 3:42 PM   
1QwkSport2.5r



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From: Cottage Grove, MN, USA
Status: offline 		Bob? Is pricing on the website current?

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RE: SportJett question... - 11/19/2012 6:19 PM   
bob27s



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Status: offline 		Abut 90% sure it is..


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RE: SportJett question... - 11/19/2012 9:57 PM   
1QwkSport2.5r



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ORIGINAL: bob27s

Abut 90% sure it is..

Great. Thanks.

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RE: SportJett question... - 1/9/2013 12:34 AM   
1QwkSport2.5r



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From: Cottage Grove, MN, USA
Status: offline 		Greetings again, Bob.

I have one question - I know Dub lists his performance figures for his engines using 15% nitro fuel. Is it necessary to break-in on 15% nitro? Does it matter if a guy switches between 5% and 15% periodically?

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RE: SportJett question... - 2/14/2013 1:49 AM   
1QwkSport2.5r



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Status: offline 		Bob.... are you out there? Just curious about my last question regarding nitro requirements. I have my BSE .35 now, and am looking to get it broke in soon so its ready for the upcoming season... I mixed up some 15% just in case, but will it perform well on 5-10% nitro? I know it will drop some performance off with a little less nitro.. Will it handle 5% nitro okay or does it really need 10-15% to run properly? In the instructions that Dub sent with the engine it said to drop to a smaller prop on FAI fuel... I intend to run some nitro just to get a little more wiggle room on the needle. All but one of my engines requires no more than 5% nitro due to comrpession ratio; It would be cool if I could run the same fuel in all of my engines but if the BSE .35 will take too much of a hit in rpm on 5%, I'll stick to 10-15%. For my application, a 9x6 or 9x7 APC prop works best. I've used an 8x6 on my SuperTigre S29 and it ran okay, but not quite enough thrust to get my desired result.

Thanks in advance for any wisdom you have to share.


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RE: SportJett question... - 2/18/2013 5:50 PM   
bob27s



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Status: offline 		hey...

sorry for the delay... I seem not to get notifications of posts in here that often.

All of the engines will run fine on lower nitro. Our friends over seas often run 0% and 5% fuel.

The key is you want to keep the rpm up where it should be, so yes, means backing off on the prop a little.

Usually the engine will not mind switching fuels. Key is not to try to stress it too much when you go to the lower nitro. If you are running at 9x7 to start with, then switch to the 9x6.

The only technical difference you might see in performance is the idle and transition. Nitro assists with both of those. But typically not a problem. You can try a few different plug temperatures and transition will be perfect.

Agian, sorry for the delay.

Bob Brassell


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RE: SportJett question... - 2/23/2013 5:55 AM   
1QwkSport2.5r



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quote:

ORIGINAL: bob27s

hey...

sorry for the delay... I seem not to get notifications of posts in here that often.

All of the engines will run fine on lower nitro. Our friends over seas often run 0% and 5% fuel.

The key is you want to keep the rpm up where it should be, so yes, means backing off on the prop a little.

Usually the engine will not mind switching fuels. Key is not to try to stress it too much when you go to the lower nitro. If you are running at 9x7 to start with, then switch to the 9x6.

The only technical difference you might see in performance is the idle and transition. Nitro assists with both of those. But typically not a problem. You can try a few different plug temperatures and transition will be perfect.

Agian, sorry for the delay.

Bob Brassell

Its quite alright, Bob. I thought about emailing you or Dub, but I wasn't in a real hurry to get my questions answered. I'll just run 15% fuel for now. I'd like to get some break-in runs done so its ready for the season, but I've been hesitant due to it being relatively cold outside lately. What is your rock bottom air temp you'd run one of these engines in at? I have an 8x6 prop on the engine and will end up using a 9x6 APC for normal use. The engine is very tight and with it being cold outside, I figured it might be a bit much to get it started even. I was going to use a hairdryer to heat the engine up beore popping it off the first time, figured this would loosen it up a little and make starting easier. I just dont want to roast the piston fit in the liner by having it too cold outside.


I'm going to use an 8x6 APC, 15% nitro 22% oil, and an old hot glow plug from my tool box. I save new plugs for after the bench runs and ready for service.

Thanks for getting back to me, Bob. I appreciate it!

-Tim

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RE: SportJett question... - 3/9/2013 2:07 AM   
bob27s



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Status: offline 		Just wanted to check in ...... how did you make out with trying a few things?


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RE: SportJett question... - 3/9/2013 2:32 AM   
1QwkSport2.5r



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ORIGINAL: bob27s

Just wanted to check in ...... how did you make out with trying a few things?

I waited until the temp was above 32°F and ran the engine per the instructions. I put the engine on the dash of my truck with the heat cranked and got the engine nice and toasty before I fired it up the first time. I used 15% nitro 25% oil, and a 25yr old OS #8 plug from my box that I'll swap out for the merlin the engine came with. The engine got plenty hot even in the cooler weather. I ran it today for 3 tanks of fuel at 16,500-16,700rpm, it was 38°F today.

I have (6) 7oz tanks of fuel through the engine so far on the 8x6 APC and put the 9x6 APC on it to see if it would turn 18k or better. It would not, I don't think its ready yet. 17,500rpm peak. I went about 100rpm lean of peak, so I richened 1 full turn on the needle, and shut it down to cool off.

I think runtime is about 20 minutes now, maybe a little less. The 7oz tank lasts for 4 minutes at 16,500rpm rich on the 8x6.

I will give it another few runs on the 8x6 to loosen it up a little more before I put the heavier prop on it.

Its getting easier to start though; my electric starter will get it going much better now.

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RE: SportJett question... - 3/14/2013 10:44 PM   
1QwkSport2.5r



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From: Cottage Grove, MN, USA
Status: offline 		I got my .35 ran in pretty good, about 35 minutes runtime on it. With the intended 9x6 APC it peaks at 17,550rpm on 15% nitro. A 9x5 APC peaks at 18,500rpm. Based on the info I got with the engine, these rpm readings are normal for a new tight engine. I'm sure as the engine gets more time on it and the weather warms, the rpms will pick up.

How long can I expect the piston and liner set to last in non-abusive conditions using good fuel? Do these engines have that legendary last-forever problem that Enya and SuperTigre have? I'm not concerned, just curious.

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RE: SportJett question... - 4/1/2013 6:07 AM   
bob27s



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Status: offline 		If you take care of it ...... will last a LONG time. Years.

I have a 12 year old SJ50 that runs better today than it did when 3 months old

Just avoid lean runs, take care of it ...... and it will get better over time


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RE: SportJett question... - 4/3/2013 4:42 AM   
1QwkSport2.5r



Posts: 3721
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From: Cottage Grove, MN, USA
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quote:

ORIGINAL: bob27s

If you take care of it ...... will last a LONG time. Years.

I have a 12 year old SJ50 that runs better today than it did when 3 months old

Just avoid lean runs, take care of it ...... and it will get better over time

Sounds great. Thanks Bob.


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