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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> BSE .50 rpm
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BSE .50 rpm - 10/23/2007 1:02:57 AM   
paolino1818


 

Posts: 48
Joined: 6/5/2007
From: swedesboro, NJ, USA
Status: offline 		Hi,
I have a BSE .50 and with a 10x6 apc prob im only getting about 16000 rpms at peak on the ground. The engine was broken in with a 9x6 at 17000 as suggusted. It now has about 10 or 15 flights on it. Im using 15% omega fuel and the mcoy 59 glow plug. I talked to Dubb and he says all engines are tested before being shipped. What could it be? I really dont feel like sending it back unless its really necessary. Also what plug do you use for testing?
Im in NJ which is about the same elevation as Houston TX.

Also once i know the engine is right i wanted to know what the fastest prop would be for this engine in a phonix F20 tigershark and what rpm i should expect to see on the ground with the prop you suggest.

Thanks alot
       Post #: 1

RE: BSE .50 rpm - 10/23/2007 4:00:25 PM   
bob27s



Posts: 4624
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: online 		Hi,

Thanks for writing......

The information on the engines being tested before shipping is correct. Nothing leaves the shop unless it meets baseline performance on Dub's test bench.

Your plug, fuel and such are good. No issues there.

The RPM you noted here is a little low. Were these measurments taken on a test bench? Or in the aircraft ? (bench is much prefered).

After the first break-in bench run, did you tighten the cylinder head bolts?
You noted the MC plug... did you change out the Merlin HD the engine came shipped with because it blew or just because ?
The glow plug itself will not affect the rpm, but a blown plug comes from a lean run, or a fuel system issue (fuel foam).

If you change a glow plug, and the HEAD bolts are loose (from a hot run, or initial bench running) the liner can/may/will rotate when you install the new glow plug. The mis-aligned ports will cause an RPM drop. Easy way to check... remove the muffler, take a flash light... look at the port alignment through the exhaust port. The port should be centered in the crankcase opening.

Break-in for the Jett 50 engines requires about 15-20 minutes on the bench. The 9x6 you noted was good. RPM target was a bit low, for the 9x6 on a .50 you want to try and set it to run 17,500 or maybe just a bit higher - expecially for the last tank or two. It will still be a bit over-rich with the 9x6 at those rpms.

For your first flights on the F-20, use a 9x7 prop. This too is a bit light, but it will allow the engine to unload well in the air and will further the run-in process. Find peak rpm, back off 600-800 rpm for flight. The 9x7 should hit 17,000 easily .... probably closer to 17,500 at ground peak.

Check the sleeve alignment before you do anything else.

Bob




_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to paolino1818)
       Post #: 2

RE: BSE .50 rpm - 10/23/2007 7:04:59 PM   
paolino1818


 

Posts: 48
Joined: 6/5/2007
From: swedesboro, NJ, USA
Status: offline 		hi,
thanks for the fast response. i did change the plug at break in because i blew it. It blew when i pinched the line while at fuel throttle. I dont do this anymore. And i did break it in on a bench. Today I took off the muffler and looked at the alignment and it didnt look right so removed the head bolts and now see how easy the sleeve could move if the head was loose. Could you please tell me a good way to reinstall the head and sleeve and insure it is aligned properly. All the detail you could give me would be greatly appreciated.
Thanks alot

(in reply to bob27s)
       Post #: 3

RE: BSE .50 rpm - 10/23/2007 8:18:45 PM   
paolino1818


 

Posts: 48
Joined: 6/5/2007
From: swedesboro, NJ, USA
Status: offline 		Also how perfect does it have to be aligned.(thousands, mm ect.)
thanks again

(in reply to paolino1818)
       Post #: 4

RE: BSE .50 rpm - 10/25/2007 5:05:15 AM   
rmenke


 

Posts: 1677
Joined: 6/25/2004
From: Merced, Ca., CA, USA
Status: offline 		palino1818:

As usual, Bob is right on. In addition to cylinder allignment, I would like to reinforce the head and other fastner recommendations, only more so. I run and maintain a 35, 50 two 60s and a 90 Jett L or LX series. After 50 plus years of wrenching on these little guys, I finally stripped a head bolt on a TT sport racer after a cleaning job. Ok, I made a mestake many make without a torque wrench. I bit the bullet and started researching where I could find a reasonable cost unit. Sticker shock, My tool dealer son offered a good one for $165.00 his cost. (he claims) After looking around for a while I found a good quality unit for about $100.00 at www.darrolcaddy.com. It comes in a case with a 4/40 driver, and t-values. Buy the other one for typical mm. In addition to the wrench, you get to talk with one of the truly nice guys in the business. I go out of my way to buy from him when I can. Good prices, excellent service. Now, I check the heads of everything after a weekend or racing. Every darned one of them need to be tightened. Guess I should not keep them so nice, clean and shiney? Until Bob or Dub tell me I can use a tad blue lock tight, am not going to do it. Nephews new BSE 60LX was bench run per requiremennts on a Friday evening. Saturday, he shows up with it installed in his go faster for the club race letting everyone know he was gonna kick old unks butt. After two races of trying, it was noticable he was not getting it needled correctly. Gave him some help between races along with some pay back mouth. Kid, let me at that thing with tack in hand, just like you was taught. Ohh, only 16.7, sumptum wrong here. Wooooa, whats that streem of fuel flying out of the right side of the engine almost like the fuel can is running wfo. Kill it, get tool box out and set up torque wrench. Wow, never have seen anything that loose and still run. Gave it as long as possible to cool, and torqued it down a little light. Lit her up, got 19.2, backed it off a full turn rich and waited for the next race. (tretchery) Say what, you want me to fly it for him also? Did not think that sucker could clean up that rich, but-- two out of three aint really bad. But he cut several times I am sure, I think?

Anyway, don't guess, get a torque wrench and keep them correct. Will save heads, plugs, and a lot of races. ENJOY

(in reply to paolino1818)
       Post #: 5

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> BSE .50 rpm
Page: [1]





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