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OS 91 FS Surpass

Old 09-17-2006, 09:19 PM
  #1  
bbbair
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Default OS 91 FS Surpass

I Have this 91 FS mounted in a Super Chipmunk (nice plane), and it moves along well, but not a 'Real Performer', I attributed this to the break in period. To date, I have run some 2 gallons of fuel through it, with lots of top to bottom speeds, and I only installed the cowl after the first gallon of fuel.

So, this engine was new in 1999 but is was still in the original box when I bought it in 2005, it was brought to life this past spring and I have had on going problems with it as well as some lack lustre performance all year... []

Specifically;
I have had to reset the valve gaps 3 times,
The Exhaust Valve spring broke, (I replaced it)
Low end idle is unreliable - (I thought that this was due to the inverted mounting... )[]
The Intake Valve spring seems weak (compared to the new Exhaust Spring)

So; I realize that there is no warranty left but it does seem like have a problem child here...

It has been suggested that I send it to the shop in Champaign, Ill., for an inspection - Is this wise? []
Do I have any other options?
How much will this inspection cost?
How long will it take?

Advise.
Old 09-18-2006, 10:33 AM
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Bax
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Default RE: OS 91 FS Surpass

It would be difficult to say what might be wrong. Just an inspection, with a test run, would cost you arount $20.00 or so, plus return shipping. If any repairs are needed, you'd be charged parts and labor for the repair work. An estimate would be sent prior to actual repairs.
Old 10-08-2006, 02:50 PM
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bbbair
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Default RE: OS 91 FS Surpass

As a follow up to this situation - it would seem that I have finally corrected the problem The last valve adjustment has corrected both the poor high end and bottom end performance!

I would speculate that this was all caused by the original exhaust spring problem... It was a weak spring from the factory and then it finally broke.

The replacement spring was much stronger and worked well BUT it was out of balance with the intake spring that had the wear / excercise of the first 2 gallons of use.

The last gap adjustment was after the new spring had a chance to 'break in' and now I have one VERY Powerful and reliable engine that makes my Super Chip move along very nicely!

... Mechanical things do require some understanding!

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