ASP 61AR 4stroke loss of power and throttle range

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ASP 61AR 4stroke loss of power and throttle range

Postby spitfire2010 » Sat Jan 22, 2011 12:15 pm

Looking at reasons why an ASP 61 Stroke has lost somepower. Also seems to have lost its throttle range and i am not sure where to start.This evening i found some bubbles appearing in the fuel line and i have now stopped it buy crimping the lines etc. I am yet to test the engine after the fuel line was crimped but the engine is not way near as powerful as it was. I will also grab the RPM readings tomorrow and report back.

Ian
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Re: ASP 61AR 4stroke loss of power and throttle range

Postby RCModelReviews » Sat Jan 22, 2011 8:58 pm

Check your valve clearances -- they tend to get a bit loose during the first few hours of running but will probably settle down after that. You want them at the tighter end of the manufacturer's suggested range of clearances. In fact, because we're running steel valves in aluminium/aluminum heads, you want only the smallest possible gap because that gap will actually *increase* when the engine is warm.

Check to see that you've still got plenty of compression when you turn the engine by hand (with the throttle open). If not, then it's possible that you've got a small bit of dirt under one of the valves which is causing it not to close properly -- this happens sometimes.
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Re: ASP 61AR 4stroke loss of power and throttle range

Postby spitfire2010 » Sun Jan 23, 2011 12:45 am

alright i'll check it out. should i oil the valves and if soi what oil?
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Re: ASP 61AR 4stroke loss of power and throttle range

Postby spitfire2010 » Sun Jan 23, 2011 5:31 am

valves felt and lookedok, well oiled and free of grit.

the valves felt fine although the rockers were out big time. one was about .8mm! the other was not good but not that bad.

I don't have a feeler gauge but i do have a good digital vernier caliper. i measured a pice of paper at .05 and i used that as the feeler gauge.

Engine started quite easily and feels much more powerful with better throttle range. My turnigy rpm tachometer wouldn't work properly. Think the batteries are gone.

thanks Bruce!
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Re: ASP 61AR 4stroke loss of power and throttle range

Postby RCModelReviews » Sun Jan 23, 2011 5:53 am

No problems... it's pretty normal for those clearances to get quite wide during the running-in process.

I think on my Saitos I run about 0.1mm of clearance -- just enough to measure reliably.
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Re: ASP 61AR 4stroke loss of power and throttle range

Postby spitfire2010 » Mon Jan 24, 2011 12:37 pm

Also the idle range is WAY better. The plane sits still rather than wandering :)

I really hated running like turtle down the strip much to the amusement of others no doubt.
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