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RCV91cd Chirping noise

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Old 06-13-2009, 10:57 PM
  #1
abufletcher
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Default RCV91cd Chirping noise

I just bought a new RCV91cd (serial # 1229) from a dealer in Japan. Today I took it to the field to begin the break in (on a test stand) and it started up right away. So far so good. I followed the instructions and let it warm up at a fast idle with the glow starter attached. This also sounded good and after removing the glow starter it continued to run well. So I after adjusting the needle valve (always keeping if below 6000) I let it run rich for about 10 minutes. Then I started to hear a high chirping noise when I throttled down (it goes away at higher speeds). So I stopped the engine and let it cool down. Then after the engine was completely cool, I started it again and the noise was still there. So I stopped and packed up for the day.

What's going on and does this mean I've got a bum engine?
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Old 06-16-2009, 05:31 AM
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Default RE: RCV91cd Chirping noise

Hi

The engine does have a problem which is easily rectified.

The problem is that the cylinder bearing is loose in its housing when hot. At full throttle the cylinder pressure keeps the cylinder pressed up against the bearing so there is no noise. But at low throttle the vacuum in the cylidner on the inlet stroke sucks the cylinder downwards until the gears over-mesh causing the chirping noise.

The problem will not cause any further damage, but it would be best if you return the engine to your dealer for repair.

Thanks

Keith
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Old 06-27-2009, 08:30 AM
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Default RE: RCV91cd Chirping noise

I'm having the same problem. I took the engine to the UK service people but they ran it and said they couldn't hear anything abnormal. After re-installing it my aircraft, I'm getting the same sound. However, it only shows up when the engine has been running a while. Maybe they didn't run it long enough. I'll have to take it back.

Even though Keith says there won't be any further damage, the sound is really odd at tickover for a Spitfire!
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Old 06-29-2009, 09:28 AM
  #4
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Default RE: RCV91cd Chirping noise

Again, it does sound like you have the same issue.

I must emphasise that this is a very rare problem. We have now produced many thousands of engines in the CD range and looking back at our service records have only seen this issue on 10 engines. The noise is a slight irritation but it wont cause any damage or loss of performance. The rectification is simple and straightforward.
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Old 06-29-2009, 10:26 PM
  #5
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Default RE: RCV91cd Chirping noise

I have two 91 CD and they also make some funny noise at low speed , they are new, I just finish running them in and will be installed in my B25, the only problem I'm having now there is some vibrations at different rpm! now woundering if I should take a chance installing them I'm running 14X6 APC , some members of our club say i'ts normal for 4S and others tell me they would not install them as it will interfear with the electronics and will start taking the plane apart. I just don't know what I should do? No one in our club has these motors, and we don't have a local RCV service center.

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Old 07-07-2009, 06:28 PM
  #6
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Default RE: RCV91cd Chirping noise

Keith, I have to say that the noise was more than a slight irritation: it was very noticeable and totally inappropriate for a 1/6 scale Spitfire (the Kyosho 90). Unfortunately, it also cost me 20 GBP for a new bearing, as although I'd only just started using the engine, I bought it about two years ago. This hasn't totally resolved the problem but reduced it to an acceptable level. (Alan Weston didn't charge me labour, even though I hadn't bought it from him.)

Having said that, the engine gives a very scale performance: this is what I recently posted in rcgroups.com in the Kyosho 90 Spitfire assembly log: "...Power is more than adequate, and should get better with more use. I have to say the sound, especially in the air, is fantastic....".

I'm not experiencing any undue vibration problems. Tickover is very smooth and transition to full power is fine.
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Old 04-06-2012, 01:35 AM
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Default RE: RCV91cd Chirping noise

Hi , the reason i have logged on to this site is i have the same problem after a min or 2 of running i get this loud chirping/screeching noise on low revs ,you say there is an easy remedy pleased tell me what this is,

many thanks Howard
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Old 01-27-2013, 04:12 PM
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Default RE: RCV91cd Chirping noise

I replaced all bearing and still this problem when the motor is warmed up. What is the easy remedy to this screeching problem?
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Old 01-28-2013, 12:46 AM
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Default RE: RCV91cd Chirping noise

Hi Wok, i can now tell you how to solve the problem as i have done ,my engine(RCV91CD) runs great without the nasty screeching all you need to do is remove the cylinder bearing you will need to use heat from a blow torch to warm the out side of the cylinder so it expands then you can carefully knock the bearing out then when its cooled clean the surfaces where the bearing has been with degreaser i used petrol then dry off with a clean cloth and apply bearing lock to the outer surface of the the bearing then reheat the outer case of the cylinder for a few mins the relocate the bearing gently tapping it back in place ,then just rebuild your engine make sure you get the timing right refer to your manual, then start it up and it will run sweet once again..

Hope this helps Howard
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