Successfully solved the operation of Rovan 45cc motor.

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Bignscale

Bignscale

Active Member
Messages
37
Hello. I would like to thank everyone for their thoughts and advice on the Rovan 45cc motor operation problem, and let me know that the engine problem that plagued me has been resolved. I replaced the standard plug from NGK CMR7H with the stock CMR6A. As a result, the condition of the engine improved significantly, starting was improved, vibrations were reduced, and the engine started to run very well up to high revolutions. I ran about 0.4 gallons of gas continuously, but there was no particular effect. Thank you so much to everyone who helped me.image.jpg
 
spents said:
question though fella,
why have you gone to a cmr6a with a shorter thread reach/length thread rather than a cmr6h?
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In my case, the knocking problem was so bad that it would seize up many times. Zenoah's G450PU for airplanes had a short reach plug, so I tried changing it.
 
TODD said:
Watch for detonation. You just went one step hotter on the heat range going to a 6. NGK numbers go higher plug gets colder. Others like Champion go higher number they get hotter.
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I tried this method and the condition of this motor improved a lot. I continued to drive at full throttle for about an hour or two in this condition, but no problems arose. This was very good. However, another problem was that the exhaust pipe was frequently damaged, so we had to stop using it again and replace it with a slightly smaller engine. It's a shame.
 
Seandonato73 said:
The zen engine uses a different head deign with less threads in the plug area. Hence the shorter plug. It makes no sense why you wouldn't have just jumped up a heat range with a cmr6h.
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I think this Rovan 45cc motor probably has the wrong standard specification for the plug. I feel better with the CMR＊A plug. I live in Japan, so I think it's probably because the ingredients are different from the gasoline made in your country.
 
The primary reason for a plug to be a certain length is to place it in the prime place in the combustion chamber for optimal ignition. Most of this is because of the head thickness, all you did was pull it back. Plug gap, and heat range play much more of a role then changing out to a shorter plug for no other reason.
 
Are you guys talking about plug length as far as thread length or electrode and ground strap length.
I am not really a 2 stroke guy but I am an engine guy. Well maybe a little 2 stroke here and there?
Plug threads end at combustion chamber. Not extending past and not recessed in the plug hole.
 
Seandonato73 said:
He put a plug in with physically shorter threads
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Doest seem to me like a thing you want to do. Recessed in the hole slows the burn in the combustion chamber.
This is done in the world of Nitrous in a drag application , they actually sell washers for doing this.
I would be willing to bet 2 stroke RC application this is probably the best choice.
 
Thank you to everyone who provided answers and opinions. I want to restore the settings, but I don't have the exhaust pipe yet. Also, my 45cc motor is equipped with a lightweight flywheel that I made myself, is this a problem?
 
Now I don't know so I will ask.

What about balance? Do you think it will have an effect on that? I see material removed from lets say the 12 o'clock and 6 o'clock side but 9 oclock side is untouched , I'm guessing this is because of the ignition coil/magnet location. I wouldn't think heavier on one side helps. Maybe I am way off thinking this , don't know.

I would also be concerned that it is only a cast piece.
 
smokinwheel said:
Now I don't know so I will ask.

What about balance? Do you think it will have an effect on that? I see material removed from lets say the 12 o'clock and 6 o'clock side but 9 oclock side is untouched , I'm guessing this is because of the ignition coil/magnet location. I wouldn't think heavier on one side helps. Maybe I am way off thinking this , don't know.

I would also be concerned that it is only a cast piece.
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https://www.amazon.ae/ATOPRC-Lightened-Flywheel-Magneto-23-32cc/dp/B09XL3L9NX

See this link. It's customized like the flywheel you see there. If this is also a problem, consider putting it back together with the plug.
 
Bignscale said:
I see, it looks very interesting, but I'm not into racing or anything, so I'm not thinking about changing the shape this much.
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Again I am far from an expert on this, but this is kind of my take on this.

If I was not racing, I would probably not mess with it, the performance gain you might gain is probably not worth it and chances are if you do notice a difference, it is most likely minimal.
A race application is a whole different story. When racing things are often run on the ragged edge and sometimes we even try to push the envelope beyond and this is the end result. That is part of racing. You want to squeeze any last bit of power out of it, sometimes at a cost.
 
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