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Old 04-05-2004, 11:06 PM
  #7816  
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Originally posted by markp27
On the subject of engine tuning.....I can get my engine tuned pretty ok these days, but one problem I often have is re-starting the engine when it is hot.
Does this indicate that the lower needle setting is too lean or too rich?

Cheers, Mark.
Problem is cause by two possible factors:

1. Crank overheat. This can come from improper clutch settings or too lean engine.
2. Carb overheat. Basically it heat soaks from a too hot engine.

Both "boil" the fuel as it enters the motor and makes it impossible to start. You actually sometimes see the fuel retreat up the fuel line just after you prime the motor when very hot.

The condition means you are running too hot generally. You need to cut more body holes or richen your motor.
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Old 04-05-2004, 11:11 PM
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Default Re: Re: Re: Re: Re: Re: engine

Originally posted by AMGRacer
Yes. I say 1/4 of a turn to be totally safe but mayby 1/8th would be sufficient you need to get a feel for your specific engine. I usually do the middle needle when I am in a rush since you can access it easily through the rear window.

If your motor still has pinch at the top when hot without the plug it actually is not even run in fully yet.

To do a proper compression test you can do this:

1. Remove the motor from the chassis and remove pipe.
2. Spray a little fuel into the exhaust port and turn the motor over once or twice.
3. Roll the flywheel over while holding the exhaust port up to your ear. You should hear hissing which then stops as the piston nears the top of its stroke.
4. Hold it still before it fully turns over. You should not hear any hissing for at least 10 seconds. Less than 10 seconds is still OK but the motor is no longer in its prime.
Thanks AMG and everbody else for your help
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Old 04-05-2004, 11:14 PM
  #7818  
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Originally posted by AMGRacer
Problem is cause by two possible factors:

1. Crank overheat. This can come from improper clutch settings or too lean engine.
2. Carb overheat. Basically it heat soaks from a too hot engine.

Both "boil" the fuel as it enters the motor and makes it impossible to start. You actually sometimes see the fuel retreat up the fuel line just after you prime the motor when very hot.

The condition means you are running too hot generally. You need to cut more body holes or richen your motor.
Thanks for the info. Pretty logical when I think about it now - if the engine allows itself to restart when it cools down, then it can only be that the engine was running too hot

I'll try and collate the information here for the FAQ - it is sadly lacking an engine section at the moment.
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Old 04-05-2004, 11:14 PM
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Originally posted by Profoxcg
how do you open an engine. Do I just inscrew the 4 screws on the back and close it when i am done? or do i need to take any special precations? or use any sealants?
There were some good instructions on the RB website with pictures. But now I cannot find them anymore...

Anyway, to access completely the internals of the engine, you need to take out the 4 screws bolting the heatsink. You need special tools (Hudy makes them) or find a slotted screw that fits very nicely the head of the screw. I don't know about Sirio engines but with all Nova engines, it comes with slotted head screw for the engine heatsink. Once that's off, you can access the button head where the plug is threaded. Be careful of the shims that come with it. Don't loose it !

Then unscrew the screws at the backplate. Before taking out the rear backplate, make sure your piston is at TDC (Top Dead Center).

If you're not sure, let your LHS guy take it out for you and watch him do it.
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Old 04-05-2004, 11:23 PM
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Default ehgine shims

My engine didnt have any shims in the head does that matter?
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Old 04-05-2004, 11:26 PM
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Default Re: ehgine shims

Originally posted by Voodo_Magic
My engine didnt have any shims in the head does that matter?
Erm. Are you sure? They sometimes are very hard to see. Check around the head near the chamber.
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Old 04-05-2004, 11:27 PM
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Originally posted by InitialD
There were some good instructions on the RB website with pictures. But now I cannot find them anymore...

Anyway, to access completely the internals of the engine, you need to take out the 4 screws bolting the heatsink. You need special tools (Hudy makes them) or find a slotted screw that fits very nicely the head of the screw. I don't know about Sirio engines but with all Nova engines, it comes with slotted head screw for the engine heatsink. Once that's off, you can access the button head where the plug is threaded. Be careful of the shims that come with it. Don't loose it !

Then unscrew the screws at the backplate. Before taking out the rear backplate, make sure your piston is at TDC (Top Dead Center).

If you're not sure, let your LHS guy take it out for you and watch him do it.
Here are some OK instructions for this:

http://www.hpiracing.com/walkthroughs/engrebuild.htm
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Old 04-05-2004, 11:34 PM
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Default engine shims

I cannot see any and i have never had the head off before!
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Old 04-05-2004, 11:36 PM
  #7824  
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Default Re: engine shims

Originally posted by Voodo_Magic
I cannot see any and i have never had the head off before!
Usually there's one shim stuck to the head.
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Old 04-05-2004, 11:38 PM
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Default Re: Re: engine shims

Originally posted by PSI Racing
Usually there's one shim stuck to the head.
yea i thought so too but i run my finger over it to check and nothing moved! But now i think about it are they copper looking?
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Old 04-05-2004, 11:39 PM
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Default Re: Re: Re: engine shims

Originally posted by Voodo_Magic
yea i thought so too but i run my finger over it to check and nothing moved! But now i think about it are they copper looking?
Some are copper and some are silver.
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Old 04-05-2004, 11:41 PM
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Default Re: Re: Re: Re: engine shims

Originally posted by PSI Racing
Some are copper and some are silver.
well there was a copper looking one but it didnt move so i just left it as is
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Old 04-05-2004, 11:42 PM
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They are like this:

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Old 04-05-2004, 11:43 PM
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Default Re: Re: Re: Re: Re: engine shims

Originally posted by Voodo_Magic
well there was a copper looking one but it didnt move so i just left it as is
That's probably it.
I had a couple of shims that were stuck to the head.
At first look, it seemed like it was part of the head.
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Old 04-05-2004, 11:45 PM
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thanks for the links..

ill just leave my engine alone for now though since its is pretty new. i will just try to tune it as Inital described.
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