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Old 21-10-2013, 07:15 PM   #1
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200hp not performing

Aving some Eire greif

My mildly tuned 200 hp motor is slow

Run it yesterday not right,,, check comp readings 115 to 120. So all is well running prop as always run, but stuck out at 6100 rpm. It used to hit 7k n be safe

Can not see what is a do , any ideas what may be a miss,,,,

Running modified stator and lightened fly wheel carbs where set proffesionaly last year , only thing I have not tried is swapping out the fuel,,,,can the octane rating make this difference,[/QUOTE]
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Old 21-10-2013, 08:37 PM   #2
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Quote:
Originally Posted by nugent View Post
Aving some Eire greif

My mildly tuned 200 hp motor is slow

Run it yesterday not right,,, check comp readings 115 to 120. So all is well running prop as always run, but stuck out at 6100 rpm. It used to hit 7k n be safe

Can not see what is a do , any ideas what may be a miss,,,,

Running modified stator and lightened fly wheel carbs where set proffesionaly last year , only thing I have not tried is swapping out the fuel,,,,can the octane rating make this difference,
[/QUOTE]

Not sure about engines, but one thing I do know and that is modern petrol is s**t and goes off very quickly depending on how it it stored. Did you have a mix with old/stale fuel? It can make big difference on power.
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Old 21-10-2013, 09:20 PM   #3
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Would think 115psi is a little low for a tuned motor. What engine is it?
And yeah if the petrol is old it can run pretty poorly!
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Old 21-10-2013, 10:44 PM   #4
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Try an earth wire on one of the coils, I had a bad one once
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Old 22-10-2013, 11:35 AM   #5
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Quote:
Originally Posted by nugent View Post
Aving some Eire greif

My mildly tuned 200 hp motor is slow

Run it yesterday not right,,, check comp readings 115 to 120. So all is well running prop as always run, but stuck out at 6100 rpm. It used to hit 7k n be safe

Can not see what is a do , any ideas what may be a miss,,,,

Running modified stator and lightened fly wheel carbs where set proffesionaly last year , only thing I have not tried is swapping out the fuel,,,,can the octane rating make this difference,
[/QUOTE]
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Old 22-10-2013, 11:39 AM   #6
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Quote:
Originally Posted by nugent View Post
Aving some Eire greif

My mildly tuned 200 hp motor is slow

Run it yesterday not right,,, check comp readings 115 to 120. So all is well running prop as always run, but stuck out at 6100 rpm. It used to hit 7k n be safe

Can not see what is a do , any ideas what may be a miss,,,,

Running modified stator and lightened fly wheel carbs where set proffesionaly last year , only thing I have not tried is swapping out the fuel,,,,can the octane rating make this difference,
[/QUOTE]

Go buy some shell 99 octane, the BP premium fuel is only 97 and your problems stand a high chance of being solved. When I was racing we bought our fuel on the day and what was left over was used for practice. Any fuel older than a couple of months was poured in my mates car (two stroke oil and all).
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Old 22-10-2013, 06:28 PM   #7
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Will give it a go

I think it's fuel related also
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Old 27-10-2013, 10:03 PM   #8
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Poor running

Sounds to me like you don't want your engine to last As you say it is mildly tuned a standard 200 Should only Rev to 5600 If you are running a standard fuel pump Ie the little square Diaphragm pump You are lucky to get 6100 rev As it We'll Run very lean To run over 6000 You need to run Electric fuel pumps And Bigger Jets In the carbs and more oil To be safe And your compressions are a little Low Should be a minimum of 125psi Hope this information helps as no one else has mentioned fuel pump And I ran some to 240hp mercury And they would not run with small pumps I Put electric pumps on and they ran great But I had heavy duty Conrods and standard 200 conrod Will not want to run for long At over 6000 So think you should keep this Things in mind if thay hav not been done
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Old 28-10-2013, 08:25 PM   #9
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Originally Posted by Sam1cats View Post
Sounds to me like you don't want your engine to last As you say it is mildly tuned a standard 200 Should only Rev to 5600 If you are running a standard fuel pump Ie the little square Diaphragm pump You are lucky to get 6100 rev As it We'll Run very lean To run over 6000 You need to run Electric fuel pumps And Bigger Jets In the carbs and more oil To be safe And your compressions are a little Low Should be a minimum of 125psi Hope this information helps as no one else has mentioned fuel pump And I ran some to 240hp mercury And they would not run with small pumps I Put electric pumps on and they ran great But I had heavy duty Conrods and standard 200 conrod Will not want to run for long At over 6000 So think you should keep this Things in mind if thay hav not been done
Many thanks for this, not sure of all mods done to it , it was done my nick marsh down Cornwall two years ago and has allways run as stated until now for no reason, not been back at it yet,, it's fuel or ht side I think, fuel pump does not look std merc unit but still not electric, oil block of fitted and on pre mix,
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Old 28-10-2013, 08:29 PM   #10
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Take it down to nic's he will sort it !
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Old 11-11-2013, 10:21 AM   #11
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For the record ,,
It was a plug cap,,, All swapped out n running as sweet as
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