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21-10-2013, 07:15 PM
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#1
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Registered User
Join Date: Apr 2012
Posts: 53
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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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21-10-2013, 08:37 PM
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#2
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Registered User
Join Date: May 2009
Posts: 496
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Quote:
Originally Posted by nugent
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,
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[/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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21-10-2013, 09:20 PM
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#3
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Registered User
Country: Ireland
Location: Dublin
Occupation: Boatbuilder
Boat make: Hydrostream V-king, 650SS OCR ,Ring 21, Ring 18, Phantom 18.
Engines: 300Hp Mercury 2.4, 130 Yamaha, Bridgeport EFI, XR6, Merc 200.
Cruising area: Malahide, Dublin
Join Date: May 2004
Location: Dublin
Posts: 1,803
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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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21-10-2013, 10:44 PM
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#4
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Registered User
Country: uk
Location: salcombe
Occupation: semi retired
Interests: racing(middle east class 3 6l)
Boat name: still no worries
Boat make: phantom18
Engines: 2.5 efi
Cruising area: salcombe
Join Date: Dec 2007
Location: salcombe
Posts: 499
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Try an earth wire on one of the coils, I had a bad one once
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22-10-2013, 11:35 AM
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#5
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Registered User
Country: UK
Location: Gosport
Occupation: Own a small building firm.
Interests: Boats, kids and looking after the Wife HaHa
Boat name: Shamu
Boat make: Banana Shark 770
Engines: Mercury XS300
Cruising area: Solent
Join Date: Aug 2013
Location: Gosport
Posts: 368
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Quote:
Originally Posted by nugent
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,
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[/QUOTE]
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22-10-2013, 11:39 AM
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#6
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Registered User
Country: UK
Location: Gosport
Occupation: Own a small building firm.
Interests: Boats, kids and looking after the Wife HaHa
Boat name: Shamu
Boat make: Banana Shark 770
Engines: Mercury XS300
Cruising area: Solent
Join Date: Aug 2013
Location: Gosport
Posts: 368
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Quote:
Originally Posted by nugent
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,
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[/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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22-10-2013, 06:28 PM
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#7
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Registered User
Join Date: Apr 2012
Posts: 53
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Will give it a go
I think it's fuel related also
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27-10-2013, 10:03 PM
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#8
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Registered User
Country: Uk
Location: Poole Dorset
Occupation: Marine engineer
Interests: Model boats and mercury v6
Engines: Mercury v6
Cruising area: Poole
Join Date: Jul 2011
Location: Poole Dorset
Posts: 1,770
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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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28-10-2013, 08:25 PM
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#9
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Registered User
Join Date: Apr 2012
Posts: 53
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Quote:
Originally Posted by Sam1cats
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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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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28-10-2013, 08:29 PM
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#10
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Registered User
Country: uk
Location: salcombe
Occupation: semi retired
Interests: racing(middle east class 3 6l)
Boat name: still no worries
Boat make: phantom18
Engines: 2.5 efi
Cruising area: salcombe
Join Date: Dec 2007
Location: salcombe
Posts: 499
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Take it down to nic's he will sort it !
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11-11-2013, 10:21 AM
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#11
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Registered User
Join Date: Apr 2012
Posts: 53
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For the record ,,
It was a plug cap,,, All swapped out n running as sweet as
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