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Old 26 August 2014, 15:27   #21
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From experience from cleaning motorbike carbs best thing to do is strip them off and take to a carb cleaner who will do a hypersonic clean on them as this gets every last bit of crap out and has the carbs looking like new.

Depending on the jets size a air line will only block them further
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Old 27 August 2014, 08:16   #22
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That does 'seem' a bit high. I'd be interested to know what you thought the consumption might be?

By way of a comparison, using the tried and tested 'man math' methodology:

The 6.5m Scorpion, with a Mariner 150hp Optimax burns around 11-13 litres on a round trip from Hamble to Cowes, cruising at about 28-30 knots. I reckon (using man math) that Yarmouth is about twice as far.

So, that would consume around 22-26 litres. Now, the Optimax burns about the same amount of fuel as a 90hp Mariner on carbs did on our previous Avon 5.4m searider.

Some say that a carbed two-stroke will burn around twice as much a Optimax / Etec / 4 stroke. I'm not sure that the difference is that great but it's probably not far off.

So, using all the above info, I reckon that when you're sure your engine is running as fine as it should, the expected fuel burn would be around 35 litres.
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Old 27 August 2014, 12:26   #23
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In the old days, (someone swing the light) before the four strokes OBMs came on the market, we used as a rule of thumb, for any OBM over 50hp the fuel consumption was about one third of the hp in litres per hour.
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Old 27 August 2014, 12:31   #24
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Lol ime lucky to get 2 ltrs per mile on my latest rig

But run many 150 carb mercury motors getting 70 mile on a 90 ltr tank
So most defo some thing a miss
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Old 27 August 2014, 14:02   #25
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What speed are you getting Nugent with the PAC....our A22 with twin ETEC 150s does about 45kts but is a bit chiney above that. Re fuel we get about 1.7l per nm at 32kts
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Old 27 August 2014, 14:08   #26
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What speed are you getting Nugent with the PAC....our A22 with twin ETEC 150s does about 45kts but is a bit chiney above that. Re fuel we get about 1.7l per nm at 32kts

Witnessed on gps at 63 mph few weeks back Rocknrolla

But on return journey around Anglesey one up very low on fuel hit the magic 58 knots and sat stable as any thing


Not meaning to hijack the thread but Vidio attached
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Old 27 August 2014, 14:19   #27
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Originally Posted by Will75 View Post
What speed are you getting Nugent with the PAC....our A22 with twin ETEC 150s does about 45kts but is a bit chiney above that. Re fuel we get about 1.7l per nm at 32kts

Witnessed on gps at 63 mph few weeks back Rocknrolla

But on return journey around Anglesey one up very low on fuel hit the magic 58 knots and sat stable as any thing


Not meaning to hijack the thread but Vidio attached


My Atlantic 21 chine walked also at first lifted engine up another inch and a half cured it. There really twitchy if weights not right
Attached Files
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Old 30 August 2014, 08:24   #28
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fuel

hi have you thought about the prop that can make it drink fuel if its set up for ski I changed mine once from a 21 prop to a 19 and when I whent on cruis it drank twice as much fuel just thought I would say hope this helps
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Old 30 August 2014, 08:53   #29
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hi have you thought about the prop that can make it drink fuel if its set up for ski I changed mine once from a 21 prop to a 19 and when I whent on cruis it drank twice as much fuel just thought I would say hope this helps
Hi spittle im still waiting for very calm weather so I can get the boat at WOT so I can see the revs and try and work out if my prop is efficient or not.

Also I thinking about getting a 4 bladed prop as well as I have a lot of traits with the engine in that it ventilates a lot on turns and harbour/river speeds of 6 knots we are sat on the plane bubble so pushing a lot of water and drinking the fuel
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Old 30 August 2014, 14:20   #30
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Engine looks too low on the transom to me. Anti vent plate is buried...
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