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08-08-2008, 02:03 PM
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#1
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sit down shut up hold on
Country: wales
Occupation: anything
Interests: boats,cars anything with a motor
Boat make: just sold it
Engines: none
Join Date: Feb 2008
Posts: 239
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carb jets
hi
could anyone advise me on jet size mariner 150 40 thou over size pistons i am running std jets at the moment could i go up a size
any info please
regards
scott
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09-08-2008, 07:47 PM
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#2
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Registered User
Country: England
Location: West Sussex
Occupation: IT Manager
Boat make: Phantom 21, Plancraft Seaflite
Engines: Merc V6, mercruiser V8
Cruising area: Littlehampton, Fowey
Join Date: Aug 2004
Location: West Sussex
Posts: 116
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Scott
What is the reason you want to go bigger with the jets?
karl
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09-08-2008, 08:24 PM
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#3
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sit down shut up hold on
Country: wales
Occupation: anything
Interests: boats,cars anything with a motor
Boat make: just sold it
Engines: none
Join Date: Feb 2008
Posts: 239
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re jets
just wondering whether i could go up a size on the jets that's all just some advice
ie 200 jets or would i over fuel
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09-08-2008, 08:46 PM
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#4
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Registered User
Country: England
Location: West Sussex
Occupation: IT Manager
Boat make: Phantom 21, Plancraft Seaflite
Engines: Merc V6, mercruiser V8
Cruising area: Littlehampton, Fowey
Join Date: Aug 2004
Location: West Sussex
Posts: 116
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2 Strokes produce maximum power when the ratio is at it's weakest and just short of melting the pistons. So if the engine is running fine now an not close to the point of damaging the piston tops, any increase in fuel will reduce power if anything. That's why I asked for the reason.
Also the jets are matched to the venturi size of the carb more than they are to the size of the engine. So you can't relate jet sizes to a bigger engine without knowing the size of the carbs it's running.
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09-08-2008, 09:41 PM
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#5
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sit down shut up hold on
Country: wales
Occupation: anything
Interests: boats,cars anything with a motor
Boat make: just sold it
Engines: none
Join Date: Feb 2008
Posts: 239
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Quote:
Originally Posted by marshan162
2 Strokes produce maximum power when the ratio is at it's weakest and just short of melting the pistons. So if the engine is running fine now an not close to the point of damaging the piston tops, any increase in fuel will reduce power if anything. That's why I asked for the reason.
Also the jets are matched to the venturi size of the carb more than they are to the size of the engine. So you can't relate jet sizes to a bigger engine without knowing the size of the carbs it's running.
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thanks for the info its running std carbs but i have a set of xr2 carbs to go on my motor do you think these carbs will work?
any advice welcome
regards
scott
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09-08-2008, 09:56 PM
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#6
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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they will need re jetting for your motor, this isn't an easy job unless you got an egt gauge and loads of different sized jets
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09-08-2008, 10:03 PM
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#7
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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If you want easy power gains i'd get the heads skimmed to about 27cc which should give you about 150 psi of compression. go up a couple of jet sizes on your present carbs and away you go. Alternatively buy yourself an egt gauge Bad Boy has one for sale, wire it in and keep changing jet sizes till you achieve approx 1150 degrees at full throttle, this will be your optium fueling and safe power without going bang.
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09-08-2008, 10:19 PM
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#8
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sit down shut up hold on
Country: wales
Occupation: anything
Interests: boats,cars anything with a motor
Boat make: just sold it
Engines: none
Join Date: Feb 2008
Posts: 239
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cheers for the info
burty why arnt you in hunstanton then?
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09-08-2008, 10:45 PM
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#9
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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going in the morning, supposed to be taking the kids to the balloon fiesta tonight but it was cancelled cus of the rain
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09-08-2008, 10:56 PM
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#10
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sit down shut up hold on
Country: wales
Occupation: anything
Interests: boats,cars anything with a motor
Boat make: just sold it
Engines: none
Join Date: Feb 2008
Posts: 239
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Quote:
Originally Posted by Burty
going in the morning, supposed to be taking the kids to the balloon fiesta tonight but it was cancelled cus of the rain
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one hell of a drive in the morning then race and drive home sod that
good luck tomorrow
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11-08-2008, 06:13 PM
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#11
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Registered User
Country: England
Location: Crayford, Kent.
Occupation: Electrical gezza!
Interests: Petrolhead
Boat name: Wayne Kerr
Boat make: Phantom xl
Engines: Mercury 2.5, 200(ish)
Cruising area: Essex, Hampshire, Mediterranean
Join Date: Sep 2004
Location: Crayford, Kent.
Posts: 1,199
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Burty;
Wos a "egt" gauge?
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11-08-2008, 06:49 PM
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#12
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Registered User
Country: uk
Location: Bristol area
Occupation: Electrician
Interests: mmm stella
Boat make: 16 reiver
Engines: mercury 125 optimax
Cruising area: Lyme Bay
Join Date: Mar 2006
Location: Bristol area
Posts: 344
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Quote:
Originally Posted by SCOTT671
one hell of a drive in the morning then race and drive home sod that
good luck tomorrow
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one heck of drive up, then NOT race then a long drive back
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11-08-2008, 08:38 PM
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#13
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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Quote:
Originally Posted by Wayne Kerr
Burty;
Wos a "egt" gauge?
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Exhaust Gas Temperature
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11-08-2008, 08:55 PM
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#14
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Registered User
Country: England
Location: Crayford, Kent.
Occupation: Electrical gezza!
Interests: Petrolhead
Boat name: Wayne Kerr
Boat make: Phantom xl
Engines: Mercury 2.5, 200(ish)
Cruising area: Essex, Hampshire, Mediterranean
Join Date: Sep 2004
Location: Crayford, Kent.
Posts: 1,199
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Quote:
Originally Posted by Burty
Exhaust Gas Temperature
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Cheers Burty ,,,,, & the cost?
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11-08-2008, 09:42 PM
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#15
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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dunno dude, have a look at digitron in the US or rex marine
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05-01-2009, 02:02 PM
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#16
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wiggy808
Country: Southampton
Location: Southampton
Occupation: Marine Engineer
Interests: wakeboarding, power boats, 900hp Audi
Boat name: Marshan19
Boat make: Marshan 19, Mirage 22
Engines: Mariner 200, 2.2 5cyl Audi
Cruising area: Solent
Join Date: Nov 2007
Location: Southampton
Posts: 133
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Egt
FW Murphy do a exhaust pyrometer kit. Single or dual read out. You'll need a dual sytem for 'v's. The full dual kit which comprises of the following 1, Gauge. 2, 2xthermocouples. 3, 2xstandard leads (14ft in length) is £196. They have them on the shelf. Also you can buy an alarm switch to work with them, They are set to switch at 1100 but you can have them altered to your spec.
I've just ordered mine, I'll tell you in a few days what I think.
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05-01-2009, 03:15 PM
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#17
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wiggy808
Country: Southampton
Location: Southampton
Occupation: Marine Engineer
Interests: wakeboarding, power boats, 900hp Audi
Boat name: Marshan19
Boat make: Marshan 19, Mirage 22
Engines: Mariner 200, 2.2 5cyl Audi
Cruising area: Solent
Join Date: Nov 2007
Location: Southampton
Posts: 133
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Egt
Just been on ebay and there are quite a few to choose from, starting from £70. Not too sure how hardy they're going to be though. They look a little 'Halfords' like!!
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