Oldman
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neet buggy man.
boat prop
- Thread starter alexanderapearce
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alexanderapearce
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ok i found the plug you was talking about but mine only has the numbers r8199818 on it and i know that the sticker says it's a 150 and when i had it rebuilt i checked the bore size(like a 305 to a 350 chevy)and that's when he said that the pistons in a 150 and 200 was the same
That is a replacement powerhead. I can't tell you jack about it.
The internal are the same just the port timing is different. To put it in relationship to a 4 stroke it is the "CAM" of the engine. When you change port timing you are changine the "CAM" and when the engine makes it's power (powerband) Stock 4 stroke cams make good power from idle to 4500 RPM but fall off sharply. Then go to a 295 Duration with .540 lift and now the engine makes it power from 3500 to 7500. You simply changed it's powerband. Same with the 2 stroke. Porting changes where the engine makes it power. 150/175/200 are same block with the 200 having different port timing and the 150/175 are same blocks. You can see Part #1 in the list.
This GT150 I am building has the same porting as a standard 150. I am changing the port timing to 200 specs thus changine the block into a 200. The block is now a 200 plus the other things will put it to making 200++. The only way to find out if it is in fact a 200 is to measure the ports. 150/175's are arounf 1.700 +/- .020 and the 200 port timing are 1.600 +/- .020, depending on year, from the deck. Intakes are pretty close depending on purpose. 2.120 is what I cut this one to 6300 and below. Cutting to 2.050 would be a better 7000+ rpm engine.
The internal are the same just the port timing is different. To put it in relationship to a 4 stroke it is the "CAM" of the engine. When you change port timing you are changine the "CAM" and when the engine makes it's power (powerband) Stock 4 stroke cams make good power from idle to 4500 RPM but fall off sharply. Then go to a 295 Duration with .540 lift and now the engine makes it power from 3500 to 7500. You simply changed it's powerband. Same with the 2 stroke. Porting changes where the engine makes it power. 150/175/200 are same block with the 200 having different port timing and the 150/175 are same blocks. You can see Part #1 in the list.
This GT150 I am building has the same porting as a standard 150. I am changing the port timing to 200 specs thus changine the block into a 200. The block is now a 200 plus the other things will put it to making 200++. The only way to find out if it is in fact a 200 is to measure the ports. 150/175's are arounf 1.700 +/- .020 and the 200 port timing are 1.600 +/- .020, depending on year, from the deck. Intakes are pretty close depending on purpose. 2.120 is what I cut this one to 6300 and below. Cutting to 2.050 would be a better 7000+ rpm engine.
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alexanderapearce
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ok what rpm should i be looking for with this stock 150 or 200 what ever it is(lol) and what would i need to do to port this xp out to make it run faster and do you have to change the reed valves or will the factory ones still work
alexanderapearce
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do the heads have to changed or can they be used
Some heads are the same for all 150/175/200 blocks. Some suffixs will use a different head. The GT/XP heads are a little looser than stock 150 Heads and that is why it runs 30* timing. Raising the compression and retarding the timing will do better. ALL the parts you have are pretty good parts. Should be a 1 3/8 throat carb which is bigger than the 1 5/16 that the 200's came with. You will need a set of intake stuffer to make the engine have a little bit of bottom end by increasing the crankcase pressure. This will help mask the bottom end loss of higher port timing. There are alot of good "TIGHT" heads for the X-flow. The thing that is different about the X-flow heads is the "flow" of the head and not just the CC's of the head. THe combustion design of the chamber channels it into the combustion chamber. Some do a better job. Hope this helps.
When I do the thread on the X-flow you will see alot more and understand what it takes to make one of these thing run. They are big Cubic Inch engines. They are 2.5L. Mercury didn't have anything this big until 91 (Except the cosworth junk). They have thier faults but a plus is the parts are relatively cheap compared to mercs and are EVERYWHERE. The V-4 X-flows use the same piston, rods, bearings, reeds, ect. Alot of parts to interchange.
When I do the thread on the X-flow you will see alot more and understand what it takes to make one of these thing run. They are big Cubic Inch engines. They are 2.5L. Mercury didn't have anything this big until 91 (Except the cosworth junk). They have thier faults but a plus is the parts are relatively cheap compared to mercs and are EVERYWHERE. The V-4 X-flows use the same piston, rods, bearings, reeds, ect. Alot of parts to interchange.
alexanderapearce
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ok how does the timing work as in advanceing or retarding it not sure on how the timing works on a boat i think it works thru the fly wheel or i think(that might be the problem)i really enjoy working on this boat it has become a passion you could say,the thing that has me puzzled right now is the water pressure it only runs around 10 to 15 pounds when i am running wide open and the mechanic at boats and motors said it was cause the way it reads the water pressure(as it exits the motor)you seem to have alot of know how on these things and i hope i don't bother you to much cause i really want to learn how these things work
alexanderapearce
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cool going in the morning to see how she is going to do i will let you know tomorrow evening
alexanderapearce
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no i have not got it yet
alexanderapearce
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ok i found it now is this going to be the same as mine cause the manual says 92 thru 01 and mine is a 89 model
alexanderapearce
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ok that will work,i just got home and it still did'nt run like it should 52 to 55 mph is still all i can get out of it,i am about ready to trade up to a mercury(lol)
Oldman
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that would be tradeing down.lol
alexanderapearce
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lol i don't care what name is on the back as long as it runs like it's supposed to lol
Oldman
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black is not beautiful(white is where it is at) lol (omc)
Sent the info. When I get a chance I will send that to you. Notice the first line tells you to use the 60,65,70,and 75HP pointer alignment precedure. That is what the 2nd attachment is.</p>
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How much did you raise the engine. What was the rpm and speed? Was the rpms different??</p>
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How much did you raise the engine. What was the rpm and speed? Was the rpms different??</p>
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