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Your running right about where im at. I believe its the carb in my situation. Lack of fuel and possibly a restrictive spark arrestor.
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Originally Posted by surmirage
(Post 3188827)
Baja h2x 24.5ft. Best top I got was 70 mph @ 4500rpm, 2 people with 40gal(1/2 tank). I have 850 carb dual plane intake. Stock 7.4mpi exhaust. When my carb wasn't jetted right it was pinging and I was turning 4500rpm also but only 65mph. With the right jets it picked up 5mph. Everyone thinks the stock exhaust is holding back at least 400rpm or more...now its waiting game for new gen3 stainless marine exhaust. Make some hard pulls and stop to check color of plugs. See if your fuel is correct. Clean the carb.
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sicksation, I had a 7.4mpi 310hp in my boat and best speed was 53mph with 23p. Looking at your numbers with 66mph, I know now that my 7.4 wasn't pulling the 310hp it suppose to.
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Originally Posted by SickSation
(Post 3188833)
750 double pumper is brand new out of the box so i know its clean. Im pretty sure i just need more fuel. Ill make some pulls and yank a plug. thanks man
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Originally Posted by surmirage
(Post 3188847)
Just to give you an idea on my rejet, we had to go 7 sizes up on the low and 5 sizes on the high. This a proform 850 race carb. We also turn back the ign timing abit. I've also done research on OSO and people picked up more hp and rpm with 1050 dominator single plane on 540ci NA.
hmm... the same guy that has the 1050 also has a performer single plane for 100.00.. Wonder if i should try it... |
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Originally Posted by surmirage
(Post 3188837)
sicksation, I had a 7.4mpi 310hp in my boat and best speed was 53mph with 23p. Looking at your numbers with 66mph, I know now that my 7.4 wasn't pulling the 310hp it suppose to.
It averaged about 64 mph, but it would do that all day. Sunsation hulls are pretty fast hulls. |
750 is not going to cut it..even the stock HP500 came with a 800 and 850 going to be a min and dominator not going to be a bad idea with a 540..will add h/p, exhaust can be a killer
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Originally Posted by ezstriper
(Post 3189436)
750 is not going to cut it..even the stock HP500 came with a 800 and 850 going to be a min and dominator not going to be a bad idea with a 540..will add h/p, exhaust can be a killer
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Any opinions on single plane or dual plane intake on this motor?
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Sicksation, your exhaust in pics looks to be sufficient for now but please check the gaskets or replace it just in case. Try the dominator first . I ordered stainless marine gen3 5" tailpipe and will let you know how it performs. I haven't tried dominator with single plane yet, thats my next step when new exhaust is calling for more fuel. good luck I think your going right direction.
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