i would have to say it depends on the cyl head, wether its free flowing out of the box or not.
i ported an 07 400 cyl head i did both intake and exh ports, i also did the bowles(under the valves
the exhaust port is what is most restrictive, thats what needs some opening up and blending
i also did some work around the intake and exh valves in the combustion chamber of the head.
after all said in done it took me roughly 4hrs and was a 10% gain on the flowbench.
after all said and done it will spin the crap out of 28in mst's and wheelie in high with no body english.
the problem today with some companys is they dont give you a before and after flow chart
myself personally want to see flow numbers.
stage 1,2,3 doesnt cut it in my book, if they cant provide flow numbers of before and after the head was ported than pass on it and find a company that does.
i would have to say it depends on the cyl head, wether its free flowing out of the box or not.
i ported an 07 400 cyl head i did both intake and exh ports, i also did the bowles(under the valves
the exhaust port is what is most restrictive, thats what needs some opening up and blending
i also did some work around the intake and exh valves in the combustion chamber of the head.
after all said in done it took me roughly 4hrs and was a 10% gain on the flowbench.
after all said and done it will spin the crap out of 28in mst's and wheelie in high with no body english.
the problem today with some companys is they dont give you a before and after flow chart
myself personally want to see flow numbers.
stage 1,2,3 doesnt cut it in my book, if they cant provide flow numbers of before and after the head was ported than pass on it and find a company that does.[/b]
well im going to have the head milled. not sure how much yet something like 10 to 15 thousandths but I gotta do a bit more investigating on that cause I wanna still run pump gas but i also wanna gain as much as possible so im still checking into that!!
Well im not expecting huge gains I just wanna give it all it has for a stock machine I dont need a penis extention just wanna have everthing at my disposal!!
i would have to say it depends on the cyl head, wether its free flowing out of the box or not.
i ported an 07 400 cyl head i did both intake and exh ports, i also did the bowles(under the valves
the exhaust port is what is most restrictive, thats what needs some opening up and blending
i also did some work around the intake and exh valves in the combustion chamber of the head.
after all said in done it took me roughly 4hrs and was a 10% gain on the flowbench.
after all said and done it will spin the crap out of 28in mst's and wheelie in high with no body english.
the problem today with some companys is they dont give you a before and after flow chart
myself personally want to see flow numbers.
stage 1,2,3 doesnt cut it in my book, if they cant provide flow numbers of before and after the head was ported than pass on it and find a company that does.[/b]
Are you going to port & polish your mudpro? Think it's worth it and would you suggest it with the stock muffler?
[/b][/quote]
i plan on doing my pro as soon as one of these companys fess up and make a fuel controller
without having that on board im thinking the stock mapping wont support porting the head
i also have a high comp piston that i had custom made due to the fact i wanted a true 12 1/2-1 compression.
now as far as the stock muffler goes, i would say that a ported head with a high comp piston will end up bottling up after 4000 rpm, but i cut my muffler open and replaced the pipes inside to 1-1/2 in tubing so no worries about flow there anymore, although it is a little louder more deep toned than raspy, if it had gotten raspy i would have thrown it away.
you can use the stock muffler with a ported head but you at least need to do the muffler mod because 1 small tailpipe will end up backing up at higher rpm
i wouldnt say that unless the cyl head flows well right out of the box.
ive had quite a few cyl heads on the flow bench and you would be suprised on some machines how restrictive they can be at certain valve lift.
as a matter of fact the 400 eng exh port shuts down at a certain valve lift, you can take the valve right out the head and it wont flow anymore.
pretty bad when the stock cam isnt getting its full potential they should have dropped the lift 0.20 they would build more cyl pressure rather than lose it.
well im going to have the head milled. not sure how much yet something like 10 to 15 thousandths but I gotta do a bit more investigating on that cause I wanna still run pump gas but i also wanna gain as much as possible so im still checking into that!![/b]
before you have it milled you might want to think about checking piston to valve clearence and also
just remember that will drop the cam sproket deeper into the head, doesnt sound like much 0.15 but it can be when it comes to clearence.
best thing is to have the combustion chamber ccd, then you can see how much compresssion will be gained by milling it, im thinking you may gain a 1/2 a point at best, imo there are better ways to get power
well im going to have the head milled. not sure how much yet something like 10 to 15 thousandths but I gotta do a bit more investigating on that cause I wanna still run pump gas but i also wanna gain as much as possible so im still checking into that!![/b]
mine is at 11.5/1 and I run 92 octaine fuel in it. with engine mods every little bit helps and will add up in the end. you may not see a large gain from porting alone but add an exhaust mod and a larger snorkel with it and then it should start to see some nice gains after rejetting.
he does have the mufler modded and a 2" snorkel and rejetted, that little 400 is pretty strong really surprised me how well it spins the 30s he has.
I would think some head work could help but i woud not go crazy on it my self, and milling the head down can help as well but its not going to be a huge gain atleast i dont think, But sense its apart i would do it to might as well get the valves redone, milled, ported and new valve guides.
Its a shame nobody makes a HC piston in somthing close to a standard bore for it as jumping up to a BBK cost alot of money and is alot of money to put into a mud /water bike thats going to be dunked again at some point..lol
Yeah thats my thoughts exactly I dont wanna dump a ton of cash into a bbk that will take a drink someday lol. At this point im gonna take the head and jug to a reliable race shop I know and see what those guys think or recommend and go from there with what everyone on here thinks and hopefully Ill walk away with some reasonably price power gains!! Only time will tell!!
well the rings went that fast because im still fighting off various little leaks but yes your right valve seals for sure and wont know about overbore till the jug comes off im not gonna do that unless its neccessary.
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