300/440/550 porting 101 Re good idea?

[screaming440]

here are the basics

put a hard card in the cylinder and make a good tracing of the ports for a visual guide. besure to mark the top and bottom of the cylinder.

 

[screaming440]

smothout and shape the pockets. use the guide to be sure you are not opening up the port at the cylinder wall yet.

these are pics with the pockets done before the ports are opened up.

 

[screaming440]

then widen the ports, lower the floor of the intake and raise the roof of the intake

these are pics of a mild port the ports are widened about 2 mm the intake is down about 1.5 mm and the exhaust is up about 2

 

[screaming440]

here are some pics of a ported 440 the are about 2mm wider the intake is down about 4mm and the exhaust is up about 4mm.

 

[screaming440]

NOTE: the patterns in the above pics are a little rough cuz they were done just as an example.

here are a few more tips:

you can use spray paint to make your patterns too they will be a little clearer but you got to clean the paint out of the pockets when you are done.

use an old piston to hold the paper in tight in the cylinder when your making the patteren

if you make measuurments off the pattern it needs to be in the shape of the cylinder

 

[yamarider]

Cool thread cheers for the info! I have a stock 440 with a mariner pipe. What carb and jetting would you recommend to run if I were to port it the same as in your pictures? Would i lose much bottom end performance from the raised exhaust ports? thanks

 

[screaming440]

a common setup we were running back in the day was a 44bn, a long pipe and mani, head or milled head, 15 or 15.5 prop, and water box.

the port specs where intake floor down 1.5 mm exhaust up 3mm and maybe 1 to 2mm wider on both.

you can get 45 to 47 mph out of one setup right and it will pick up power on the low and mid too.

 

[fastgtfairlane]

i wouldnt go much more than 3mm raising the exhaust port.. it will make the powerband peaky and load up in no wake zones...

 

[pillazilla]

Best tools for the job?

 

[screaming440]

summitt has a p&p kit that i use. this is all sanding discs but you can use rasps too. the rasps cut faster so for you first time just use the sanding discs. cut your air pressure back too and go slow till you get the hang of it.

these are all 1/4 inch shank so any air diegrinder will work.

http://www.summitracing.com/parts/SUM-G1060/

 

[fastgtfairlane]

to best port the engine i would recommend using smaller 1/8 inch carbide bits to get into tight places in the cylinder.. such as the transfer ports.. i just did my reed cylinder with my dremel and bits like these.. http://www.ccspecialtytool.com/carbide-cutters-18 on the exhaust port, the idea is to get the ports as smooth as possible.. start with the carbide burr, then go to a grinding stone, then use a sandpaper roll on your dremel or die grinder.. then to get the final polish, wetsand the port starting with 220 grit, then 400, then 1000 grit... after wetsanding with 1000 grit the port will be very shiny so that carbon will not stick to the port... it should look something like this when youre done... again this is only the exhaust ports..

also a good rule of thumb on widening exhaust ports is not to exceed going more than 70% of the bore of the cylinder

expect to spend atleast 12-15 hours porting the entire cylinder haha i spend over 7 on my exhaust ports..

 

[dunnville jetbum]

a common setup we were running back in the day was a 44bn, a long pipe and mani, head or milled head, 15 or 15.5 prop, and water box.

the port specs where intake floor down 1.5 mm exhaust up 3mm and maybe 1 to 2mm wider on both.

you can get 45 to 47 mph out of one setup right and it will pick up power on the low and mid too.

you can actually get a 440 to go that fast, what about reliablity

 

[screaming440]

i've had a sport radar gun for about 20 years and radared hundreds of PWCs. these are real speeds not guessing.

these are flat water speeds with a 170 lbs. +- rider.

getting a js ski to run 45 is no problem getting it to 48 is a lot harder and breaking 50 is almost impossible but can be done by people who know what they are doing.

 

[pillazilla]

Hi Guys late checking in..

Do you also have to port the exhaust and intake manifolds and cut the gaskets to match, or are you only porting inside of the edges?

 

[screaming440]

Hi Guys late checking in..

Do you also have to port the exhaust and intake manifolds and cut the gaskets to match, or are you only porting inside of the edges?

that does help but the big gains are from what you do at the cylinder.

 

[dunnville jetbum]

good tips i plan on porting my 550 pp later this winter, i am sure i will be asking alot of questions

 

[Nottjbarlow]

This is why you want to port and polish your cylinder!

^^ Stock 550^^


^^ Not so stock^^

And don't forget the transfer ports!


Chances are that your stock transfer ports look similar to this.

Thanks for the write up Screaming440.