How exactly do I port the intake and exhaust?

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StrontiumEthics

New Member
How do I port the intake and exhaust I spent a couple of hours browsing this site, and the things that I have found didnt quiet tickle my fancy. It was really to specific. So how exactly do I port the intake and exhause. What exactly do I have to do. and how to do it. Thanks!
 
Pretty simple really. Here is what I do. First I make a new intake and exhaust gasket that matches the intake and exhaust ports on the cylinder. Then I use those as templates to make my intake and exhaust manifolds match the gasket. A dremel tool with a 3/8 sanding drum works well. Don't over do it, especially if you have an aluminum intake manifold. You will never get it perfect since you can't make something round oval but you can make the transition smooth.
 
And again.. How will this increase performance? Sofar, I was having problems with the engine acceleration, so I removed the baffler, and muffler cap. Now it runs SWEET!!! Since I have a jackshaft kit its like im shifting gears like a motorcycle. I love it . Its a bit loud but I will work something out. Will this porting give me an increase in power? anything along that line?
 
So by removing the baffle on your pipe you did what? Increased the engines ability to flow exhaust gasses. By porting and making sure that your intake and exhaust gaskets are not blocking flow you are doing the same thing. So yes it will increase performance. You may even be able to put your baffle back on. I would recommend cutting part of the tub or drilling holes in the baffle though.
 
I Took Mine Out After Break In More Than 4000 Miles Ago. I Left The End Cap On Because Of No Back Pressure Deal And It's Way Too Loud,but I Cut The Baffle Flush With The Inside Of The End Cap. Its Like A Cheesy Makeshift Expansion Chamber. Works For Me. I Did File Down The Exhaust Port, But Forgot The Intake...smart Me.
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I'd Rather Be Riding A Mb Not A Bm.
 
DEATH4OF4 said:
I Took Mine Out After Break In More Than 4000 Miles Ago. I Left The End Cap On Because Of No Back Pressure Deal And It's Way Too Loud,but I Cut The Baffle Flush With The Inside Of The End Cap. Its Like A Cheesy Makeshift Expansion Chamber. Works For Me. I Did File Down The Exhaust Port, But Forgot The Intake...smart Me.
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I'd Rather Be Riding A Mb Not A Bm.
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I had the same round about Idea recently as well. Only I made a homade baffle at the bottom of the pipe. I still need a little more restriction but not much. This thing is already as quite as a little honda generator. Still not officially a tuned pipe , but what a difference. SBP is about to release a tuned pipe for the Chinas http://motorbicycling.com/f15/sbp-jack-shaft-rules-6862.html.
 
More on the porting side, I lowered the intake port on mine and raise the exhaust port. This changes the port timing much like a higher lift cam in a car and rpm is increased. more power down low and much more up top, also smoother. As always ride it flat all the time and life will be short.
 
Ok fellas, I just ported my intake yesterday (Thursday), I used a dremel sanding drum, and sat there grinding it down. I managed to increase it to a good amount. Its alot bigger than another intake manifold that I used to compare on an 80cc engine. Now that I made it bigger will I see a big difference in perfomance? Im running it without a baffle, just open exhaust pipe. I cannot start the engine b/c I ordered some parts for it. Where will I feel the pull? Low end, high end, or both? Do I need to adjust anything else?
 
You'll need to do the same on the exhaust manifold.

What are you using for gaskets?
 
Even more than the inlet? Wow. I thought that me taking out the baffle might do it. So, no I have to get back with my rotary tool and sand away? Again? lol
 
I did mine on sunday, not very clean but good enough the engine still works. Tok about 1/16-in of the bottom of the intake and maybe 1/16-in of the top of the exhaust port. As for performance a decent increase in power is evident. Top end is much improved but acceleration is the biggest difference I noticed.

BTW I ported mine using a hand file, a hand file is fine for doing it but it takes much longer.
 
Did mine with a hand file as well, works fine but does take longer. I used too have most of these tools, but tools have a habit of growing legs and walking away. I understand now way my dad was always so adamant about putting his tools back in there specific spot.
 
What material do you use for a gasket? I was just gonna try and sand down, at high speed, a spare gasket for the exhaust.

I also heard cereal boxes with RTV sealer.
 
theycallmebob said:
What material do you use for a gasket? I was just gonna try and sand down, at high speed, a spare gasket for the exhaust.

I also heard cereal boxes with RTV sealer.
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I have a roll of gasket paper from the local auto parts store, for like $12. Which should be more then enough to last a few years and will cover just about all my gasket needs.
 
i just recenley putt one of these engines on a bike .and from looking the motor over i would just port match th exaust and intake and then widen them as much as posibule with out making a hole in the jug or into the transfer port. pay alot more attention to the transfer ports (taper the ports from botom to top ,wider at base than port .add a 1/4 in spacer to the bottom of the jug and mill a 1/4 in off the top of the jug.mill the head and change the squish. put the pistion in the jug at top dead center and match the intake port side of the pistion skirt to the intake port. sorry for the spelling.
 
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I just attempted to port the exhaust with a dremel. the gasket and pipe match pretty well now, not perfectly, and it has made no difference. what did i do wrong? what did i not do at all?
 
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