what do they do to port a two stroke? also reed cage question

[Hoosier_Daddy]

I understand porting on a four stroke engine but There is no valves on a 2 stroke I just don't get it. Do they just gently grind off any manufacture flash or something?


I want to upgrade my reeds. I noticed someone selling a reed cage with their performance reeds that supposedly increased power. It that true? Or is is a gimmick, i thought the reeds are what mattered. Is is best to replace the reed cage and reeds with performance ones for best gains?

What are good reeds to get?

[cr480r]

Well unlike a 4-stroke the piston does the job of the valves... The ports on a 2-stroke combined with the pipe basically performs the function of the cylinder head and cams of a 4-stroke.. 2stroke porting usually involves removing casting imperfections and other flow obstructions as well as alterering the shape and sizes of ports to achieve the desired results.. porting works in conjuntion with other variables such as the pipe, head, and intake system to control what rpm range the engine makes power and how broad the powerband is... Higher rpm power gains are usually a trade off for low speed perfomance and vise versa...

[Hoosier_Daddy]

Well unlike a 4-stroke the piston does the job of the valves... The ports on a 2-stroke combined with the pipe basically performs the function of the cylinder head and cams of a 4-stroke.. 2stroke porting usually involves removing casting imperfections and other flow obstructions as well as alterering the shape and sizes of ports to achieve the desired results.. porting works in conjuntion with other variables such as the pipe, head, and intake system to control what rpm range the engine makes power and how broad the powerband is... Higher rpm power gains are usually a trade off for low speed perfomance and vise versa...

I see. So a novice doesn't want to go in and lightly remove some casting imperfections or flash because it could screw it all up?

[beets442]

Not at all. You can take emery cloth and lightly smooth your exhaust port. Take bluing ink and match the header. Doesn't hurt a thing.There is a book called Two Stroke Performance Tuning by A. Graham Bell. It mostly talks about twin cyl. and cart engines, but gives you the basics to tuning and light mods to the stock engines. Good book $20- Amazon. Beets

[MTS]

Lighter reeds generally give you a crisper throttle response, not much in the hp gains, it helps to match the "ports" on the reedcage with the pedals for better flow, you have to watch on some bigger bore 2 strokes iv found fiber reeds to flutter under hard decel causing a nice eratic poping,

[brapp]

well dependign what sort of power toug going for you can widen the ports, raise them for a mor etop end scream, change transfer port height and angles to modify the power delivery and found otu that the crankcase also has alottttt to do with the power delivery inmy experiments also i picked up almot 4 hp by reducign the dead volume in the crankcase. it is also calle dpackign the crankcase. but it also make sit a catastrphe if somethign small goes trough the motor. but also dependign on if your lookign for a fullout drag port its raise the exhaust port and make it flow as much as possible and chenge the size and angle of the transfer ports. and also may include adding boost ports into the intake sid eof the cylinder between the reeds and piston dependign on the motor. i know quite a bit of info on this just dont knwo how to out it into words.

[cr480r]

I see. So a novice doesn't want to go in and lightly remove some casting imperfections or flash because it could screw it all up?

I would remove all the imperfections.. it will help just dont expect huge gains from a simple clean up.. The main thing is just dont make modifications the shape or sizes of the port windows unless you thoroughly understand why you are doing it.. and what the results will be.. As mentioned above alot of info on the basics can be learned by reading books and finding bits and peices of info on the web..

[cr480r]

found otu that the crankcase also has alottttt to do with the power delivery inmy experiments also i picked up almot 4 hp by reducign the dead volume in the crankcase. it is also calle dpackign the crankcase. but it also make sit a catastrphe if somethign small goes trough the motor.

I have my 480 apart right now doing porting and some things to stuff the crankcase.. Do you think its possible to over-stuff an engine? I think with an outdated pipe design it would be difficult...

[Shawn72]

I can't talk much about the technical aspects of porting, but a set of boyesen Pro reeds will def help your throttle response alot. Instant power.

[Derek]

I can't talk much about the technical aspects of porting, but a set of boyesen Pro reeds will def help your throttle response alot. Instant power.

I agree, I'm running a set of Boyesen Pro Series carbon fiber reeds in my RM125. They are way better than stock.

[Hoosier_Daddy]

You guys are greatly helpful. Thank you. And boysen pro series reeds it is. lol

[old-yellow]

I agree on the reeds it made my trike much snappier.

[brapp]

480 you can over stuff the cases by taking away and makignt he tolerances so tight that th crank lobes rub the packing materialswether it be a sleave or weld or what not. et your tolerances too close and it will expand under heat and will rub. i always say .030 ths minimum

[Hoosier_Daddy]

OK, to be more specific, this reed cage for my T3. Is it overkill? Or should I keep the stock cage and go with pro series reeds?

http://cgi.ebay.com/ebaymotors/ws/eB...3AIT&viewitem=

[beets442]

I would call Boysen reeds and ask. They are very nice people.