2stroke guys i need advice/help

[bradj]

If i was to build new intake runners for reed block in a 500cc piston port twin how would i figure size of the reeds and distance form the piston? what would the piston need to look like windowless like a titan or windowed like a rd? i want to do this and ive seen other piston port motors ie h2 's with reeds but a picture of a bike is little to go on , and h2 are soooo fucked with its hard to say what snow moble the pistons came from. if i were to say copy a single reed valve dt250 would it work on a 500 piston por twin. im sure there is more to it. any help would be great

 

[xb33bsa]

yes copy the 250,but it is a lot of trouble for what ?

 

[xb33bsa]

have you done the squish bands? that is the most important thing to do first

 

[grcamna5]

What bike ? The T500 Titan ??

 

[bradj]

Yea a titan

 

[Drewski]

ive seen other piston port motors ie h2 's with reeds but a picture of a bike is little to go on , and h2 are soooo fucked with its hard to say what snow moble the pistons came from. if i were to say copy a single reed valve dt250 would it work on a 500 piston por twin. im sure there is more to it. any help would be great

I know you sometimes butt heads with "Reds" : , but he's had some significant time working with reeds on h2's. He's in the middle of at least 2 h2 reed projects at this very moment.

No "snowmobile pistons" here bud!

He might provide some info of value Brad.

 

[bradj]

I don't think i remember bumping heads with reds but it could have happened at some point. He pm me already, Im getting a few questions ready in my head, for him. He seemed willing to throw me a few pointers

 

[Drewski]

I don't think i remember bumping heads with reds but it could have happened at some point.

Hey, who haven't you run up against here?!?! That would be a shorter list. ;D

(all in good fun pal! )

Reds is good people, just like you.

 

[VonYinzer]

Hey, who haven't you run up against here?!?! That would be a shorter list. ;D

Again... Like drops of water in a lake.

 

[reds]

bradj??!! Fuck that guy!!!

Just kidding! Even though we are both really opinionated, or more Brad is opinionated and if I agreed with him we'd both be wrong ;D , we have had a mutual 2 stroke respect and a mutual yamaha respect so I don't think we have butted heads on here. With only 286 posts on here and i am not a active member of any other forums even though I should be part of KTC, I think I would remember.

I sent him a PM with a push in the right direction when I read this thread yesterday as i'm too busy right now to be part of an active open thread right now.

cheers

 

[Drewski]

I think you guys might be brothers...



Ya, that "Yamaha thing" you guys have... I suppose I'll have to overlook that.

 

[bradj]

But this is a suzuki sugar

 

[Drewski]

But this is a suzuki sugar

Haha...

 

[crazypj]

Build the mounting flange and reed 'box' then see how much extra depth you can add.
T/GT500 probably has plenty of space but if it's the one in RD frame things may get a bit tight.
You can get some idea how much extra depth you need from RD 350
Ported pistons will be best, the reed prevents blow back into carbs (it's why Yamaha use 'four stroke' emulsion tubes in carbs)
If anything, reed motor will cut off reverse flow better than a four stroke as the reeds close as soon as positive pressure is applied (actually a little earlier because of spring in reed)
You can also go a bit wild with lowering the intake port when piston no longer controls closing point plus, add a 'boost port' above piston crown on intake although that takes a little more measuring and work not to end up with a 'free port'
I'm not sure but I thing I have 2 reed blocks for Honda CR250 ;D (DT will be plenty for the MZ twin though )

 

[bradj]

Na pj i dug up a old project to take center stage after the rd is finished

 

[stroker crazy]

Yessss!

Crazy

 

[teazer]

Check out an RM250 for ideas. Don't worry too much about reed distance from the piston, but in general, shorter is better. Pistons need windows as a rule. Intakes can be as wild as you like but try to keep the port a similar size to the carb. Start with a reed cage and block from 250 single and check out the port timing on the donor as well for ideas. try normal 34mm carbs and throw the old oem carbs on ebay.

Check out Arctic Cat triples - you can cut the reed boxes off a crankcase and weld them onto your cylinders.

 

[xb33bsa]

do the heads first

http://www.ozebook.com/compendium/t500_files/morgan/head.htm

 

[mydlyfkryzis]

2stroke guys i need advice/help

I think you guys might be brothers...



Ya, that "Yamaha thing" you guys have... I suppose I'll have to overlook that.

I heard Brad is a secret Honda lover.....but don't let is out, he would deny it anyway....

 

[teazer]

Squish heads are necessary for big HP for sure, but at a lower level of tune they are less necessary. The higher the combustion pressure, the higher the probability of detonation with a quiescent head shape.