Two Stroke Motocross

Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: Uniflow on December 14, 2012, 12:38:17 AM

Title: YZ 361
Post by: Uniflow on December 14, 2012, 12:38:17 AM
In the real world, if a 361cc barrel was available for the YZ250 ( new ) nikasiled with a head and piston, suit V force reeds, who would want one? Is there a real market or just talk? There must be a lot of YZ 250's out there. Would it be best to suit the original power valve or go electronic now? It could get expensive.
Just asking.
Title: YZ 361
Post by: TMKIWI on December 14, 2012, 02:35:02 AM
You thinking of casting one ?
Title: YZ 361
Post by: Jeram on December 14, 2012, 02:58:41 AM
Hey uniflow, although a 361 is great, would it be hard to offer a 250cc version as well for pro mx racers who want a shot at beating 450's?

I think lozzas going to give you a call very soon as we might want to buy a few of your other cylinders :)
Title: YZ 361
Post by: SachsGS on December 14, 2012, 03:08:28 AM
Years ago Ohlins offered a 360 kit for YZ 250s. In today's tight economy price would greatly affect demand so probably mechanical powervalve.
Title: YZ 361
Post by: factoryX on December 14, 2012, 05:53:08 AM
ESR is about to release one with a powervalve as well. What would the cylinder/head end up costing after everything is said? An Electronic powervalve would be cool, but as you mentioned it would be pricey.
Title: YZ 361
Post by: MOTORHEAD on December 14, 2012, 07:07:43 AM
Athena now has a 300 kit for the YZ250, also. 72mm bore.
Title: YZ 361
Post by: Jeram on December 14, 2012, 08:56:44 AM
Both the esr and Athena cylinders are currently only 300cc. You can bore your stock cylinder out to this size!
I'd also imagine that uniflow is completely revising the port layouts and cooling whereas the others are pretty much stock std replicas with larger bores :)

Correct we if I'm wrong but you can make the cylinder mechanical pv and then If soneone wants servo control they can easily retrofit it :)
Title: YZ 361
Post by: 2T Institute on December 14, 2012, 01:21:10 PM
Why confine everything to a YZ, why not cast the net a bit wider. The GAS GAS 250 has a 6sp and a balance shaft a throughly modern engine. Not legal for AMA racing unfortunately. A modern cylinder for case reed CR250 you would struggle to keep up demand for 250 National karts.
Servo PV is simple upgrade and worth it weight in gold and easy to realise.
A 72 X 72 mm format for big bore would be ideal bigger wouldn't be any better
Title: YZ 361
Post by: factoryX on December 14, 2012, 09:48:25 PM
Both the esr and Athena cylinders are currently only 300cc. You can bore your stock cylinder out to this size!
I'd also imagine that uniflow is completely revising the port layouts and cooling whereas the others are pretty much stock std replicas with larger bores :)

Correct we if I'm wrong but you can make the cylinder mechanical pv and then If soneone wants servo control they can easily retrofit it :)
ESR is 325 and up and using 75-80mm bore. As for boring out the stock cylinder you do plan on replating as well right? And we could talk about how the stock powervalves are failing due to how close they are to the piston. Watson777 can chip in on that one.

Title: YZ 361
Post by: factoryX on December 14, 2012, 09:53:11 PM
How much would you sell you cylinder for Uniflow? Price with and without electronic powervalve would be cool.  8)
Title: YZ 361
Post by: Uniflow on December 14, 2012, 10:56:11 PM
TMkiwi, I've got several barrels sitting on my bench at the moment. I've thought about casting a new cylinder for the YZ for a while but what is the real market? Perhaps I just cast a few and see what happens? It would be cast with lugs for injectors and would be nikasil only, no sleeves.
Power valve would be easier electronic and a Ignitec would run it easily. We already build curved power valves for wobbly.
Title: YZ 361
Post by: Uniflow on December 14, 2012, 10:57:48 PM
Cost? I don't know, I'll check with the foundry on casting costs.
Title: YZ 361
Post by: Jeram on December 15, 2012, 03:27:28 AM
Both the esr and Athena cylinders are currently only 300cc. You can bore your stock cylinder out to this size!
I'd also imagine that uniflow is completely revising the port layouts and cooling whereas the others are pretty much stock std replicas with larger bores :)

Correct we if I'm wrong but you can make the cylinder mechanical pv and then If soneone wants servo control they can easily retrofit it :)
ESR is 325 and up and using 75-80mm bore. As for boring out the stock cylinder you do plan on replating as well right? And we could talk about how the stock powervalves are failing due to how close they are to the piston. Watson777 can chip in on that one.

no the ESR is 325 and they hope/plan to do larger in the future! big difference ;)

if you can tell the difference between a 325 and a 295 then ill be damned.
going out to 265/295 in a stock cylinder isnt hard when done properly, I've taken my late model CR cylinder out to the limit and no dramas so far apart from a lean sieze which was purely my fault.
when the PV is too close to the piston you machine it down, I spent 2 hours on my PV with a die grinder until it was perfect!
Title: YZ 361
Post by: Jeram on December 15, 2012, 03:29:23 AM
A modern cylinder for case reed CR250 you would struggle to keep up demand for 250 National karts.

THIS

I think you would sell atleast 25 a year if not more, and Id buy one too!
Title: YZ 361
Post by: offroader on December 15, 2012, 09:41:43 PM
A modern cylinder for case reed CR250 you would struggle to keep up demand for 250 National karts.

THIS

I think you would sell atleast 25 a year if not more, and Id buy one too!

I agree with this.When can i order mine?
Title: YZ 361
Post by: offroader on December 15, 2012, 09:45:48 PM
Forgot to mention not for a kart.Just a two wheeler. ;D
Title: YZ 361
Post by: _X_ on December 15, 2012, 10:00:53 PM
man looks like there's some intersest, you all should buy two for a spare.
Title: YZ 361
Post by: offroader on December 15, 2012, 11:01:43 PM
man looks like there's some intersest, you all should buy two for a spare.

Well if it gets produced i might just purchase two. ::) Might wind up with one or two of the gorr kits.
Title: YZ 361
Post by: _X_ on December 15, 2012, 11:07:21 PM
screw gorr, uniflow is one of us.
Title: YZ 361
Post by: offroader on December 15, 2012, 11:54:43 PM
screw gorr, uniflow is one of us.

Ok.At this point at least gorr is developing.ESR is developing also.The yz cylinder will be used for the 92-01cr also.Should uniflow develop one and give us another option that would be great!As of right now it is just talk.
Title: YZ 361
Post by: Jeram on December 16, 2012, 02:39:16 AM
screw gorr, uniflow is one of us.

Ok.At this point at least gorr is developing.ESR is developing also.The yz cylinder will be used for the 92-01cr also.Should uniflow develop one and give us another option that would be great!As of right now it is just talk.

yes, but this is a guy who casts engine cylinders and other parts for a living, not some pimply faced teenaged with epic dreams.

I trust that uniflow will get around to making these cylinders whether they be for the YZ of the CR... or whichever bikes he wants.

If there is enough demand for both the CR and YZ cylinders, hopefully we can talk him into making both for us :)

Title: YZ 361
Post by: factoryX on December 16, 2012, 03:49:23 AM
As does ESR, for the last twenty approaching 30 years. If I had to chose it would be between ESR and Unifow. What would be cool is if he threw in a counter balancer.
Title: YZ 361
Post by: Uniflow on December 16, 2012, 05:23:32 AM
You are right offroader, it's only talk. The thing is I have made cylinders but only for my own consumption. I will go ahead with a cylinder for the YZ ( as a test ), if they are any good I will make them available. A set of YZ 250 cases turned up today to measure up ( I'm not pulling mine to bits yet ). Seems there will need to be a slight crankcase change to get an 80mm piston in. I'll look at some smaller piston options also, although I like the 80mm piston.
Title: YZ 361
Post by: Jeram on December 16, 2012, 06:11:55 AM
What would be cool is if he threw in a counter balancer.

or you could just get a gas gas motor which is 300cc's std and already counterbalanced from the factory :)
Title: YZ 361
Post by: factoryX on December 16, 2012, 07:47:51 AM
Does it still have the counter balancer?
Title: YZ 361
Post by: Jeram on December 16, 2012, 09:54:35 AM
I know for certain that up until 2005 they had one, dunno bout the newer bikes.

Otherwise if you want a six speed, counterbalanced CR265 shoot me a PM and Ill show you how.
Title: YZ 361
Post by: bearorso on December 16, 2012, 10:36:58 PM
Does it still have the counter balancer?

No, the last GG 2ts to have them, "I think", were those in Pampera 2ts. But I could be mistaken.

I think for a while, the empty housing, on the front of the cases  was left on. Then deleted?
Title: YZ 361
Post by: Kurtis on December 16, 2012, 10:47:59 PM
I will purchase a 360 kit whenever its available as long as it makes more power than a 450.  I can't stand 450s and I want something for Glamis with a little more juice than my EG295. 
Title: YZ 361
Post by: SachsGS on December 17, 2012, 12:44:11 AM
Time for a YZ (and WR) 400 2T.
Title: YZ 361
Post by: offroader on December 17, 2012, 01:54:05 AM
You are right offroader, it's only talk. The thing is I have made cylinders but only for my own consumption. I will go ahead with a cylinder for the YZ ( as a test ), if they are any good I will make them available. A set of YZ 250 cases turned up today to measure up ( I'm not pulling mine to bits yet ). Seems there will need to be a slight crankcase change to get an 80mm piston in. I'll look at some smaller piston options also, although I like the 80mm piston.

Uniflow,wasn't doubting your abilities.Great to hear that you will try the yz first.Hopefully you will do the case reed cr also.Smaller piston options would be nice also.Should you decide to do the cr I will purchase one asap.Should you need some help testing it i can assist with that also.This is good stuff! :)
Title: YZ 361
Post by: factoryX on December 17, 2012, 06:29:47 AM
I will purchase a 360 kit whenever its available as long as it makes more power than a 450.  I can't stand 450s and I want something for Glamis with a little more juice than my EG295.
You can do that with a 265 let alone a tuned 250. The problem is pro built 450's..