250r cool head o-rings?

[wilkin250r]

I've been searching for about 20 minutes, which is a long time for me.

I can't find replacement o-rings for the 250r cool head. I have found them for the DOME, but not the actual head itself, to seal against the cylinder.

What gives?

[methyman]

The cool head I have uses a head gasket and not a o-ring. What brand of cool head for a TRX250R uses o-rings?

[deathman53]

there are cool-head that use o-rings. Pro Design sells them both ways. There is a Pro-x branded type and there is a 2 OEM yamaha parts that are exactly the same for 250-310 or was it until a 330? The o-rings for a yz250 are exactly the same. Most of the esr, Lrd, Ct, Duncan and pro-x brand(source for the other brands, but they are modified in different ways) are almost all o-rings cool-heads.

[methyman]

http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=14800&utm_source=google&utm_medium=cse#fitment

[methyman]

I know about the other heads for the aftermarket cylinders using o-rings in the cylinder but not in the head for a stock cylinder.

[wilkin250r]

Originally posted by methyman
http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=14800&utm_source=google&utm_medium=cse#fitment

Yeah, notice how it says none in stock. That's because I just bought the last one, and it turns out it's only for the dome, it doesn't include the o-ring to seal the head against the cylinder. Denniskirk part number 14-800

[mxduner]

wilkin i have, somewhere, some o rings from an 03 yz250. Do you want me to dig em up for measurment? All i have thou is a 310 top end apart to compare with.

ironically i have the gasket cool head, and got the yz o rings to convert, as you see i never got around to it:D

[derby]

Originally posted by wilkin250r
Yeah, notice how it says none in stock. That's because I just bought the last one, and it turns out it's only for the dome, it doesn't include the o-ring to seal the head against the cylinder. Denniskirk part number 14-800


I have about 20 sets of inner and outer orings left that I use to oring stock cylinders and stock heads.

You will have to measure the inside and outside diameter of your grooves. Mine are
Outer 3.989" X 4.129"
Inner 2.854" X 3.004"

http://i28.tinypic.com/2dmnbp.jpg

[spdygonzalez450]

I had a problem finding o-rings for my head as well. I ended up doing some research in the industrial area around me and found an o-ring shop, took my head there and asked them if they could match the size. it took about ten min and I walked out with 5 inner and 5 outer for under 20 bucks. plus they were rated for higher temps. it seemed like a win win for me.

Derby: On the "O-Ring" groves you show on the stock head, the dimension given don't make any sense, can you please check again?

Also; do you have any of the "O-Ring" Part numbers?

Thanks!

[wilkin250r]

Originally posted by spdygonzalez450
I had a problem finding o-rings for my head as well. I ended up doing some research in the industrial area around me and found an o-ring shop, took my head there and asked them if they could match the size. it took about ten min and I walked out with 5 inner and 5 outer for under 20 bucks. plus they were rated for higher temps. it seemed like a win win for me.

Any way you can find the manufacturer and part number for those o-rings?

[wilkin250r]

I want to revisit this thread. I've had good luck just cleaning up and re-using the old O-rings, but I'd really like to get some new ones.

Some people have said they went to an o-ring specialty store and got suitable sets. Any way we can get the specs on those? The size I can probably figure out for myself, but I'd really like to know the exact material...

[derby]

Any oring specialty place can measure the orings you got. They have these cones you slide the oring over to get the inside diameter. Then they measure the thickness and give you the od. Anytime you buy orings size should be listed O.D. x I.D.

[woodsracer144]

Originally posted by acecarlos
Derby: On the "O-Ring" groves you show on the stock head, the dimension given don't make any sense, can you please check again?

Also; do you have any of the "O-Ring" Part numbers?

Thanks!

that is the inside and the out side of his grooves in dia. I assume. so its
inner part of the groove is 3.989" and 4.129" to the outside of the ring groove. giving you a ring dia of .14 and to me that sounds about right.

[wilkin250r]

Originally posted by derby
Any oring specialty place can measure the orings you got. They have these cones you slide the oring over to get the inside diameter. Then they measure the thickness and give you the od. Anytime you buy orings size should be listed O.D. x I.D.

And like I said, the I'm not worried about the size, I can easily figure that out. Even if I couldn't nail it down exactly, I'd just get a few of each size I thought was close, the only danger there is a couple bucks.

It's the MATERAIL I'm much more concerned about. Combustion chamber temperatures can exceed 1000 F. Now that doesn't mean the O-rings need to be able to withstand the full 1000 degrees, but I want to know which materials have been proven to work, I don't want to do my own trial-and-error research. Because if I'm wrong on the size, I just buy another. If I'm wrong on the material, I risk catastrophic engine failure.

[wilkin250r]

And I can't get Pro Design on the phone.

What other heads do you guys know that use O-rings? Duncan Racing does, I'm pretty sure. Does ESR use o-rings in their heads? Perhaps we can get the material specs from another manufacturer. The size might not be exact, but if we know the inner ring is a Kalrez compound, and the outer is Viton, then we know those materials will survive the envoronment, then we just order them in the proper size for the Cool Head.

[Langbolt]

Wilkin250R,

What ya wanna do is order up some SILICONE O-rings....

I use Silicone on the INNER and Viton on the OUTER.

Check out:

www.globalrubber.com

That's where I get all my O-rings from

Sizing is Inner Diameter x Thickness

:devil:

[wilkin250r]

I can tell from the O-rings that I have, the inner looks to be a different material than the outer, and I would assume the inner has to be able to handle higher heat.

Duncan racing says Viton, but I got the impression that because I wasn't ordering parts, they knew I was looking for information to use somewhere else. They may have been just giving me an answer to shut me up and send me on my way.

[Pumashine]

I believe the outer ring is Nitrile or Buna-N. The inner ring is Silicone or Viton depending whether it is American or metric

I recommend calling the o-ring guys. They are most helpful for this information. The cycle companies have already done the research and are not always willing to give out secrets.

[mx91a]

Good thread. Hopefully I can help out a little.

According to Derby's measurements:

Outer 3.989" X 4.129"
Inner 2.854" X 3.004"

The outer O-ring is a -045 and the inner is a -040

Here is the sizing chart:

http://www.allorings.com/size_cross_reference_framed.htm

As for materials, both Viton and Silicone are rated to around 400F but I think the Viton has the better fuel resistance so this would be my choice for the inner ring.

Wilkin on the inner o-ring you have if it is black it is most likely Viton, if red or orange it's silicone.

Order the Viton o-rings here:

Order Viton O-Rings (http://www.allorings.com/cgi-bin/CatalogMgr.pl?cartID=b-5842&SearchField=category&SearchFor=Viton+O-Rings&template=Htx/order_viton.htx&hdr=Order+Viton+O-Rings&displayNumber=369)

Order the silicone ones here:

Order Silicone O-Rings (http://www.allorings.com/cgi-bin/CatalogMgr.pl?cartID=b-5842&SearchField=category&SearchFor=Silicone+O-Rings&template=Htx/order_silicone.htx&hdr=Order+Silicone+O-Rings&displayNumber=369)

I have a stock cylinder done up by LRD cut for o-rings with a coolhead on top sealing up 240 psi. I might take it apart this weekend and verify the o-ring dimensions and material for you guys.

[wilkin250r]

Originally posted by mx91a

Wilkin on the inner o-ring you have if it is black it is most likely Viton, if red or orange it's silicone.

The set I have, one is black, the other is a dark brownish-gray, but I can't remember which is the inner and outer.

I was thinking about Kalrez for the inner ring, it's rated up to 600 F degrees, and now I'm wondering why it isn't used. The specs say it has good chemical resistance, I wonder if it's just too hard, or the chemical resistance isn't good enough, or if it's just too dang expensive (I didn't check the price on it).

[Pumashine]

Originally posted by mx91a
Good thread.

Wilkin on the inner o-ring you have if it is black it is most likely Viton, if red or orange it's silicone.

Agreed, my new Viton inner rings are brownish and the new silicone are orange.

[mx91a]

I looked into the Kalrez too. Save those for the space shuttle, our 250R's don't need something that exotic.

Here's why they aren't used:

$195 for an 040 size o-ring and

$251 for an 045 size o-ring!!!

http://www.sisweb.com/vacuum/o-rings/viton.htm

[wilkin250r]

Originally posted by mx91a
I looked into the Kalrez too. Save those for the space shuttle, our 250R's don't need something that exotic.

Here's why they aren't used:

$195 for an 040 size o-ring and

$251 for an 045 size o-ring!!!

http://www.sisweb.com/vacuum/o-rings/viton.htm

Holy s#!t. Ok, I'm thinking Viton!!!