Does this gasket look normal?

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1/2/2019 3:42 PM

hey yall. Im building a 2005 rm250 that I picked up for 1000 bucks. I just got my cylinder back from Eric Gorr and the gasket kit looks like this. Is this normal to have the gasket a circle instead of following around the intake? Photo
Photo

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1/2/2019 3:52 PM

I'm not an engine builder but it looks like exacto knife time to me

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1/2/2019 4:06 PM
Edited Date/Time: 1/2/2019 5:57 PM

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1/2/2019 4:07 PM

Looks like it's not the right gasket to me.

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @2HRacing
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1/2/2019 4:27 PM

Aren't those circles just covering the coolant passages? If so I think that's probably normal, the RM's don't have a traditional head gasket so the restriction is probably just done in those areas rather than the head gasket like on Hondas.

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1/2/2019 4:43 PM

That is perfectly normal. That is indeed the correct gasket.

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1/2/2019 4:44 PM

40acres wrote:

That is perfectly normal. That is indeed the correct gasket.

He's right, I deleted my post to avoid confusion.

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1/2/2019 5:15 PM

The electronic parts catalog confirms that is the correct gasket.

Photo

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Braaapin' aint easy.

1/2/2019 5:27 PM

Right on guys! thanks so much for all the replies. Looks like I can finish my build!

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1/2/2019 5:29 PM

Any reason you cant open those up for increased coolant flow? Seems like they only made them circles to keep from making a custom punch on the trim die.

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1/2/2019 5:32 PM

Not to sound stupid here (too late ? laughing ) but what's the point of having large openings if you cover 90% of the hole with a gasket, and isn't there a risk of the gasket breaking down and the pieces getting sucked into said holes ? If that's right it's a good thing I don't build motors cause I'd of trimmed it to the size of the holes...

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1/2/2019 5:43 PM

The holes are there to restrict the coolant flow. It will be fine as is.

Paw Paw

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1/2/2019 5:46 PM
Edited Date/Time: 1/2/2019 5:49 PM

kb228 wrote:

Any reason you cant open those up for increased coolant flow? Seems like they only made them circles to keep from making a ...more

More flow doesn't always mean more cooling. I have an RM250 and have not had any cooling issues even doing enduros in plus 100 temps crawling over rocks.

and yes...that is the proper gasket

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1/2/2019 6:13 PM
Edited Date/Time: 1/2/2019 6:15 PM

Paw Paw 271 wrote:

The holes are there to restrict the coolant flow. It will be fine as is.

Paw Paw

Makes sense, still seems weird to me, but I get it. Learn something everyday !

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1/2/2019 6:25 PM

Paw Paw 271 wrote:

The holes are there to restrict the coolant flow. It will be fine as is.

Paw Paw

sumdood wrote:

Makes sense, still seems weird to me, but I get it. Learn something everyday !

I hear ya man. Thats why I made this post!

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1/2/2019 9:08 PM

The restriction is by design. If coolant flows too fast it can actually cause overheating because it does not stay in the radiator long enough to cool down before circulating through the engine again.

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1/2/2019 9:14 PM

What does the bottom of the cylinder look like?

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1/3/2019 2:25 AM
Edited Date/Time: 1/3/2019 2:34 AM

I have a hard time believing they would rely on a paper gasket to function as a "restricted orifice" that controls flow..

Butwaduino

I would be tempted to cut to match cases, but I wouldn't. If it was causing problems, they would have revised the part.

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2 Stroke, Drum Brakes, Finned Cylinders!!!

1/3/2019 2:40 AM

sumdood wrote:

Not to sound stupid here (too late ? laughing ) but what's the point of having large openings if you cover 90% of the hole with a ...more

Has to do with the casting process, cooling and cylinder weight. MotoChris is spot on about controlled water flow. You want water to cover as much of the cylinder as possible, so the casting would be very complex to do that with aluminium. It would also add more weight. Then you get into thermodynamics of a fluid. As the fluid is forced through the restriction it expands on the exit and cause a release of heat energy...... Blah Blah Blah. I could go on and on about this but y'all would just be bored.

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1/3/2019 3:14 AM

MotoChris wrote:

The restriction is by design. If coolant flows too fast it can actually cause overheating because it does not stay in the ...more

Interesting. Makes sense

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1/3/2019 8:41 AM
Edited Date/Time: 1/3/2019 8:42 AM

sumdood wrote:

Not to sound stupid here (too late ? laughing ) but what's the point of having large openings if you cover 90% of the hole with a ...more

racingfortheson wrote:

Has to do with the casting process, cooling and cylinder weight. MotoChris is spot on about controlled water flow. You want ...more

I've installed passive (thermo siphon) and active dhw solar systems, heat exchangers, swimming pool solar and pool heaters, and deal with water flow (hydro dynamics) with pool and spa plumbing, negative and positive pressures yada yada, and feel like I have somewhat of a handle on water flow etc, but am always open to learning more. You said "when the fluid is forced through the restriction it expands on the exit and causes a release of heat energy..." That ones over my head, wouldn't whatever heat energy released "balance out" any heat energy created by forcing it through the restriction first ? netting a heat release of zero ? Don't worry you won't bore me I find it interesting smile

The other thing is using a gasket to restrict flow, seems rinky dink to me and like a weak link, those gaskets must be tough sob's !!laughing

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1/3/2019 9:28 AM

sumdood wrote:

Not to sound stupid here (too late ? laughing ) but what's the point of having large openings if you cover 90% of the hole with a ...more

racingfortheson wrote:

Has to do with the casting process, cooling and cylinder weight. MotoChris is spot on about controlled water flow. You want ...more

sumdood wrote:

I've installed passive (thermo siphon) and active dhw solar systems, heat exchangers, swimming pool solar and pool heaters, ...more

Technically (in a perfect system) the pump is pulling cool fluid from the bottom of the radiator. As the fluid is forced into the larger space around the cylinder there would be a measurable pressure drop, which would aid in cooling. The pressure isn't creating the heat as water isn't compressible like air ( technically speaking). Diesel engines don't ignite from compressed diesel fuel, the heat from the air in the cylinder being compressed ignites the fuel. The friction from rate of flow would create heat, why a lot of the aftermarket pumps don't move fluid faster, but move more fluid at a smoother rate. I'm sure I'm over thinking this and the difference is negligible, but I'm a nerd lol. I work with fluids, pumps, hydraulics and temperatures on a daily basis. I would put money on the holes being there to control flow rate more then anything.

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1/3/2019 10:18 AM

racingfortheson wrote:

Has to do with the casting process, cooling and cylinder weight. MotoChris is spot on about controlled water flow. You want ...more

sumdood wrote:

I've installed passive (thermo siphon) and active dhw solar systems, heat exchangers, swimming pool solar and pool heaters, ...more

racingfortheson wrote:

Technically (in a perfect system) the pump is pulling cool fluid from the bottom of the radiator. As the fluid is forced into ...more

"The friction from rate of flow would create heat, why a lot of the aftermarket pumps don't move fluid faster, but move more fluid at a smoother rate."

That friction is resistance, resistance + flow = system pressure. If you increase your volume over time (GPM) where resistance does not change, pressure goes up.

So the prime mover (motor) basically provides variable displacement because of RPM is variable.

My guess those holes regulate system pressure at idle. A gasket can be changed easy, so making low idle pressure adjustable.

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