Posts: 3493
Joined: 3/21/2014
Location: Saratoga Springs, NY USA
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Rebuilding my 88 RM250. I have a Cometic head gasket and an Oem Suzuki gasket that has been superseded, but according to Suzuki is correct. Question? Why would the superseded Oem gasket block off water passages on the Right/water pump side? Cometic on the left, Updated Oem center with "E" facing north & the old one I removed. 
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Joined: 12/9/2009
Location: Mattawa, WA USA
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I’m definitely not an expert...but I just ran into this exact thing on some old KTM 125 head gaskets. Turns out the one that seemed to be missing the holes was intended to direct water better...to get the cooled water to the hottest area first (exhaust port).
Possible that Suzuki figured something like that out and updated the gasket with the superseded number.
Posts: 3493
Joined: 3/21/2014
Location: Saratoga Springs, NY USA
wpark89 wrote:
I’m definitely not an expert...but I just ran into this exact thing on some old KTM 125 head gaskets. Turns out the one that seemed to be missing the holes was intended to direct water better...to get the cooled water to the hottest area first (exhaust port).
Possible that Suzuki figured something like that out and updated the gasket with the superseded number.
Thanks for the reply wpark89. You are correct, the smaller holes should be at the exhaust area to slow down coolant flow to help aid cooling. I found a good explanation for the reduced holes at the water pump/rt side of the head. " reducing the holes in the water pump side of the head gasket will help flood the cylinder with coolant before it goes straight through the head." Seems logical, apparently Suzuki engineers felt this was needed. Now, the funny part...I found this on a quad site! I will use the updated Suzuki head gasket, after all I paid 30.00 for it!!
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Joined: 4/1/2008
Location: Visalia, CA USA
wpark89 wrote:
I’m definitely not an expert...but I just ran into this exact thing on some old KTM 125 head gaskets. Turns out the one that seemed to be missing the holes was intended to direct water better...to get the cooled water to the hottest area first (exhaust port).
Possible that Suzuki figured something like that out and updated the gasket with the superseded number.sandman768 wrote:
Thanks for the reply wpark89. You are correct, the smaller holes should be at the exhaust area to slow down coolant flow to help aid cooling. I found a good explanation for the reduced holes at the water pump/rt side of the head. " reducing the holes in the water pump side of the head gasket will help flood the cylinder with coolant before it goes straight through the head." Seems logical, apparently Suzuki engineers felt this was needed. Now, the funny part...I found this on a quad site! I will use the updated Suzuki head gasket, after all I paid 30.00 for it!!
To be more accurate the reduced outlet sizes from the head will aid in cooling by raising the pressure in that local area, thereby reducing the chances of boiling in that area. Slowing the coolant down does not aid in cooling the engine.
Posts: 3493
Joined: 3/21/2014
Location: Saratoga Springs, NY USA
wpark89 wrote:
I’m definitely not an expert...but I just ran into this exact thing on some old KTM 125 head gaskets. Turns out the one that seemed to be missing the holes was intended to direct water better...to get the cooled water to the hottest area first (exhaust port).
Possible that Suzuki figured something like that out and updated the gasket with the superseded number.sandman768 wrote:
Thanks for the reply wpark89. You are correct, the smaller holes should be at the exhaust area to slow down coolant flow to help aid cooling. I found a good explanation for the reduced holes at the water pump/rt side of the head. " reducing the holes in the water pump side of the head gasket will help flood the cylinder with coolant before it goes straight through the head." Seems logical, apparently Suzuki engineers felt this was needed. Now, the funny part...I found this on a quad site! I will use the updated Suzuki head gasket, after all I paid 30.00 for it!!
Matt Fisher wrote:
To be more accurate the reduced outlet sizes from the head will aid in cooling by raising the pressure in that local area, thereby reducing the chances of boiling in that area. Slowing the coolant down does not aid in cooling the engine.
Sounds reasonable...I read that slowing down the flow from the exhaust area will let the coolant absorb/ transfer more heat before it moves back to through the system.
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Joined: 4/1/2008
Location: Visalia, CA USA
sandman768 wrote:
Thanks for the reply wpark89. You are correct, the smaller holes should be at the exhaust area to slow down coolant flow to help aid cooling. I found a good explanation for the reduced holes at the water pump/rt side of the head. " reducing the holes in the water pump side of the head gasket will help flood the cylinder with coolant before it goes straight through the head." Seems logical, apparently Suzuki engineers felt this was needed. Now, the funny part...I found this on a quad site! I will use the updated Suzuki head gasket, after all I paid 30.00 for it!!
Matt Fisher wrote:
To be more accurate the reduced outlet sizes from the head will aid in cooling by raising the pressure in that local area, thereby reducing the chances of boiling in that area. Slowing the coolant down does not aid in cooling the engine.
sandman768 wrote:
Sounds reasonable...I read that slowing down the flow from the exhaust area will let the coolant absorb/ transfer more heat before it moves back to through the system.
Very common misconception. Faster moving water will absorb more of the heat than slower moving water (yes, there are lots of other variables to consider such as heat transfer back into the air through the radiator). A simple example is standing in 30 mph winds will make you much colder than 3 mph winds.
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Location: DNK
Matt Fisher wrote:
To be more accurate the reduced outlet sizes from the head will aid in cooling by raising the pressure in that local area, thereby reducing the chances of boiling in that area. Slowing the coolant down does not aid in cooling the engine.
sandman768 wrote:
Sounds reasonable...I read that slowing down the flow from the exhaust area will let the coolant absorb/ transfer more heat before it moves back to through the system.
Matt Fisher wrote:
Very common misconception. Faster moving water will absorb more of the heat than slower moving water (yes, there are lots of other variables to consider such as heat transfer back into the air through the radiator). A simple example is standing in 30 mph winds will make you much colder than 3 mph winds.
A local higher pressure makes no sense, it defies the laws of physics.
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Joined: 1/2/2019
Location: Merced, CA USA
sandman768 wrote:
Rebuilding my 88 RM250. I have a Cometic head gasket and an Oem Suzuki gasket that has been superseded, but according to Suzuki is correct. Question? Why would the superseded Oem gasket block off water passages on the Right/water pump side? Cometic on the left, Updated Oem center with "E" facing north & the old one I removed.
The rule of thumb is you look for the name on the head gasket and it faces you when you put it on. At least with my experiences with head gaskets that's always how it was. I wouldnt want my ports blocked at all
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