High Compression Head
- Thread starter gasIdaho
- Start date
The part number you just posted is the same number that is cast on all 250 and 300 gasgas heads (2001 and later) that I have seen to date.
Ron
Hi gasIdaho,
I am not really sure about the numbers my self. A long time ago I wrote the numbers that were on a gasgas 250 head that I was working on (thinking that there were different numbers between the 250 and 300's, but not so).
Every time I do head work on the gasgas, I will compare the numbers. Each time they read ME25-3091600 and it does not matter if it was a 250 or a 300. I have always assumed that the cast in number was just that, a casting mold number.
The 250 and 300 heads are the same casting as far as I can tell, they are naturally machined differently.
It will be nice to hear how the new head works.
Ron
I am not really sure about the numbers my self. A long time ago I wrote the numbers that were on a gasgas 250 head that I was working on (thinking that there were different numbers between the 250 and 300's, but not so).
Every time I do head work on the gasgas, I will compare the numbers. Each time they read ME25-3091600 and it does not matter if it was a 250 or a 300. I have always assumed that the cast in number was just that, a casting mold number.
The 250 and 300 heads are the same casting as far as I can tell, they are naturally machined differently.
It will be nice to hear how the new head works.
Ron
GMP
Active member
Ron is correct. I have an '07 250 and an extra head from a '02 XC250. The '07 has slightly different machining on the top of the head for clearance using 13mm hex bolts rather than cap screws. Both heads are ME25-30916000, its the same casting. There are high compression heads, and likely yours is one. Measure the squish band width, I was told the the hi comp heads are cut narrower than the standard EC heads, on the 250s anyway.
iancp5
New member
Guys,
Surely they would not have the same part no. unless they were the same part! Even if they're machined differently they would have to be marked differently - how would you order a spare? It makes no sense - it would even be confusing at the factory. An order arrives from the sub-contractor or head making department and no one knows what bike they are for! I can see the delivery note: "Heads for some GasGas or other"!
I can understand how there might be one number the same but there must be something else to easily separate them.
Surely they would not have the same part no. unless they were the same part! Even if they're machined differently they would have to be marked differently - how would you order a spare? It makes no sense - it would even be confusing at the factory. An order arrives from the sub-contractor or head making department and no one knows what bike they are for! I can see the delivery note: "Heads for some GasGas or other"!
I can understand how there might be one number the same but there must be something else to easily separate them.
If you have both GG heads in your hand you can measure down from the lip on the outside to the machined surface and see which head is which. I think its about .025 difference. My heads I had were the same part# on the top but one was machined more than the other. Don't know if this was stock or someone did the work. But fairly easy to tell which one will have more compression.
Hi, I bought an MC250 head which has catalog part number MC250116000 printed on the packing with CR 250 2001 also printed, while the casting has ME25-30916000 molded on the head. I'm about to change my stock head and I'll check out the differences on squish width and compression and of course the added performance.
I justs opened up my top end for a piston change (about 70 hrs) and had a good look at the difference between the standard EC head and the new MC head I have bought.
Well to my suprise the MC head had a norrower squish width (about 8mm while the EC head has a width of around 13mm!), the same deck height (3mm) and a larger combustion volume compared to the EC head.
I think I'll just keep the EC head and use one 0.5mm base gasket to increase the bottom end. The factory had one 0.5mm and one 0.3mm gasket!
What is your opinion? Is the MC head shaped to increase the hit or what?
Well to my suprise the MC head had a norrower squish width (about 8mm while the EC head has a width of around 13mm!), the same deck height (3mm) and a larger combustion volume compared to the EC head.
I think I'll just keep the EC head and use one 0.5mm base gasket to increase the bottom end. The factory had one 0.5mm and one 0.3mm gasket!
What is your opinion? Is the MC head shaped to increase the hit or what?
GMP
Active member
All other things being equal, the narrower squish would favor top end. However, its all about effective squish. If the head is cut so that the squish angle does not match the piston dome close enough (higher clearance toward center of head), and the clearance is high overall, a wider squish band will have a narrow effective squish.
Thanks GMP,
Comparing the squish angle, they are equal so I went ahead and kept the original EC head but put in one .5mm base gasket. I still have to run the piston and rings doing a few heat cycles before I can see any difference in the bottom end.
As you stated the MC is shaped for more top end power, how would it compare with the EC head for bottom to mid pull?
Comparing the squish angle, they are equal so I went ahead and kept the original EC head but put in one .5mm base gasket. I still have to run the piston and rings doing a few heat cycles before I can see any difference in the bottom end.
As you stated the MC is shaped for more top end power, how would it compare with the EC head for bottom to mid pull?
