Ec 300 (wec) Is It True ????

[Jim Cook]

Originally Posted by gasser

The 250 and 300 have the same stroke and there is no difference in the bottom end components. The 200 shares most of the parts with the bigger bikes but not all. A 250 can easily be made into a 300 by just replacing the top end (I've got an 01xc300 top end on my 07ec250).

There was talk in one of the forums about a "275" gasser. If I remember right it was one or more bikes modified by the French TEAM for racing in the ISDE.

Good Day everyone!
You were quite correct in your 250-300 statement above.

Re: the "275" gasser.
We made several 274cc Gassers out of 250cc bikes. We would take a cylinder slated for repair, and send it, the head, and a 14th oversize Wiseco piston built for the TRX250R Honda quadracer to the cylinder repair business.
They would bore the cylinder to work with the oversized piston, and then coat the cylinder bore with their version of "nikasil" and hone the cylinder to match the piston for proper clearance.
They would build up and then machine down the head to match the new bore.
The piston kit we used was the Wiseco 526M06950. You can tell by the designation that it has a 69.5mm diameter, instead of the normal GG 250 size of 66.40 (minus a few hundreths) Wiseco kit #849M06640 Roughly 3.1 mm larger in diameter.

One more thing... the exhaust valve "flapper" had to be trimmed a bit to keep it away from the larger piston.

We also did this to several Honda CR250R bikes.


Good Riding!
Jim

[Fred1956]

Originally Posted by Jim Cook

Good Day everyone!
You were quite correct in your 250-300 statement above.

Re: the "275" gasser.
We made several 274cc Gassers out of 250cc bikes. We would take a cylinder slated for repair, and send it, the head, and a 14th oversize Wiseco piston built for the TRX250R Honda quadracer to the cylinder repair business.
They would bore the cylinder to work with the oversized piston, and then coat the cylinder bore with their version of "nikasil" and hone the cylinder to match the piston for proper clearance.
They would build up and then machine down the head to match the new bore.
The piston kit we used was the Wiseco 526M06950. You can tell by the designation that it has a 69.5mm diameter, instead of the normal GG 250 size of 66.40 (minus a few hundreths) Wiseco kit #849M06640 Roughly 3.1 mm larger in diameter.

One more thing... the exhaust valve "flapper" had to be trimmed a bit to keep it away from the larger piston.

We also did this to several Honda CR250R bikes.


Good Riding!
Jim

Jim, Did this setup yield the desired results? And what were the desired results? Grunt of a 300 with the hit of a 250? or....? Thanks

[coopernicus]

Fred1956,

I have Boomhauer's/Nambotin's GG 275 from the 2007 North American WEC rounds and, to me, it bridges the gap between the 250 and the 300 right down the center. It's made from a 300 bottom end and a 250 topend (so I'm told as I've only had it a short time). Everyone who rides the bike here in Colorado wants it as they love the power and delivery. I'm big (235lbs) and here's my impression: Early in the ride I wish I had a little more power down low but halfway through the day I'm glad there is no more power. Like all GGs it runs like it will never stall, the gearing spacing with the power is perfect, and there is less vibration than my 300. It does rev a touch quicker than the 300 but it seems to have the same rev ceiling. There you go, if you have any questions, let me know!

Eric

[dlf]

I have a 2011 cc300. I am finding a bit if a handful even with a flywheel weight fitted. Reading this topic about common components shared between the 250 and 300, is it possible/easy for me to convert my 300 to a 250? If it is possible what components would i require to change and would I have to re-jet?

[twowheels]

Originally Posted by dlf

I have a 2011 cc300. I am finding a bit if a handful even with a flywheel weight fitted. Reading this topic about common components shared between the 250 and 300, is it possible/easy for me to convert my 300 to a 250? If it is possible what components would i require to change and would I have to re-jet?

Assuming OE GasGas cylinders and Woessner piston kits the breakdown is as follows >>> Going from a 250 to a 300 would cost ~1300 USD, while dropping from a 300 to a 250 would cost on the order of 1050 USD. You need to add the cost of an outer o-ring if your stocker is bad and the appropriate base gaskets.

[rgranger]

Hey Eric,
you one of the guys we road with that bought Robby's bike? I had the loaner yz250. I should be sending my check to hall's for my GG next week
Cheers,
Rob

Originally Posted by coopernicus

Fred1956,

I have Boomhauer's/Nambotin's GG 275 from the 2007 North American WEC rounds and, to me, it bridges the gap between the 250 and the 300 right down the center. It's made from a 300 bottom end and a 250 topend (so I'm told as I've only had it a short time). Everyone who rides the bike here in Colorado wants it as they love the power and delivery. I'm big (235lbs) and here's my impression: Early in the ride I wish I had a little more power down low but halfway through the day I'm glad there is no more power. Like all GGs it runs like it will never stall, the gearing spacing with the power is perfect, and there is less vibration than my 300. It does rev a touch quicker than the 300 but it seems to have the same rev ceiling. There you go, if you have any questions, let me know!

Eric

[Fred1956]

Originally Posted by coopernicus

Fred1956,

I have Boomhauer's/Nambotin's GG 275 from the 2007 North American WEC rounds and, to me, it bridges the gap between the 250 and the 300 right down the center. It's made from a 300 bottom end and a 250 topend (so I'm told as I've only had it a short time). Everyone who rides the bike here in Colorado wants it as they love the power and delivery. I'm big (235lbs) and here's my impression: Early in the ride I wish I had a little more power down low but halfway through the day I'm glad there is no more power. Like all GGs it runs like it will never stall, the gearing spacing with the power is perfect, and there is less vibration than my 300. It does rev a touch quicker than the 300 but it seems to have the same rev ceiling. There you go, if you have any questions, let me know!

Eric

Thanks Coopernicus, I have the '274' cylinder and I'm pretty sure I'm putting it on my 250, just wondering what to expect

[cyclecat]

I wouldn't care if the 300 had a 50 cylinder on it, I love it!

I have a 2011 EC 250 that is awesome. But had I known how smooth the 300 was compared to a KTM, that's what I would have gotten.


dlf, I'll trade you my 250 for your 300.