mx factory bikes VS gp factory bikes

doofy
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doofy
Edited Date/Time 8/10/2017 6:09pm
alright, I have a limited understanding of the rules - but as far as I know here in the states the mfg's are limited to using oem cases, frame and swingarm and in Europe its anything goes correct? I don't read too many tests of GP bikes but I wonder how big a difference there is between Cairoli and Herlings KTM vs Marvins.

I could be totally wrong about this, someone smarter than me help me out
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David934
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David934 8/11/2017 2:06am
8/11/2017 2:06am
I think Marvin must have standard oem frame, while Tony and Jeffrey have frames on request (no frame rules)
UpTiTe
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UpTiTe 8/11/2017 6:38am
8/11/2017 6:38am Edited Date/Time 8/11/2017 6:40am
The biggest difference is the frame, on faster tracks the Euros are allowed to use longer frames and on slower tracks with turns shorter frames. They get to have foot Peg placement rake all seat height and other stuff built into the frame.

The other difference is a Transmissions, a lot of the factory bikes use two and three speed transmissions in Europe.

Most American teams don't exactly follow the rules to the T, but they can't outright build a different frame.
Wandell
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Wandell 8/11/2017 7:44am
8/11/2017 7:44am
My understanding is that today, it's the Japanese National series that has the really exotic, one off stuff.
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Rooster 8/11/2017 4:42pm
8/11/2017 4:42pm
Wandell wrote:
My understanding is that today, it's the Japanese National series that has the really exotic, one off stuff.
That's always been the case. Like the 125 twin cylinder ribi lever Hondas. I think the Japanese series is for experimentation whereas a works bike is no place to experiment with stuff that may or may not work right. They have too much invested to lose races due to experimental equipment in a major racing series.

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loftyair
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loftyair 8/11/2017 5:00pm
8/11/2017 5:00pm
Different fuel use also contributes to different engine configs.
kzizok
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kzizok 8/11/2017 6:15pm
8/11/2017 6:15pm
Rooster wrote:
That's always been the case. Like the 125 twin cylinder ribi lever Hondas. I think the Japanese series is for experimentation whereas a works bike is...
That's always been the case. Like the 125 twin cylinder ribi lever Hondas. I think the Japanese series is for experimentation whereas a works bike is no place to experiment with stuff that may or may not work right. They have too much invested to lose races due to experimental equipment in a major racing series.

The American works bikes often had experimental equipment. Heck, the whole bike of the first Yamaha fourstroke was experimental. Disk brakes, radiators and their placements and sizes, low boy gas tanks, frames, carbs, FI, transmissions, etc.
doofy
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doofy 8/13/2017 8:13pm
8/13/2017 8:13pm
I assume the GP guys are allowed to use their one-off equipment in the MXON?
doofy
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doofy 8/13/2017 8:14pm
8/13/2017 8:14pm
loftyair wrote:
Different fuel use also contributes to different engine configs.
I think I remember RV saying he thought the engine package was terrible when he went over there - and attributed it to the fuel used. Is it an octane thing?
scott_nz
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scott_nz 8/13/2017 8:22pm
8/13/2017 8:22pm
doofy wrote:
I assume the GP guys are allowed to use their one-off equipment in the MXON?
yes the rules are MXGP rules, which means different fuel, and more stringent noise regs, along with no production rules,
dilligaf
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dilligaf 8/13/2017 8:56pm
8/13/2017 8:56pm Edited Date/Time 8/13/2017 8:58pm
I'm sure this has been answered many times in the past but a short list:
AMA bikes
production base frame (that can not have material removed only added support)
production base swing arm (a grey area if you ask some)
cylinder, head and case casting need to start life as a production unit
bore x stroke the same as the homologated unit
Transmission needs the same amount of gears as the homologated unit.
Ti axles and pivot are allowed in AMA (not allowed in gp's)

GP bikes
Frame : anything goes
Engine: anything goes displacement needs to be under the CC limit
Steel axles and pivot
Fuel is of FIM motocross regulations (a little more rescrictive than ama).The reality between the two series is the fuel rule is a bit tighter, sound limit is a bit lower and enforced a bit harder. 4 speed transmissions are a bit more common with VERY few using the 3 speed set up as it is tricky and the engine needs to operate in much wider rpm window. As for the engine packages the 250's tend to be a bit more high rpm top end focused in Europe with a bit of focus on keeping the rev's up. Rumors fly all over the paddock on engine set up with bore and stroke figures sounding more like Moto 3 than a MX set up.
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kiwifan 8/13/2017 9:12pm
8/13/2017 9:12pm
UpTiTe wrote:
The biggest difference is the frame, on faster tracks the Euros are allowed to use longer frames and on slower tracks with turns shorter frames. They...
The biggest difference is the frame, on faster tracks the Euros are allowed to use longer frames and on slower tracks with turns shorter frames. They get to have foot Peg placement rake all seat height and other stuff built into the frame.

The other difference is a Transmissions, a lot of the factory bikes use two and three speed transmissions in Europe.

Most American teams don't exactly follow the rules to the T, but they can't outright build a different frame.
'Most American teams..' ...really? Does that imply some are breaking the rules?

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