How often are 250/450 race engines rebuilt?

teggers
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5/20/2017 3:21pm
I know as a vet rider, I would go in entire season without worrying about it, but these guys are running the piss out of these bikes.

I almost wonder if they just replace the engine between Moto's or do you have to have the same serial number for both Moto's.

What's the cost of a "Refresh" these days? And what's included?
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rmoto003
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5/20/2017 3:24pm
pretty sure they can change the engine out as much as they need to between motos and stuff, just the frame has to be the same

5/20/2017 3:32pm
On the recent racer x video when they tested the traders Yamaha they said there Race motors are 5 hour engines and practice motors are 15 hour engines
adjentleman
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5/20/2017 3:39pm
teggers wrote:
I know as a vet rider, I would go in entire season without worrying about it, but these guys are running the piss out of these...
I know as a vet rider, I would go in entire season without worrying about it, but these guys are running the piss out of these bikes.

I almost wonder if they just replace the engine between Moto's or do you have to have the same serial number for both Moto's.

What's the cost of a "Refresh" these days? And what's included?
Race bikes every 5 hours, and practice engines every 15.
imoto34
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5/20/2017 3:40pm
On the recent racer x video when they tested the traders Yamaha they said there Race motors are 5 hour engines and practice motors are 15...
On the recent racer x video when they tested the traders Yamaha they said there Race motors are 5 hour engines and practice motors are 15 hour engines
It would be cool to tear down a 5 hour motor vs a 15 hour motor.

I have been under the impression that bikes are pulled down, inspected each weekend and replace parts based of a schedule.

The Shop

wreckitrandy
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5/20/2017 4:05pm
I'd be surprised if PC engines aren't changed every moto and rebuilt every week.
KMC440
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5/20/2017 4:10pm
I'd be surprised if PC engines aren't changed every moto and rebuilt every week.
You'd be surprised then. No one changes between moto's if they don't have to.
CarlinoJoeVideo
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5/20/2017 4:56pm
I'd be surprised if PC engines aren't changed every moto and rebuilt every week.
Race engines on factory teams get done every week. I believe most of them have a few per rider they cycle through. Live seen on a video JGR say they don't have not get torn down but they need to make sure everything is 100%. I'm sure for all of us, we could ride those engines for 25+ hours.
wreckitrandy
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5/20/2017 5:12pm
I'd be surprised if PC engines aren't changed every moto and rebuilt every week.
KMC440 wrote:
You'd be surprised then. No one changes between moto's if they don't have to.
Maybe. I remember Mitch saying that at one point, at one race, they went through every engine they had in the truck.
jaredkeller96
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5/20/2017 5:57pm
I'd be surprised if they replaced more than the bearings and seals every week. id assume they have a few heads they put in rotation. I'd like to see what they are replacing
TXDirt
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5/20/2017 6:00pm
I suspect they swap out motors each week. Each team has multiple motos available. I was told they dont switch out between motos. But I venture to guess they swap it out during the week when rebuilding the race bike.
2thefront
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5/20/2017 6:02pm Edited Date/Time 5/20/2017 6:04pm
They get FedEx'd back to HQ after every race and torn down, inspected and parts changed as needed. Then fedex'd back to the hotel.

Frames get swapped out every 4 races or so.
LumpDog841
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5/20/2017 6:22pm
I'd be surprised if PC engines aren't changed every moto and rebuilt every week.
KMC440 wrote:
You'd be surprised then. No one changes between moto's if they don't have to.
Maybe. I remember Mitch saying that at one point, at one race, they went through every engine they had in the truck.
That was '04 at Southwick, those bikes were garbage. They would have failures, such as breaking the cases.
Racer142
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5/20/2017 7:57pm
A few years ago one of the Magazines tested Blake or dean's championship pro circuit kx250f and they said the motors were designed to last 2 hours. Just long enough for 2 practice sessions and 2 30 minute motos on race day.
SCR
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5/20/2017 10:58pm
Thought I remember reading Mitch say they could get some more power out of the 250s but they start pushing reliability. So they design them to last 5hrs before they blow but tear them down each race weekend. That was a number of years back if I remember.
teggers
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5/21/2017 12:57am Edited Date/Time 5/21/2017 12:58am
SCR wrote:
Thought I remember reading Mitch say they could get some more power out of the 250s but they start pushing reliability. So they design them to...
Thought I remember reading Mitch say they could get some more power out of the 250s but they start pushing reliability. So they design them to last 5hrs before they blow but tear them down each race weekend. That was a number of years back if I remember.
It would be a nice info story to report. I am really interested in the answer.

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