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Motocross Star/Valli Yamaha 250F's putting out over 50hp.....WOW

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Read on twitter feed a discussion about the Yamaha boys bikes and JT$ mentioned that they are pushing over 50 pony's......damnnnnnnn

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If that's true, it's amazing they last two motos

The PC Kawi's were rumored to be at 47 a couple of years ago

Edited by meyermetal
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they are likely doing it with lots of RPM. they could hit that if they are reving to 17k+

 

Not a recipe for longevity tho. 

 

do you have a link to any evidence or just twitter info?

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If that's true, it's gotta be ready to grenade by the end of the moto.

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Who knows, it's possible. I know the Factory bikes overseas don't have the restrictions that AMA racing has, but the '13 Cosworth YZ250Fs supposedly put out over 50hp, 3spd gearbox etc etc. So who knows what these high-level teams are doing with this new motor. I personally think the '14 YZ250F is the best stock 250F motor I have ever ridden, hands-down. So those Star/Valli bikes are probably unreal, as it is pretty obvious by the results. In saying that, I honestly don't think it is just the bike that turned JMart around. Last year's Nationals the 2nd half of the series, he was by far the best rider out there who wasn't Eli or Kroc. They are gone, JMart has another year of experience and is on a likely better bike. Webb too had a few flashes last year where he looked awesome. He's a year better, smarter etc. Either way, great to see those guy (and bikes) up front.

Edited by ah665
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I think it was the May issue of MXA they had a YZ250f project bike they had Pro-circuit do the engine mods to that put out 44hp. I think it had a little headwork, cams, exhaust, and a high comp. piston that's all. Stuff any of us could buy if our pockets are deep enough. Sending the head to P.C. was probably the most expensive part. So who knows what a race team with factory support could squeeze out.

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Who knows, it's possible. I know the Factory bikes overseas don't have the restrictions that AMA racing has, but the '13 Cosworth YZ250Fs supposedly put out over 50hp, 3spd gearbox etc etc. So who knows what these high-level teams are doing with this new motor. I personally think the '14 YZ250F is the best stock 250F motor I have ever ridden, hands-down. So those Star/Valli bikes are probably unreal, as it is pretty obvious by the results. In saying that, I honestly don't think it is just the bike that turned JMart around. Last year's Nationals the 2nd half of the series, he was by far the best rider out there who wasn't Eli or Kroc. They are gone, JMart has another year of experience and is on a likely better bike. Webb too had a few flashes last year where he looked awesome. He's a year better, smarter etc. Either way, great to see those guy (and bikes) up front.

Couldn't agree more that it's not just the bike. JMart's corner speed was noticeably faster all day.

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If that's true, it's amazing they last two motos

The PC Kawi's were rumored to be at 47 a couple of years ago

How do you know the motors don't get swapped out between motos?

Is JGR building the motors?

Edited by Kev_XR

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How do you know the motors don't get swapped out between motos?

Is JGR building the motors?

For what it is worth, PC motors supposedly have a 2hr lifespan, according to MXA on AC's bike.

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How do you know the motors don't get swapped out between motos?

Is JGR building the motors?

I'd bet they are. 

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How do you know the motors don't get swapped out between motos?

Is JGR building the motors?

I guess they could be swapping engines

250 racing is already expensive....more than 450's....and they would be raising the bar

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Lets say the motors are good for two hours, a moto has to be at least 40 minutes of time once you take in the sighting lap into it. I doubt they'd let a motor that is only good for 2 hours go to 1.5, seems risky. And with actual practice you know they aren't riding all day on one motor. 

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I wonder what makes them last such a little amount of time, really tight clearances/compression?

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How do you know the motors don't get swapped out between motos?

Is JGR building the motors?

 

 

No.

And while I do think 50 is possible within 3-4 years, I don't think on "most dynos" they are at 50 yet.

46-47  at 12k or so holding flat power till 14500 rev limiter while making about 23 lb/ft of torque at 8000 rpm is about the "best" out there yet.

 

the moto3 engines are close to 50 on that scale but have less torque and are too peaky for a good moto engine.  If you listen closely to the star bikes they are able to lug down very low in the rpm and pull hard. This is probably their advantage over the field - making more torque earlier in the powerband which wins starts and drag races turn to turn also making them easy to ride with less shifting (more 450 like)

 

On an engine dyno 50 hp is very likely already.

 

Our best yamaha makes peak torque a full 1000 rpm earlier than any other race bike we build - and on the track this equates to a bike that yanks your arms out coming out of turns.  In order to chase down the big power numbres the new yamaha requires bigger buckets both intake and exhaust to get lots of cam lobe.

 

IMHO the fastest bikes this year at the pro level are the yamaha's followed very closely by the hondas then with ktm making as much peak power as both but less torque followed by the pc bikes.

The kawi head is just total shit to start with for making huge power. Unless kawi redesigns the location of their head bolts and goes to a much steeper down draft - their engine package wont be able to match both the power and torque of the honda and new yamaha. The pc bike will make the torque - or the hp - but not both due to cam design having to make sacrifices for the poor head.

The ktm valve train is rock solid to 15k on a stock bike - at the factory level I wouldn't doubt they can spin it 16500 if desired.  If they make head improvements - their engine IMHO due to it's finger follower cam design will be untouchable in power.  

 

 

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I wonder what makes them last such a little amount of time, really tight clearances/compression?

Spinning at speeds turbines run. (well not really)

12,000 rpm or 200 revolutions per second. Mind boggling really.

Any oil break down and the engine is gone.

Detonation from lean gas air mixtures.

Not to mention valve float.

Does the AMA have a rev limit yet? I can see that coming when 250F bikes start blowing up like the old 125s.

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Big deal, I gotta a blender from Costco that puts out at least that much

Edited by Bobby_Treen
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they are likely doing it with lots of RPM. they could hit that if they are reving to 17k+

 

Not a recipe for longevity tho. 

 

do you have a link to any evidence or just twitter info?

 

Just what i read on twitter. A discussion between JT and Keefer. Daniel Blair said he knows for a fact that Pourcel's bike is putting out over 50. JT said he heard the blue bikes are pushing 50-52HP.

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How do you know the motors don't get swapped out between motos?

Is JGR building the motors?

 

No, They JGR doesn't build their motors. Brad Hoffman has built them in house for a while but had help from Cosworth this year with the new design. He says the bike doesn't make huge horsepower compared to last years bike, he said the team is just better prepared. He also says the new head design helps it make better power at lower revs.  

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Just what i read on twitter. A discussion between JT and Keefer. Daniel Blair said he knows for a fact that Pourcel's bike is putting out over 50. JT said he heard the blue bikes are pushing 50-52HP.

 

 

On what dyno???

That's always the "question"

On an engine dyno it's possible to be at 50 with what we call 45-46 horse bikes.  On a buddies rear wheel dyno the a GP winning 250f last year made 38hp.

On a different "rear wheel" dyno it makes 47hp. 

It's pissing contest to see who can claim a higher number.  Whats more important is which bike wins starts and turns fast lap times.  Big hp number dont accomplish this - I build 45 horse two stroke 144's that make more power down low and rev farther than stock and are up 10hp from stk.  Sounds great on paper.  But over 5 laps with identical riders a 40 horse 250f will kill it in lap times. 

 

The statement above of more low end is why they are getting such good starts and so fast around the track.  the hardest a bike pulls in ANY gear ISN'T at peak hp.  It's at peak torque.  So if you make peak torque better and/or earlier - the bike accelerates faster.

 

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