OzVMX Forum
Clubroom => General Discussion => Topic started by: Boyracer on November 24, 2014, 08:10:58 pm
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Just wondering are modern two stroke MX bikes really better than say a CR250RF 85 model?
Do modern engines really make more or better power than water cooled engines from back in the day?
From what I can work out there doesn't seem to be much of a power advantage, sure suspension technology may have improved but a good rider on a VMX should be able to be competitive with the modern iron.
Any thoughts?
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2 strokes do produce power
i have a cr500 which i love to race flat track
the power is exillerating
4 strokes have engine braking
2 strokes do not
end of debate
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Just wondering are modern two stroke MX bikes really better than say a CR250RF 85 model?
Do modern engines really make more or better power than water cooled engines from back in the day?
From what I can work out there doesn't seem to be much of a power advantage, sure suspension technology may have improved but a good rider on a VMX should be able to be competitive with the modern iron.
Any thoughts?
Wondered that myself.
Looking at videos of early 80,s 500cc World championships they look to be insanely fast.
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IMO, modern 2 stroke dirt bikes do have better power than say the mid eighty's. But a fully sorted mid 80's 250 compared to a run of the mill modern 250 will probably perform better, but not for longer.... I do hear that a late model yz250 is quite well squished and tuned off the floor though...
Brett
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the 300 ktm is a bit sharper than the 400 husky. the powervalve allows its useful range to run from idle or less RPM to 7000 (I think that's about where they sign off.)
the 400 will match it in a drag race (must check this, its a gut feel statement). the 400 will fluff out and die at about 1000 rpm under strain. just wont pull cleanly and is quiet till its gets some velocity in the intake.
the broad spread of the kato engine is definitely better and easier to ride than the 400.
in answer to the question I say yes, the engines are better but I don't thinks there is any more power (of a significant amount!)
the brakes are the biggest advantage and will always see a modern hammer a old dunger on a track although watching the number of "over the bars and tuck unders" on utube, I don't believe the geometry of the modern fourstrokes is better than the older bikes. Much more steady and easy to ride than the new "nervous nellies"
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Yes, new ones are better.
I've got a 2013 Beta 300. Straight out of the box, it has excellent jetting, beautiful power curve, plenty of power, it hardly vibrates, it always starts, and it's still like new with 1,500km on the clock.
That's stock.
An 80s 500 will outrun it in sheer grunt, but is a complete pig to live with in comparison.
A properly built 86+ CR250 would probably be in the same league, but only after you've replaced and/or modified the carb, ignition, exhaust, head, piston, barrel - basically by turning it into a modern motor... You still would be stuck with a much more difficult-to-live with power valve, no electric start, and more vibes.
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Old bikes can be competitive with moderns. But as an all-round, do it all regardless of conditions race bike, you would ALWAYS pick the modern.
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Modern bike makers have realised that they have built in too much rigidity in their frames and are actually going backwards to put more flex in them.
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Modern bike makers have realised that they have built in too much rigidity in their frames and are actually going backwards to put more flex in them.
Very common comment re rigidity when watching mx Dungey on the KTM (not as harsh on the body as the jap bikes)
Many riders comment the flex/feel of frames.
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Twin spar aluminium frames don't work for 2T dirt bikes. They're semi-OK for 500s that have the extra weight and torque, but if you think of a 2T dirt bike that handles well, it probably has a steel frame...
But the question was about motors rather than the whole package.
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Modern bike makers have realised that they have built in too much rigidity in their frames and are actually going backwards to put more flex in them.
Very common comment re rigidity when watching mx Dungey on the KTM (not as harsh on the body as the jap bikes)
Many riders comment the flex/feel of frames.
Isn't that why KTM has stayed with steel frame.
Try that CR in a modern frame. ;)
Cheers us2
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I have raced a 2011 yz250 and 1982 husky 250 on modern tracks for 3 years and the big difference is when you get out of shape on the modern bike it more often rides out of it safely but when you get out of shape on the old bike its all over!
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A couple of years ago (2010) I had a 10 Ktm 250 sx and a 86 Husky 250 and nothing on the Husky even came close. Rear suspension on the Husky was good, but that's about it.
Far as I'm concerned they are chalk and cheese.
2012 I had a 87 cr 250 and a 2013 Ktm 300 exc, again same deal, the Honda was a much better bike than the Husky, but neither can compare to a modern.
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My observations are that modern 2T bikes do have the edge in all engineering and mechanical departments. They just don't have the "quaint quirky" looks of old ones.... ;) Tim754
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A couple of years ago (2010) I had a 10 Ktm 250 sx and a 86 Husky 250 and nothing on the Husky even came close. Rear suspension on the Husky was good, but that's about it.
Far as I'm concerned they are chalk and cheese.
2012 I had a 87 cr 250 and a 2013 Ktm 300 exc, again same deal, the Honda was a much better bike than the Husky, but neither can compare to a modern.
It would also appear I can time travel....
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"It would also appear I can time travel...." or perhaps multitask Evo like drink beer whilst ya type ;) Cheers and crack another!
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Yep, bottoms up, it's Monday night....
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Yes.
The big advances come mostly from ignitions and power valves. The new 300's are just great motors.
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Modern materials, electronics, CAD/CAM design and manufacture last but not least the benefit of knowing what not to do. Unfortunately in dirt bikes only a tiny fraction of the past 10 years of two stroke engine development has been applied.
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Yes of course they are better, but they haven't had the development the four strokes have had. But I don't think we want that. More development means more cost.
I rode a 2014 YZ125 at CD10 and I was very surprised by how good it was even down low.
The SCBs need to re-introduce a 125 clubman class. Bring back cheaper MX.
Apparently KTM have fuel injection for the two strokes but don't want to bring it in because of cost.
Also please note the last two stroke to win the 500 MX Champs was only a 360. 500s were just too much.
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I have a modern 250 2t, it's super light weight, goes unreal & is extremely civilized & easy to ride. The big bonus is I'm not rooted at the end of a long day by fighting a heavy 450 4t. Having said all that last time I timed myself on a new bike against an old bike (1980 Husky CR390), I was only 3-4 seconds a lap slower on the old girl. I'm sure it was only the brakes that made the difference.
K
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I jumped off my 1993 CR250 straight on to a new YZ250 and I found the biggest difference was the frame. It's amazing how rigid the aluminium frame is. It just thuds into the bumps, where you can really feel the chassis working on the old steel bike. The motors on both bikes were lineball, maybe the YZ has a bit more up top (both motors are fresh). Motocross Action didn't call that year's CR engine the 'Motor of Doom' for nothing (mine is stock apart from a vforce reed block) - it really was head & shoulders above anything else back then. On the downside, in stock form, the suspension on the 93 is complete garbage!
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My '06 KTM 300 much easier / less tiring to ride through the bush all day ( perfect mid sized capacity & power ) compared to my ( '83 mod) 250 , 490 & 500 cc 2str enduro bikes
but the older bikes have much nicer (comfortable) seats ;D
Regards ,
Steve
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Yes of course they are better, but they haven't had the development the four strokes have had. But I don't think we want that. More development means more cost.
Apparently KTM have fuel injection for the two strokes but don't want to bring it in because of cost.
Development costs are amortised over the model run , history has proven we are happy to pay for improved performance and an overall "better bike". The cost of a injected KTM can't be the issue as hardware is the same as 4T, that story has only been doing the rounds since 09, but we never see the bike.
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http://twostrokemotocross.com/2008/12/worlds-fastest-dirt-bike/
http://www.bioflexbeast.com.au/inspiration.html
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Willing told me whilst working for KTM that they tested some different types of FI on the 300.
He implied cost being the main factor in it not being fitted. For those who dont know Willing worked in the R&D after the failed Moto GP project and designed the linkage rear suspension used today.
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Sherco have a fuel injected 300 proto type and a video.. https://www.youtube.com/watch?v=j-hTHqF_KeE
I raced my AE500 and WR300 a couple of weeks ago....the WR is more civilised.
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Modern bike makers have realised that they have built in too much rigidity in their frames and are actually going backwards to put more flex in them.
and
Has always been the problem with Alloy frames. I set my '97 CR250 up with a set of conventional forks off a RM250 and it turned in to a much better feeling and performing bike.
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Sherco have a fuel injected 300 proto type and a video.. https://www.youtube.com/watch?v=j-hTHqF_KeE
I raced my AE500 and WR300 a couple of weeks ago....the WR is more civilised.
The Sherco prototype somehow sounds fatter but yet more sharper off idle than the carb bike. I wonder if the injection toned the documented aggressive nature of the carb bike?
Having owned a '04 and an '06 KTM300, I can honestly say that if I was to ever buy another new 2st, a 300 would be my choice. They are so easy to live with. The power delivery is incredible. It can be ridden a gear higher up snotty hills etc without having to rev the thing in an attempt to stay on the pipe and then it has enough top end to scare the pants off of any 450st. They really are the 3stroke dirt bike.
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I set my '97 CR250 up with a set of conventional forks off a RM250 and it turned in to a much better feeling and performing bike.
I have a 93 CR250 with a set of 86~89 RWU forks in it, with 93 125 triple clamps (less offset) & adaptors. I barely rode it with the (corroded) 93 USDs, but with the RWUs, it is brilliant: it turns well, and has none of the headshake these bikes were known for.
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http://twostrokemotocross.com/2008/12/worlds-fastest-dirt-bike/
http://www.bioflexbeast.com.au/inspiration.html
speeds at Bonneville are 20-30mph more than Lake Gardiner, 132 for a KX without a fairing is very good.Willing told me whilst working for KTM that they tested some different types of FI on the 300.
He implied cost being the main factor in it not being fitted. For those who dont know Willing worked in the R&D after the failed Moto GP project and designed the linkage rear suspension used today.
Last I heard Warren was a bit crook ???
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There is a manufacturer out there with both a 125 & 250 smoker that was developed many years back that had all sorts of trick stuff and at a certain gnarly track in the middle of Un Zud the 125 was blowing away the 250Fs of the day quite easily and the 250 smoker made the 450 compressor look decidedly slow.
I didn't get a close look at the 125 plant, but the 250 was 4 point injection with 2 spark plugs. Injection and ignition were fully programmable independently from a laptop and only took seconds to achieve. There was also the ability to adjust the power valve if I remember correctly.
There was some other trickery they played around with such as air forks & shocks but they were just separate testing. Interestingly enough the frames were perimeter steel & not alloy.
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http://twostrokemotocross.com/2008/12/worlds-fastest-dirt-bike/
http://www.bioflexbeast.com.au/inspiration.html
speeds at Bonneville are 20-30mph more than Lake Gardiner, 132 for a KX without a fairing is very good.Willing told me whilst working for KTM that they tested some different types of FI on the 300.
He implied cost being the main factor in it not being fitted. For those who dont know Willing worked in the R&D after the failed Moto GP project and designed the linkage rear suspension used today.
Last I heard Warren was a bit crook ???
Yes sadly Warren is in the wars health wise. Haven t had a update for a few weeks but was still in hospital last I heard.