OzVMX Forum
Marque Remarks => Yamaha => Topic started by: Tahitian_Red on March 31, 2009, 09:29:07 am
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(I posted these in the Competition section also.)
Here are two interesting bikes seen at the Brad Lackey Nor Cal Classic for the Yamaha guys.
Gary Jones' personal vintage racer.
(http://www.post-vintage.com/images/NCC_JonesYZ.JPG)
A ProFab Yamaha RD motocrosser
(http://www.post-vintage.com/images/NCC_ProfabRD.JPG)
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hmmmm late model YZ pipe butchered to fit looks pretty hideous, I have seen a couple of US YZs like that.
The pro tec twin just got a good write up in VMX magazine, gearing was a little off apparently.
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That little profab bike is in thr current VMX. I'm not too sure about that fat pipe on Gary Jones YZ though. The photos are great Red. Any more? It looks like Marty Tripes has dropped a few pounds as well. Lets hope it continues, I'm sure we'd all like to see the big fella back on a bike.
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HE should be nuetured for putting that pipe on. l
ooks bloody hideous
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you guys all missed the point it is his race bike.the rules in the usa are a little different.i can tell you if the pipe didnt work for gary jones it would not be on.its no 100% resto or garage queen.you can even use snail pipes if you like.a lot of czs have them
cheers
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That RD powered thing is very cool bit of kit
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YEH
but i bet the bike is very quick just like its rider.they just turn a blind eye??? thats how you can run snail pipes on czs pre 75
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NAh i got the point alright jim, but do you ?
The point was and still is, it looks shitful,
i also dont care what you can do AHRMA or if Gary Jones shits factory turds, that thing is just an ugly SIN on that bike and he still needs to be Neutured for doing it, its abhorant :(
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thats why its a fee world put what you like on your bike.each to your own.i have had tm enduro bikes and ktm they have similer pipes i like them.also i like getting the best out of a 2 stroke,if thats what it takes go for it i say.
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Wow guys! I didn't mean to get a brawl started. ;D
I actually agree with both of you. I hate the few YZ's I've seen using those modern "Fatty-LowBoy" pipes (I would call myself a purist, not like Firko, but almost), but Gary Jones' dad Don invented the the 1974 YZ for Yamaha, so I think I'll cut him a little slack. If you take away the pipe it may be the stockest looking YZ250A I've seen at the track! I see bikes with crazy paint jobs or too blinged out and think I wouldn't have done it that way, but hey it makes them happy.
Gary doesn't race AHRMA and was only there for the exhibition race, although he did take it out for one moto I think.
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OK ok ill lower it to a sucks arse. But if its all about getting more out of 2 strokes then heck jim why not put a set of decent shocks on it, fat bars and risers, a gripper seat, extended swing arm and a plastic tank ? i mean where do you stop, all of the above would turn that bike into a joke.
i have one word. Posin liL' ( well thats 2 words, but tell me im not crazy right)
Red, thanx for the photos, wasnt that twin banger the one up for sale a while back ? didnt go for that much if i remember rightly
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they just turn a blind eye??? thats how you can run snail pipes on czs pre 75
Jim. I was around in the pre 75 period racing CZs and other bikes and snail pipes were around then. A friend of mine has one on an Ossa Phantom that's been there since 1974 and another mate has an Aaen Engineering one made for a 1974 Maico. If you go through the pre 1975 American magazines you'll find snail pipes as early as '73 or even earlier.
Even though I agree that Gary Jones and other legends should be cut some slack, I reckon he'd be setting a better example and also creating a better legacy to his dad by running the YZ in reasonably stock trim. Lets face it, he doesn't need a fat boy pipe to win races.
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I have seen other USA bikes running similar pipes so a bit like other places, they are happy to have people turn up and not racing for sheep stations.
Look on the bright side, you can spent the rest of your life saying you could have won if that bloody guy on the YZ hadn't cheeted. ;D One great thing about VMX is there is always a good excuse for riding badly.
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Here is Jones' YZ from the other side. Like I said, if you take away the pipe it looks like a "Time Warp" racer. I'm sure the porting and compression are not stock, but everything else looks the way it did in 1974. I've seen two other YZs, two Hodakas and one Phantom with those pipes and I still don't get it. It seems like you could build a pipe with close to the same specs and performance that would look closer to stock or like a factory pipe from the correct era. Maybe it's more psychological than anything by making the competition think you are running something really trick?
(http://www.post-vintage.com/images/NCC_JonesYZ2.JPG)
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With the seams that is a later production pipe rather than a custom pipe - anyone recognise the pipe?
I agree, it really does spoil the appearance of the bike. I wonder if its worth the gain?
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I can't imagine a production pipe from an engine with totally different bore, stroke, porting, carb, ignition and cooling system, being the best pipe you could put on YZ-A.
So I'm not sure why 'psyche out value' a clearly wrong pipe has? Maybe "Hey! Better stay away from me on the track, cause my eyesight is so bad that I put this abomination on my bike! I'll probably take out half the field in the first corner without even noticing, Mr Magoo style".
(none of which is intended to be a personal slur on Gary Jones, who is clearly a legend - just one lacking in taste, it would seem).
Surely a designed-for-YZA pipe would be the way to make it go best, and then you could make it look a lot better.
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Keep the photos coming Red, have you got any of the Legends on the track? Who gives a f#*k about what pipe Gary Jones is running, it's not in our back yard so it's not an issue. I don't like the look of it either but if it didn't work he wouldn't use it, he's smarter than the average backyard tuner. Snail pipes were around in '74 and they do use them in vmx in the US.
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yes he is smarter than the average tuner.mybe it is inside yz250 2008 spec.when i used to road race there was a 125 bsa bantam with yz125 yamaha inside.back then no one cared about is elebility.this was about 1981/82.
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oh I think you can make a lot of internal changes but is it cricket,
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I personally think the pipe on Gary's bike is cheating and regardless of how well it works and how much respect I have for him it borderlines insanity rather than absolute brilliance. It isn't vintage and simply does not belong and infact is detrimental to the sport. Yes, I maybe a purist but modern technology and design parts simply do not belong anywhere near a vintage bike ;)
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you could build a pipe or use late 70s YZ pipe the original position easily anyway, they were just being lazy, looks like CR pipe.
back to playing with those motors, I just ported my MX250 and added new slightly larger carb, boyesan reeds, its the same basic engine setup I used on IT250H that went like hell.
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Sounds good Marc. Are you gonna race it?.
The MX was a very good but underrated engine of the day. Obviously had a lot of potential as well. With a 34mm carb, the back of the piston cut away and the Webco head mine use to blow away Elsies (which were the benchmark of the time) at Nepean's main straight - two bike lengths every time ;D. But then it might have been the rider as well ;).
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Sounds good Marc. Are you gonna race it?.
The MX was a very good but underrated engine of the day. Obviously had a lot of potential as well. With a 34mm carb, the back of the piston cut away and the Webco head
Exactly, i see no reason why the MX250 shouldn't haul and it is easy to get parts for. I hve 34mm carb on it already, looking for Webco head, do you have details of the piston modification.
BR Marc
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back to that pipe on the yz it isnt the only 1 in the usa to have it.vmx mag no 28 2006 page 50.the pipe is from 1998 yz250 noleen.also this bike has been ported to go hence the pipe quote the power that this bike puts out is amazing though it comes with a price.the power band is narrow and ther is very little power down low.
jim
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Sounds good Marc. Are you gonna race it?.
The MX was a very good but underrated engine of the day. Obviously had a lot of potential as well. With a 34mm carb, the back of the piston cut away and the Webco head
Exactly, i see no reason why the MX250 shouldn't haul and it is easy to get parts for. I hve 34mm carb on it already, looking for Webco head, do you have details of the piston modification.
BR Marc
They were pretty staightforward 'home brew' mods. We started moding the OEM Dykes Ring MX pistons. We started by filing and opening up the original holes in the back of the skirt. After use we noted cracking. Not wanting a catastrophic failure we thought 'why not cut away the back of the piston entirely?'. Which we did. Just hack saw the skirt away and trim up and chamfer with a file. We timed the piston so that the port was fully opened all the time relying on the reed to keep the charge in the cases.
We were concerned about the resulting extra tilting, thrust and accelerated wear but we countered that by frequent piston replacement. For this reason we swapped to using DT pistons. In the day they were about 1/3 the price of the 'race' MX pistons.
In this configuration the motor did MX, D/track, club road race and enduro without failure. It run the Castrol Nepean Six Hour and was second in class before my 'know better mechanic mate' took the ride and did clutchless gear changes expiring the bike with a blown third gear before it was to be handed back to me ::). It was fast and reliable.
Mind you, Yamaha pretty much did the same thing with the later model pistons.