>>BIKE have dynoed one at over 135bhp at the rear wheel, that's over 150 at the crank
I doubt these figures, although I'm sure Cheddar has reported them accurately. I don't see how 15bhp is "lost" between the crank and the wheels. Chains are fairly efficient, and each spur gear pair in the gearbox will be over 98% efficient. I am always dubious of the way that dyno operators take one measurement at the wheels, and then guess the other at the crank!
All other things being equal, particularly BMEP and cylinder capacity, the stroke of an engine isn't related to the torque it produces. The old idea of long stroke = higher torque is a bit of a myth, although a widely circulated and believed myth.
Number_Cruncher
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That gearing is interesting. My BMW twin, a very different animal, will, in theory, only do around 65mph in second before hitting the rev limiter at 7500rpm.
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I wasna fu but just had plenty.
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The RC45 is an homologated race bike produced in only limited numbers (1000) for general sale so it was able to qualify for the World Superbike race series (until relatively recently 750cc four cylinder, 900cc three cylinder and 1000cc twins).
So basically it is a race bike with lights, hence a close ratio 6 speed gearbox and a high first gear (you only need it to start the race and for tight hairpin bends).
Makes interesting riding in traffic, particularly as two of the cylinders and their exhaust header pipes (V4 motor) are almost under your bum!
Fantastic fun on a trackday though :-)))
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On the run up to Scotland for our last rideout, and filtering in motorway traffic, a friend's SP2 (another road bike built to homologate a track bike) was often in first gear (still only donk-donking away) whilst I was in 3rd on my Hornet. His first gear also reaches to ninety odd, and I read that the new Fireblade won't clip the limiter in first until the wrong side of a ton.
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>> His first gear also reaches to ninety odd, and I read that the new Fireblade won't clip the limiter in first until the wrong side of a ton.
The ZX10R will reputably do 110 in 1st, it is easy to see how a bike that rev to 12000 rpm plus can do such speeds it it can pull an 8mph / 1000 rpm first gear. It also true to say that sports bikes are light and dont often take a pillion and a load of lugage so can afford to have a higher first gear.
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My Philips Gadabout used to do 35mph (I swear it) in second, whilst chucking lumps of glowing carbon out of the exhaust ;>)
I hope this link works www.autocycles.co.uk/Archive/autocycle_137.htm
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>>BIKE have dynoed one at over 135bhp at the rear wheel, that's over 150 at the crank I doubt these figures, although I'm sure Cheddar has reported them accurately. I don't see how 15bhp is "lost" between the crank and the wheels. Chains are fairly efficient, and each spur gear pair in the gearbox will be over 98% efficient. I am always dubious of the way that dyno operators take one measurement at the wheels, and then guess the other at the crank!
I agree, a chain is very efficient at transferring power, Yamaha claim 150 and it dynos at over 135, "more than adequate" describes it well however there always seems to be a 10 to 15% difference between claimed and back wheel BHP on motorcycles.
>>the stroke of an engine isn't related to the torque it produces. The old idea of long stroke = higher torque is a bit of a myth, although a widely circulated and believed myth.
Surely a myth with some foundation, a longer stroke provided more momentum once the power of the burning charge has diminished albeit the narrower bore allowing a smaller valve area and a small piston crown for the charge to push upon.
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I meant to say that the feeling of more inherrant torque could simply be due to a heavier fly wheel.
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Yes, you're absolutely right when you mention the interplay between bore size and stroke length.
For the sake of an example, assume the con rod is vertical, below the piston, and the crank is at 90 degrees after tdc, but the crank is offset, or desaxe (These assumptions don't change any principles, but do get rid of all of the complicating trig!)
The torque is then
T= Pressure * (pi * (bore^2) / 4) * (stroke / 2)
Now, the cylinder swept volume is (pi * (bore^2) / 4) * stroke
So, the torque is
T = Pressure * cylinder_volume / 2
That you can reduce this expression for the torque of an engine down to just pressure and volume is my reason for suggesting that long stroke = high torque is a bit of a myth.
This argument is also true with a real engine with all the complicating angles and trig - the complicated trig appears in the same form in both equations for T, and doesn't really affect the thrust of the argument.
The kinetic energy stored in reciprocating pistons and rotating flywheels doesn't change the steady state torque delivered by the engine, it just smooths out the irregularities which occur during different parts of the cycle.
I'll have to have a little think about how long stroke / short stroke affects the rotary inertia of the engine, but this doesn't affect steady state figures.
Number_Cruncher
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An RC45!
Maximum cool points that man!
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An RC45! Maximum cool points that man!
I agree Thommo, there is something about race bikes for the road as opposed to superbikes, a rawness, I had a 2003 ZX7R WSB replica though the RC45 is legendary and still looks contemporary 13 years on, I really fancy a 1999 / 2000 R7 OW02, one of the last 750s, not really able to show it's worth before the new regs came in.
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IThe RC45 has got a friend in the garage too in the shape of aalmost BRAND NEW 1990 Yamaha FZR750-R, probably better known as an OW01 (the foreunner of the OW02).
Actually its done about 650 miles (in 16 years), but I'm taking it to Cadwell Park next Tuesday (Classic Bike trackday) for its first proper outing. I just hope its dry!!!
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1990 Yamaha FZR750-R, probably better known as an OW01 (the foreunner of the OW02).
I remember looking at one in a dealer in Guildford around about early 1991, I was looking for a bike at the time and bought a new 1990 model FZR600 in white, the one with the twin headlamp fairing similar to your OWO1. The OWO1 is iconic, it must be worth a lot thse days, a superb machine, please, please dont drop it.
Of course in superbike racing Yamaha raced the YZF750-R and SP after the OWO1 though both were production bikes so dont have any rarity value, then of course came the OWO2 (YZF R7) though as I said earlier it did not have the chance to prove itself before the regs changed.
I remember watching Noriuka Haga on the R7 at Hockenhiem on the old circuit through the forests, must have been 2000, long straights and tight chicanes, the 750cc R7 was superb on the brakes, had great drive out of the corners and was neck and neck on the straights with the 1000cc Honda SP1 of Colin Edwards (now with Yamaha of course) right up to around 300kph where the bigger Honda would just edge ahead, Yamaha were confident that the R7 had enough power though needed to refine the aero. For a couple of season prior to that the 1000cc twins (Ducatis and Hondas) had been pretty dominant, it was intersting that Yamaha stuck with the 750cc four when Honda built the 1000cc twin.
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Cheddar,
To be honest the OW01 in general dosn't seem to fetch really good money for some reason! Much more than a standard bike of the same era, but nowhere near the Honda RC30. If my OW was an RC30 in the same condition it would easily fetch £15,000+. I think mines probably worth about £10,000, (certainly to me because its a really nice bike) but I'd struggle to get that for it. They were about £13,500 OTR back in 1990!
If you're near Cadwell on Tuesday, call in and make yourself known, it will be open to spectators FOC and I doubt if there will be any other OW01's there.
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If you're near Cadwell on Tuesday, call in and make yourself known, it will be open to spectators FOC and I doubt if there will be any other OW01's there.
Thanks Nick, I cant get up there on Tuesday though I would love to see it some time, what part of the country are you, do you have any other track days planned?
Regards.
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Thanks Nick, I cant get up there on Tuesday though I would love to see it some time, what part of the country are you, do you have any other track days planned?
I'm it the North West (Merseyside). I have no other trackdays planned this year. Always manage to make Donington in May on the Ron Haslam Race School. The best bit about that is the bike belongs to the school, so no wallet damage if you fall off. Makes the bike at least 30mph faster too!!!
Hope to be at Oulton Park 28th Oct. where my friend Dave Molyneux hopes to make his comback after a BIG crash at this year's Isle of Man TT races. (Dave is the 11 times IoM TT sidecar champion and lap record holder - average speed of 116 mph on a 600cc SIDECAR). He is competing in the F1 (sidecar) World Championship next year.
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I'm it the North West (Merseyside). >>
Hi Nick, How about posting a few pics on here:
groups.msn.com/honestjohn
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Chedder,
Hi Nick, How about posting a few pics on here:
Yes I'll try soon when I get time.
Trackday yesterday was awesome. No too many bikes on the circuit at once and really warm and dry.
Only downside is I damaged the paintwork on the bellypan (lower fairing) 'cos I was leant over too far (should have firmed-up the suspension beforehand!)
"Classic Bike" magazine will be doing a feature on it sometime in the next couple of months.
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Only downside is I damaged the paintwork on the bellypan (lower fairing) 'cos I was leant over too far (should have firmed-up the suspension beforehand!)
Although that is a shame it is also something to be proud of in a "look how far I got it over" kind of way. What tyres are you running, I guess the rear is a 5" rim on a OWO1, do you run a 170/60 or a 180/55?
"Classic Bike" magazine will be doing a feature on it sometime in the next couple of months.
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Look forward to that, perhaps post on here and let us know which issue!
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What tyres are you running, I guess therear is a 5" rim on a OWO1, do you run a 170/60 or a 180/55?
180/55 rear and 120/70 front Pirelli "Super Corsas" Best tyres I've ever used. I couldn't believe how good the bike was. Easily as good (if not better) than the 2006 Fire Blade......although not as quick........it is only a 750 after all!
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I'll have to have a little think about how long stroke / short stroke affects the rotary inertia of the engine, but this doesn't affect steady state figures. Number_Cruncher
From memory I beleive that for the same cyl capacity a longer stroke motor has more rotary inertia and less piston to bore friction.
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Nice test, I rode an earlier version of this bike a few years ago, I was riding something much softer at the time and remember thinking how much like a video game the FZ was, superb bike but alas not for my middle age style....:-(
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Thanks PU, I tell you the new one is as easy, perhaps easier, to ride than a GS though has so much useable performance.
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I suppose there's no reason for there to be any difference in the rotary ineria of a long stroke engine - again, there is a trade off between piston mass and the stroke moving the reduced mass of a smaller piston further from the crank.
Even if there were any inherent difference, the flywheel may be adjusted to provide good slow running behaviour. So, for any engine type and application , the rotary inertis will be remarkably similar, whether the inertia is in the crank/pistons, or in the flywheel, it doesn't affect the way the engine spins up.
I don't have any info about the piston to bore friction. Cheddar, do you know the logic behind the reduction in friction?
Number_Cruncher
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I suppose there's no reason for there to be any difference in the rotary ineria of a long stroke engine - again, there is a trade off between piston mass and the stroke moving the reduced mass of a smaller piston further from the crank.
The throw of the crank of a longer stroke engine is greater, the big ends of the conrods traverse a wider arc so I guess would ensure greater rotary inertia subject to augmentation by a the flywheel.
I don't have any info about the piston to bore friction. Cheddar, do you know the logic behind the reduction in friction?
I am thinking simply that a smaller bore means a smaller piston to bore contact area, on the other hand the piston travels further in the bore. Simple maths should provide the answer, it is rather late to get the calculator out however I guess the small bore / longer stroke would generate less friction because the piston to bore surface area reduces out of proportion with the increase in stroke for a given capacity.
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>>The throw of the crank of a longer stroke engine is greater, the big ends of the conrods traverse a wider arc
Yes, but the piston is lighter. I think these effects will, largely, cancel.
For non-conforming surfaces, friction is independant of area. The true area of contact between two metal surfaces is always much much smaller than their apparent contact area, to the extent that the apparent contact area isn't important. For an excellent description of this, I recommend the first chapters of the "Friction and Lubrication of Solids", by Bowden and Tabor.
The obvious exception when surfaces do conform is in tyre to road friction, and hence there can be an increase in grip to be had by having a larger contact area. But, tyres do conform to the road surface, and hence are an exception to friction being independent of area.
Number_Cruncher
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>>The throw of the crank of a longer stroke engine is greater, the big ends of the conrods traverse a wider arc Yes, but the piston is lighter. I think these effects will, largely, cancel.
Quite possibly.
For non-conforming surfaces, friction is independant of area. The true area of contact between two metal surfaces is always much much smaller than their apparent contact area, to the extent that the apparent contact area isn't important. >>
The true area of contact is the piston ring to bore, everything else being equal it surely takes more energy to move a larger piston in a larger bore that it does a smaller piston in a smaller bore.
it seems that we have rather drifted away from the original point however.
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>>it seems that we have rather drifted away from the original point however.
As ever! - but hopefully in at least a slightly interesting way?
>>The true area of contact...
Sometimes, yes, that's true, because there will be a film of oil which effectively smooths out the worst of the asperities, and the viscous friction force in such a case would be proportional to apparent area, the piston speed, the viscosity of the oil, and inversely proportional to the film thickness (which itself depends on speed, piston ring radial force, detail piston ring geometry and oil viscosity).
In the case where the contact isn't effectively lubricated (such as at and near the end of travel where the hydrodynamic lubrication breaks down), the contact area is far smaller. Only the tips of the asperities contact. As Bowden and Tabor put it, it's like turning one mountain range upside down, and placing it atop another. The apparent contact area is many square miles, but the true contact area is only at a few of the peaks, perhaps only a few tens of square yards. This is why there isn't an area term in the friction equation, F = mu * N.
So, I think you are right that a larger piston will have more viscous friction, because of the larger area.
Number_Cruncher
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>>it seems that we have rather drifted away from the original point however. As ever! - but hopefully in at least a slightly interesting way?
Agreed!
So, I think you are right that a larger piston will have more viscous friction, because of the larger area.
On the other hand you mention another factor, the piston speed, the longer stroke engine will have a higher piston speed at a given RPM so perhaps you are right, NC, and it all pretty much evens out after all.
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Cheddar,
Some pic's of the my OW01 here from last Tuesday:
www.britishsportphotography.com/gallery2/main.php?...5
Nick
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Some pic's of the my OW01 here from last Tuesday:
Hi Nick,
Pics look great, nice liitle wheely on a few of them, I guess you were taking that NSR around the outside! Cracking bike the OW01, a real classic, I cant remember if you said before, have you had it from new?
For info I might be taking another Yamaha "01" for a run later today, an MT01 interesting concept, 1700cc V twin in a contemporary sports chassis, will report back if i do it.
Regards.
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Thanks Cheddar,
Yes I was just going around the ouside of the NSR400 at "Mansfield"
The bike was "new" when I got it in 2001 but was actually 11 years old at he time (if you see what I mean).
I think the dealer had decided to sell some of his collection, but as I never dealt with the actual owner of the business directly, I never found out for sure.
Good luck on the MT01.
Nick
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