650/1000 conversion

[northwind]

Originally Posted by zadar

yep,if it was designed to be 650 in first place rod bearing would not seize on 99 and cranks would not break on half

Could just as easily be down to crap design though, is the thing After all they ended up changing the cases again, so even when they redesigned it, they obviously weren't happy.

that would be a lot of mistakes for designers

[northwind]

Yup, it would. But then it wouldn't be the first or last time an engine was launched with some gigantic screw-up that wasn't noticed til it was out in the real world...

ARGH! I can't believe I'm having this conversation with you again. How many times?

Originally Posted by northwind

ARGH! I can't believe I'm having this conversation with you again. How many times?

longest it takes
what was first year of 650 in UK?
400 was out in 98 in Japan.

[northwind]

Doesn't matter, development and launch aren't the same thing

ok.

[northwind]

(Incidentally, Zadar knows more about SVs than anyone else on here... But it's fun to argue with him, even when you lose, which you always do, you learn something )

How about instead of looking at the stuff which gave them problems- which they still changed again even after a whole redesign of the cases- how about all the stuff that DIDN'T cause any problems, in standard tune and useage. Bores are, what, 9mm bigger, but the liners don't distort, in fact you can bore them out further before that happens. Cooling system is the same and still comfortably more than adequate. Stroke is something like 13mm longer but the cases have clearance for it. How about ancillaries- clutch, starter... Is the frame identical? That I'm not sure of, I know the early 400 has different forks but the frame is certainly the same design if not exactly the same construction. How about the gearbox?

I've never actually met an SV400 crank, but I'm sure I've read that the design is identical, and that the difference in stroke is just down to where the crankpins are mounted. Is that right?

And sure, it's a big design error but either way they made it- they either failed to adequately adapt a 400, or they failed to adequately build a dual-use motor, but either way the exact same mistake was there, made by the same engineers.

I am not normal user
cylinders do destort,get oval or develop hot spots.they wear out faster than anything else out there
stroke has nothing to do with clearance,like you said it is just crank pin at different location and rods at different length.
frame is same.forks are same except for 98 which had one rotor only.rotor diamter was different on that one.
gearbox is same,primary ratio is different.which is just gear with different number of teeth.
400 or 500 that I made has no problem with oil or crank
long stroke/big piston pumped lot more which caused oil starvation due to hole under piston(the one you see on pics).

[northwind]

Yah, but for 99% of users the pistons'll last the life of the bike, 5 times the life of the bike probably. And it's a road bike, so that's fine. So, gearbox is built strong enough for 70bhp, clutch is built for 70bhp (is it the same for the 4? I guess so.), frame is stronger than the 650 needs never mind the 4... Cooling system does the job too.

The crank, too- the fact that there's space to change the crank pin location outwards by what, 6.7mm or thereabouts, without causing any problems is either a big stroke of luck, or when they designed the crank it was designed to have room to expand, no? And again, for day to day use the crank's not a weak spot, it's really only tuned and race bikes that have a noticable fail rate other'n oil starvation.

So, when I look around the motor and see that most of it's strong enough for a lot more power than the 400 made, to me that suggests that it's not just a 400 motor. Either that or a stupidly overbuilt 400 that they just coincidentally decided to bore and stroke out to 650.

And like I say, the mistakes with the oil starvation issue are the exact same whether it's an upsized engine or a dual purpose one, either way it didn't work for 650.

See me use all this stuff you've told me to disagree with you

crank pin is not same diameter
factories don't design engine and its parts to be at their limit.they have safety margin(probably 30%+).we racers explore that 30%.
400 makes 50hp.650(99-02 65hp)30% more
look at gsxr's.there are lot of parts that can be swapped between engines,600,750,1k.they can use common design for most of parts and just change specs here and there,stiffen up here or there,upgrade most critical parts and make bigger motor.so,I guess gsxr600 came from gsxr1k
or you can look at old fzr 400 and 600.same bottom end and top end interchangeable.neither had problems.
sv just has to many things that don't seam to be thought through.
on pointy they drilled cases around crank to help with pumping.some cracked there between holes from stress.or main crank bearings walking around.
on street bike with normal use most of this problems will not show up,or bike will not be used long enough to show up,or it may have problem but still run.you would need to open bunch of street motors lets say after 40k miles and look in there.most don't live that long