Virago 535 vs V star 650 info
by Metric Sal (TeamPSP)
Here's some info for everyone, concerning the whole Virago 535 vs the V star 650 motors:
The 650 is NOT a bored out 535. It's a bored AND stroked 535. That means that not only are the pistons larger, but the crank throw is also longer, adding the displacement over the 535.
The 535 is 32.64 cubic inches in displacement. It uses a 76mm bore, x a 59mm stroke. In inches, that's a 2.99 bore x a 2.32 stroke.
The 650 (really 649) is 39.60 cubic inches. It uses an 81mm bore, and a 63mm stroke. That's 3.18 and 2.48 in cubic inches.
That's a 114 cc or a 6.96 ci difference.
The larger bore size, is a .190 inches. The longer stroke size, is .160 inches.
Comparatively, a typical "boring" a motor for a new piston because of damage or whatnot, is about a .030 overbore. That would only take a 650 to 657 cc's, or from 39.60 to 40.14 inches. Not even one full cubic inch in displacement.
Onto the basic characteristics of each motor...
Both motors are 9:1 compression, so they are equal there.
The 535 uses two 34mm carbs. The 650 uses two 28mm.
The 535 makes 46hp at 7500 rpms. It makes 34.66 ft-lbs of torque at 6000 rpms.
The 650 makes 33hp at 6500 rpms. I could not find a rating online for torque (other than the Dragstar, but that has different power ratings). However, Yamaha says the 650 makes maximum torque at 3000 rpms.
So what does that mean? Well, the 535 was meant to rev. It's peak hp is higher then the 650's rev limiter. Also, the 535 makes peak torque all the way up at 6000rpms, where as the 650 makes peak torque at only 3000 rpms. What the means... is that the 535 really has to be ridden hard to get the power out of it, but it will scream nicely at full throttle. The 650 will get you moving quicker from a stop, without working as hard, but doesn't breathe as well up top.
You'll notice the 535 uses larger carbs. That's to support the higher rpms of that power range. The 650 uses smaller carbs, which help give it more air velocity into the cylinders at a lower rpm, which also helps the lower powerband.
As far as the difference in displacement, the 535 has a smaller bore, and a smaller stroke. Engines like this, are typically high rpm power engines. The lack the "force" to make low rpm power. The longer stroke on the 650, gives it more torque by having more mechanical leverage on each power stroke. This is more typical of a motor that produces lower to mid range power.
So that's the differences between the motors, and why each version works as it does. I hope this information is useful, and the mods can feel free to add it to the main website if they choose.