Reply To: 125 vs 250 VTwin engines
AFAIK the workshop manual on oil presure check gives a higher number for 250 than 125: 250 -> 2.0 ± 0.5 ㎏/㎠ (at 65 ℃∙3,000 rpm) 125 -> 0.9 ~1.1 ㎏/㎠ (at 65 ℃∙3,000 rpm) Unless it’s a typo maybe that suggests that oil pumps can be adjusted for increased oil presure?
Pressure is changed inside the engine because there is bigger holes for oil to flow around the pistons and cylinder head, also the 250cc has a bigger cooler, so need to move oil quicker as the 250 cylinders warms up quicker. But i personally have taken apart both engines, the oil pumps look the same. My suspicion is that the 250 will have a smaller internal sprocket for the 250 to spin the pump a little faster, but alas, i did not measure both oil pump sprockets. The manual is correct that it makes more pressure, so i have been corrected there.
Both GT125R and GT250R have identical redline, it’s strange on GV Aquila as the redline is longer (doesn’t mean it’s good for it) , its the same engine used on both GT and GV. Engine acts funny around 11,000 rpm (it doesn’t like it for too long) but peak power is at 10,000-10500 rpm. Good cruising RPM is 6500-7000 rpm. Higher good revs is 8,000 to 9,000 rpms (you will feel it when you hit a certain RPM the engine has a better rhythm between 6500-8000 rpm, either 250 or 125cc) . Engine will last longer if you don’t redline it.