The “PerCiVal Mod,” or PCV valve modification, is a well-regarded upgrade for KLR motorcycles, gaining traction within the KLR community thanks to enthusiasts like The Patman, Marty, and MADMAX. This modification involves integrating an automotive PCV valve into the crankcase breather hose of your KLR. The primary goal? To reduce crankcase pressure, leading to some noticeable improvements in your ride.
Understanding the KLR PCV Mod and Its Benefits
So, what exactly does the KLR PCV Mod bring to the table? The core advantage lies in its ability to diminish crankcase pressure. By employing a PCV valve, airflow is strategically managed to exit the crankcase without allowing backflow. This clever manipulation creates a vacuum-like environment within the crankcase, which translates to tangible benefits for your KLR.
Enhanced Engine Performance
One of the immediate perks reported by KLR riders who’ve implemented the PCV mod is a boost in engine performance. Many describe the engine as feeling “snappier” and more responsive, with a noticeably freer revving action. This improvement stems from the reduced resistance the piston encounters during its downstroke. In essence, by alleviating crankcase pressure, the engine operates more efficiently, translating to that enhanced “snappy” feel and improved throttle response.
Reduced Oil Consumption
Beyond performance gains, the KLR PCV Mod also contributes to decreased oil consumption. Lower crankcase pressure means less oil is forced past the piston rings. While some users have observed oil consumption reductions at higher RPMs, the majority report a significant decrease in oil usage during regular riding, especially below 5000 RPM. Real-world measurements, like those reported by KLR owners, often show oil consumption reductions in the range of 20-25%, making this a worthwhile modification for both performance and maintenance.
The Mechanics Behind the Mod
To further clarify, let’s delve into the mechanics of why this mod works. As NOBRAKES from KLRWORLD aptly described, the air within the crankcase can act like a spring. In a traditional setup, this air is compressed and released with each piston stroke, creating resistance. The PCV mod, however, disrupts this dynamic.
By allowing air to vent out but preventing it from re-entering, the PCV valve eliminates the “spring” effect of the air within the crankcase. This means the piston moves with less resistance, contributing to both the performance increase and the reduction in oil being pushed past the rings. Compared to simply enlarging the crankcase vent, the PCV mod offers a more refined approach to crankcase pressure management, theoretically yielding even better results.
Conclusion: Is the KLR PCV Mod Right for You?
The KLR PCV Mod, or PerCiVal Mod, presents a compelling case for KLR owners seeking to enhance engine performance and reduce oil consumption. While not a drastic overhaul, the reported improvements in throttle response and the measurable decrease in oil usage make it a worthwhile consideration for many riders. If you’re looking for a relatively simple modification to give your KLR a bit more pep and potentially save on oil in the long run, the PCV mod is definitely worth exploring further.
