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By: Dan Wade

LRD Performance Specialties in Gresham Oregon is well known for their pro level engine building, and with that, their dedication and focus is providing that same level to the everyday rider.  Arlan Lehman, LRD's head man, has the philosophy of "We do not reserve quality and performance for our pro riders.  Each engine we build gets the best we have because each customer is as important to us as our top riders are.  When I port your cylinder, I will put the same effort and care into your engine, as the ones that has won LRD over 20 National championships."  In todays economy, the almighty Arlan's Lonestar 350 PowerValve Honda dollar often wins out in favor of customer service and support, and most importantly quality.  LRD is a national level shop that gives each customer personalized service and delivers high quality products.

While at DuneFest at Winchester Bay, Oregon, I had the opportunity of a lifetime.  I was able to get to test ride one of the premier national level engine builder's personal quad.  Not everyone gets to make the claim to having ridden Arlan's own ride. I met up with LRD's crew on a typically Oregon Coast Saturday afternoon.  I had anticipated this ride for some time.  Not only as mentioned about who's quad I was riding, but also what it was.  Arlan's bike is a full Lonestar and Custom Axis chassis, but at its heart is what we were there for.  The LRD Pro-X 350cc Powervalve cylindered engine.

LRD Powervalve Motor

I had the opportunity to discuss the theory of the powervalve with Arlan to great detail.  The advantages the powervalve provides are many.  Arlan explains that "The main exhaust port has a gate valve that lowers the effective roof of the exhaust port at low rpm and raises it at high rpm."  This gate valve is controlled via exhaust pressure against a simple diaphragm that over comes spring tension and will open the valve as exhaust pressure increases, but allows the valve to quickly come lower when the exhaust pressure lowers.  The increase and decrease of the exhaust pressure is tied directly to the RPM of the engine.

Arlan explains the theory of the exhaust port set-up "At low rpm you need a low exhaust port roof (less duration).  This lengthens the amount of time the expanding gases from the combustion process can push the piston down."  Further explaining the importance the exhaust port height at low RPM "The slower moving piston also increases the opportunity for the incoming fuel charge that is flowing out of the transfer ports, to escape out the exhaust port, instead of staying in the combustion chamber where it can be converted into heat energy.  By lowering the roof of the exhaust port at low rpm much more of this fuel charge is captured in the combustion chamber which increases low rpm power."

Arlan then explained how the exhaust port height affects higher RPM power as well "At high rpm there is not as much time for the fuel charge to be lost out the exhaust port. If fact clearing the exhaust out of the cylinder becomes more of a problem.  The exhaust pressure must be out of the cylinder before the transfer ports open, or the exhaust will blow down into the transfer ports and at least interfering with filling the combustion chamber." Continuing Arlan explains even further "The exhaust port must evacuate the exhaust gases efficiently or peak performance will seriously suffer.  At high rpm there is less time for this to happen.  The higher exhaust port increases the amount of time the exhaust can flow out of the cylinder, and reduces the chances of the exhaust mixing with the incoming fuel charge.  The shorter distance that the expanding gases from the combustion process push on the piston is made up for by the occurrence of more combustion events."

How does all this tie into a powervalve engine?  The powervalve, as referenced to the above-explained importance of exhaust port height, allows for variable exhaust port height to match the RPM. Truly the best of both worlds, low port height for low-end power, and a higher port height for road racer-like top end power.  When altering cylinder-porting arrangements, the engine tuner is restricted to one port height for all RPM's.  That is why most engines are marketed under various packages either Levels, Ultra-this, Spec such and such, Duner, MX. er, etc, etc, etc.  The powervalve engine via some simple changes can allow for ONE engine to perform nearly all the above.

So how was the ride?  I have had the opportunity over the years to ride many different bikes by many, many different engine builders. Each in their own right were unique.  However, the LRD 350 Powervalve, is at a level unto it's own.  I swung a leg over the quad, and kicked it. It was still warm, so no choke was needed. One kick and it came to life.  On a related side note: Arlan understands how noise can adversely impact the ATV sport, and in particular the sound restrictions that are in place in the Oregon Dunes National Recreation Area.Arlans Personal quad  The ODNRA sound restriction limits the sound levels to 93 decibels when tested.  LRD has designed and implemented a new silencing system that easily meets these requirements. Arlan had the new quiet silencer installed on a chrome LRD 350D adjustable exhaust system.

I gave it a few moments to warm up and clicked it into gear.  I eased the clutch lever out and BAH, I killed it.  What a spode.  I quickly recovered and started it again, this time getting used to the feel of the clutch.  No knock on Arlan's ride by any means, I just wasn't used to where he had his clutch lever set to engage, the engagement was super smooth with the RTC easy-pull lever and the Hinson billet clutch basket.

I cruised off to a hummocky area to begin some of the various type terrains I wished to throw at it.  Again in my best spode fashion, I about put it on the grab bar.  This was at about 3500 RPM in 3rd gear & the engine has massive, amounts of low-end power.  That's the "hit" and that's it, at about off idle, the power rolls on very strong, and that is the only real hard hit.  From there out the power is seamless, almost electric like.  I pointed the quad towards some small hills and purposely tried to lug the engine and see how it would react. Stellar.  The engine would allow you to bog it, wick the throttle and it would pick up power immediately.

I then headed to towards some tight trail like areas with tall banks and some sharp corners to see how the power delivery would be there. Again, stellar.  The power delivery was smooth, predictable, and consistent.  I was able to really launch out of a tight corner, with good control and speed.  The engine made itself very easy to ride.  Where on other quads, I would have been stirring the transmission, the LRD engine would allow me to lug it in a gear, gain speed and RPM, but allow me to rev that gear much further than I would have been able to on a standard ported cylinder.  I would compare this to being able to explode out of a corner on a MX track, hold that gear down the straight much longer, and harder, then enter another corner, and repeat.  The power delivery itself the whole time retained a near electric like smoothness.

After giving it some trials in the tight stuff, I decided to head out to more open country.  Near the drag strip there are some flats and some small roller hills.  I was cruising in 4th gear, almost clicked it down into 3rd to wick it and take off across the flats, but decided again to lug it and see how it responded.  It shot off like a rocket. No need to downshift to take off, the engine answered the input of more throttle and took off.  I clicked into 5th still holding wide open and decided to see how well it revved out.  There are many people who have become of the notion that a larger bore engine does not rev and does not rev out nearly as well as a 250cc engine will.  This engine even with 225 psi cranking pressure, revved up and out very well.  Back to the ride though, I held it in 5th gear as long as I had room, I actually ran out of room before I felt any drop in power indicating an over-rev, the LRD Hi-rev 250R CDI ignition allowed the engine to rev to these high RPM's.  I was able to find a longer straight stretch and really gave it to it hard. I ripped thru 4th and 5th, and clicked into 6th.  The engine pulled through each gear superbly and pulled all the way to the top of 6th gear with 14/36 gears.  The power and speed was incredible.

Begrudgingly I had to return Arlan's bike to him, I went back track-side and had to work to peel my fingers off the bars.  I was grinning ear to ear as I had very much enjoyed the ride and was very pleased with the engine and it's characteristics.

In summary, I found that the LRD Performance Specialties Pro-X 350cc Powervalve engine to be an excellent engine for any terrain or abuse I could throw it's way. LRD PV Kit  It readily accepted being lugged and then repeatedly asked to roost off like a rocket, as well as, accepted being spurred on to near road racer RPM's and speeds down the flats.  This engine truly is a great all around engine that can and does make it easy to ride with levels of performance most are not able to achieve.  The power delivery is consistent and predictable, as mentioned the low-end power is stout, the mid range robust, and the top end revealed itself to be equally impressive.

LRD Performance
200 NE Victory Ave. #A
Gresham, OR 97030
Phone: (503) 661-6700
Fax: (503) 492-3747


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