review of Rock Solid reed valve

[Deleted member 12676]

Just got it in. Here is my technical review:

Design flaw
Sucking on the intake side of it reveals an air leak. Took it apart (3mm allen wrench) to discover the internal gasket covers only half of two 1/16" diameter holes that bypass the reeds. not good. (see drawing)
So all owners need to take it apart and glue those holes shut with something gasoline resistant like JBWeld. (silicone sealant wont work). It will run much better sealed. And trust me, there is no reason to have bypass holes. The reeds need to completely prevent all blowback.

Flow Volume
Looks like the maximum possible flow volume (cross sectional area with both reeds open) should be 111 square millimeters which matches the 113sqr mm of a 12mm carb. But since they didn't angle the valve downward it then hits the upper port surface after only opening 2mm which results in only 84 sqr mm volume.

Performance
This is going on my 55cc engine with 12mm Dellorto carb ported out to 14mm. If I bore the intake to give the upper reed more room to flex then I expect to be able to rev even higher since this ported engine is limited by my homemade reed valve which has stiff reeds and only around 88 sqr mm flow area. But the crankcase on mine is stuffed which makes it favor high rpm power. I am making an expansion chamber for a peak rpm of 9300. See my web site (click on my signature link) for info on how to drill holes in the pistons intake skirt and make a boost port. These are essential steps for use with a reed valve. I expect this valve will give low rpm gains for both 48cc and 66cc engines but will limit revs on the thirsty 66cc engine.

My recommendation to Rock Solid:
Seal those holes to begin with. And design a wider reed valve to be sold with 66cc ported cylinders that allow a wider design. And angle the valve downward. (And make the mounting hole spacing 40.5mm for the 55cc and 66cc engines.)

 

[Lunardog]

Perfect timing Jag. I am looking for a little more low to mid range torque for climbing the hills here in Pa. Have a 66cc Stinger and a SBP shift kit and wanted to add the reed valve and maybe a slant head to up compression just a little without getting crazy.Rock solid also makes a billet preformance head and trying to decide if that would be a better investment than a slant.Whats you take on these mods. Sound like a worthwhile investment? Have you heard anything about this billet head? Ill look forward to hearing your review after youve run this reed valve kit for a bit. Thanks.

 

[Fabian]

@ Jaguar

When i recieved my Reed Valve Intake, the first thing i did was to try and draw a vacuum from the carburettor side orifice. I had a complete leak free seal. Maybe your intake is different?

My personal opinion is that a reed valve intake will do nothing to improve peak (high) rpm horsepower as the reeds will offer some restriction to intake flow.
An engine revving over 5500 rpm and designed to make power over that rpm range with such porting modifications will most likely benefit from not having a reed valve intake, as the time window for (reversion) blow-back is minimal; 9300 rpm being such high rpm that intake velocity may overcome any reversion forces.

Where this reed valve intake has proven to be tremendously beneficial is "below" 5,000 rpm; the sweet spot being 2,800 to 4,500 rpm; the most noticeable improvement being at around 3,200 rpm where the engine seems to generate much improved torque, almost like a diesel engine.

 

[Lunardog]

Fabian I'd appreciate any comments to my above post from you as well. You seem to know Rock Solid's products. I'm going for that reed valve based on several of your posts. Any comments or input on the heads? Slant vs their billet preformance head?

 

[Fabian]

High compression cylinder heads will require a higher octane fuel

High compression cylinder heads will be best complimented with the adjustable (and correct 2-stroke ignition curves) of the Jaguar CDI.

High compression cylinder heads will give more power and torque provided the jetting and ignition timing are correct.

There is no real down side to a high compression cylinder head, providing the ignition and fueling and oil quality and ratio are up to spec for the application.

I choose to run a low compression cylinder head because it makes the engine easier to start; also gives flexibility to use any kind of fuel and oil quality and given that some of my touring adventures take me out to rural country areas where fuel quality may be suspect - a low compression engine is beneficial for my specific application.

I also need to add that having a SickBikeParts shift kit with low range functionality which doesn't have me looking for more horsepower - my focus isn't on speed, but hill climbing ability - if i'm climbing at 8 miles an hour or 10 miles an hour if running a high compression cylinder head, the end result gives little difference to overall trip time.

 

[Deleted member 12676]

The slant head is a bad idea if it places the tip of the spark plug off center. Research and my tests show that a centered plug gives the best power.
Don't up the compression more than 110psi if you haven't at least changed the wrist pin bearing. I've changed all my bearings and so can go as high as 170psi.
For low end power gains the reed valve is a good way to go.

 

[Lunardog]

Thanks for the feedback guys. Think Ill just go with the reed valve kit for now, and get rid of the thick stock headgasket I have along with maybe milling the head down just a touch.

 

[Lunardog]

Ok, first report. Im so far not impressed with the bolt and go aspect,at least with the nt carb setup I currently have anyhow. I actually have lost low end power and a bit of top end speed as well. Next stop will be a larger jet for the carb as Fabian suggested and maybe that will cure my issue. I have already moved the clip on my needle to its lowest setting and driven the air mix screw near to the seat and it seems to have no effect.Will post on the outcome when I order the new jets.

 

[Deleted member 12676]

see my carb jetting tips at http://www.dragonfly75.com/motorbike/jetting.html

Someone with an Arrow reed valve informed me that the flow area is almost twice as much as with the Rock Solid reed valve. But it sits farther back making it even more necessary to stuff the crank to bring the crankcase compression ratio back to where it should be.

 

[Fabian]

There is a good reason why the Rock Solid Reed valve is designed the way it is, and it's plain obvious even with simpleton logic, and follows the maxim of 2-stroke port-situated reed valve development: minimise the reed valve cage receiver volume to maximise crankcase compression.

At the end of the day a significant change in the path of intake flow will also require a corresponding change in the jetting requirements.