review of Rock Solid reed valve

Discussion in 'Dealer Reviews' started by jaguar, Jun 4, 2012.

  1. jaguar

    jaguar Well-Known Member

    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.

    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.)

    Attached Files:

    Last edited: Jun 5, 2012

  2. Lunardog

    Lunardog Member

    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.
  3. Fabian

    Fabian Well-Known Member

    @ 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.
  4. Lunardog

    Lunardog Member

    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?
  5. Fabian

    Fabian Well-Known Member

    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.
    Last edited: Jun 5, 2012
  6. jaguar

    jaguar Well-Known Member

    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.
  7. Lunardog

    Lunardog Member

    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.
  8. Lunardog

    Lunardog Member

    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.
  9. jaguar

    jaguar Well-Known Member

    see my carb jetting tips at

    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.
  10. Fabian

    Fabian Well-Known Member

    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.
  11. Fabian

    Fabian Well-Known Member

    As far as i am aware of, there is no mixture screw on the NT carburettor, but only an idle speed screw.

    There is nothing wrong with the standard carburettor but a Walbro style carburettor commonly used in chainsaws is by far the better option.
    I will be purchasing a Walbro carburettor (with adjustable low speed and high speed mixture screws) from Rock Solid Engines as a stop gap measure until their Electronic Fuel Injection kit hits the showroom floor.
  12. Lunardog

    Lunardog Member

    Ok guys heres a quick semi update. Found some micro drillbits in my box and tried to open the jet in my carb. Bad Even as small as I opened it , it was too much. Ordered a set of 5 jets from dax. 60 ,65 ,70 ,75 ,and 80. Put the 80 in and it was drawing too much fuel regardless of clip placement on the needle. Dropped to the 75 and she responded better however I adjusted the float also and went too far as my carb is on a bit of a slant and this allowed the bowl to overflow. During the run even with the float incorrect I did experience a better low end torque on the hills. I have some steep inclines here in Pa. and even the worst on my trips she almost climbed completely without peddaling. The long gentle slopes she pulled at a steadier pace and without having to downshift as much. I have reset the float and verified seal and will test again in the next couple days. There may be a need to get 71 thru 74 jets to tune it perfectly but for now I will play with this one and see what happens. I recently purchased a boat and that has eaten up my bike time for the last month or Ill post again when I finish testing this 75 jet. Thanks again for the help and info guys. As always you save me a lot of trial and error testing with your knowledge.
  13. Ivan H

    Ivan H New Member

    Hi, I have RSE reeds & have just cut 2 ports in the piston, 2 Jags heights, both r 9mm wide with 6mm left between, removed 5mm from skirt & port floor + boost port. Cut intake ceiling horizontal depth 8mm, width 20.5 to allow upper reed clearance as its needed. Jetting went from 25 pilot 72.5 main to 32.5 pilot 92.5 main & will order 1 richer main to get it spot on. Very good power ncrease right thru. Cheers
  14. jaguar

    jaguar Well-Known Member

    good for you. all you need now is a good expansion chamber.
    I was experimenting today with my 55cc cylinder with the same reed valve and got it up to 7830 rpm with very tame porting and just the stock exhaust. Of course I have a Dellorto 14mm carb and a Honda piston, 120psi compression, Jaguar CDI. Like you, I also dremeled away some of the ceiling aluminum at the intake to make more room for the upper reed movement.
  15. Ivan H

    Ivan H New Member

    Hi Jag, have SBP plated chamber, but wouldnt mind 1 of ur designs next. Also have SBP shifter/8 speed shimano, RSE head, NTN main/4thou end float, countershaft/10x14x15 small end, 16mm mikuni, RSE pull start & home made CDI along ur lines, on hi strength hand made frame I scored from Op Shop for $60. U do some good development work on these Jag, cheers
  16. BadgerMW

    BadgerMW New Member

    Recently bought a RSE reed valve kit, installed it once but was too lazy to re-jet carb and possibly boost port the jug.

    Let me know if anyone wants it, I paid $80 from JNM looking to get some of it back.

    The reed valve is in almost brand new shape, installed it on new engine, rode it to the end of driveway and back and took it off...been sitting in the garage ever since.

    Jag's site has some very detailed instructions on setting it up right.
  17. jaguar

    jaguar Well-Known Member

    maybe you gave up on it because you saw no improvement. Why don't you drill a couple holes in the piston skirt in order to see some benefit from the reed valve?
  18. BadgerMW

    BadgerMW New Member

    Ill PM you :)
  19. jaguar

    jaguar Well-Known Member

    For the benefit of all this was his concern:
    "I really like the product but I'm worried about the reliability of the piston and jug in the future. I saw other members that had gone and drilled holes in their pistons and it resulted in small scratches in the cylinder walls. At first I am sure I will see good results but over time i feel it will lower its reliability and life."

    I replied:
    1st, these engines are too low power to put stress on the piston. I used to run a piston with 27 holes in it. I ran up to 8500rpm no problem, going downhill with throttle full on to see if anything would break. nothing. ran great for a few months till I switched for different testing.
    2nd, any idiot can feel that drilled holes leave raised edges that need to be taken off with an exacto knife or something. It was the raised edges that scratched the cylinders.
    3rd, you can always slap in a motorcycle piston that has the windows in the intake skirt:
    47mm Hoca Minarelli piston and rings for reed valved engines -
    Thinner rings, preserve cylinder coating, less friction for higher RPM's and less blow-by for better compression. 85mm rod motors (Grubee brand/Type A) will need a 5mm spacer (between crankcase and cylinder).

    46.8mm Honda Hobbit overbore piston kit for reeded engines $66
    Compression height of 25.5mm and overall length of 50mm, it'll need to be trimmed 2mm at the skirt but it should work in the 80mm (dax) rod 66cc engines. Sits 0.5mm higher than stock and will boost compression significantly

    The only tricky thing to drilling the holes is that you have to make a mini-ditch for the bit otherwise the drill bit will wonder off center. I used a rotary tool but even a pointy hunting knife can do that.
    If anything a reed valve can increase reliability by reducing the vacuum on the crank seals caused by piston port intake as the piston raises. Rvalve only allows crank pressure (and just a little vacuum).
  20. bahramu

    bahramu Member

    Badger, too bad you didn't also get the Walbro carb with reed valve adapter. The walbro kit + RSE reed-valve kit from JNmotors is on my "dream" list. I'd love to pick up one of those second hand.