Motorized Bike Forum
Welcome to!

Feel free to log in, register, or just browse around and see what we're all about here at MxB Forum.

If you got help here, REGISTER and help the next guy!

If that's not enough motivation, the ads will go away when you are logged in!

If that doesn't do it for you - registering will allow you to search the forum!

Ride safe and have fun!


Rock Solid Engines - Reed Valve Installation for 2-stroke 50cc, 60cc, 66cc 70cc & 80cc Engines

Go down

Rock Solid Engines - Reed Valve Installation for 2-stroke 50cc, 60cc, 66cc 70cc & 80cc Engines

Post by Fabian on Mon Apr 09 2012, 11:16

These photos give some idea of the basic cylinder modification required to install a Rock Solid Engines, Billet CNC Reed Valve Intake, which should take around half an hour if you have a die grinder or Dremel tool.

Just a word of warning: don't use any silastic, permatex or any other sealing compound because it will inevitably get on the reed petals as you try and install the aluminium cage and gasket. Once that stuff gets on there you will no longer have an air tight seal between reed valve block and reed petals. Just do the install without sealant, otherwise you'll be spending time carefully cleaning the reed valve surfaces.

The most surprising thing when running is significantly less engine noise through the carburettor; music to my ears as i was sick and tired of the overly loud intake.
After fitting your RSE reed valve setup, be prepared for mechanical civility; with non of that rattly induction clatter usually associated with a standard setup.  

Now for the good news regarding the power curve: low and midrange torque is noticeably improved with top end power remaining about the same.
Because of the torque improvement you'll spend much less time using high rpm as it's simply not necessary. The engine is equally happy, if not more happy chugging away at lower rpm using a faster gear, resulting in similar speeds.
This has an added benefit of markedly reducing oil and filth dripping from the air filter and reducing vibration transmitted through the bike, not to mention reducing engine noise; making the riding experience much more pleasant.

Onto the fueling requirements.
After fitting the reed valve kit, i needed to increase the jet size by 6 increments from a Dellorto 68 to a Dellorto 74.
I'm suspecting the reason for such jetting increase is the air stream is no longer picking up fuel a second time (on the induction stroke) as it previously doubled back over the main jet due to reversion; the reed valve effectively eliminates back flow through the intake port upon the starting phase of crankcase compression.

I can strongly recommend the Rock Solid Engines, Billet reed Valve Kit, for it does everything that you would expect of such a design.
For me personally, i'm more overjoyed with reduced engine noise than the extra low and midrange torque.

Of note, the Billet CNC Reed Valve Intake will not add any extra length, compared to a convention Rock Solid Engines Billet Intake Tube. An important feature for those who have an already tight fit between bicycle frame and air filter.
A very well designed and engineered product from Rock Solid Engines.

Their website page here:








In addition to the reed valve intake, Rock Solid Engines now sells a Walbro style "diaphragm carburettor" which is an incredible improvement over the standard (float style) NT carburettor, or any after-market float style system.
The ease of tuning offered by this design makes it significantly more user friendly than messing around with an endless set of main jets and needle settings, typically associated with a conventional carburettor.

MxBF Power User

Posts : 338
Reputation : 3
Birthday : 1970-09-03
Join date : 2011-06-08
Age : 47

Back to top Go down

Back to top

Permissions in this forum:
You cannot reply to topics in this forum