Manufacturer C.M.B. Country Italy Type 21 EVO 2 BUGGY 2000 DD

* factory supplied numbers

An Italian buggy engine from one of the famous world champion manufacturers of 3.5 cc boat engines.
With the knowledge of these boat engines C.M.B has manufactured a nice looking and good performing buggy engine.

When we received the engine from the German C.M.B distributor HS Micro Motor Service the box with the engine it was factory sealed with a label. When you buy an engine be sure that label is intact. If not, ask the shop owner to check the contents before buying it.

I broke the seal and looked into the box. The engine is nicely packed in two plastic airtight bags so no debris can enter. One is with bubbles. Further the user guide with instructions to maintain and break-inn the engine (all in German language!).
*Also an explanation with drawings are there for the proper pipe length.
*A normal type 6 glowplug
*A boost bottle with tube and ty-wraps.
*The black carburator.
*And some stickers.

I first took all the papers out and read them carefully. (who isn't?!)
One paper is dedicated to:
*the engine break-in and maintenance.
*how many head shims are required.
*which glowplug to use in which condition.
*which fuel to use and most important the amount of oil required! In this case even the maximum and mixture between synthetic and risinus oil is provided.
*the correct length of the pipe.
*the warranty regulations.
Paper two is dedicated to the flat slide carburator only.
Paper three is the parts/price list of the engine.

After reading all papers (I understand the German language) I opened the engine and took all parts apart.
The factory claims that the engine does not need extra cleaning as this is done in the factory already before assembling. And they were right. The engine parts inside were covered with a film of oil and no metal debris parts were found.  

 A full normal ABC piston-liner is naturally used in this race engine. The sleeve is nicely chromed .

More features are the  C.M.B Multi Exhaust System "MES". The system speeds up the gasses leaving the exhaust and fills it with fresh fuel mixture. Beside the 5+1 ports in the liner there are two extra ports in the piston. They are working together with the "MES" ports to provide more power and better fuel economy.

The engine is a short stroke one and the cranckshaft measures 13 m/m. It has two carved TURBO cutouts at the end near the cranck pin (bigend). This is to better the fuel flow to the combustion chamber.

The crankcase of this engine is nicely finished. Two extra ribs at the bottom are making it stronger.

A purple tapered cooling head makes it looks nice and also efficient for the right amount of cooling without making it too heavy. The cooling head is constructed with a head insert that accepts normal glowplugs only.

A boost nipple is located at the right side of the engine. This means normally that there is not much space to prevent the silicone line get in contact with the central drive shaft. So it would have been better if this nipple was located at the opposite side of the engine like all other manufacturers do. You can replace it with an 90 degree angled nipple but this should come as a factory standard! 

The flat barrel slide carburator is nicely black colored (anodized) and is fully made out of aluminum and is a story of its own. There were already flat barrel slide carburators made by Picco for car engines but they were made out of composite plastic. As producing and maintaining the right specification over a period of time the composite material could give problems in settings and reliability. Instead of plastic this carburator is completely manufactured with a CNC machine out of aluminum. This means that the tolerance of the carburator will stay the same. Around the throat of the carburetor that goes into the crankcase there is nice nylon isolation bushing. This is to prevent the full metal carburator to get warm by transporting the heat from the crankcase and causing "vapor lock" in the fuel system. Manufacturing this carburator is a costly process, but it looks very nice and stable.
Three needles in total for adjusting high speed, bottom speed and idle speed at one side of the carburator. The angle of the idle needle is horizontal and can easily be accessed from the left side of the car.
The airflow of the intake and the part that fits into the crankcase is nicely tapered to give better airflow and so performance of the engine.
The carburator is large. Then I mean with in all areas. Fitting this one in for example a MUGEN MBX-4 needs rework over the throttle linkage. The total width differs 12 m/m compared with a Nova Rossi based 8 m/m carburator. Also due to the larger height the airfilter is touching the inside of the body more. This all shouldn't be a big problem. But when you are used to swap Nova based engines (training/competition engine) this could provide a little more work. A Nova Rossi 15 m/m throat diameter based carburator fits without rework on it. Only add the o-ring that comes with the original CMB carburator on the throat of the Nova based carburator. The throat is a 1.5 m/m longer and will not fit airtight against the crankcase if the extra o-ring is not placed.
An other small disadvantage is the throttle connection ball that moves the flat slide barrel. This one can rotate freely. So no fixed angle can be obtained. In the test set up of this engine in a MUGEN MBX-4 the ball was changing position every time and no constant push-pull motion could be achieved.

A rubber shielded NMB bearing is sealing the front. A large main bearing does its job inside.

The purple boost bottle that comes with this engine is not build inside the rear cover plate but is an external one. This is to prevent the bottle to become the same temperature as the engine. The bottle needs to be placed somewhere on the rear stiffener bar. If boost bottles are useful in all cases is to be discussed. But it is standard so try and error will prove if it works on different tracks.

The claim of the working of boost bottles is to enhance the idling and pick up from low speed.
Also better fuel economy is an advantage that is described to the use of boost bottles.
Boost bottles do not boost the maximum power of the engine itself!

The first impression of this engine out of the box is OK. 
Parts and engine are nicely machined and assembled!
Although the manual is completely in German language it is crisp and clear. (an English version will be available soon)
The specs tell us it is a medium power engine. click here for the power/torque graphics
The real engine performance and fuel economy can not be judged by looking at it. So we will track test this engine and compare it with others and if possible dyno test it.

TWF8 rating **** stars

Paco Raap

	The box with the engine with a sealed label!
	The right side of the engine with the boost nipple
	The left side of the engine
	All mechanical parts of the engine
	The two slots "TURBO" cranckshaft and bigend
	The exhaust port with the two MES booster channels
	One of the booster ports and channel clearly visible
	The other side with the second extra booster port and channel
	The other of the 5 normal ports. Watch how low the center port is.
	The nice chromed layer inside the bronze sleeve
	The piston and the connecting rod with a bronze bushing.
	Watch the small cut out for easy removal of the piston pin retainer spring (good job)
	The crankcase inlet for the carburator and the old straight nipple for the boost bottle connection
	Those two screws need a little silicone sealing
	The high performance 8 m/m flat barrel slide carburator
	The complete engine equipped here with the angled nipple and boost bottle

Comment by Dieter Suchan from HS Micro Motor Service the CMB car engine distributor for Germany:

Regarding the carburetor, CMB claims that a flat slide ( they had already one in the early 80 ths)
provides always the same vacuum because the air-stream is always forced to pass the needle directly in all stages of the slide. This leads to more power of the engine. 
We tested this and found that the claim  is correct !

We have already discussed why the carburator is that big. 
Mauro Braghieri of CMB argues that he wanted to make it in the same way he builds his engines: stable and of high quality. We have made some suggestion how to alter the carburator in the height, but Mauro claims then the air-intake will be badly influenced what will cost power.

The rotating lever is also a point we claimed. It is easy to solve the problem and CMB will do this
also. (You open the carburator and cut away the piece of the of the lever with the carving around (which holds the slide). Then you grind a groove right and left of the lever and fit the slide in this grooves=the lever cannot rotate any more!)
You must however watch these two grooves are uniform in depth and measurements otherwise the slide may stick in some positions. 
However the carburator as it is now, is different from all the other buggy carburators for the 3,5 cc engines and this causes doubt about the performance. But according to our experience it does not cause problems when installing it in off-road cars, as this is the case in the on-road cars.
CMB thinks about that and will surely bring a solution in the near future.

Now to the nipple for the "pressure-hose" at the engine. We have no problems with those. If the engine is properly installed the hose will not touch the driving shaft! If you mount this nipple on the reverse side (left), than those can touch the hot pipe!
On the Mugen MBX4-RR we used in Las Vegas the stiffener was vertical and not
horizontal. I have sent you the 90 degree nipples and shall pack those into
every box of new engines until CMB uses those. (That is called super service and customer voices response, Paco)

If you want a engine with that can be used > 25 liters.
I recommend the use of the 21 EVO 2000 Buggy and can give you references of a consumption of > 40 liters with our fuel "Runner -Time ® TOP 25 - 7 % Castor/ 3 % Synthetic oil.
Now coming back to the reality: Those numbers of consumption are the exception of high revving 3,5 cc power model-engines! I know makes of engines where you can be happy if they go over 5 Liters! Regarding the lifetime of CMB car -engines we have made the best experiences. I can compare this , because we have been the German distributor for the OPS - engine program for more then 5 years!!

When no original C.M.B muffler is used the best options are Picco mufflers. Nova Rossi based mufflers do not give good performance in combination with C.M.B engines!

Dieter Suchan, C.M.B Germany.

Mail address C.M.B. Germany: DSuchan@t-online.de

Comment by Paco Raap 28-12-2000:

As promised I received the angled nipples and mounted them. This makes the fuel line running beside the engine instead of away from the engine where is might get tangled with the center drive shaft. Good point CMB Germany will put an angled nipple in all boxes with no extra charge. The top picture with the original straight nipple. The bottom picture with angled nipple.

Comment by Paco Raap 30-12-2000:

The manual was already warning for this and take care of it! If you mount the engine on the engine mounting blocks be sure that the bottom surface of the engine mounting blocks is flat. The engine mountings blocks of the Mugen (MBX serie) and Kyosho will have no problem. However the engine mountings blocks from Thunder Tiger are not straight at the inside and they conflict with the two extra ribs that are on the bottom of the crankcase, so flat mounting is not possible. Therefor remove some material (the marked triangle) at the marked spot of the engine mounting blocks. If the engine is mounted check if the ribs are not touching the inside of the mounting blocks anymore.

Comment by Dieter Suchan from HS Micro Motor Service the CMB car engine distributor for Germany:
We have discussed the dimensions of the CMB flat-slide carb and the fact it brings some trouble due to this mainly in on-road cars, but also in sometimes in off-road cars. However this carb is very expensive in production. 
Mauro Braghieri has tried to solve those problems; he used a injection-molded Aluminum for the body, at the same time trying to reduce the dimensions. 
The result was not to his satisfaction, because the accuracy and the function was not to his standards.
Though he decided to make use of a composite barrel-slide carb, he was able to get
from the market.
This carburetor corresponds mainly to those Picco introduced in Sept.1999 which you show on Picco page .But the main needle corresponds to those of the CMB flat-slide. 
Those carb will be standard with all CMB engines ( Buggy 7mm / Rallye and Car 9mm) from
February 2001 supply.
The CMB flat-slide will remain available as an "Extra". 
With this, we will be able to keep the price low as well as solving the space problems with some cars.

The new style CMB carburator is an OEM product and is made by Picco. There are two things to take care of! * first is when you want to rotate the fuel nipple on the high speed needle housing for better alignment. Take a 7 m/m wrench and turn it anti clockwise gently!! * when the high speed needle housing is removed check for thread blur on the aluminum body part. If it is there (see red arrow) take a 8 m/m drill bit and slowly rotate it one turn to remove the blur. Do this with the carb upside down so no metal debris will fall into the carb housing!! This blur can cause a fuel leak as the washer that will be on top of it is not sealing perfectly between the aluminum body and the high speed needle housing.

15-06-2001 comment by HS Micro Motor Service
The 2000 shortstroke engine is now also standard fitted with the Intelligent piston/sleeve like is used in the rally game LSi version. The name is now CMB 21 EVO 2 Buggy SSi DD.
This Intelligent piston/sleeve will reduce the break-inn period and and add lifetime to the engine.

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