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Quoted from PocketBikePlanet:

How-To's - Performance Tips & Tricks

Want to Increase the Performance of your Cag?
Getting Used to the Stock Speed and Want More?

You've come to the right place. Here's a list of modifications that you can do to your cag that can increase its performance a great deal.

This thread is provided to alleviate redundant questions and to help inform our members about methods that may increase the performance of their bike.

Disclaimer: Altering the original configuration of a product my void the manufacturers warranty. Do these modifications at your own risk and understand that the results stated in this article are not guaranteed, endorsed or recommended by Pocketbike Planet; nor is Pocketbike Planet or the contributing members; liable in any way for personal injury, engine malfunction or any other issue resulting in the information provided. PERFORM MODIFICATIONS AT YOUR OWN RISK.


Engines

We have identified four different types of engines used in the Cagllari (Cag) Pocketbike. They are:

1. SY Engine
2. ZH-1 Engine
3. BD Engine
4. 48cc Engine


The SY, ZH-1, and BD engines, are all basically the same, design-wise, but there are little differences between the engines that I will point out (also, remember that the tolerance factors between the engines are so great, that there may be a few SY engines that perform better than ZH-1, BD, etc, and vice versa).


It has been shown, that the ZH-1 has b***** intake ports (look inside the cag's head, and you will see two ports, one on opposited ends of the head) than the SY head. B***** ports will give you higher RPM numbers, but the low end will be somewhat decreased due to a larger surface area. Remember, b***** isn't always better. There is a sacrafice. With b***** ports, air/fuel velocity will be decreased, but again, since more air/fuel is introduced, you will reach higher RPMs. Again, since the tolrance levels are not that great with these engines, you will find that some SY engiens will perform better overall than the ZH-1 engines. I'm not familiar with the BD engine, to give a thorough review.

The 48cc engine, compared to a ZH-1, has noticeably b***** intake ports, as well as the piston is b*****. This engine is commonly referred to as having the Big Bore kit. This engine, is definitely faster than any of the stock cag engines. The power is greater at all ranges, low, mid, and high. If you're lucky enough to find one of these engines stock on a cag, congratulations. How can you tell or look for one of these engines on a stock cag? You pretty much can't tell the difference, without taking off the head and measuring the bore and stroke. It's a pretty much hit and miss type of deal.


Stock Performance in mph

The following are approximations:

SY, ZH-1 and BD engines - 30 mph (+/-) at 9500-10,000 RPMs
48cc engine - 33 mph (+/-) at 11000 RPMs

Here's a list of modifications that can be done to ones bike that can increase its performance at the low-mid and top end.

1. Work from the inside out. What this means is, you'll get the most performance by doing work to the inside of the engine. Ports inside the head are located on opposite ends inside the head. These ports allow the air/fuel mixture inside the head. When the spark plug ignites the air/fuel mixture, therefore driving down the piston and allowing more air/fuel mixture into the head, having the ports opened up will let more air/fuel mixture inside the head than usual. This, couple with the spark plug igniting the newly increased air/fuel mixture will create more power.

It is recommended to do port work to the barrel before doing anything else. If you have a dremel tool, use carbide bits to open up the two intake ports, about 1-2mm all around, and then using the sanding bits to smooth it out. To get the intake ports even smoother, use some fine sandpaper and sand the intake ports down by hand. Next up, is smoothening out the exhaust port. Use some fine sandpaper to smooth out the exhaust port. Sand down the transition and smooth the exhaust port as much as you can, port match it to your exhaust if possible. If you're brave enough, add a boost port, opposite to the exhaust port. If you don't know what I'm talking about, don't try it. You can easily have a very expensive ash tray if you mess up. What is needed: Dremel Tool, Carbide bits, Sanding bits, sand paper (grit??) Cost: Your time and price of the tools and sand paper. These modifications should only be done if one is proficient in porting or under the supervision of someone who is.

Performance gains: This can help achieve higher RPMs. You may lose a little bit low end, because the ports will be opened up, but you can achieve much higher RPMs.

2. Carburetor - Port the carburetor (do not use abbreviations) using a carbide bit first to take off approx. 15-16mm, and finish off using some fine sanding paper and perform a taper bore. When you're finished smoothening it out and polishing it, you should have ported it to about 17mm. Port and polish the intake side 1mm if you'd like, as well as the black intake block. With porting of the barrel and carburetor, you'll need to rejet (especially if you ported the head), meaning, more fuel is needed. Either buy an adjustable needle/jet and triple tapered needle kit to increase the amount of fuel needed to mix with the added airflow. Another solution for rejetting, is to use mm64's method of retapping dellorto jets (look at the mm64 how-to part I).

Or purchase a dellorto 14/14 carburetor with a Blata 2.5 intake. Very easy to rejet as well. Price of porting the carb: Free if you have the tools. Price of the adjustable jet/needle & triple tapered needle kit: Approx. $10.00. Price for the dellorto 14/14 carburetor with Blata 2.5 intake: Approx. $75.00.

Performance gains: You will achiever higher RPMs throughout the power range if you rejet properly.

3. Air filter mod - Here's an easy and cheap way to modify your air filter. First, take it off the carb. There are two phillips head screws that attaches the filter box to the carb. Use a stubby phillips screwdriver to take it out. Then, get some aluminum window screening, and wrap it around the carburetor's mouth. This mod, will flow better than any air filter out there and will keep out the big rocks from entering the engine.

Little specs of dirt will get in the carb and will eventually clog it up, where you'll have to pull out the carb and clean it, but it will take time for this to happen. Cost: If you can get scrap aluminum window screening, its practically free, or $7.00 from Home Depot that will last you a lifetime

Performance gains: Increased RPMs throughout the powerband.

4. Reeds - Either purchase CF (Carbon Fiber) reeds from any reputable cag performance shop or purchase some solid fiberglass reeds.

To even get greater air/fuel mixture into the case, cut out the center reed block and use a single piece reed. Or use two (0.3 & 0.5) fiberglass reeds to have a dual stage reed setup. Again, this should be done under the supervision of someone who has experience in doing this, also, a bit of rejet and tuning will be required.

Price for CF reeds: $15-20.00. Price for fiberglass reeds: $10-15.00

Performance gains: This will alleviate most if not all high RPM flutter. These reeds will open and close faster helping the engine reach its max RPMs faster.

5. Exhaust - There are two pipes out in the market that have been proven to add great performance to the cag. Polini's 6.2 pipe modified to fit the cag (take it to a muffler shop if you don't know how to weld), and IP2's race pipe, which looks like a Blata Elite pipe. Price for both pipes: Approx. $100.00

Performance gains: Quite possibly the best upgrade you can do to any two stroke engine. A high performance pipe alone such as the Polini 6.2 and IP2's pipe can give substantially higher RPM's while keeping the low end intact.

6. FC (Full-Circle) Crank - The stock crank, is not balanced. If you take apart the engine, you can see the crank is practically a half circle crank. With the full circle crank, the engine will turn easier, faster, and will be balanced which means no loss of power throughout its power cycle, and will essentially add higher RPM's throughout the powerband. Cost: approx. $60 - $70.00.

Performance gains: This mod will increase rev's by at least 1000 RPM's. This mod is very difficult for the average mechanic, and wil require a complete teardown of the engine, as well as minor modifications (i.e porting) to the case in order for it to fit. This modification should not be performed without the supervision of someone who has performed this previously, with success. Adding this mod, will require a retune of the engine as well.

7. Brake levers - With all this new power, you need a better way to stop. Upgrade your brake levers with some mountain bike levers, from Avid or Shimano. Price: $20-30.00

Performance gains: Helps you stop a lot faster and easier.

8. Tachometer - Purchase a GPT tach that will tell you whether or not your mods actually work. Don't rely on the Butt Dyno. Price: $80-100.00

Performance gains: Knowledge of how your performance mods are working and also helps with tuning the engine as well.

If you're on a budget, like most cag owners are considering the cag costs about $2-300, you can do a lot of the mods listed above for free and not purchase a few of the items listed. If you were to just port the barrel and carb, all you would need to buy is the jet kit so you can idle correctly and make use of all that porting work, you can get away with a cag that will spank any stock cag out there for about $10.00. Not bad eh?
 
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