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ADA Head Kit Review

Project Chinese Pocketbike Review – ADA 44mm Head Kit w/ Boost Port, 13:1 Dome
By: Snowboardgeek1 (Eric)

As always, many thanks have to go out to our performance parts providers. Once again, Brooks from ADA Racing has provided another quality product, which will be sure to add great performance to any air-cooled cagllari, at an awesome price.

Parts Overview:

The ADA 44m head kit can be purchased with either a 13:1 (91 Octane), 15:1 (105 Octane), or 17:1 (Alcohol) compression dome, depending on the users needs. This test was conducted using a 13:1 dome. Further test results using the 15:1 and 17:1 will be provided in the future, and will be added to the bottom of this review. As we all know, refining/tuning these bikes is a never ending process.

The quality of craftsmanship from this head kit is amazing. The parts that come with the kit are as follows.
• 44mm Big Bore machined cylinder, w/ boost port
• Billet Head Shell
• 13:1 dome
• Thin race rings
• Piston with boost port window
• All required hardware and gaskets

Quick Rundown:
Who would buy the kit: Performance-minded enthusiasts and budget-minded racers

KIT RATINGS: (poor, satisfactory, good, very good, excellent)
Instructions: Very good
Parts fit/finish: Excellent
Durability: Excellent
Overall performance: Excellent
Price: $199.00 retail price

Typical Performance numbers*: 12.2K RPMs w/ load

*Numbers generated using a GPT Tachometer, on a straightaway (longest straightaway is 400ft) at Rialto’s Racetrack. Performance numbers will vary according to each person’s bike configuration. Not everyone will achieve these same numbers.

Test Tools & Conditions:
• Half fairing Cag (stock 6/68 gearing)
• ADA 44mm head kit, with 13:1 dome
• ADA 4 petal reed kit, with fiberglass reeds
• ADA billet intake manifold, designed for Dellorto SHA 14/14 carburetors
Dellorto SHA carburetor, with 82, 75, and 73 main jets
• ADA Chromed Race Pipe
GPT Tachometer
• Rialto Race Track – Conditions were great. Temperature at the track was in the low to mid 70’s.

For this test, I decided to use ADA’s 44mm head kit, in conjunction with their other performance products, to make this an all ADA Racing Performance Products type of test. What better way to show how ADA’s performance products work when they’re all used together?

When I first received the head kit, I was truly amazed at the craftsmanship of the kit. I felt like a kid at a candy store. This is definitely the best looking kit I have seen.

Prior to installing the ADA Racing 44mm Head Kit, I noticed the design of their boost port. I discussed this design with Brooks, and this is what he had to say.

“There is one important thing I want to point out on the boost port in our cylinder. Take notice of the angle. All of the other boost ports that I've seen are made with a ball end mill just cutting a slot down the cylinder. That puts a flat top on the boost port, which directs the flow of the port straight across out of the exhaust port. Our boost port is directed at the center of the combustion chamber. All boost ports are not created equal!”

Installation of the head kit was a very straightforward affair, BUT, if you are not an experienced tuner/installer, please do not attempt to install this headkit. As stated on ADA’s instruction sheet:

This is not an installation for beginners. This should be done by an experienced high-performance mechanic only. Improper installation can result in damaged parts!

Now I don’t profess to be a professional tuner/mechanic, but I have worked on these cag’s long enough to have a good idea on what I’m doing. I won’t go over the installation process step by step, as these instructions can be found on ADA’s website, at http://www.adaracing.com/pdf/21-1540.pdf

First thing I did, was take out the engine from the bike. From there it was much easier to work on the engine and install the 44mm head kit. You’ll have to take out your stock head/cylinder and piston. After installing your new 44mm head kit from ADA (use blue loctite on the head bolts), you must set the squish (clearance between the dome and piston at “Top Dead Center” TDC). Following ADA’s instructions, the squish was set at 0.030” (0.76mm). At first I thought it was a bit too high, since the usual squish distance that I have seen with pocketbikes is set anywhere from .4 - .7, with the usual squish set at .5. General rule of thumb is, the lower the squish, the higher your compression and low-end speed will be. A higher squish will give you better top end speed, but your low end will suffer.

I could have lowered the squish to .5, if I were to not use a base gasket, but that is definitely not recommended since this is a head kit and head kit’s will increase compression tremendously compared to a stock head/cylinder. I decided to proceed on with the test using this high squish, and see what the results would be.

After installing the head kit, I installed ADA’s 4-petal reed block, ADA billet manifold made for a Dellorto 14/14 carb, and a Dellorto 14/14 carb with a main jet of 82. I always choose a high sized main jet to begin with, as it will serve two purposes. One, it’ll give me peace of mind knowing that the engine is running rich with minimal chance of any detonation during the break in process. Two, it’ll give me a good idea on how far I should lean out the carb to fine tune everything.

Once everything was set up properly, I installed the engine onto the bike, and drove off to Rialto Racetrack (www.rialtoairportspeedway.com)

As I have done for previous reviews, I did two different types of tests with the bike. I tested top end speed and also, how the bike and its engine modifications react in a real racing environment.

I fueled up the bike, and started her up with ease. It took me literally 3 pulls to get the engine started. Amazing considering it’s a cag. I took the bike around the track for 2 laps and noticed the bike sputtering a little bit, as it was hitting a flat spot on the top end. At that point I noticed my top end RPMs to be at 11.3K RPMs. I took out the spark plug and sure enough, the bike was running too rich. I decided to drop down to a 75 main jet from my initial 82 setting, and the bike improved tremendously. I took out the spark plug once again and still noticed it ran a little rich, so I dropped down to a 73. Now we’re talking.

The maximum RPMs that I achieved with this setup was 12,200 RPMs with load. The bike probably would definitely have achieved higher numbers, but I ran out of room on the straightaway. Acceleration was EXCELLENT throughout the whole RPM range, low, mid, and top end. This setup had the best low and mid end power out of any Cag setup I have tested. Power coming out of the corners was unbelievable, and the bike wanted to wheelie every time. With stock 6/68 gearing, that equals to 36 mph. With a 7/68 gearing, which this motor can pull easily, that equals to 42 mph. I will be testing this setup with a 7 tooth in the near future. Honestly, I’ve never had a Cag where I felt it would pull a 7 tooth at the local racetrack that I go to. Rialto’s racetrack is filled with technical corners, so having such a high gear ratio wouldn’t be beneficial, but this engine setup can pull it easily.

The track was setup as usual, a technical track, meaning, lot’s of turns. The track is setup for both pocketbikes and karts, so for top end speed, I used the outer part of the track which is setup for karts (circular track). Power delivery coming out of the turn and into the straightaway was instantaneous and powerful. I did about 7 laps, twice, to see the consistency of the results and they all were pretty much the same.

For this test, I also had another rider, use the bike. My cousin (who weighs about 120 lbs) and I(160lbs) were smoking every single Cag out at the racetrack on Sunday. There were a few good Cag riders out there, and they had similar setups (head kit, pipe, carb, etc). The ADA Racing equipped Cag beat every single one of them on the straightaway and turns, and couldn’t match the cag’s low-end or top-end speed. I truly felt we had the fastest Cag at the track that day.

Would I recommend getting the ADA Racing 44mm Head Kit? YES! I don’t know how I lived without one on my cag! I’ve had some fast setups before, but there was something always missing, whether it be bad low end speed and great top end speed, or vice versa. This setup has everything. Great low, mid, and top end. As for the top speed, if I didn’t run out of room, I definitely would have achieved a much higher top speed. Also I still feel that the jetting I had was a little high. I believe a 70 main jet would have been perfect that day, and easily have gained an extra 1-200 RPMs up top. As we all know, jetting is not an exact science.

To gain even more top end RPMs, a bigger pipe can be used. I believe the best setup would be to use the ADA 44mm head kit and team it with a big bore Walbro carb. This will simplify the tuning process even more.

With other reviews I have done, I stated top end RPMs somewhat similar to what I have achieved with ADA’s 44mm head kit. So what’s the difference? ACCELERATION. What good is achieving 12, 13, 14K RPMs if the low-end acceleration is bad and it takes you a long time to reach the top end speed? Although I have achieved similar top end RPMs using different setups, none of those setups are even close to the acceleration I achieved with ADA’s 44mm head kit.

Another question people have asked me, how is this setup compared to a polini 4.2? Well, I have ridden a 4.2 and used to own a 6.2 water-cooled Polini. This Cag setup can hang with a polini 4.2 easily, and will beat it in a short technical track. Granted, the polini 4.2 has a screaming top end, the Cag I have will easily beat it at the low and mid end acceleration. Top end, it would either be a tie, or the polini would win, by a small margin (Those damn Italian motors rev really high!). Now this is just my opinion.

For the price of this head kit, you can’t beat it. The power you will gain from this head kit will be much better than quite possibly, any other modification you do to your cag. I would suggest, if you’re looking for the ultimate best performance from your cag, look no further that ADA Racing’s Performance Products.

PBP and ADA will not be responsible for any damages to yourself or your pocketbike resulting from these modifications. Perform these modifications at your own risk.


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