Bright Logic Carbed Tuned Roadster
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Let’s welcome in Roadster shop Bright Logic, located in Yamagiwa, Atsugi City, Kanagawa Prefecture. In recent years the shop that specialized in tuning Roadsters have now turned to motorcycles, so if you’re hoping to find Roadster related information I have looked and did not find any on their website. Going over this article myself, Bright Logic seems to favor tuned response in a Roadster over sheer power. Which honestly in my opinion is definitely a way to go in such a small chassis. There is nothing more fun that pushing a small, underpowered, well-balanced car through the torture my foot has to offer. Lets take a look into this carbureted NA Roadster and see what information we can find out by translating this article found in CARBOY 1998.6!
Starting center of page. Translation:
The engine directly connected to the accelerator is Yoshimura’s KNOW HOW! B6 & BP with carburetor TUNING!
Words in green. Translation:
Emphasizes the feel of the Solex intake sound. Head tuning is the open air sound that the resonant fun comes from
Translation:
BP Head Tune Data
Basic head tuning work / Toda 288 & 272 degree cams / Adjustable cam sprocket / Lash adjuster lock / Port enlargement & shape change / Combustion chamber shape change / Seat cut & modified / Head 1.5mm surface grinding / Solex 44mm & intake manifold
Translation:
Only the head is taken down and processed. The basic work alone costs 120,000 yen. However, this menu is so large that it can be called tuning.
Translation:
The most common tuning for both BP and B6 is a specification in which only the head is modified. If you attach a Solex carburetor to this engine, it will become so responsive that you won’t believe it’s the same engine.
Translation:
Mr. Shimazaki says there’s nothing to be nervous about just because the it’s a carb. If the installation is done properly and the carb is new, it can be completed without any trouble. The settings after that can be done once in a while.
Translation:
If you look at the head being processed, you can see the craftsmanship throughout. When it comes to head processing, it costs 80,000 yen to enlarge the ports, change the shape of the combustion chamber, and create a racing shape.
Translation:
The Roadster of Mr. Shimazaki, representative of Bright Logic, is based on the B6. The finished product is very elaborate, as it was created based on personal taste.
Translation:
The first generation Roadster, which sparked an open two-seater boom around the world, included equipped with 1600cc B6 and 1800cc BP. Each has it’s own characteristics; the B6 is fun to rev up to high revs, and the BP has a sense of torque from its displacement, so whatever you choose, you’ll have a lot of fun.
However when it comes to whether the engine can rev comfortably, I am not satisfied with either engine. It doesn’t have a pleasant feeling. Therefore, in order to pursue comfort we rely on tuning. A large number of tuned parts have been released for the Roadster, and you are free to take it in any direction. However, don’t worry if you only aim to increase power.
Durability is halved. Just power what I can’t talk about is the Roadster.
The basics of this car are to enjoy driving. At CB (CARBOY), we believe that analog is basically the way to go, as it requires a quick response to the accelerator, and when the engine is turned to high speeds, the sound quality changes, but you can experience a noticeable increase in speed.
That is why CB suggest carb.
Translation:
The feeling and sound when the throttle opens, the response that is directly connected to the pedal, is something you cannot experience with injection. This is a unique feeling, and it leads to the ultimate joy that only you, the driver, can experience. However, by attaching only the carb to a normal engine, you can only enjoy the sound and atmosphere. That is not the essence of NA tune.
The ideal CB is for the accelerator response and power to follow. What’s more, the carb only comes to life when matched with a tuned engine that can rev up to high speeds. To do that, we have to modify the engine itself. Although it is not, it is a full-scale product that has been carefully prepared. In this case, the cost also increases.
Taste the feeling of a plus carb tuning. You can do it. This is a head tune performed by Bright Logic. The parts used are based on 1800cc BP, Toda racing 288 degree and 272 degree cams (46,000 yen x2 + relief processing fee 12,800 yen) and cam sprocket (16,000 yen x2), and L/A lock (12,000 yen), 60mm normal metal headgasket, Solex 44
mm intake manifold, regulator (194,000 yen) and the rest is manufactured through processing. When I say processing, I only increase the compression ration to 10 by grinding the surface to 15mm.
The head overhaul here includes carbon removal, seat correction, port correction, sand removal, deburring, and piston carbon removal. If you do this much, it would be no surprise to call it a tuning engine, but at Bright Logic, this is just basic work. In addition to 18,000 yen, the price is 120,000 yen all included in the grade. This is cheap.
Here is the real tuning menu. From here, the ports are enlarged and the shape changed, and the combustion chamber shape and volume are adjusted. With Yoshimura’s know-how, you can modify the engine. If that happens, you will be able to achieve sharper response and acceleration, and feel will change as well. Even if you add this menu, it will cost 80,000 yen.
It’s totally unbelieveable. This can be understood by looking at the finished head. It’s not the kind of shape you can make yourself, and if you’re not used to it, it will take a lot of time.
Touch up the Solex set on this and you’re done. The price of the carb includes the settings. Even if you include the cost of parts, the total will be 600,000 yen. 600,000 yen may seem a considerable amount of money, but when you look at the actual work, I’m sure you’ll understand.
(Akihiro Takahashi)
Translation:
Equipped with original rollers to prevent the timing belt from bending at high speeds. Parts like this are Mr. Shimazaki’s hobby.
Original here meaning an original part made by Bright Logic.
Translation:
It looks like a motorcycle carb, but it was originally developed for use on motorcycles. Yoshimura has been using it for quite some time.
Translation:
Gift to senior carb driver.
TMR by Bright Logic Tune
In addition to the head tune menu introduced this time, Mr. Shimazaki’s Roadster was equipped with a carb called Mikuni TMR. The throttle shape is not a butterfly type like Solex, but a slide valve type, so there is suction resistance in the carb when the throttle is fully open, allowing more air to be fed and increasing output. Since the slide valve contains a bearing, it is characterized by a unique bearing noise that occurs when idling or when the accelerator opening is small. The short carb length also improves fuel atomization efficiency, and the fuel injection position is close to the engine, which improves accelerator response. Depending on the opening of the throttle valve.
Translation:
You can make detailed settings, and enjoy many benefits such as improved feeling and increased fuel efficiency. However, since it is basically for motorcycles, there is no manifold that can be attached to it, so Mr. Shimazaki carves an intake manifold from solid aluminum and installs it using insulator rubber made for motorcycles.
Translation:
Below graph
Comparison of Mikuni TMR carb and Solex. Although there appears to be no major change in the line, the arrival time is said to have been significantly shortened.
Bottom
TMR can control fuel by dividing into five sections this means that even more severe setups are possible.
Thank you for your support if you have got this far through the article. Translations aren’t the best, but I bet it’s a little easier now than trying to decipher a foreign language! In an age of electric vehicles slowly becoming more normal in society, how would you feel about bringing back carb tuning into the light with cars like the Roadster? What about carbed rotaries? Carbed SRs? There’s a lot to be had it seems from a carbed engine when it comes to response. Response in an engine is crucial to feel connected to a vehicle and is also a vital part of enjoying the ride! I hope you enjoyed reading through this article and have found an appreciation for Bright Logic!