Katerina Swanson
The Honda CT90K, also known as the Honda Trail 90, is a motorcycle produced by Honda from 1966 to 1968. The fuel line diameter for this model is listed as 5.5mm, which is also the stock size for many of the Honda twins, singles, and fours produced between the 1960s and 1980s. This includes models such as the CB160, CB175, CB350K, and CB/CL450K, among others. While some sources suggest that a 1/4-inch fuel line can be used, others have found it to be too loose, even with clamps, and recommend the 5.5mm size for a snug fit.
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What You'll Learn
Honda CT70 & ST90 fuel line replacement kits
If you own a vintage Honda mini motorcycle, you may need to replace the fuel line at some point. This can be a tricky process, but there are kits available that make it easier. Here is some information about Honda CT70 & ST90 fuel line replacement kits to help you get your bike back on the road.
First, let's determine the size of the fuel line you need. The fuel line on a 1970 Honda 90 is 5.5mm in diameter, which is equivalent to about 3/16 inches. This size was used on various Honda models from the 1960s to the 1980s, including the CT70 and ST90.
Now that you know the size, you can consider the different replacement kits available. There are two main options:
- Kit 1: This kit includes 3 feet of 5.5mm fuel line and 4 Honda clips. It provides you with the necessary parts to replace your fuel line, ensuring a secure connection.
- Kit 2: This kit comes with the same 3 feet of 5.5mm fuel line and 4 Honda clips, but it also includes 2 K&N fuel filters. The addition of fuel filters provides extra protection for your motorcycle's fuel system.
Both kits offer a straightforward solution to replacing the fuel line on your Honda CT70 or ST90. The fuel line in these kits is made of high-quality rubber, which is stronger and more resistant to swelling, hardening, and cracking when compared to vinyl and polyurethane fuel lines.
You can find these replacement kits on websites like trafficautodriving.com and phatmx.com. Additionally, sites like Amazon and eBay offer fuel tanks and other related parts for the Honda CT70 and ST90, which you may find useful during your maintenance projects.
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$12.99
Fuel line size and length impact fuel pressure drop
The fuel line size for a 1970 Honda 90 is 5.5mm, or 3/16" . This is the stock size for many
Now, onto how fuel line size and length impact fuel pressure drop. It is important to understand the relationship between fuel line size, length, and fuel pressure when planning a fuel delivery system. Fuel systems can be incorrectly designed if the pressure loss attributed to the length of the fuel lines isn't taken into account.
Every fuel line experiences some pressure loss, depending on its length and the fuel flow rate. The longer the line, the more friction is incurred, and the higher the flow rate, the more friction there is. This friction reduces the pressure under which the fuel is delivered.
Excessive pressure drop in the fuel lines feeding a carburetor or EFI system will inhibit their proper function. In the case of a bypass or return-style regulator, excessive pressure drop through a return line will affect the regulator's ability to operate correctly.
Therefore, careful consideration of fuel line diameter and length is very important to deliver fuel at the correct flow rate and pressure.
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Genuine Honda black fuel line
The Genuine Honda Black Fuel Line is a 5.5mm, 5-foot fuel line that was used in many of Honda's motorcycles in the 60s, 70s, and 80s. It is a stock size fuel line that was used in Honda's singles, twins, and fours, including the CB160, CB175, CB350K, CB/CL450K, CB550, and CB750. The Honda Part Number for this fuel line is 95001-55008, which replaces the older Honda Part Number: 15761-045-000.
The Genuine Honda Black Fuel Line has an internal diameter of 0.2" (5.5mm) and an outside diameter of 0.4" (10.3mm). It is made of high-quality rubber and is sold as a 5-foot length, which is the standard size for many of Honda's classic motorcycles. This fuel line is also compatible with Honda's CT70, CT90, and CM91 motorcycle models from the late 1960s to the early 1970s.
The Genuine Honda Black Fuel Line is a direct replacement for the stock fuel line on many of Honda's classic motorcycles. It is a good choice for those looking to replace their fuel line with a genuine Honda part. This fuel line is known for its good quality and affordable price, and it fits perfectly with the stock petcocks on many of Honda's classic models.
In addition to the 5.5mm fuel line, Honda also offers a 3.5mm Genuine Honda Black Fuel/Drain Line, which is sold as a 10-foot roll. This smaller fuel line is typically used on the brass fittings at the base of the carburetor (overflow lines) and as vent lines on many SOHC carburetors. It is compatible with a range of Honda motorcycle models, including the CB125, CB175, CB200, CB350, CB450, CB550, and CB750.
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Fuel line diameter
The fuel line diameter of a vehicle is important to know, as it directly affects the amount of fuel pressure drop the system will experience. For a 1970 Honda 90, the fuel line diameter is 5.5mm, or 0.2 inches. This is the stock size fuel line that was used on many of the 60s-80s Honda twins, singles, and fours.
The fuel line diameter of 5.5mm is specifically for the Honda CT90K model from 1966 to 1968 and the CM91 model from 1966 to 1969. The Honda CT90K is often referred to as the Trail 90, and both models fall under the umbrella of the Honda 90 family of motorcycles.
It is worth noting that some sources suggest that a 1/4-inch fuel line, or 6.3mm, can also be used for the Honda 90. This size may be a little loose, but it can work with clamps. The 5.5mm size is a tighter fit and may be preferred to avoid leaks.
The fuel line diameter is important when replacing or upgrading fuel lines, as too small a diameter will not fit, and too large a diameter will leak. The length of the fuel line is also a consideration, as it needs to be long enough to reach between the fuel tank and the engine, with some additional length for routing.
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Fuel line colour
The fuel line colour for a 1970 Honda 90 is black. Honda fuel lines are typically black, as seen in the Honda Part Number: 95001-55008, which fits the CT90K model from 1966 to 1968 and the CM91 Honda 90 from 1966 to 1969.
Black is a common colour for fuel lines in general, and it is often the stock option for many vehicles. However, there are other colour options available for fuel lines as well. For example, Fast Flow Fuel Line offers a 1/4" fuel line in a variety of colours, including clear, neon green, neon yellow, neon orange, blue, red, smoke, pink, and purple. These fuel lines are suitable for various motor sports applications, including motorcycles.
The colour of a fuel line can vary depending on the vehicle make, model, and year, as well as the type of fuel line (rubber, vinyl, or polyurethane) and the supplier or manufacturer. It is always a good idea to consult a professional or a mechanic when replacing or repairing fuel lines to ensure that you are using the correct parts and that the job is done safely.
When it comes to fuel line size, it is important to note that the inner diameter (ID) plays a crucial role in fuel system performance. A fuel line that is too small can restrict fuel flow, while a line that is too large can cause fuel to push back and fight the fuel pump, leading to cavitation. The correct fuel line size ensures optimal fuel pressure and engine performance.
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Frequently asked questions
The Honda CM91 90, produced between 1966 and 1969, takes a 5.5mm fuel line. This is the stock size fuel line that was used on many of the 60s-80s Honda twins, singles, and fours.
You can buy a 5.5mm fuel line for a 1970 Honda 90 from Amazon or 4into1.com.
The Honda part number for the 5.5mm fuel line is 95001-55008, which replaces the older part number 15761-045-000.
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