How to make a kickstarter for a motorcycle with your own hands: from drawings to assembly

Kickstarter is not just a mechanism for starting an engine, but key element of reliability for motorcycles, especially when it comes to retro models or custom projects. Many owners Nissan GT-R, Skyline or even 350Z (where kickstarters install tuned versions) face a problem: original parts are either unavailable or cost exorbitant amounts of money. Making a kickstarter with your own hands allows you not only to save money, but also to adapt the mechanism to specific needs - be it an enlarged flywheel or a non-standard gearbox.

In this article we will analyze the process from A to Z: from the selection of materials to the final setup. You will find out what 3 critical errors make by 90% of beginners when assembling, how to avoid play in gears and why standard drawings from the Internet may not be suitable for your model. And if you are working with a motorcycle based on an engine from Nissan (for example, in projects with SR20DET or RB26DETT), you will find adapted solutions for these units here.

1. Preparation: tools and materials

Before you start making, collect the necessary equipment. Without the right tools, even a perfect drawing will not save you from defects. Here is the minimum set:

• 🔧 Lathe (for machining shafts and gears) or access to a CNC workshop
• 🔨 Welding machine (argon arc welding for stainless steel parts)
• 📏 Vernier caliper and micrometer (error more than 0.05 mm is unacceptable)
• 🔩 Set of taps and dies for cutting threads (for example, M8×1.25 for attaching the lever)
• 🖌️ Punch and marking tool (for precise hole marking)

Based on materials, the optimal choice is steel 40Х for shaft and steel 20ХН3А for gears (after carburization). Aluminum alloy is suitable for the lever D16T - it is lightweight and durable. If your budget is limited, you can use St3 for a prototype, but the service life of such a part will be 3–4 times lower.

⚠️ Attention: Do not use “ferrous metal” of unknown origin (for example, bars from the market without certificates). In 2023, cases were recorded when low-carbon alloys were sold under the guise of 40X steel, which broke after 5-10 starts.

For engines Nissan RB or SR Additional details required:

Detail	Material	Dimensions (example for RB26DETT)	Note
Drive gear	Steel 20ХН3А	Module 2.5, 18 teeth	Heat treatment HRC 58–62
Kickstarter shaft	Steel 40Х	Diameter 14 mm, length 180 mm	Gear splines – 6×6 mm
Return spring	Spring steel 65G	Wire diameter 3 mm, 8 turns	Free length 120 mm
Lever (pedal)	Aluminum D16T	Thickness 8 mm, width 50 mm	Anodizing for corrosion protection

2. Drawings and calculations: why standard diagrams don’t work

The mistake most DIYers make is downloading the first drawings they come across from the Internet. The point is that Kickstarter geometry depends on:

• 🔄 Clutch type (wet/dry, number of discs)
• 🛠️ Gearbox designs (for example, in Nissan Skyline R32 And R34 different input shafts are used)
• 🔋 Flywheel moment of inertia (lightweight flywheel requires shorter lever stroke)

For an accurate calculation, use the formula:

L = (T × π × D) / (F × η × 180°)

Where:

• L — lever length (mm)
• T — torque for cranking the engine (Nm)
• D — gear diameter (mm)
• F — leg force (usually 150–200 N)
• η — mechanism efficiency (0.7–0.85)

For engine RB26DETT with a lightweight flywheel, the optimal lever length is 180–200 mm (with a standard flywheel - 220–240 mm). Increasing the length by more than 250 mm leads to the risk of shaft breakage during a sudden start.

3. Manufacturing of shaft and gears: turning and heat treatment

The kickstarter shaft is the most loaded element the entire structure. It is made in several stages:

1. Roughing: turning the workpiece to a diameter of 14.5 mm (with an allowance of 0.5 mm for grinding).
2. Spline milling: a modular cutter is used for the gear (for example, for module 2.5).
3. Heat treatment: oil quenching at 850°C followed by tempering at 200°C (hardness HRC 50–55).
4. Sanding: final processing to a diameter of 14.0 mm with a roughness of Ra 0.8.

The gear is manufactured separately. Here it is critical to comply engagement angle (usually 20°) and center distance between the kickstarter and flywheel gears. For engines Nissan this distance is 68.5 ± 0.1 mm.

⚠️ Attention: If the gear is made without heat treatment, its resource will not exceed 500–1000 starts. Signs of wear: chipped teeth and metal shavings in the oil.

To check the build quality, use the following test:

Rotate the shaft in the bearings - play no more than 0.03 mm |

Check the gear engagement for runout (maximum 0.05 mm)|

Apply lubricant Molykote G-Rapid Plus to the splines|

Make sure that the return spring does not block the lever travel-->

4. Assembling the mechanism: step-by-step instructions

When all the parts are ready, start assembling. Use torque wrench for tightening the bolts - the tightening torque for attaching the kickstarter to the crankcase is usually 25–30 Nm.

Procedure:

1. Bearing installation: Press them into the body using a mandrel. For engines Nissan bearings will fit 6202-2RS (inner diameter 15 mm).
2. Shaft installation: Insert the shaft into the bearings and check for smooth movement. If the shaft bites, check the alignment of the holes in the crankcase.
3. Gear installation: place the gear on the shaft splines and secure with a retaining ring 14×1.5 mm.
4. Lever attachment: Use M8 bolt with spring washer. Pre-treat the thread Loctite 243.
5. Spring adjustment: Adjust the tension so that the lever returns to its original position in 0.5–1 second.

After assembly, be sure to check lever free play — it should be 5–10 mm before engagement with the flywheel. If the stroke is less, the risk of teeth breaking during startup increases by 3 times.

What to do if the lever does not return to its original position?

This is a typical problem when the spring tension is weak or it is not installed correctly. Check:

1. Integrity of the spring (are there any cracks or deformations).

2. Coaxiality of the spring mounting holes - they must be strictly on the same line.

3. Lubricate the guide bushing (use Liqui Moly LM 50).

If the problem persists, replace the spring with a stiffer one (for example, with a wire diameter of 3.5 mm instead of 3 mm).

5. Installation on the motorcycle and final adjustment

Before installing a kickstarter on a motorcycle necessarily:

• 🛑 Remove the battery (to avoid short circuits when working on the crankcase).
• 🧹 Clean the seat from old grease and metal shavings.
• 🔍 Check the condition of the shaft seal - if it is worn out, replace it with a new one (NOK 15×24×7 for most models).

After installation, perform a test run:

1. Turn the lever idle (without ignition) - it should move smoothly, without jerking.
2. Turn on the ignition and try to start the engine. If the starter "slips", check the gear engagement.
3. Measure the force on the lever with a dynamometer - it should not exceed 20 kgf (for engines up to 2.5 l).

For engines Nissan RB with turbocharging it is recommended to install enhanced kickstarter with a shaft with a diameter of 16 mm (instead of the standard 14 mm). This is due to the increased drag torque due to the turbine.

6. Common mistakes and how to avoid them

Even experienced mechanics make mistakes when making a kickstarter. Here TOP-3 critical misses and their consequences:

Error	Consequences	How to avoid
Failure to comply with the center distance of the gears	Accelerated tooth wear, jamming	Use a gauge or template to check
No shaft heat treatment	Shaft deformation or breakage under load	Quenching + tempering (HRC 50–55)
Weak lever fixation	Thread stripping, leg injury	Use a bolt with strength class 10.9

Another common problem is play in bearings. It appears due to:

• Insufficient fit of bearings into the housing (you need to use a press with a force of 1–1.5 tons).
• Wear of seats in the crankcase (solution - boring to repair dimensions).
• Lack of lubrication (kickstarter bearings require lubrication every 10,000 km).

If after assembly you hear a metallic grinding sound when turning the lever, immediately disassemble the mechanism. The scratching indicates gear contact at an angle, which leads to their instant destruction.

7. Maintenance and increase in resource

The service life of a homemade kickstarter depends on three factors: materials, assembly and maintenance. With proper care, the mechanism will last 50,000–100,000 km. Here's what to do:

• 🛢️ Lubrication: Apply every 5,000 km Molykote BR2 Plus onto the shaft and gear.
• 🔧 Adjustment: every 20,000 km, check the gap between the gears (should be 0.1–0.2 mm).
• 🔍 Diagnostics: at each maintenance, inspect the lever for cracks (especially at the welding site).

For motorcycles with engines Nissan SR20DET or RB26DETT it is recommended to install oil mist into the kickstarter crankcase. This reduces gear wear by 30–40%. The system can be made from a standard oil trap and pipes with a diameter of 4 mm.

If you use the motorcycle in extreme conditions (such as rallying or drifting), replace the standard spring with two-turn with increased resource. Such springs can withstand up to 50,000 actuation cycles (versus 10,000 for standard ones).

FAQ: answers to frequently asked questions

Is it possible to make a kickstarter from parts from a car?

Yes, but with reservations. For example, a starter shaft VAZ-2108 Suitable in diameter (14 mm), but requires alteration of the spline part. Gears from gearboxes Nissan (for example, from Skyline R32) can be adapted to a motorcycle, but you will have to sharpen new teeth (module 2.0 or 2.5). The main thing is to check the compatibility of the center distance.

Which welding machine is best to use for the lever?

For aluminum lever (alloy D16T) suitable only argon arc welding (TIG) with alternating current. Use filler wire ER4043 and gas Argon 4.6. If you are welding a steel lever, use electrodes UONI-13/55 (for structural steels). Before welding, heat the part to 200–250°C to avoid cracks.

What to do if the kickstarter does not turn over the engine?

There may be several reasons:

1. Poor gear engagement - check the center distance.
2. High engine resistance - measure compression (normal: 12–14 bar).
3. Shaft bearings are worn out - replace them and check the play.
4. Weak spring - install the spring with a force of at least 15 N.

If the problem is high resistance, try lightening the flywheel (remove 100–150 g from its edge) or use a starter with a gearbox.

Can a kickstarter be installed on a motorcycle with an electric starter?

Yes, but it will require crankcase modification. Usually they cut out a window for the lever and install an additional shaft with an overrunning clutch. For engines Nissan SR20 or RB there are ready-made kits from companies Tomei or N1, but their price starts from $300. A homemade version will cost 3–5 times less.

Which lubricant is best for a kickstarter?

Optimal options:

• For shaft and bearings: Molykote BR2 Plus (works at temperatures up to +150°C).
• For gears: Liqui Moly LM 50 (high pressure, anti-scuff).
• For spring: CRC 2-26 (prevents corrosion).

Do not use Litol-24 or Solid oil — they cannot withstand the loads and temperatures typical of a kickstarter.