GUIDE
Installing and Removing Clutches on Go Kart Engines

Looking for a new clutch? You can find our range with free delivery here: https://www.cutpriceracing.com.au/store/Budget-4-stroke-Clutches/

This month, we're turning our attention to your clutch - how to remove your old one and install a new one. Sometimes you'll need to do this if you want to change gearing, clutch styles or even if you damage a clutch. It's all rather easy really, but to clear up any mis-conceptions of difficulties, let us run you through the process to avoid any headaches and colourful language!

In this guide we'll swap out the standard 18T clutch supplied with our ST1 engine for a 12T model.


CONTENTS

1. Removing the spark plug

2. Installing the piston locking tool

[b] 3. [/b]Removing the clutch

4. Installing the new clutch

This guide explains how to easily remove and install a clutch using the Piston Stop Crank Locking Tool.

You can also substitute the tool for a lower cost alternative, such as a screwdriver or other tool to lock the flywheel in position which can be purchased from most automotive stores. However, in our experience this tool is much safer to use and will avoid damage to yourself, and your engine. Once you've used one, you'll think you were crazing doing it the hard way.

This tool can be operated with low strength and allows virtually anyone to change a clutch.

Using this tool dramatically reduces the time and effort required to remove and install a clutch.

Want to buy a Piston Stop / Crank Locking tool? You can get one with free delivery here: https://www.cutpriceracing.com.au/store/Piston-Stop-Crank-Lock-Clutch-Removal-Tool/

REMOVING THE SPARK PLUG

1. Remove the spark plug lead from the plug by pulling (do not twist)

2. Using a deep cylindrical socket or spark plug socket, remove the plug by winding anti-clockwise. Be careful not the damage the tip of the plug.

INSTALLING THE PISTON LOCKING TOOL

1. Wind the tool into the spark plug hole as far as possible by hand

2. If it's the first time you have used the tool, you may find it difficult to wind in after a six or seven threads. This is because there is sometimes some residue from the manufacturing process of the billet on the thread of the tool. Use a large flat-head screwdriver to wind the tool in further until you feel it touch the top of the piston or it winds it's thread completely in.
The screwdriver also helps if you have a recessed plug, or there is an airbox and/or exhaust system in the way of getting your hand inside.

3. If the piston locking tool doesn't wind in very far before it hits the top of the piston, unwind it completely then turn the crankshaft 1/4 turn at a time by connecting a socket and ratchet or spanner to the retainer bolt on the end of the crasnkshaft and re-check. This will relocate the piston so that it is further down the bore and allow the tool to wind in completely.

4. Once the piston stop is all the way in, wind the crankshaft ANTI-CLOCKWISE slowly using a ratchet and socket until the piston locks on the tool (you'll feel a very light thud) - WARNING DO NOT WIND TOO FAST or you risk damaging the piston stop tool and/or piston. Generally the softer billet alloy will not damage the piston, but if you wind it in hard enough it may dent the top of the piston.

REMOVING THE CLUTCH

1. With the piston locked against the piston locking tool, put more pressure on the crankshaft retaining bolt with the ratchet and socket in an ANTI-CLOCKWISE direction until the bolt cracks and loosens.

2. Wind it all the way out. Do not lose the retaining washer or bolt. NOTE THE BOLT IS NOT AN M8 THREAD - Do not try to replace with an M8 bolt if you lose the retainer bolt. Replacement bolts are available in our store if required.

3. Slide the clutch off by pulling away from the engine. If the clutch has been in place for a long time, and has been exposed to moisture, dirt and other contaiminants it may become stuck (rusted/oxidised in place). It is possible to use a gear pulling tool to remove the clutch in this case - we do not have a picture of this process but it is very straight forward.

INSTALLING THE NEW CLUTCH

1. NOTE Generally your clutch will be shorter than the length of the shaft. There are two ways to solve this issue. #1 is to use a 19.05mm spacer (for 3/4 clutches) and #2 is to use a grub screw/set screw if your clutch has provision for one. Place the spacer on the shaft before the clutch if you are using a spacer, or if you are using a grub screw, wind it in until just before it pokes through the hole where the shaft will go through the clutch before installing the clutch.

1b. Note also that there are two ways the clutch can generally be mounted - Inboard, and outboard. Inboard means the sprocket is close to the engine with the drum on the outside. Outboard means the drum is on the inside and the sprocket is on the outside. We are mounting a clutch using the outboard style in this example. Always check with the clutch manufacturer to ensure the clutch can be mounted in the direction you are wanting to install it - the clutch will spin the opposite way in each configuration.




2. Slide the clutch onto the shaft after the spacer (if using a spacer)

3. If you have used a grub screw/set screw to position your clutch, leave the clutch end overhanging the shaft by approximately 2mm and screw the grub screw in further to lock into the shaft.

4. Replace the retainer washer and retainer bolt in the crankshaft. Using the socket and ratchet, tighten the bolt in a CLOCKWISE DIRECTION until the crankshaft starts rotating. When the crankshaft starts to rotate, turn it slowly until it hits against the piston stop (you'll feel a very light thud) - WARNING DO NOT WIND TOO FAST or you risk damaging the piston stop tool and/or piston.

5. Now put some pressure on the bolt and tighten. The crankshaft bolt can be tightened up to 30ft/lbs.

You're now ready to attach a chain and go have some fun!