When it comes to being a master at-home mechanic there are a number of tools you should keep in your garage when you need to rebuild your dirt bike or motorcycle engine. I picked out my top five most important specialty tools to share with you and encourage you to add your favorites to the list by leaving a comment. Read on to learn more about these top five tools that are vital for dirt bike or motorcycle engine building.
Torque Wrenches
Believe it or not, every nut and bolt on your machine has a torque specification associated with it so that you do not run the risk of over tightening, damaging the fastener, or leaving something too loose. Even simple things, like the bolts holding your plastics on and your seat down, have torque values that you should aim to follow. While you might not get into trouble if you overlook using a torque wrench on these fasteners, I consider everything in the engine torque wrench territory. In order to build a good sound engine it is critical to follow the manufacturer's suggested torque specifications for all the fasteners and use a good quality torque wrench...
Believe it or not, every nut and bolt on your machine has a torque specification associated with it so that you do not run the risk of over tightening, damaging the fastener, or leaving something too loose. Even simple things, like the bolts holding your plastics on and your seat down, have torque values that you should aim to follow. While you might not get into trouble if you overlook using a torque wrench on these fasteners, I consider everything in the engine torque wrench territory. In order to build a good sound engine it is critical to follow the manufacturer's suggested torque specifications for all the fasteners and use a good quality torque wrench...
On a four-stroke engine I would say the single most important thing to torque properly is the cylinder head nuts or bolts, depending on the model you have. If you over tighten it is very possible that you could strip something whether it be the nut, the bolt, or the crankcase threads. Ultimately if you overlook it or do it incorrectly, you have created additional work for yourself and taken a step backwards. Now let's assume you under-tighten the cylinder head. This won't result in a favorable outcome either. Your cylinder head gasket and base gasket both require a certain amount of pressure to compress them properly so that they seal. If you under-tighten your cylinder head the gaskets may not seal correctly and you may end up with coolant in your combustion chamber, coolant leaking out around the cylinder head, a cooling system that blows coolant due to the combustion pressure pushing it out, or oil leaks around the base gasket. In other words- bad news for a healthy engine.
Usually the range of torques you will need to cover will require you to pick up a couple different wrenches. Right now I've got a small one that goes from 30-150in lbs for the delicate stuff and a larger wrench that goes from 20-100ft lbs. As for what brand is the best, everyone seems to have their favorite, but I personally like the wrenches CDI offers. CDI is a branch-off company of Snap-On and they offer great quality at less cost. I paid around $100 a piece for my wrenches, which came with all the necessary calibration paperwork I like to see.
Usually the range of torques you will need to cover will require you to pick up a couple different wrenches. Right now I've got a small one that goes from 30-150in lbs for the delicate stuff and a larger wrench that goes from 20-100ft lbs. As for what brand is the best, everyone seems to have their favorite, but I personally like the wrenches CDI offers. CDI is a branch-off company of Snap-On and they offer great quality at less cost. I paid around $100 a piece for my wrenches, which came with all the necessary calibration paperwork I like to see.
Flywheel Puller
If you have to split crankcase you will have to remove the flywheel. I have heard stories and seen video footage of folks beating off their flywheels, but I definitely would not recommend this tactic. Picking up a flywheel puller for your specific model so you can do the job right is a much better option. The pullers are fairly cheap, easy to use, and make the job extremely easy.
If you have to split crankcase you will have to remove the flywheel. I have heard stories and seen video footage of folks beating off their flywheels, but I definitely would not recommend this tactic. Picking up a flywheel puller for your specific model so you can do the job right is a much better option. The pullers are fairly cheap, easy to use, and make the job extremely easy.
Strap Wrench
The strap wrench is a great versatile tool. My favorite spot to use it is on the flywheel when I'm removing the flywheel nut. In order to remove the flywheel nut you will need to secure the crankshaft in some way. A lot of people will lock the crankshaft from the clutch side so they can remove the flywheel nut, but in my opinion this is not the best practice. If you lock the crankshaft on the clutch side and apply torque to the flywheel side, the crank will tend to twist around the crankpin. This may not be a huge problem when loosening the nut, but when you reinstall and torque the nut you run the risk of twisting the crankshaft. If you do end up twisting the crank you can expect expedited engine wear, excessive vibration, and main bearings that will not last long. Again, not good news for a healthy engine.
The strap wrench is a great versatile tool. My favorite spot to use it is on the flywheel when I'm removing the flywheel nut. In order to remove the flywheel nut you will need to secure the crankshaft in some way. A lot of people will lock the crankshaft from the clutch side so they can remove the flywheel nut, but in my opinion this is not the best practice. If you lock the crankshaft on the clutch side and apply torque to the flywheel side, the crank will tend to twist around the crankpin. This may not be a huge problem when loosening the nut, but when you reinstall and torque the nut you run the risk of twisting the crankshaft. If you do end up twisting the crank you can expect expedited engine wear, excessive vibration, and main bearings that will not last long. Again, not good news for a healthy engine.
Crankcase Splitter
Splitting crankcases should be a delicate procedure, especially if the crank is to be reused, and having a crankcase splitting tool on hand makes the job a lot easier. I have seen videos of people beating on the end of the crank to push the cases out, but I assure you this is not the right way to do it and may put the trueness of the crank in serious jeopardy. The case splitter is a must-have and provides a way to evenly and gently separate the cases. Along with the other tools listed, the crankcase splitter is relatively cheap and will pay you back handsomely by helping you perform a top quality trouble-free build.
Splitting crankcases should be a delicate procedure, especially if the crank is to be reused, and having a crankcase splitting tool on hand makes the job a lot easier. I have seen videos of people beating on the end of the crank to push the cases out, but I assure you this is not the right way to do it and may put the trueness of the crank in serious jeopardy. The case splitter is a must-have and provides a way to evenly and gently separate the cases. Along with the other tools listed, the crankcase splitter is relatively cheap and will pay you back handsomely by helping you perform a top quality trouble-free build.
Clutch Basket/Sprocket Holder
The clutch basket holder locking pliers are truly the only answer for properly disassembling and assembling clutches. In the past I have seen screwdrivers jammed into the hub to keep them stationary while trying to tighten or untighten the nut. This sort of thing typically ends with damaged clutch parts, meaning more cost to you in the long run. The clutch basket holder locking pliers are great because they can be adapted for pretty much any size clutch hub and provide a solid means to retain the hub while fastening the nut. The pliers are fairly inexpensive at around $30 and some even double as sprocket holding pliers.
The clutch basket holder locking pliers are truly the only answer for properly disassembling and assembling clutches. In the past I have seen screwdrivers jammed into the hub to keep them stationary while trying to tighten or untighten the nut. This sort of thing typically ends with damaged clutch parts, meaning more cost to you in the long run. The clutch basket holder locking pliers are great because they can be adapted for pretty much any size clutch hub and provide a solid means to retain the hub while fastening the nut. The pliers are fairly inexpensive at around $30 and some even double as sprocket holding pliers.
I hope you guys agree with my top five specialty tool picks. If you enjoyed this post I think you will love the book we just published The Four Stroke Dirt Bike Engine Building Handbook. The book is available in print as well as an eBook. To learn more about this comprehensive guide to rebuilding your four stroke, click here.
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