Honda CRF450 Top End Rebuild | Honda CRF450 Engine Build | Dirt Bike Top End Rebuild | Partzilla.com

Check out the Wiseco Garage Buddy kit for the Honda CRF450R here: http://partzil.la/Honda-CRF450-Garage...

See a CRF450 top end rebuild from start to finish in this video from Partzilla.com.

We’re doing a complete rebuild on a 2005 CRF450R. If you’d like to see the whole project, check it out here:    • Honda CRF450 Engine Rebuild  

We’ll start with some calculations and prep work on our rings and piston. Because we’re using a mix of OEM and Wiseco components here, we have to decide which manufacturer’s ring gap recommendations we’ll use. Because we’re using a Wiseco piston that will behave differently than a Honda OEM piston, we’ll use Wiseco’s ring gap specs on the CRF450. Once we get the gaps correct with our grinder, we’ll use Honda’s specific recommendations for how the rings need to be oriented on the piston.

Then, we’ll work on getting the piston installed and then we’ll add the rings and get the cylinder slid down over the top.

Next, we’ll move to the top end, and that starts with the valves. We’re using a new cylinder head for this project, so there should be minimal lapping required. However, we will use some Prussian Blue just to verify that our valves are seating properly before we get on with building the head up.

We’ll then add in our spring seats and valve seals, which will let us work up to installing the springs and valves. A nifty valve spring compressor by Motion Pro is the star of this part of the process. Find it here: https://www.partzilla.com/catalog-pro...

With the head built up, we’ll get it installed. This will involve a multi-step process to torque the head to make sure it's done evenly.

Adjusting the valves presents a challenge initially. Since we’re using new valves, we really don’t have a starting point. To get started on the valve adjustment on the CRF450, we’ll use the old shims from the old head and then install the cam and cam holder. This will give us a jumping off point for our measurements, and then we'll adjust accordingly. For this, we’re using a shim kit from Hot Cams. Check it out here: https://www.partzilla.com/catalog-pro...

A quick word of advice: you’re dealing with lots of REALLY small pieces here. Stuff a towel down into the cam chain opening to keep anything from falling down into the motor while you’re doing the valve adjustment and swapping out shims.

After we have the valves adjusted, we’ll torque down the cam, bolt in the timing gear, and confirm the timing. Once that’s complete, we’re ready to close the engine up by bolting down the valve cover.

Read how to do this job step by step: https://www.partzilla.com/blog/honda/...

Find 2005 Honda CRF450 diagrams here: https://www.partzilla.com/catalog/hon...

Get supplies here:

Ring grinder: https://www.partzilla.com/catalog-pro...

Ring installer: https://www.partzilla.com/catalog-pro...

Feeler gauge: https://www.partzilla.com/catalog-pro...

Maxima Assembly Lube: https://www.partzilla.com/product/aft...

VIDEO HIGHLIGHTS:
Intro - 0:00
Setting and grinding ring gap - 1:50
Finding ring orientation - 5:00
Installing piston - 6:20
Installing rings - 8:30
Installing cylinder - 11:00
Checking valve seats - 17:00
Installing springs and valves - 19:30
Installing cylinder head - 23:30
Adjusting valves - 26:45
Installing cam - 30:45
Installing timing gear and setting timing - 31:50
Installing head cover - 35:00

Shop for OEM Honda motorcycle parts here: https://www.partzilla.com/catalog/hon...

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In the video we’re working with a 2005 Honda CRF450R, but you may have similar steps for your Honda dirt bike. If you’re not sure whether these steps apply to your machine, leave a comment and we’ll get back to you.