CMS-Japanese Motorcycle Supply Parts

Fork swap considerations - Honda CX500, GL500, CX650, GL650


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This is a work in progress - incomplete

Interested in upgrading your front end/forks to a more modern setup? The Honda CX500 is a good candidate for a front-end swap - the front forks are a tiny 33mm in diameter and aren't exactly stunning performers. You can see some information on some existing swaps that we have documented on the Fork Swap Database page. The comparison has been made numerous times to a pair of wet noodles holding up the front end. So how simple is it to bolt on a new, modern front end?

Things you have to consider include:

Bearings

For bearing choice and availability, a good place to start looking is the All Balls conversion kit. Check out their website here:

All Balls Racing

The All Balls site will only provide you with bearing kits based on the inner and outer dimensions of the bearings, and does not take into account things like steering stem length or whether that particular model is an upgrade or downgrade!

Brakes - master cylinder + calipers

If you have a CX500 with a single-disc front end and you want to use the existing master cylinder on a newer, dual-disc setup you may find that the master cylinder is the wrong size. If you're getting a complete front end you'll likely find a properly matched master cylinder and caliper setup, but if you're mixing and matching it will pay to check.

Brake lines

Changing front ends and going from the standard bars to clip-ons, or trying to use your existing upgraded lines with a new front end? Make sure that your brake lines are the right length, as both too long and too short are bad.

Controls

Using another bike's controls? How will they match up to the existing wiring harness electrically? Is the kill switch wired the same? If you're trying to use the stock CX500 controls on a new set of bars, are the new bars wide enough to accomodate them? Does the donor bike use the same 7/8" or 22mm bars that the CX/GL range does?

Handlebar options

Certain front end choices will largely restrict you to clip-ons without further modification, e.g. CBR600RR. Clip-ons aren't for everybody! Check that you're comfortable with them before committing to a front end which has them.

Ignition switch

If you're getting a whole front end make sure you are confident that you can wire the ignition switch into the bike's harness, or pay someone who can...

Rake

Text somehow deleted, will re-write shortly.

Speedometer

The CX500 and some other bikes have a mechanical speedometer drive attached to the front wheel - if you change to a more modern bike with a different speedometer setup you will have to utilise the new front end's speedometer or find an aftermarket way of reading your speed.

Stem Length

The steering stem has to be of a compatible length to the recipient bike's frame neck. In addition, the threads for the nuts that hold it in place must be in compatible locations on the stem. If the stem is too long or the threads too high you won't be able to tighten the nuts to hold the stem (and thus front end) in place, and if it's too short there will be nothing to thread the nuts on to! We are trying to gather lengths here: Fork Swap Length Database.

Triple Trees

One oft-asked question is "Can you use bigger forks with the stock CX500 triple tree?" - and the answer is no. The stock triple tree has holes in it to take a certain size of forks - mostly 33mm for CXs - and you can't physically fit the larger tubes through them. Particularly with inverted forks, where the section going through the triple is relatively huge.

Wheels and Tyres

The chances that your much more modern front end's wheels are a match for your rear wheel is slim. You need to consider whether you will run two different looking wheels, or try to find a front end which allows you to utilise your existing wheel. This may require custom machining of spacers and the like. And if that works, you also need to consider whether the new front end's brakes will work with the old wheel.

Further to this, your older motorcycle may be using bias ply tyres, and the newer one probably uses radial tyres. If you're changing from one to the other you should thoroughly read up on the possible consequences of mixing types and the differences between the two - you don't want to discover a sudden difference in the handling on a 60mph bend.

Brakes

The braking setup on a modern sportsbike is light years ahead of what a commuter bike designed in the '70s has. If you're planning on utilising your existing controls, you need to make sure that the master cylinder is a good match for the new brakes.



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