Tag Archives: Cafe Racer Exhaust

Honda CX 500 Cafe Racer custom exhaust build part 2


custom exhaust CX500 Cafe Racer

It has been a while since I last updated my CX-500 Cafe Racer project.   There has been lots of progress on the bike, but very little posting. I hope to get caught up on sharing this project here on projectsbyzac.com in the coming weeks.   In my previous post I shared some of the trials and tribulations involved in building a custom exhaust for my cafe racer bike.   I started with the back half of the exhaust as I knew where I wanted the muffler to be placed on the bike.  This post shares the issues working with the front section of the exhaust from the cylinders to the previously built back half.

 CX500 exhaust Cafe Racer build    CX-500 Cafe racer exhaust 01

Far and away the most difficult part of the entire exhaust build was balancing and centering the front pipes. My first attempt used mandrel bent tubing that was too tight a radius.  The tight bend radius(2.5″ radius) of the  turn downs coming out of the cylinders looked nothing less then ridiculous.  I switched to a larger 4.5″ radius tubing.  Additionally the cylinders are offset so centering and matching the length was challenging.  Work slowly, drop a center plumb bob line and measure everything with a magnetic angle guage three times before welding the pipes in place.  I also had to machine short clamps and spacers for this step of the build.  So I could align and weld to the original exhaust flanges that mount to the heads.  You can see them in the above picture. I used the cnc mill to machine them from 1/4″ steel.  Here is the drawing of the Honda Cx500 exhaust clamp flange showing dimensions for those that want to make your own exhaust clamps or need to have replacements machined.

custom exhaust using cardboard templates   building a custom exhaust using cardboard templates

The next challenge was making a smooth merger for the 2 to 1 exhaust pipe transition. I was certain I only wanted one muffler on my bike. This is a much more difficult exhaust to build then one with two matching independent mufflers, but is lighter and more refined. I also hope that the exhaust pulses will smooth out the sound and cancel out some of the noise.  To make the y-pipe merger I used a template made from a cut up cardboard tube.  I slit the tube and made it the same diameter as the 1.5″ pipe with some tape. Then I notched the cardboard (much easier to work in paper then metal) to fit at the precise angle I wanted.

Make a Y pipe exhaust notching tubing   smoothly merging exhaust pipes

After transferring the pattern to the steel tubing I easily cut a clean notch out.  I spot welded the tube  in place on the bike to make sure I had the precise location, fit and angle.  I used a hole saw matching the inner diameter of the tubing and a hand drill to cut out the notch slug from the tube the notched stubb of tube was welded onto.  This is an easy way to make the second notch in the tubing.

make a y-pipe exhaust collector

When making custom exhaust mergers, take the time to go in after fully welding and clean up the inside of the pipe with a carbide burr.   You are taking all of the time to build a custom exhaust for your ride so spend the extra few minutes to clean up the insides of transitions.  If you have ever done any fluid flow analysis and modeling at a merger you would understand how much a little time spent smoothing the inside aids in maintaining a nice laminar flow as the two streams mix.

cafe racer exhuast progress

The fully welded merger in place, the last step is to fit some pipe between the other cylinder and the merger. Pretty straight forward.

custom cafe racer exhaust

That finishes up the exhaust build.  I still need to finish all the welding at the joints and then clean it up in this photo.  I realize this is not a symetrical design. If I cared a bit more I may have gone through the trouble of turning both exhausts in and under the center of the bike making a more equal length flow path for the gases and a more symmetrical look on the bike.  I think I’ll leave that for the next bike I build.  I plan on building a bolt in baffle on the exit of the muffler should the noise level be louder then I want it to be.

CX-500 Cafe racer exhaust 02

A final note about project and shop safety.  I’m often asked what tool I consider to be the most dangerous in my shop. I typically respond: right angle grinders. I have 4 of them in different sizes. One always fitted with a knotted wire wheel for cleaning joints up just prior to welding.  I’ve had more scary incidents with right angle grinders then any other tool, for example a cutting wheel explodes.  I always use a face shield when using a right angle grinders and you should too! Sure safety glasses are going to protect your eyes, but a full face shield is mandatory in my shop when using grinders.  The cutting wheel in the picture below bounced of the face shield with quite a bit of force while I was trimming the stubb of tubing I welded on making the y connector in this project.  I’d hate to have pulled bits of cutting wheel out of my face had I not been wearing the full face shield.

shattered cutting wheel safety






Building a Cafe Racer Custom Exhaust – Part 1

Building a cafe racer custom exhaust system

I started in on the exhaust system for my CX-500  Cafe Racer project.   I started with the rear of the exhaust for the CX500 Cafe Racer, placing the muffler exactly where I wanted it to be on the bike as the first step.  This build was going to be a 2 into 1 style motorcycle exhaust,  with only one muffler for a  cleaner and cooler look.   Investigating hundreds of photos and parts catalogs I could not find exactly what I wanted for a muffler. I did not want anything chrome, megaphone or cone style mufflers, or anything flash in general.   I wanted something vintage,  flat black, and a little bit crude to go with the Cafe Racer style.  I ended up buying some mandrel bent tubing, and a bare muffler core to fabricate a custom exhaust.  I’ve done a lot of custom exhaust builds over the years, check out an earlier post where I show an exhaust build on a Ferrari 308   from last summer.

Custom Cafe Racer Exhaust system parts

Here are the parts needed to build the custom exhaust system for my cafe racer CX500 motorcycle exhaust.  I ordered up two 1.5″ diameter  U bends (PN: SCH-015016U) ,  two 1.75″ diameter J Bends (PN: SCH-017516J),  & a 12″ muffler core (PN: JEX-A3012B)   from Summit Racing.   Summit Racing is a great cheap place to buy exhaust tubing and mufflers.  They have been my go to auto parts supplier since high school.   I have a fairly large selection of nominal auto exhaust tubing in stock from previous projects but nothing in the motorcycle size range so I ordered everything needed to build the Cafe Racer Exhaust.  The tip on the muffler core I fabricated from some 2.5″ tubing and I will put an internal removable baffle into it to help quiet the exhaust some.  I am certain that  just the core it will be louder then  I want for regular daily riding.

Cafe Racer Exhaust build  muffler mounting    

Mounting the muffler was trickier then I anticipated. I had my CNC Milling Machine  bang out a variety of different mounting brackets for this project.  I ended up using several of the smallest of the three sizes I made and one of the larger skeletonized mounting tabs to put the muffler on the bike.   In the above pictures you can see where I located the muffler on the bike.  I am pretty happy with where it is mounted.

custom motorcycle exhaust build for cafe racer CX500

The exhaust tubing runs inboard and under the lower motor/frame mounting. This is important as I plan to lower the foot pegs a bit and make a new foot shift lever for the bike.  I find with the new seat and the low forward clubman handlebars that it is a bit uncomfortable with the stock foot pegs on the bike.

In the next post on the cafe racer custom exhaust system build,  I show how I make the 2 primary pipes merge into this rear exhaust system.

Mounting and Balancing a CX500 motorcycle tire

Bonus Photo:  The mounted and balanced new front tire on the painted wheel.  I will paint the wheel weights black before mounting them permanently with double sided tape.