Honda CX500 & GL500 Forum

Search Sort Posts:  Oldest to newest Newest to oldest

07-18-2010, 11:23 AM cbkurvenkratzer Joined on 07-18-2010 Posts 3 sportster exhaust question I have been reading a lot about people putting harley mufflers on their cx. I have taken out my H-Box and bent straight pipes to fit headers and fit sportster mufflers on them. The set-up looks awesome, but sound and performance......not as expected!! I have rejetted the carbs (85/125) and added a K&N drop-in air filter. The fuel/air mixture seems slightly on the lean side (according to the looks of the spark plugs). The torque in midrange has decreased. According to one member a washer welded to a bolt and attached to end of exhaust might help. Well, my sportster mufflers look a little different than his, not that simple to drill hole......so, since my washer has exactly the same diameter as my added pipes, I squeezed them into the sportster mufflers and by sliding them back over the pipes the washers stay in place. A very nice fit. I have a little more torque now and the pipes are little quieter (sound is still not that great). My question is: does it matter, if the washer is placed in front of muffler? Obviously I won't be able to adjust the backflow by changing the angle of washer. Also has anyone tried my combination. Do I need to change jets to bigger ones. Do I need to play more with backpressure? Thanks P.S. I have a 1980 CX 500 Deluxe with 25,000 miles on it    Report

07-18-2010, 12:06 PM Blindstitch Joined on 03-14-2009 Greenfield Wisconsin Posts 9,861 Re: sportster exhaust question We really need to see a picture of your mufflers to tell you otherwise. Can you see baffles in them or are they hollow? Most that do the sportster/dyna mod don't have to rejet unless they take the h box off. When I didn't have an hbox and had mac pipes hooked up my combination was 90/120. 1979 CX500 Supertanker ATGATT makes riding a bike like a sled easier. Quick Reference    Report

07-18-2010, 1:22 PM cbkurvenkratzer Joined on 07-18-2010 Posts 3 Re: sportster exhaust question Attachment: DSC_0030.JPG no H-Box and mufflers have baffles.    Report

07-18-2010, 1:31 PM cbkurvenkratzer Joined on 07-18-2010 Posts 3 Re: sportster exhaust question Attachment: DSC_0031.JPG this one shows the washer inside the muffler where it slides over pipe.    Report

07-18-2010, 4:34 PM Blindstitch Joined on 03-14-2009 Greenfield Wisconsin Posts 9,861 Re: sportster exhaust question Holy pipes. You might want the washer or another washer on the outside. 1979 CX500 Supertanker ATGATT makes riding a bike like a sled easier. Quick Reference    Report

07-19-2010, 12:22 PM Shep Joined on 01-30-2007 UK.2x1980CX500A Posts 7,647 Re: sportster exhaust question I have two sets of Harley 883s cans and they are both different.I've modded them both, http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=9&t=324&p=1667&hilit=883#p1667 There was no need to reject however even with this modification my fuel consumption went way up especially on the cans that are straight through.It's hard to say if they give more power but with the modification they seem to give a pretty good even power-band.     You must remember though that Honda will have used specialist test equipment when designing the original exhaust systems to take into account the collector box and semi-sealed Constant Velocity carburettor system and the stock exhausts will have had their baffles tuned to this to give the correct exhaust scavenging.Changing any of the components will affect other parts of the system including the engine.   If when you are happy with your set-up it would be worth taking the bike down to a shop with a Dyno and exhaust emission test system and getting a,"Pro" just to give it a quick run through and take advice from them should something need fine -tuning or changing to get the best out of any changes. My Music http://www.reverbnation.com/pauldouglas/ Join Just In Case :) http://globalcxglvtwins.hostingdelivered.com/ Id quot circumiret, circumveniat    Report

07-21-2010, 3:35 PM Porkchop Joined on 04-26-2010 Guntersville, Alabama Posts 27 Re: sportster exhaust question I recently put a set of 883 Sportster mufflers on my CX. They were freebies from my Wife's uncle. He had already knocked the baffles out with a steel re-bar when they were on his Sportster. I removed the H-box because it was rusted beyond repair, ran straight pipes on both sides, and clamped on the Sportster mufflers. I didn't re-jet the carbs, and the bike still runs great and sounds better than it ever has since I've owned it. I don't know if anyone else that has done this conversion has had the same results as I have, but I hope this helps you to figure this out for your own bike. I will post some pics as soon as I can. Best of luck with your bike. 1978 Honda CX500 Bike's Name: "The Pork-Chop Express"    Report

07-21-2010, 4:25 PM Doward Joined on 05-11-2008 Alachua, FL Posts 814 Re: sportster exhaust question Not to thread-jack, but Shep, can you expound on where the 'semi' part of semi-sealed is?   I was under the impression that save for the float bowl, the carbs were sealed... 1978 CX500 motor + 1980 CX500C frame    Report

07-21-2010, 5:03 PM Shep Joined on 01-30-2007 UK.2x1980CX500A Posts 7,647 Re: sportster exhaust question I just meant that the whole input and output of the engine is tuned/Semi-sealed sort of,not the carbs as such but part of a whole system. The air-box and filter will have been taken into account for the carburation as will the back pressure breather system that feeds into the air-box/recycled and been tested against and in tune with the Constant Velocity Carburettors.    The stock exhausts are 23" long and including their baffles these will have been designed for the optimum performance along with the collector box and down-pipes to provide the correct scavenging/back pressure during combustion and exhaust related to the Cam-shaft profile and Inlet and exhaust valve timing-overlap to be the most efficient as possible at all and increased revolutions to aid in the pulling through of more fuel at higher revolutions and under load.    Changing to Pod filters and straight through exhausts can decrease BHP but may increase some mid-range torque.It's common to believe there has been an increase in power when the sound of the exhausts has been increased when in reality it has been decreased or made uneven.The only way to really tell and tune is with the correct diagnostic equipment.         This is not to say that some people by trial and error will not attain good results but the only way to really tell is by comparing a stock set of figures on a,"Dyno" against any modifications and adjusting to suit.   My Music http://www.reverbnation.com/pauldouglas/ Join Just In Case :) http://globalcxglvtwins.hostingdelivered.com/ Id quot circumiret, circumveniat    Report

Honda CX500 & G... » CX500 GL500 Tra... » CX Customizatio... » sportster exhaust question

(please select) Forums Home |- Search Forums |- Active Topics |- Unanswered Posts User Options |- Sign In |- Join this community |- Forgot Password CX500 GL500 Transverse Twins Discussion Forum |- General Discussion |- CX Customization and Modifications |- CX500 & CX650 Turbo Forum |- Travelling, Friends, and Trips |- Selling and Buying Forum |- Technical Help Forum Other Forums |- Off-Topic Posts |- Test Forum