This street exhaust system ( 07-0748 ) is a complete replica of the beloved Norton Commando system, made specifically for the XS650. The single thick-wall headpipes are matched perfectly with mufflers that are fitted with the OEM-type internals for that sweet, unrivaled sound. The all-inclusive kit supplies you with a pair of finned exhaust flanges, gaskets, and complete mounting bracket and hardware to get the job done.
Fitment: 1974 – 1979 Yamaha XS650 “Standard” models
1. Do not install this system without first having your bike tuned and running properly in its existing configuration.
A) 1974 – 1979 XS650 “Standard” models have Mikuni BS38 CV carbs installed as the stock original carburetors. We recommend that the stock jetting or richer jetting be used, especially if there have been other modifications done to the motorcycle, such as aftermarket pod air filters installed. Again, the final tuning should be done by someone who knows how to tune and read spark plugs.
Stock jetting for 1974 – 1979 XS / TX650 models with stock 38mm Mikuni CV Carburetors are listed below:
Main Jet ( Mikuni N102/221 – Small Round Type )
#127.5 for TX650A / XS650B (1974 – 1975)
Pilot Jet ( Mikuni BS30/96 )
#45 for TX650A / XS650B (1974 – 1975)
#25 for XS650C / D (1976 – 1977)
2. Remove the old exhaust system and gaskets from cylinder head ports, as well as the rider footrests and passenger pegs.
3. Unpack the new 07-0748 system. Examine, wax and polish the chrome mufflers and headpipes.
4. A hardware kit is included with your Exhaust system and is packed with related parts in sequence.
5. “Standard” models have a passenger peg frame loop that looks like this.
6. Install new headpipes, cylinder head port gaskets and headpipe flange crown nuts and lockwashers (HDW Ref. A). Tighten but leave just loose enough that the headpipe will still rotate in the head. Note: there is always an even gap between the finned flange and the head.
7. Insert the thick washer between each headpipe and the frame. Then, insert the fine thread bolt with washer, (HDW Ref. B) and tighten.
8. Mount the black hanger straps (HDW Ref. D) with the small slotted hole in the bracket to the mufflers. Slip the right-side muffler onto the headpipe and secure with the crown nut and lock washer supplied (HDW Ref. C) at the angle shown. The weld on the muffler end cone should be even with the end of the swingarm as shown in the next photo (9). Tighten the muffler bracket and clamp and the crown nut at the passenger peg end. Check the angle of the muffles verses the headpipe as it may be necessary to pull up on the muffler when you tighten the mounting brackets to get the alignment correct. Stand back and check the final alignment by eye.
9. Slide the right-side muffler onto the headpipe until the weld on the end cone is even with the end of the swingarm as shown.
10. Drill the end of the center stand stop bracket and mount the stop rubber (HDW Ref. D) to the end of the stop bracket (it may be necessary to trim the rubber to get it through the hole). Install the hanger strap on the left side muffler and mount the muffler to the bike. Mount the hanger strap and the center stand stop as shown in the next two photos (11 & 12).
11. Position the muffler as shown in the photo above and tighten the muffler.
12. Tighten the hanger strap and passenger footrest crown nut as detailed in photo 8 and check the headpipe-to-muffler alignment as detailed. Check the position of the center stand stop and adjust as needed. Tighten the headpipe nuts and bolts (flanges and lower brackets).
13. Check the clearance of the mufflers to the rear axle and if the distance differs much on any side this can be adjusted by simply pushing in on the muffler (this will bend the muffles hanger straps a small amount).
14. Re-install the rider footrests and check the rear brake adjustment and the travel of the brake pedal to be sure it does not hit the headpipe.
15. Wipe down the entire exhaust system and remove all dirt, oil, and fingerprints from it before starting or these markings will embed in the chrome plating once the exhaust is hot.
16. Start the bike and let it warm up a few minutes. Check for any exhaust leaks and adjust the idle speed as needed. Shut off the engine and re-tighten all the mounting hardware.
17. Road-test, adjust jetting and idle as necessary and re-tighten all fasteners again.
You have now installed the ‘Commando’ Exhaust System.
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