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| techtalk:ref:carb01b [2019/09/08 21:16] – created hippysmack | techtalk:ref:carb01b [2024/01/10 02:38] (current) – hippysmack |
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| ====== Rebuilding a Mikuni HSR42 ====== | ====== Rebuilding a Mikuni HSR42 ====== |
| Article by rubine of the XLFORUM ((http://xlforum.net/forums/showthread.php?t=1891451)) \\ | Article by rubine of the XLFORUM ((https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
| Some guys maybe do it a little differently but below is documentation of how he rebuilt his carb. \\ | Some guys maybe do it a little differently but below is documentation of how he rebuilt his carb. \\ |
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| * Compressed air | * Compressed air |
| * Some nitrile gloves are a good idea as the carb cleaner will eat through nylon gloves pretty quickly, and also some good ventilation. \\ | * Some nitrile gloves are a good idea as the carb cleaner will eat through nylon gloves pretty quickly, and also some good ventilation. \\ |
| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_1_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_1_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| Parts: \\ | Parts: \\ |
| * Replace the 4 bottom float bowl Phillips head screws with 4mm (.7 pitch) x 12mm Allen head cap screws (esp if your changing jets a lot) \\ You may want to (carefully) use an impact driver to remove the old Phillips head screws from the bowl. | * Replace the 4 bottom float bowl Phillips head screws with 4mm (.7 pitch) x 12mm Allen head cap screws (esp if your changing jets a lot) \\ You may want to (carefully) use an impact driver to remove the old Phillips head screws from the bowl. |
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| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_2_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_2_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| First up remove choke cable, cable pulley bracket and idle adjuster. Record a reference of the idle adjuster so you know where to put it back. \\ | First up remove choke cable, cable pulley bracket and idle adjuster. Record a reference of the idle adjuster so you know where to put it back. \\ |
| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_3_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_3_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| Undo the 3 Phillips screws and remove the top cover. \\ | Undo the 3 Phillips screws and remove the top cover. \\ |
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| With the pin removed the slide assembly will slide out. \\ | With the pin removed the slide assembly will slide out. \\ |
| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_4_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_5_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_6_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_4_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_5_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_6_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| You can then remove the 3 remaining screws to remove the back carb body and 4 screws to remove the float bowl. \\ | You can then remove the 3 remaining screws to remove the back carb body and 4 screws to remove the float bowl. \\ |
| Remove the pilot air screw making sure the spring, washer and O-ring comes out with it. The O-ring has a replacement in the kit. \\ | Remove the pilot air screw making sure the spring, washer and O-ring comes out with it. The O-ring has a replacement in the kit. \\ |
| Also remove the fuel joint. The 2 O-rings also have replacements in the kit. \\ | Also remove the fuel joint. The 2 O-rings also have replacements in the kit. \\ |
| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_7_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_8_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_9_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_7_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_8_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_9_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| Remove the float assembly by unscrewing the float pin screw. The plunger of the needle valve assembly will come out with it. \\ | Remove the float assembly by unscrewing the float pin screw. The plunger of the needle valve assembly will come out with it. \\ |
| Then remove the seat screw that holds the needle valve seat. \\ | Then remove the seat screw that holds the needle valve seat. \\ |
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| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_10_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_11_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_12_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_10_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_11_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_12_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| Unscrew and remove the main jet, main jet extender and the needle jet underneath should come out with a tap, as well. \\ | Unscrew and remove the main jet, main jet extender and the needle jet underneath should come out with a tap, as well. \\ |
| * Accelerator pump rod boot | * Accelerator pump rod boot |
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| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_13_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_14_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_15_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_13_by_rubine.jpg?direct&250|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_14_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_15_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| So now just clean the everything up. \\ | So now just clean the everything up. \\ |
| The second pic is the bits in the rebuild kit, including an extra spigot body seal. \\ | The second pic is the bits in the rebuild kit, including an extra spigot body seal. \\ |
| So its as simple as putting it all back together in the reverse order. \\ | So its as simple as putting it all back together in the reverse order. \\ |
| {{:techtalk:ref:carb:mikuni_hsr42_rebuild_16_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_17_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM http://xlforum.net/forums/showthread.php?t=1891451)) \\ | {{:techtalk:ref:carb:mikuni_hsr42_rebuild_16_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) {{:techtalk:ref:carb:mikuni_hsr42_rebuild_17_by_rubine.jpg?direct&300|}} ((photo by rubine of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/176219-hsr-mikuni-rebuild-with-pics?t=1891451)) \\ |
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| ====== Helpful Links ====== | |
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| * [[http://www.mikunipower.com/HSR01.htm|Mikuni website (HSR page)]] | |
| * [[http://www.mikuni.com/fs-carburetor.html|HSR Installation Guide]] | |
| * [[http://www.mikuni.com/fs-performance_guide.html|Performance Guide]] includes: | |
| * Air Cleaner Basics, Exhaust System Basics, Cam Basics and Ignition Basics | |
| * [[http://www.mikunipower.com/Manuals/HSR_SportsterBuellInstallation.pdf|Sportster / Buell Installation Instructions PDF]] | |
| * [[http://www.mikunipower.com/Manuals/HSR42-48_Manual.pdf|HSR42/45/48 Tuning Manual PDF]] | |
| * [[http://www.mikuni.com/pdf/how_to_choke_cable.pdf|HSR Choke Cable Installation Tips]] | |
| * [[http://www.mikunipower.com/Manuals/HSR_PATInstallation.pdf| PAT Upgrade Kit Installation Instructions PDF]] | |
| * [[https://www.jetsrus.com/a_jets_by_carburetor_type/jets_mikuni_HSR_series.htm|Genuine Mikuni jets for HSR series carbs]] | |
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