Differences
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| techtalk:ih:oil03u [2025/06/25 20:29] – [1972-1974 XR-750 Oil Pump] hippysmack | techtalk:ih:oil03u [2025/10/21 03:14] (current) – [1988-up XR-750 Oil Pump] hippysmack | ||
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| ====== IH: Oiling & Lubrication - Sub-03U ====== | ====== IH: Oiling & Lubrication - Sub-03U ====== | ||
| ====== XR-750 Oil Pump - Parts Lists and Information ====== | ====== XR-750 Oil Pump - Parts Lists and Information ====== | ||
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| 1970-1987 racing pumps ran 1/4 speed of engine RPM.\\ | 1970-1987 racing pumps ran 1/4 speed of engine RPM.\\ | ||
| The 1/4 speed gears on the both the breather shaft and pinion shaft were cut at a taller angle than on street motors.\\ | The 1/4 speed gears on the both the breather shaft and pinion shaft were cut at a taller angle than on street motors.\\ | ||
| Below is a pic showing the difference in teeth angles. | Below is a pic showing the difference in teeth angles. | ||
| - | {{: | + | {{: |
| ====== 1970 XR-750 Oil Pump ====== | ====== 1970 XR-750 Oil Pump ====== | ||
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| ====== 1972-1974 XR-750 Oil Pump ====== | ====== 1972-1974 XR-750 Oil Pump ====== | ||
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| * Pump speed is 1/4 of the engine speed. | * Pump speed is 1/4 of the engine speed. | ||
| * Return gears operate at a 2:1 ratio of the feed gears. | * Return gears operate at a 2:1 ratio of the feed gears. | ||
| * Gear Dims: | * Gear Dims: | ||
| - | | + | |
| - | * Feed Gears: O.D. (1.115" | + | * Feed Gears: O.D. (1.115" |
| - | * Return Gears: O.D. (1.115" | + | * Return Gears: O.D. (1.115" |
| - | * The crankcase breathing system was used to return oil from the crankcase into the cam / gear cover using the timed breather valve gear. \\ From there, the oil drained directly onto the return gears of the oil pump. ((-2003 HD XR-750 Service Manual pg 27)) | + | * The crankcase breathing system was used to return oil from the crankcase into the cam / gear cover using the timed breather valve gear. \\ From there, the oil drained directly onto the return gears of the oil pump. ((1972-2003 HD XR-750 Service Manual pg 27)) |
| - | * Breather Timing (standard): Valve opens at (14°-16° ATDC) front cylinder. Valve closes at (85°-90° ABDC) front cylinder. \\ Adjust breather timing by adding shims behind oil pump drive gear (on pinion shaft) and by increasing slot width in breather. | + | * Breather Timing (standard): Valve opens at (14°-16° ATDC) front cylinder. Valve closes at (85°-90° ABDC) front cylinder. \\ Adjust breather timing by adding shims behind oil pump drive gear (on pinion shaft) and by increasing slot width in breather. |
| - | * Breather Timing (improved): Valve opens at (5° ATDC) front cylinder. Valve closes at (105° ABDC) front cylinder. \\ Slot in upper cover must be widened to app .340" to make this possible. | + | * Breather Timing (improved): Valve opens at (5° ATDC) front cylinder. Valve closes at (105° ABDC) front cylinder. \\ Slot in upper cover must be widened to app .340" to make this possible. |
| - | * The motor is no longer fed only a portion of the pump's full capacity of oil as the bypass system of previous year pumps has been deleted. \\ Coincidently, | + | * The motor is no longer fed only a portion of the pump's full capacity of oil as the bypass system of previous year pumps has been deleted. \\ Coincidently, |
| - | There is a desceprency between the 1972 and 1975 parts books in where the upper and pump mounting gaskets are switched between the 2 catalogs. \\ Special thanks to the The French Owl for providing period specific parts catalogs. \\ Parts List is for XR and XRTT models: ((XR-750 Parts Catalogs)) | + | There is a desceprency between the 1972 and 1975 parts books in where the upper and pump mounting gaskets are switched between the 2 catalogs. \\ |
| - | + | Special thanks to the The French Owl for providing period specific parts catalogs. \\ | |
| - | ^{{:techtalk: | + | Parts List is for XR and XRTT models: ((1972 XR-750 Parts Catalogs)) ((1973 XR-750 Parts Catalogs)) ((1975 XR-750 Parts Catalogs)) |
| + | ^{{techtalk: | ||
| |Oil Pump \\ Assembly|Oil Pump \\ Body|Upper Cover / \\ Breather Tower|Lower Cover \\ Plate|Oil Pump \\ Drive Gear|Feed Gear \\ (driver)|Feed Gear \\ (idler)|Return Gear \\ (driver)|Return Gear \\ (idler)|Idler Gear \\ Shaft| | |Oil Pump \\ Assembly|Oil Pump \\ Body|Upper Cover / \\ Breather Tower|Lower Cover \\ Plate|Oil Pump \\ Drive Gear|Feed Gear \\ (driver)|Feed Gear \\ (idler)|Return Gear \\ (driver)|Return Gear \\ (idler)|Idler Gear \\ Shaft| | ||
| |26203-54RB|26217-72R|26241-54R|26250-56|26318-54R|26323-52 \\ 26323-52A*|26322-52 \\ 26322-52A*|26320-72R|26317-72 \\ 26317-72A*|26327-52| | |26203-54RB|26217-72R|26241-54R|26250-56|26318-54R|26323-52 \\ 26323-52A*|26322-52 \\ 26322-52A*|26320-72R|26317-72 \\ 26317-72A*|26327-52| | ||
| - | |Breather Gear|Feed Gear \\ Lock Pin|Return Gear \\ Woodruff Key|Breather Shaft \\ Split Ret \\ Washer|Oil Pump \\ Check Ball \\ (3/ | + | |Breather Gear|Feed Gear \\ Lock Pin|Return Gear \\ Woodruff Key|Breather Shaft \\ Split Ret \\ Washer|Oil Pump \\ Check Ball \\ (3/ |
| - | |26331-72R|603|26347-15 \\ 26340-36*|26341-37|8866|26364-57|26420-57|45830-48| ::: || | + | |26331-72R|603|26347-15 \\ 26340-36*|26341-37|8866|26364-57|26420-57|45830-48|::: |
| - | |Pump \\ Gasket \\ Lower|Pump \\ Gasket \\ Upper|Pump \\ Gasket \\ Mounting|Oil Seal| | + | |Pump \\ Gasket \\ Lower|Pump \\ Gasket \\ Upper|Pump \\ Gasket \\ Mounting|Oil Seal| |||||| |
| - | |26258-52|26256-72R|26259-72R|26227-58| ::: |||||| | + | |26258-52|26256-72R|26259-72R|26227-58|::: |
| - | + | * Parts updated through the 1975 XR-750 Parts Catalog. | |
| - | * Parts updated through the 1975 XR-750 Parts Catalog. | + | |
| ====== 1975-1987 XR-750 Oil Pump ====== | ====== 1975-1987 XR-750 Oil Pump ====== | ||
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| * Pump speed is 1/4 of the engine speed. | * Pump speed is 1/4 of the engine speed. | ||
| * Return gears operate at a 2:1 ratio of the feed gears. | * Return gears operate at a 2:1 ratio of the feed gears. | ||
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| ====== 1988-up XR-750 Oil Pump ====== | ====== 1988-up XR-750 Oil Pump ====== | ||
| + | The original 1988 oil pump body was made out of magnesium and later it was made out of aluminum but the part number for the body stayed the same. The part number for the pump assembly did change from 26203-88R to 26203-88RA at least by 2002. However, the only part number that changed between the two assemblies was the 1/4" return outlet fitting from 62570-83 to 25259-93A. \\ | ||
| + | |||
| * Pump speed is 1/2 of engine speed. | * Pump speed is 1/2 of engine speed. | ||
| * Return to feed ratio is 4:1. | * Return to feed ratio is 4:1. | ||
| * Oil pump drive gear was re-activated as a breather only. Design same as 1975-1980 but with a more efficient gear design and improved oil routing. | * Oil pump drive gear was re-activated as a breather only. Design same as 1975-1980 but with a more efficient gear design and improved oil routing. | ||
| - | * Timing: Turn rear piston to T.D.C. and line up 0.12" dia. hole in gear shaft with notch in breather sleeve. | + | * Breather timing: Turn rear piston to T.D.C. and line up 0.12" dia. hole in gear shaft with notch in breather sleeve. |
| * Interchangability: | * Interchangability: | ||
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| |45830-48|62570-83|25259-93A|63541-74R|26227-58|11159|::: | |45830-48|62570-83|25259-93A|63541-74R|26227-58|11159|::: | ||
| - | Pump Body 26217-88R \\ | + | Below is the magnesium pump body (26217-88R) and parts including |
| - | This is just the body without upper and lower covers. | + | The left side of this pump has 5/8" dia. fitting for scavenging the sump and the 3/8" dia. for oil supply from the tank. The right side of the pump has ball/spring check valve and 3/8" dia. oil return line to tank. The front side of the pump body has NPT plugs to block off passages from manufacturing/ |
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| - | This is a used pump showing | + | |
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| + | And here is the aluminum pump body (26217-88R): | ||
| + | This is just the body without upper and lower covers. ((photos courtesy of ROBERT EVANS)) \\ | ||
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| ====== Feed Bypass System ====== | ====== Feed Bypass System ====== | ||
| ===== 1958-1968 KR, KRTT, KHRTT, XLR, XLRTT and 1970 Iron XR-750 Pump ===== | ===== 1958-1968 KR, KRTT, KHRTT, XLR, XLRTT and 1970 Iron XR-750 Pump ===== | ||
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| - | ====== Oil Line Diagrams ====== | ||
| - | ====== 1975-1987 XR-750 ====== | ||
| - | Overall line diagram. \\ | ||
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