Valve adjustment - Honda Rebel Forum
 
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post #1 of 6 Old 10-04-2012, 12:34 PM Thread Starter
 
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Join Date: Jul 2012
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Valve adjustment

Have been going through the bike from top to bottom since buying it a few weeks back. Next up on the list is checking the valve adjustment, then carb synch. By the manual the valves look pretty easy to check and adjust. Any warnings or suggestions of what to look out for from anyone that has already done this on their 450?

Living large by going small. '86 Rebel 450
Those that have come and gone:
'74 Moto Guzzi 850T '82 Yamaha Seca 750 '85 Honda Rebel 250 '99 Honda VFR 800 '05 Suzuki AN650 '05 Yamaha V-Star 650 '07 Suzuki AN650 '07 Moto Guzzi Breva 750
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post #2 of 6 Old 10-04-2012, 12:58 PM
 
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The valve cover can be a little finicky getting it off. I take it off to the right side of the bike (from sitting position). Take the breather tube off first.

Bikes:
87 Honda Rebel CMX450C, freshly rebuilt 12K mi.
79 Honda CB750F Super Sport 21K mi.
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post #3 of 6 Old 10-04-2012, 08:40 PM
DNC
 
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Valve cover is frustrating, seems like the planets need to be in the right position or something, but it does come off.

Choose the right side and the force will be with you!

Do when engine is cold and make sure you do not accidentally change your adjustment when locking the nut to the screw by re-checking it. You want it to be very secure so it does not change when in use, but the act of tightening can change it post setting.

It is pretty straightforward and with the proper tools can be done in an hour or so.

'86 CMX450C Gin-ba
'87 CMX450C Kuro
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post #4 of 6 Old 10-04-2012, 11:12 PM
 
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Make sure you remove the coils for the extra room required. As previously noted take it off on the right side and try to keep it fairly level with a slight tip forward if anything. It gets hung up on the cam chain tensioner assy at the rear centre of the motor.
Do you have a shop manual for the other details on getting the TDC positions on the crank? It can be done without the crank positioning and just by feel on the rockers if you have some experience there.

Cheers,

David

"Common Sense" .... really isn't that common!
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post #5 of 6 Old 10-05-2012, 09:01 AM Thread Starter
 
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Thanks for the pointers. The cover took a bit of fiddling to remove, and honestly, I couldn't say exactly what the right motion was to get it to come clear but when it did it slipped past the chain tensioner with ease. The clearance on all 4 intakes was too loose (around .007") and the exhaust were both too tight (around .004").

Intakes are now set to where a .004" feeler gauge fits, but will not let .005" pass through. Exhausts now fit an .006" but too tight for an .007".

Time ran out last night to finish, so tonight it will get all closed up again and then synch the carbs. I don't think it was out of spec far enough to make any noticeable difference in how it runs but to paraphrase Forrest Gump it is "one less thing to worry about".

Living large by going small. '86 Rebel 450
Those that have come and gone:
'74 Moto Guzzi 850T '82 Yamaha Seca 750 '85 Honda Rebel 250 '99 Honda VFR 800 '05 Suzuki AN650 '05 Yamaha V-Star 650 '07 Suzuki AN650 '07 Moto Guzzi Breva 750
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post #6 of 6 Old 10-09-2012, 10:22 AM Thread Starter
 
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Quick follow-up...
It runs beautifully.

Even though the valves weren't too far out of spec made a very noticeable difference in how it runs. Both quieter and smoother, and a mild surging at steady throttle openings is gone. I had synched the carbs the week prior to doing the valves, and again afterward. Changing the valves changed the vacuum on each side requiring the carbs to be set again.

Cold starts are easier and after 30 seconds or so no choke is required before driving off.

Living large by going small. '86 Rebel 450
Those that have come and gone:
'74 Moto Guzzi 850T '82 Yamaha Seca 750 '85 Honda Rebel 250 '99 Honda VFR 800 '05 Suzuki AN650 '05 Yamaha V-Star 650 '07 Suzuki AN650 '07 Moto Guzzi Breva 750
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