Author Topic: Keihin 627b parts questions  (Read 552 times)

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Offline PatMustard

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Keihin 627b parts questions
« on: February 18, 2013, 11:26:19 AM »
I'm doing some routine maintenance on a friends CB500 for him and have run into some missing pieces along the way. The bike has been running way too rich with it's stock jetting so I've started from the beginning and worked my way back to figure out the problem, valve lash is in spec, timing is dead on where it should be, spark is great (thanks to the classic bikes greatest friend the Dyna coil) the cam chain is tensioned where it should be. So I went to have a quick check of the sync on the carbs before pulling them to clean and check the circuits and emulsion tubes, I had a #$%* of a time getting them to sync evenly, only to realize the throttle linkage rail moves side to side so much that depending on where the throttle is, it pulls itself waaaaay out of sync. Pulled the carbs only to find them put together incorrectly in spots and missing pieces. I've been searching but can't find any dimensions and was curious if you guys could provide me with a little more info.

First, what size are the nylon and felt washers that go on the individual throttle linkages? None of the carbs have any of them so I can't get a size comparison to find something comparable:



Second, what are the washers that go under the dust covers for each carbs adjustment screw? The manuals all say Special washer D or whatever so no help there.

This is the first time I've actually gotten to work with these carbs before, how much play should the throttle rail have in general? It doesn't seem like there's a way to set it in a rigidly defined spot, so I'm guessing it's important to have every piece spaced properly to allow a certain amount of acceptable play with all the actuating arms. Anyone have any tips or tricks to offer? (beyond getting a set of mikuni smoothbores). Also, the manual I have didn't mention it, but am I correct in assuming that the honda needs to be synced to the #1 carb? Thanks in advance for your help!

Offline dave500

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Re: Keihin 627b parts questions
« Reply #1 on: February 18, 2013, 11:39:01 AM »
if you cant see sunlight through the air filter replace it,try it with the filter removed and see how it runs,youll never get them to sync absolutley perfect,measure the shaft and the opening to see what size those missing washers are,see if you can find another set of carbs at the right price?