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Motorcycle Repair/1980 honda cb900


QUESTION: Im having issues where my bike doesnt run right once it gts hot bogs very bad and battery doesnt chargeright and when i goto start just clicks. I ohmed my coils out and they were fine and spark is being created, my stator brushes seem to be in good shape so i looked towards my pulser so i removed the case and a bunch of oil dumped out. My question is that should my pulse case be full of oil?

ANSWER: Yes, it is an oil-cooled stator and rotor system.

These bikes have common charging system issues, generally the rotor...

Bill Silver

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QUESTION: It seems i have thrown my timing off by a very small amount thought i made all the marks i needed to put back together correctly but i must have been off a lil. Was wondering how i go about properly timing this the book drags it out to far with to many dumb numbers that i end up gtn lost in.

ANSWER: Basically you want the engine to be up on the 1-4 T mark on the rotor with 1eft side cam lobes facing each other (compression stroke). Find the punch marks on the sprockets and verify that they are level with the cylinder head cover.

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If they are not you will need to loosen the cam chain tension and remove the cam bearing caps to allow the cam to be re-positioned, assuming that the exhaust cam is off. The intake cam tensioner is separate, as you know and needs to be backed off to give some chain slack so you can re-position the intake cam. Once the intake cam is set, then you can followup with the exhaust cam.

Bill Silver

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QUESTION: So im wondering if i didnt take any part of my motor apart all i did was remove the ATU unit and then put back could that have thrown off my timing?

I am not sure what you are calling an ATU unit. There are spark units on the back, by the battery, one services each coil set. If you are losing spark to either 1-4 or 2-3, then swap the spark units and see if the problem follows the switch. If so, you need a new spark unit.

The pulse coils which are triggered off the end of the crankshaft on the left side are mounted on a plate, which can be adjusted, as I recall. If the plate is not put back to where it was from the factory, then the ignition timing will be off on all cylinders.

Just unplugging and plugging in an electronic control unit doesn't change the ignition timing. If you didn't pull the engine apart, then the cam timing should be fine unless one of the tensioners have failed and the timing jumped, which is highly unlikely. The way you wrote the first question, I assumed that you had taken the engine apart and got the cam timing off a tooth.

Bill Silver

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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