Topic: 1981 CB650 Carb photo, is there a jet missing?

[gilesclement]

The manual shows a a jet which I can't seem to find, anyone know if anything goes in the hole marked or if it's just a blank? Thanks

http://www.flickr.com/photos/illumiquest/3484015693/

[Hush]

Beats me, looks nothing like the CB650Z I have.

[cb650]

Come on Hush you have a 82 now right?        OK nothing goes there.

[scunny]

as CB650 said, there is nothing in there, been gawking at my spare set and wondered what they were meant to do ?

[cb650]

Might be the vent.  Somewhere there someone posted a diagram of what all the holes did.
On the carbs that is

[themotoworks]

could have been used to locate the carb casting for machining

[Hush]

Nah only got the 79 CB650PZ now cb650.

[mystic_1]

Looks to me like its a drill passage.  If you look on the side of that part you'll see a boss where they drilled a passageway and then capped off the end.  They do this because drill bits cannot turn corners

I don't see anything on the fiche for those carbs that looks like it goes there.  Sometimes other carbs have rubber plugs to cover passageways like that.

mystic_1

[gilesclement]

Righto, thanks.

I guess this leads me to my next question of: Why aren't my two inner cylinders running at idle? I've had the carbs stripped once, blew through every hole i could find (ha, ha) with carb cleaner and reassembled. I've got them apart again and doing the same thing, there seems to be a little bit of sediment buildup in the bottom of the bowls but it's very very minimal and more like light dust. The tank has been gelled. Last week while running I was also having it drop power after a long run on freeways, the filter looks ok, haven't checked the tank filter yet as I cant figure out how to remove it. There does seem to be a decent fuel flow coming out though. Any suggestions on how to set the carb pilot jets? The manual goes about some long procedure involving half turns and rpm drops of 50 or something, seems there should be an easier way.

Thanks

[Soos]

could have been used to locate the carb casting for machining

+1



l8r

[Soos]

Righto, thanks.

I guess this leads me to my next question of: Why aren't my two inner cylinders running at idle? I've had the carbs stripped once, blew through every hole i could find (ha, ha) with carb cleaner and reassembled.

Have you tried cutting 1/4 (or so) off the wires to the center 2 cylinder spark plugs, and re-installing them?

Sounds like a bad spark plug wire going on you.



Perhaps a bad spark plug?
(yes it really happens)



l8r

[mystic_1]

Problems on both 2 and 3 does make it look like a coil problem, those cylinders share a coil.

You said

Why aren't my two inner cylinders running at idle?

So you've confirmed those two cylinders fire properly above idle?

I suppose it could be clogged idle circuits or overly high float bowl levels.  Only advice here is be meticulous and blow through all passages with compressed air to verify they're flowing properly.

mystic_1

[gilesclement]

Thanks for the replies,

I've confirmed that they're running above idle, pulling the wires makes a difference if it's running above about 2k. The bike also goes 85 which I don't think it'd do on two cylinders

I've swapped coils from one side to the other to cross check them, no difference between the outside coil and the inside one. I haven't tried cutting the wires yet but that sounds reasonable. I've got the carbs apart again and will try to get some compressed air tonight.

I've got all new plugs in.

[mystic_1]

Shoulda asked earlier, but have you synced the carbs?

mystic_1

[gilesclement]

just bench synced so all the flappers are approximately in line, didn't want to pay to get them synced until I can get it running on all four.

[WFO]

just bench synced so all the flappers are approximately in line, didn't want to pay to get them synced until I can get it running on all four.

Where do you live?

[gilesclement]

Well i've reassembled and the bloody thing runs a bit better, now seems to be hitting on all four at idle but there's still a pretty big difference between pulling a plug wire on the outside cylinders and pulling the inner ones. Phoey. I still haven't tuned the pilot jet on them, just set it at 2 1/2 out. Any suggestions on how to go about doing that better? They're calling for a tachometer which I don't have