The International CBX Owners Association

I don't think that you can get them spot on just very very close to it and enough to eliminate clutch rattle and sluggish idle drop

I'll probably do a sync. I've got a morgan carbtune 4x setup and the fancy Honda screwdriver tool for the adjuster screws. And with the carbs off I can be sure to be setup with the appropriate extensions and stuff for the taps.

Anybody have any thoughts about other things to take care of while the carbs are off. The intake rubbers (aka "carb holders") are obviously ripe for replacement, but they're not cheap and I may try one of the restoring techniques using wintergreen oil. I see a throttle cable is only $11 from Z1. Worth replacing? Anything else while I'm in there?

- Mark

You definitely want to check your valve clearance and manually adjust cam chains.
There is a lot of info on here on both. Unplug and clean all electrical connections, use electrical grease on all.
I would also inspect alternator brushes and clutches. Check your steering bearings for play and resistance, flush your brake fluid with good quality brake fluid with higher rated temperature such as ATE type 200.
You have plenty time to do all this before your carbs come back from rebuild.
I'm sure other people with chime in with more items to check

I bought all the required chemicals for the rubber softening trick but it's only a temporary fix until they harden so I spent the cash and bought new rubbers and didn't regret it...and if they harden/crack/leak then you're back to tilting the engine...

another thing that's easier to do with the carbs off is construct a 6 into 2 drain manifold for the carbs it's prevention for the dreaded # 1 hydrolock...instead of building a manifold I went with six individual drain lines, it can be done while the carbs are on it's but much, much easier when they're off...

putting the carbs back in can be very frustrating as you'll find out when you get there...forum members have a number of techniques, a heat gun or hair dryer plus grease are common aids as are a 2nd set of hands...

I've found the easiest method for doing it by myself is to let the hydraulic jack used for tilting the engine back into position do the work...grease on the inside of intake rubbers and the outside of carbs, then while supporting the carbs with one hand aligning them between the intake rubber and air box, lift the engine back up into position until the carbs are beginning to be squeezed between rising engine and air box, at this point you should no longer need to support them with your hand ... gently/slowly keeping lifting the engine into position and the the carbs will almost begin to insert themselves "go slow"... check all carbs to ensure they're still aligned and that the intake rubbers have slipped over the carbs and not caught an edge and begun folding in, I use a slim screwdriver insert under the rubber where it has gone over the carb then slide around to correct that any folding, if it's too tight I'll back off the jack and try it again...if it all goes good it's a 5 minute process...

daves79x wrote:There are VERY few CBXs out there now doing well on their original carb O-rings. No matter what you did to store the bike (and you did it correctly), these 40 year-old O-rings fail. Carbs have to come off and be totally dismantled. No way around it. Get them off and send them to Mike!

Dave

Spot on, Dave. It's pretty amazing the stock o-rings last as long as they do, 30 years or moe! And thanks for the referral!

Well, after two years of sitting off the bike after Mike Nixon's rebuild, I'm finally getting around to putting my carbs back on. (Usual excuses: family emergency, house building project, my own health issues, etc.). Not looking forward to the job. Currently deciding whether to spend $130 for new carb boots - my old ones have cleaned up pretty well, but they're definitely stiffer than new. OTOH, I've often found that NOS OEM rubber parts can be in mediocre condition after sitting on shelfs for years. I think I'll give re-using the olds a try. May bench-fuel the carbs prior to putting them on just to be sure I don't have a stuck float.

Much appreciate everyone's help.... great group.

- Mark

A good carb rebuilder like Dave or Mike can get the carb bench sync spot on. CBX carbs were all bench synced at the factory when built and they ran great.

hondaman160mph wrote:A good carb rebuilder like Dave or Mike can get the carb bench sync spot on. CBX carbs were all bench synced at the factory when built and they ran great.

That is true, for sure. But they were also synced after installation on the bike, with the airbox connected and the engine running as part of final inspection/adjustment.

EMS wrote:
That is true, for sure. But they were also synced after installation on the bike, with the airbox connected and the engine running as part of final inspection/adjustment.

So they managed to put the "yellow paint" on the adjusters while the carbs were on the bike? Most of them are pretty inaccessible, so had always assumed that was done before carbs were installed.

Paul.

Have to agree you have a point there, Paul! Never really thought about it.

Dave

If you can get there with a tool to adjust it, you can get there with a paint marker You really think Honda finally adjusted the carbs off the engine? If it wasn't done on the bike, it was done during the Dyno run.
Have you ever been to any vehicle assembly plant?

EMS wrote:If you can get there with a tool to adjust it, you can get there with a paint marker You really think Honda finally adjusted the carbs off the engine? If it wasn't done on the bike, it was done during the Dyno run.
Have you ever been to any vehicle assembly plant?

Mike,

One of those things that doesn't really matter some 40 years later. Just an observation that the carb linkages were "sealed" with the yellow paint at some point. Maybe the carbs were bench synched and sealed, or synched on the dyno and sealed before fitting the engine, or synched on the bike after assembly.

Not something I will lose any sleep over

Paul.

Well, I guess I'm next to revive this thread; just decided to get my slightly ratty 1980 running after 3 years of sitting. I bought the bike to resto mod and never started it when I bought it a few years ago. On the first attempt I got a huge amount of fuel out of the left side drain line. I guess a float valve is stuck. At the moment, I'm hoping the 94 octane Chevron with Seafoam added will "unstick" it magically. That and a few "whacks" on the float bowls? Anybody ever try vibrating the carbs somehow while still on the bike? It would seem to me you could almost ultrasonically clean them while still on the bike, given the right set up.
Still in the "denial" stage.

Might as well get over the denial as soon as possible - the only fix is a complete rebuild. There's no fixing 40 year old o-rings and rubber parts, for the first thing, and usually no cleaning gummed-up float valves. Not to mention plugged up low speed circuitry. You are just chasing your tail trying anything else.

Dave

Since this thread got some life, let me ask some advice.
My carbs are rebuilt and I have bench synchronized them to best of my eyes ability.
I referenced the three tiny holes at the bottom of butterfly and made sure they all open and move in harmony. Is there anything else I need to do?
Now, before I install them, I want to do leak test.
Since there is the vacuum fuel pump, I am assuming I have to bypass that and just put a T to feed both rails via auxiliary tank ? Should the carbs be sitting flat or an angle similar to how they get installed ?
Thank you