The International CBX Owners Association

Hi Guys

I am in the process of getting a 79 Z up and running after several years being stood, the carbs needed cleaning out totally and new slow jets put in.
On starting it up and letting the engine get warm when it is revved it hangs onto the revs at about 2000rpm and slowly comes back down to idle (tick over )
there is plenty of slack in the cables and they are routed correctly, I am not sure if I have read somewhere ( but now cant find it in a search of the forum ) that it could be that the carbs require sync- ing or am I in the wrong ball park.


Thanks Sneck

It's a must to sync the carbs if you have removed and cleaned them, did you chase all the passages in the carbs to make sure they were clear? If the choke isn't closing all the way it will also make the revs hang up because it mechanically opens the throttle plates while closing the choke plates.

That was a quick reply Jeff,
I had the carbs ultrasonically cleaned but will check the choke. I haven't got the equipment to sync. them though.
Thanks Sneck

sneck wrote:That was a quick reply Jeff,
I had the carbs ultrasonically cleaned but will check the choke. I haven't got the equipment to sync. them though.
Thanks Sneck

Been up since 4:30am, just came in from the garage for a break, it's going to be 70 degrees today and I needed to do some maintenance on the bikes so I can enjoy this crazy beautiful weather we are having here in the rust belt.

Hanging on to revs and not wanting to return to idle is also a common symptom when you have an airleak between carbs and cylinders. Spray some starting fluid in that area and see if the revs go up.

EMS wrote:Hanging on to revs and not wanting to return to idle is also a common symptom when you have an airleak between carbs and cylinders. Spray some starting fluid in that area and see if the revs go up.

Will try that tomorrow morning - Thanks Sneck

Jeff Bennetts wrote:

sneck wrote:That was a quick reply Jeff,
I had the carbs ultrasonically cleaned but will check the choke. I haven't got the equipment to sync. them though.
Thanks Sneck

Been up since 4:30am, just came in from the garage for a break, it's going to be 70 degrees today and I needed to do some maintenance on the bikes so I can enjoy this crazy beautiful weather we are having here in the rust belt.

Jeff, having seen some pics of your stuff i doubt very much there is any rust.
This early spring is great.

EMS wrote:Hanging on to revs and not wanting to return to idle is also a common symptom when you have an airleak between carbs and cylinders. Spray some starting fluid in that area and see if the revs go up.

I sprayed started fluid on the rubbers and there was no increase in revs. Just out of curiosity I totally backed off the tickover and obviously it wouldn't idle but it also didn't hang onto the revs does this mean or point to anything ?


Sneck

My '82 would do something similar, idle around 2500 when warm ... a real hassle when at a stop sign/light!. I then noticed that I could 'drag' the rev's down by applying the rear brake and slowly releasing the clutch. Bike would then idle fine until I bleeped the throttle again. Tried syncing carbs, which didn't work for me and finally discovered a worn throttle plate rod was allowing air past. I'm thinking by loading the engine down with rear brake, maximum vacuum is attained which 'pulls' anything loose/worn closed???
But if the carbs haven't been synced, it'd still be first thing I would go for, then start looking deeper.

Correct me if I am wrong but according to the manual the idle jet is initially set at 1 1/4 turns out, then when the engine is warm and after a run each idle carb screw is adjusted in turn till the tickover rises, what does this equate to as a ball park figure in turns of the idle screw from the initial 1 1/4 turns out ?


Sneck

sneck wrote:Correct me if I am wrong but according to the manual the idle jet is initially set at 1 1/4 turns out, then when the engine is warm and after a run each idle carb screw is adjusted in turn till the tickover rises, what does this equate to as a ball park figure in turns of the idle screw from the initial 1 1/4 turns out ?


Sneck

Are you referring to the 6 'air screws located on the bottom rear of each carb? If so, my understanding is that those were set very lean at factory (1.25 turns) to meet the era's EPA requirements. Most user's now set to 2 to 2.5 turns.
Guess I'm used to different terminology as I have to ask what you mean by 'tickover'?

Yes they're the screw I mean, Tickover - idle speed. approximately 1000 rpm
Thanks Sneck .

bobber01 wrote: Guess I'm used to different terminology

We may need an English-American dictionary

Mudguard = Fender
Tickover = Idle Speed
Tyre = Tire
Clocks = Instruments ........

EMS wrote:

bobber01 wrote: Guess I'm used to different terminology

We may need an English-American dictionary

Mudguard = Fender
Tickover = Idle Speed
Tyre = Tire
Clocks = Instruments ........

Being from the 'Rock' may need to toss in a Newfoundland version as well if I get side tracked.

EMS wrote:

bobber01 wrote: Guess I'm used to different terminology

We may need an English-American dictionary

Mudguard = Fender
Tickover = Idle Speed
Tyre = Tire
Clocks = Instruments ........

there is also

yoke = triple tree
brake disc = rotor

http://en.wikipedia.org/wiki/Rotor_(brake)

I never gave it a thought ,I just assumed everyone would know what I meant
Sneck