Idle speed at around 1500 rpm after a 30 minutes rides ride

[cbxsei]

Gents,
Just have a quick question in regards to a high idle speed after riding for over 30 minutes.
Haven't done anything so far.
Bike is an 82, everything is standard, no upgrades or modification.

The engine started fine every time and idles at around 700 rpm after warm up.
The idle speed is normal without any engine misfire, however, after riding for a while, I noticed that the engine idle speed is kind of high (1500 rpm).
I made sure that the choke lever is fully at rest, nothing abnormal except that the speed is kind of high.
All spark plugs (D8E) colour are normal bit brownish colour and not dark as over fuelled.
Before removing the seat and gas tank to check the cable for stickiness on top of the engine, I was just wondering whether anyone of you has previously seen it?

Thanks in advance for your input.

[steve murdoch icoa #5322]

sei, as a starting point i think the manual calls for a 900rpm idle point.
I always check the easy things first so i would check for an air leak around the carb boots.

[EMS]

The CBX, like all Hondas, is rather cold-blooded. I do experience a different idle after "warm-up" than after a real ride, which is always a little higher. First try adjusting your idle speed manually.

[daves79x]

This ethanol gas is really getting bad. I see the same thing on the CBXs I've worked on. Carbs are right, but true warm-up takes forever. Once fully warm - let the bike idle where it will. Then set as close to 1000rpm as you can and it should be steady there. Blipping the throttle should return the bike right to 1000rpm immediately. That used to work great, but now, you have to drive forever on a pretty warm day when running ethanol gas to get the bike to idle as described. Anything less than fully warm and they want to stall at a stop sign and hesitate when taking off. I'm going to fiddle around with a couple of sets and see what might cure this, without killing gas mileage with an over-rich fix.

Shimming the needles works OK sometimes, but with '79 carbs, you can go up to #68 or #70 on the primary mains. Sirius even now sells a #38 pressed-in slow jet (as opposed to the stock #35). Must be a reason they are making them - ethanol gas???

Dave

[EMS]

I know, in the "old days" the gasoline was better. Still we always poured some additives into the tank, thinking we could squeeze another horsepower out of it. If I think about the amount of Wynn's,STP,Bardahland Lubral I wasted my money on. I know gas is expensive enough as it is, but how about one ounce or two of a good fuel improvement per tank?

[cbxsei]

Thanks for the advice
Will work on it next week and post my findings.

[cbxmel]

Balancing the carbs with set of gauges does sometimes cure your issue.

cheers Mel 1876

[CBXTRA6]

I know, in the "old days" the gasoline was better. Still we always poured some additives into the tank, thinking we could squeeze another horsepower out of it. If I think about the amount of Wynn's,STP,Bardahland Lubral I wasted my money on. I know gas is expensive enough as it is, but how about one ounce or two of a good fuel improvement per tank?

I was skeptical in the beginning but a riding buddy convinced me to put a little bit of Seafoam in the tank !
anybody tried it yet ? seems to help.

[asacuta]

I use SeaFoam once a year. Other than an infrequent sync, I haven't done anything else to my carbs since new, and they seem to work. That's not evidence that it works, but I think it is evidence that it doesn't hurt.

[EMS]

I do use Seafoam with any motor with carbs that gets infrequent use. Even the weed-wacker...

[bikeymikey748]

Mine has the, very same, characteristics. Before I shut it off, coming in from a ride, I adjust the idle a bit higher to help during the next restart. It'll, easily hold 900rm., when leaving the house, but a short time later ( 10-15 min.) it's too high (+1,200). I'll back the idle down to where it should be,and there it will stay for the rest of the day.
Big 'ol air-cooled six just getting up to operating temp., I guess. Sure glad I modded the idle adjuster

[solarmoose]

Higher idle after warm-up is typical for my '81. I adjusted the idle set after the engine is fully warm and use the choke to keep the R's up during warm-up.
I know it could use a carb rebuild since its never been done, will be interesting to see what the improvements are.

You mention the idle was 700 after warm up, was the 1500 idle a change or has it always been this way?

Am glad they don't put ethanol in Alaska gas. When we were riding in the lower 48 a couple years ago we looked for the pure gas stations. hard to find.
My wife and I stored our bikes in Seattle over winter and found pure gas to fill the tanks for the six month storage time.