Choke kill the bike?

[Guest]

Well the weather has gotten warm and I've discovered a weird quirk that I haven't noticed before.

After sitting for 18 hours the bike absolutely refuses to start with full choke. With no choke the mixture is too lean and the idle too low without throttle so I have to have just the right amount of choke for it to be happy while warming up.

Not really a BIG deal but the annoying part is turning on the choke (even just a little), even when the engine is already warmed up, will kill it.

My question is, is this normal behavior? From what I recall opening the choke would just raise the idle speed but now it's flooding out.

The only noticeable changes that occurred right before I noticed this is the temps got really nice (70°F temps) and I filled the tank after running it down towards empty (didn't switch to reserve) at BP with their 89 octane.

[MisterCinders]

Might be too rich at idle, such that additional fuel from the choke bogs it out once warm.

What kind of bike (it's not in your sig)?

[tom203]

The only noticeable changes that occurred right before I noticed this is the temps got really nice (70°F temps) and I filled the tank after running it down towards empty (didn't switch to reserve) at BP with their 89 octane.

I'd suspect a bad lot of gas.

[Killer2600]

Might be too rich at idle, such that additional fuel from the choke bogs it out once warm.

What kind of bike (it's not in your sig)?

It's an '82 GS750E, she runs quite beautifully idles just below 1000 rpm when cold, 1100-1200 area when hot and takes throttle at idle or speed as well as I could expect. Last tank averaged 50.2 mpg and it wasn't being babied or grandpa'd.

My only complaints about the bike are handlebar vibration, and she could putty along in gear at idle smoother and less jerky. Did a carb cleaning with new o-rings and a sync about 2 years ago.

[DannyMotor]

Time to re sync... and re clean... if the bikes not ridden regularly it should be done every year.

[Killer2600]

Time to re sync... and re clean... if the bikes not ridden regularly it should be done every year.

I'm sorry but with the miles I put on her and how well she runs there's no way in hell I'm going to pull the carbs "just cuse"

I admit handlebar vibration can be a sync issue but nothing points to dirty/clogged carbs and last time I was in them they were clean as a whistle after 3 years.

I'm gonna run threw the tank and throw in some 93 octane from a better station, maybe even a bit of seafoam. For the vibration I'll check the sync later but I think I've synced it to solve this before but the vibration still remained.

[Gonzo]

I'm gonna run threw the tank and throw in some 93 octane from a better station...

You had to swat that hornets nest, didn't you?

[Killer2600]

You had to swat that hornets nest, didn't you?

???

It was my first time at that station and my girl has been spoiled with 91-93 premium before this year when I tried to switch her to 89 midgrade

[Steve]

II'm gonna run threw the tank and throw in some 93 octane from a better station, maybe even a bit of seafoam.

Skip the "premium", fill it up with 87 and ride.

.

[JEEPRUSTY]

The bike was engineered to work on regular gas.
Its a true fact.

Throw some techron and run that through the bike.

When is the last time you cleaned the carbs?

[tkent02]

The choke is for cold weather. Shouldn't need full choke unless it's around freezing, above about 65 or 70 f it shouldn't need any even choke at all with a stone cold engine. In between use partial choke, whatever works.

[Killer2600]

Thanks for all the replies, and yes I should use 87 octane but my cousin who is a motorcycle mechanic and the previous owner who is a marine engineer both recommended that I use premium because the bike is old and air-cooled. So with their qualified advice, I have used premium since I first got her. I'm just now experimenting with going cheap on the wine and I have to wonder if the ol girl expressing her distaste for it.

I have no doubts about the carbs being clean and not needing to be cleaned, dirty carbs don't run this good and leave such nicely colored plugs. Again the only carb symptom is putting on the choke tends to flood and kill the engine rather than just raise the idle speed. With the right amount of choke she'll run at a fast idle, with too much choke she won't start just cough, with too little I have to be on the throttle to keep her running smoothly to warm up.....this is annoying part where I try to choke her into a fast idle and she typically dies out.

The real question I have is how do your bikes handle in this situation? Can you apply full choke when you don't need any to get started? and if it starts without any choke but needs some throttle to up the idle speed for warm-up does it tend to object to opening the choke?

[tkent02]

Again the only carb symptom is putting on the choke tends to flood and kill the engine rather than just raise the idle speed. With the right amount of choke she'll run at a fast idle, with too much choke she won't start just cough, with too little I have to be on the throttle to keep her running smoothly to warm up.....this is annoying part where I try to choke her into a fast idle and she typically dies out.

The real question I have is how do your bikes handle in this situation? Can you apply full choke when you don't need any to get started? and if it starts without any choke but needs some throttle to up the idle speed for warm-up does it tend to object to opening the choke?

They are all different after thirty years of who knows what, but that's pretty much how they roll. The choke will kill a hot engine.
There is also the possibility that the fuel passage to the choke is open, but the air passage is blocked, or visa versa. If this has happened in one or two carbs, it may run funny with the choke on. All of this would have zero effect on anything once the choke is turned off.

I have yet to see an old GS that wasn't vastly improved by a complete carburetor cleaning and new orings in the carburetors and intake boots.
And of course, the ever neglected valve clearances.

[jesustheplumber]

i cant help much with the choke problems but i may be able to enlighten you about different grades of gasoline. different octane levels are made to be used with different compression ratios. the reasoning for this is ignition timing. many people are suprized to find that higher octane gas actually burns SLOWER than lower octane(technically it burns at the same rate, there just more to burn so it takes longer.) most cars and bikes have around a 9-1 compression ratio. and when you get into higher performance motors, it is beneficial to raise the compression ratio(sometimes as high as 13-1) but this creates a problem because as you compress the mixture, it burns at a faster rate. this is where high test gasoline comes in to play. the higher compression could cause regular pump gas to pre-detonate, and do very very bad things to your bearings. so the high test gasoline lengthens the burn back to the optimal timing, and adds a little power too. so the next time someone tells you to run high test gas because "shes old" or to "clean her out" politely shake your head and disregard their statement.

[Killer2600]

Well thanks for all the help, it seems the ol girl is behaving better today so maybe it was a "her time of the month" thing, I dunno

Thanks for the info plumber, I splurge on premium because my (motorcycle) mechanic and the PO (a kind of marine mechanic) told me it was best otherwise the ol girl will probably start knocking on heavens door. It's what they both choose to put in, I can't argue with that. Also the fuel from the early eighties isn't anything like the watered down ethanol induced crap at the pump today.