Idling well at 1200 cold, then 4000 when warmed

[GeorgioP_Ohio]

Hi,

I had been posting at various stages of a BS34SS carburetor rebuilds on my 1980 GS540L with 20K miles and got everything back on and working well except for the warmed up engine idle speed that is higher than you would ever want.
Here is the situation: When starting from cold, I choke it for 1 minute or less. It starts easily, it idles well close to 1200, but after 3-4 minutes of riding, the idle creeps of to 4000 RPM and engine throws out a lot of heat. Yes, The choke was turned off before riding. Adjusting the choke at this point is fruitless regardless. The idle is always steady, no hovering.
Here is a background: New carburetor rebuild, got rings in kit from Robert Barr including manifold O-rings, Dipped in Berrymans, so I followed all of the guides to a T. No leaks starts very easily, 3 turns out on the mixture screws.
Stock jets, stock air box, new B8ES plugs, new oil change, correct oil level, fresh 87 octane 10% EtOH gas.

The Air box and manifold clamps are tight, but will do a spray test with some aerosol on the air box tonight to make sure there are no leaks.
The throttle cable seems fine, thought I will lubricate it and give the butterflies more slack if needed to relieve any tension, but again, it idles when cold just fine.
I have the idle adjustment knob backed all of the way off, so there is no pressure on the plate that connects to the butterflies.

Had not checked the valve clearances yet, since with this bike could not get a clear description as to shims or no shims.
If there is a good description , and this could possibly be a valve adjustment issue, please post the link to perform the valve adjustments.

The carbs have not been synced, but can't see how this could cause it to idle higher when warmer. The adjustment balancer screw between them is centered at 50/50.
I am sure that somebody else on here has had this problem before, just hoping that they see this and are like " Oh yeah, it's just .............."

Any ideas would be appreciated.
Thanks,
George

[tkent02]

Oh yeah, it's just.....

A serious lack of maintenance. Adjust the valves, fix the air leaks, make sure the choke is closing all the way, set the idle mixture screws, synch it, do it all.

Have you seen Basscliff's site yet?

It has everything you need.

[GeorgioP_Ohio]

Please post a link for the valve adjustments for 1980 GS450L the Clymer is confusing

Thanks,

[tkent02]

Clymer's does the valve adjustments wrong, use the Suzuki service manual technique, but that isn't causing yur high idle problem.

Again, Cliff has all the answers.

[tkent02]

Cliff will be along soon, but here's a little light reading to get you started:

http://members.dslextreme.com/users/bikecliff/

[Steve]

I have the idle adjustment knob backed all of the way off, so there is no pressure on the plate that connects to the butterflies.

That only means that something else is providing enough air/fuel mix to make it run fast.

Had not checked the valve clearances yet, since with this bike could not get a clear description as to shims or no shims.
If there is a good description , and this could possibly be a valve adjustment issue, please post the link to perform the valve adjustments.

Your bike has shims. Procedure is in the service manual. Have you gotten BassCliff's "Welcome Package"?
You can get a copy of the manual from his website, which is linked in the Welcome Package.

The carbs have not been synced, but can't see how this could cause it to idle higher when warmer.

Coud be that the carb that is causing it to run so fast is not contributing anything while cold, so when the bike warms up, it takes over.

The adjustment balancer screw between them is centered at 50/50.

There is nothing that says the balancer screw has to be in the middle.
In fact, if you moved it to put it there, you might have upset what might have been a good sync setting.


What part of oHIo are you in? You might be close enough for a visit.

.

[tkent02]

Steve to the rescue.

Hey Steve, can you ride out to Colorado and give me a hand with a bike or two?

[GeorgioP_Ohio]

I am in North Canton, Near Akron, 1 hr South of Clevelend

Thanks, I did not really think that the high idling issue was the valves, thought I do want to check the clearance on them at some point and learn how to change out shims in my spare time. My next guess is some phantom tension on the throttle cable to the butterflies that causes them to remain just a hair open.
I don't get any noise or vibration at higher speeds, though there is a slight whine from the speedometer cable or box over 25MPH.

I'll look to see if I can borrow a carb sync tool for a two cylinder from somebody. Let me know if you have any other suggestions in the meantime. Yes, I did the reading and got the welcome kit from BassCliff a long time ago. I have been a bit selective up to this point just making sure I have a running bike before investing into other procedures..
Thanks,
George

[Larry D]

Of course you want the bike to start easily, but, carb tuning should be done with the engine completely warmed up....ie. syncing, idle adjustments, etc....the exception to this is a valve adjustment, which should be done with the engine "stone cold".

[tkent02]

Thanks, I did not really think that the high idling issue was the valves, thought I do want to check the clearance on them at some point and learn how to change out shims in my spare time. My next guess is some phantom tension on the throttle cable to the butterflies that causes them to remain just a hair open.
I don't get any noise or vibration at higher speeds, though there is a slight whine from the speedometer cable or box over 25MPH.

I'll look to see if I can borrow a carb sync tool for a two cylinder from somebody. Let me know if you have any other suggestions in the meantime. Yes, I did the reading and got the welcome kit from BassCliff a long time ago. I have been a bit selective up to this point just making sure I have a running bike before investing into other procedures..
Thanks,
George

There's a thing about lubing speedos and tachometers in Cliff's site too.
Don't bother synching the carbs until you adjust the valves, it all changes with the valve clearances.

It is usually better to get everything right before going out and getting in trouble with failures that could have been prevented.

[robertbarr]

Unbalanced carbs will cause that. I learned that after my very first carb rebuild years ago. It's really unnerving when the 'idle' creeps up to crazy r.p.m.'s when you're out riding.

[Steve]

Hey Steve, can you ride out to Colorado and give me a hand with a bike or two?

Think you could put up with a chrome-laden GL in your driveway?

After all it is a GL1500SE.

I'll look to see if I can borrow a carb sync tool for a two cylinder from somebody. Let me know if you have any other suggestions in the meantime.

The offer in post #6 still stands.

Send me some contact info, we can make arrangements.

.

[tkent02]

No, you can park it in the garage. I'll roll about five bikes out into the yard to make room for it. I almost bought an early wing the other day, just as a fix and flip. Then I changed my mind.

[luvnwunderwoman]

Be sure to read Adjusting the Idle Mixture on CV Carbs . It is under tips and tricks. Thanks to the koolaid kid.

[GeorgioP_Ohio]

leaky carb intake boot seal at airbox

Hi Guys,

I did the leak test last night with some carb cleaner.
When the bike was idling at 1200, I sprayed some carb cleaner at the right hand intake where the carb body meets the air box, and the bike shut off.
There are those moveable seals in the airbox that are supposed to seal the carb body , but on that side, they are not sealing well. After 33 years, must be getting too loose.
What is the trick when installing the airbox to keep them in place?
In case I get the nerve up to take off the airbox again in the near future? I still need to sync my carbs after a valve adjustment.
Robert, do you still sell the air box intake clamps and boots pictured on page 2 here http://members.dslextreme.com/users/...ake_repair.pdf ?
Steve, I sent you a PM in case you can make it over one day, not sure what part of Ohio you are in to guess driving distances and such.
A buddy is going to let me borrow his 2 cylinder sync tool next week, I can smell progress.

Thanks,

George