Carb %#&@*&^ adjustment $%@#^% what the hell did I do!!

[Boriqua]

So .. I am sure that there are others here like me that have a hard time leaving well enough alone. oh it can always be one minuscule bit better ... yes let me mess with it some more .. yea that's it its almost there ..... until I screw it up!

I decided a couple of weeks ago to reclean my carbs since I was having trouble getting the bike to idle well and I knew I could do a better job than I did the first time 3 months ago. I ordered a new throttle cable and new airbox to carb clamps.

Put it all together and except for a little adjustment of the idle screw underneath it was pretty good. I broke out my nifty new carbtune and did the sync and happy day. Took it out for a 55 mile ride .. no worries idled great and pulled right up to 7500 rpm with no hiccups.

Took the wife out couple of days after that on a super hot day and went about 40 miles. All good. I changed my oil to 20w50 and my idle dropped a little but actually brought it more inline with what it should have been. Still fine.

Then I got an email from Dynatek suggesting a gap of .32 for my setup and decided for 10 bucks I would buy brand new plugs. I put in new plugs when I started three months ago with this adventure but they have been run rich, lean and everywhere in between and adjusted 8 ways to sunday since then so I figured why not splurge.

Gapped my new plugs .. did nothing else. Bike has been sitting for 2 days. Went to take it out this morning. Stall. I adjust the idle screw under the carbs as its idling to low and get to the first corner and its at 3000 rpm. At the light it will drop down to 1800 on my tach but if I blip the throttle it hangs then slowly drops. I changed NOTHING else but the plugs.

Get home and pull the plugs and they are dead man bones WHITE and ashy. Alrighty .. to lean. I figure since I increased the gap I must have needed to readjust the carbs to allow for more gas ... Right??:-k

No way to get the bike to idle without hanging up or stalling so I pull the plugs and regap them to .27/.28 ish. I start the carb mixture screws at 2.5 turns out and hooked up my carbtune again and made the slightest adjustment but they are in sync. I burned the flesh off my hand trying to adjust the idle screw under the carbs because no matter how I adjust the mixture screw I either get stalling or hanging up when I blip.

5 hours later .. and I have to stop.

To get consistent high rpm my 1 carb likes 3 turns my 2 likes a heavy hand with almost 3.5 and my 3 likes 2 3/4 the 4 doesnt seem to effect the machine much in either direction so I leave it at 2.5.

Should I make all these settings and then adjust the idle screw under the carbs? I should add that when I pulled the old plugs .. you know the ones that were in the bike when it was working great .. they were all a beautiful dry tan .. sigh .. why couldnt I have just left them alone!
Alex

 

[hannibal]

Put the old plugs back in...

You sure you tightened all the airbox to carb boots?

 

[BigD_83]

Put the old plugs back in, reset the A/F mix and the idle control to as close as what you had it before, and see if it runs better. When it does, have a beer.

On #4 A/F mix, the tips can break off and lodge in the circuit, but you'd probably have noticed something amiss, like a broken tip when you cleaned the carbs.

 

[TxGSrider]

The plug gap should have no effect on the mixture. Now it they were opened up too far they could foul and appear to be rich, but that's not what seems to be happening.

It sounds like maybe you got some crud settling in your carbs and may need to clean them.

 

[Boriqua]

Maybe a crazy thought .. the mixture screws have the spring followed by the metal washer and then closest to the tip a rubber washer. when I pulled the carbs apart a couple of weeks ago the screw, spring and metal washer came out lickety split but I had to fish the rubber washer out with a thin wire. Is it possible that by backing out the screws several times while adjusting that the rubber washer is partially blocking the hole? Guess I might be removing the carbs again .. I am like an EXPERT now.

 

[Boriqua]

The plug gap should have no effect on the mixture. Now it they were opened up too far they could foul and appear to be rich, but that's not what seems to be happening.

It sounds like maybe you got some crud settling in your carbs and may need to clean them.

No quite the opposite .. the new plugs were ashen white so some how something got way leaned out.

 

[Nessism]

It's normal for the plugs to look white until you get some mileage on them.

 

[Guest]

Are you certain the vac sync ports are sealed & not leaking? Vacuum line isn't cracked or disconnected? Choke isn't hung up?

Very odd it was running well, then not.

 

[Steve]

In the midst of doing all this work and removing the carbs multiple times, have you ever inspected/replaced the o-rings on the intake boots? :-k

If you haven't, you should know that is a very common cause of the exact symptoms you are experiencing. A simple message to cycleorings.com and the transfer of just a few dollars will fix that quickly.

While you are ordering the o-rings, be sure to also get the stainless bolts that hold the boots in place. The stock screws will probably be damaged when they are removed, so install new, better hardware.

.

 

[Guest]

In the midst of doing all this work and removing the carbs multiple times, have you ever inspected/replaced the o-rings on the intake boots?.

This is one of the models that doesn't use o-rings at the head... the intake ports are cast into the head. The rubber boots use clamps on both sides to seal.

To Steve's point though, make sure those boots are not rock hard or split, and the clamps are tight.

It does sound like you have an air leak somewhere

 

[Guest]

Went to take it out this morning. Stall. I adjust the idle screw under the carbs as its idling to low and get to the first corner and its at 3000 rpm. At the light it will drop down to 1800 on my tach but if I blip the throttle it hangs then slowly drops.

That is an air leak about 98 times out of 100.


Mark

 

[JJ]

That is an air leak about 98 times out of 100.


Mark

At least 110 times out of 100.

 

[TxGSrider]

I actually think its more odd that it waited until AFTER you took your wife out for a ride. That kinda thing usually happens to me after I convince my wife to go for a ride. So in some way, consider yourself fortunate. lol

 

[Guest]

No help here, but your story-and the way you wrote it-made me chuckle. It sounds like me. Great attitude for what I'm sure is a very frustrating situation. Good luck!

 

[Nessism]

Another bit of maintenance you can perform is to remove all the plug caps and check the resistance. They unscrew from the wires. Standard resistance is 5k ohms. If the caps check out snip off 1/2" of wire from the leads and screw the caps back on. I mention this because it almost sounds like your bike is randomly dropping a cylinder.

 

[TeamDar]

Another bit of maintenance you can perform is to remove all the plug caps and check the resistance. They unscrew from the wires. Standard resistance is 5k ohms. If the caps check out snip off 1/2" of wire from the leads and screw the caps back on. I mention this because it almost sounds like your bike is randomly dropping a cylinder.

He just installed a Dynatek ignition and Dynatek coils. I doubt if he has the old spark plug wires. Dar

 

[Steve]

This is one of the models that doesn't use o-rings at the head... the intake ports are cast into the head.

Gotcha. I only noticed the "GS750", did not notice the year.

.

 

[Hinermad]

While you are ordering the o-rings, be sure to also get the stainless bolts that hold the boots in place. The stock screws will probably be damaged when they are removed, so install new, better hardware.

Would a touch of anti-seize compound on those new bolts be in order? Or are they okay to install dry?

 

[Boriqua]

No plug caps in the true sense. It has new sparkplug wires along with the dynatek coils and ignition but the "cap" part is just a condom to cover the end of the lead.

I think the damn bike is possessed. All I did was take out the old plugs and install new ones and shubang. Does anyone know and can demonstrate a spirit chasing wookie dance?

I am 90% sure it is not an air leak. I have been over looking for leaks a dozen times. Its sealed up tight. I should have mentioned that when I reinstalled everything I put in a can of seafoam. The tank is still half full. Could the 95 miles with seafoam ... I dont know .. altered something from the time of install??

I tried following along with the post on this page
http://www.thegsresources.com/_forum/showthread.php?199096-Adjusting-the-Idle-Mixture-on-CV-Carbs
but
1. If I could get it to idle reliably enough to test it at 1300 rpm .. I would be riding it
2. my carbs are a little all over the place when it comes to adjustment so when I tried just turning everything up half a turn or down half a turn it got worse. I had better results when I went at it the first time and fiddled with each carb independently. You know .. when it was running before I messed with it some more!! :culpability:

I found something on a general google search that may or may not have suggested that by widening the gap it can do something to the timing? Cant play with it today but tomorrow I will pull the new plugs and install the old ones. I will pull out the mixture screws and make sure the assembly is still together and I will make quadruple sure that I tightened everything that could admit air.

 

[Boriqua]

Ok so I wanted to lay out my process for when I got the bike running well and see if I made mistakes or will it be repeatable.

I turned up my idle adjustment so it was at about 2200 2500 rpm. I then went to each individual carb that had been set at 2.5 turns out and slowly turned them clockwise until I heard the bike start to stumble then went counter clock wise until I hear the engine gaining speed then on to the next carb. Now when I was done with all 4 the rpm had increased say another 200 or so rpm. Then I went back to the idle adjustment and brought it down to idle speed. For me that was about 1400 ish but I dont trust my tach right now so I did it by ear. Does that sound like the right procedure or at least one that will work. Its freagin hot out so I would like to see if I can make my next adventure in mechanics just an hour or so and not 4. I dont want to be this guy anymore