Around the world on a GS850G for a cause

[shirazdrum]

Well thank you guys for the diagnosis and the manual offer. I made it safe and sound to Buenos Aires with no trouble at all except the very hot waether down here. I met up with Adrian and we took the bike to his friend's shop for further check up to be sure. The engine sounds and runs great and except the little seal leak on the clutch shaft, no other issues.

We pulled the spark plugs to double check everything, and it's running lean again. They are definitely white this time. First we checked the timing, and it was dead on. The petcock is flowing good, no restriction in the fuel delivery system until it reaches the carbs. The boots are brand new and nothing else I can think of other than the carbs that can cause the lean condition.

Now carburetors are out my world, so I?m no expert here. From what the guy explains to me, the air flow for high RPM cannot be adjusted with the air screw and the air screw only controls the idle and low rpm conditions. His recommendation is to measure the float height level first and if that's in spec, move up one size on the main jets to give it more fuel. I think (can't be sure though) that the jets are stock, and if that's the case, why would it run lean to begin with? Colder plugs maybe?

Are we missing something here? I?m trying to read through the carb papers but any help would be appreciated before we do more damage.

 

[shirazdrum]

One more thing, the exhaust pipes are in great shape with new gaskets and no leak there. Also the filter is a new K&N (not pods) which might increase the air flow a little, but since the last motor blew because of leanness, i rule out the the K&N for being the only cause, since before that i had a UNI foam filter.

The crabs idle very nicely, no jumping around, noting at all. It runs like a champ.

 

[ironfoot]

From what I have read here at GSR, a single inside airbox K&N filter requires a 1 size increase on your main jet as a rule of thumb.

http://www.thegsresources.com/_forum/showthread.php?t=73055&highlight=jetting+recommendations

 

[rustybronco]

We pulled the spark plugs to double check everything, and it's running lean again. They are definitely white this time. First we checked the timing, and it was dead on.

Now carburetors are out my world, so I’m no expert here. From what the guy explains to me, the air flow for high RPM cannot be adjusted with the air screw and the air screw only controls the idle and low rpm conditions. His recommendation is to measure the float height level first and if that's in spec, move up one size on the main jets to give it more fuel. I think (can't be sure though) that the jets are stock, and if that's the case, why would it run lean to begin with? Colder plugs maybe?

Colder plugs won't change the heat of combustion, nor will they affect the air fuel ratio. the '82 850's are jetted lean from the factory. on my '82 the color on the ceramic is a light gray color using the fuels we have available in this part of the world. if you can find a way to make a fitting to insert into the drain screw (bolt) hole, coupled with a piece of clear plastic tubing so that you would be able to check the 'wet' fuel level, might make it easier to double check the fuel levels than pulling the carbs. then, IF you can find or make some small washers to replace the plastic spacers on each of the needles to effectively raise the the needle one half step, might be a better idea than bumping the mains up a size, which will only help enrichen the 3/4 throttle and above fuel mixture.

see>>> http://thegsresources.com/_forum/showpost.php?p=1318297&postcount=4

 

[Dogma]

Chris, please post these questions in the tech section for a quicker response. Some of the brightest GS minds never leave there. I'll go link back to this thread when I've said my piece.

I have been told that the K&N filters require a jet kit on the 1000G. I would imagine the same is true for the 850. Your plugs trump whatever I've heard though. Stock jetting with the UNI filter should have been right. Perhaps gasoline is formulated a little differently in SA.

The tech heads will want to know as much of the carbs' history as possible. Were they disassembled & dipped before your trip? New o-rings in the carbs? Have the diaphragms developed pinholes? Do all 4 plugs read the same?

The carb cleanup series shows pictorially how to clean the carbs, but says nothing that I recall about tuning. The factory service manual (on BassCliff's site) has a section describing the theory of operation of these carbs, and you can gain an understanding of how they work by studying that.

It is correct that the adjusting screw only controls the mix at idle. Everything else is controlled by the jets and the needle attached to the slide. You might try raising the needle in the slide and see how that behaves. Some people recommend this anyway to get rid of the flat spot around 5k.

The height of the needle is controlled by the tiny circlip that holds the needle in the slide. Aftermarket needles often have several grooves for the circlip, just for this kind of tuning. Stock needles only have one groove. You'll need a small washer to insert under the circlip, and that will raise the needle relative to the assembled carb. Folks here in the States have a hard time finding appropriate washers. Some careful work cutting and drilling a soda can might be your best option if you pursue this. Can walls have very consistent thickness. So consistent that I've known machinists to use them for shims. The change in height necessary will be something like 0.3 mm [0.01"]. The wall of a soda can is a little thinner than that, so you'll need to double or triple it.

Shimming needles is fiddly, spring-loaded work. Be prepared for tiny parts under some spring tension. Getting the slides out of the carbs is simple. Getting the needle out will be impossible without appropriate snap-ring pliers. They will need to be very long and thin. The set I have started life as needle-nose pliers with most of the steel removed on a bench grinder. The mechanic you're working with may have a set you can use. He knows what the mix screw does, he may be familiar with the rest of these carbs too. A lot of bikes used them.

With all the environments and fuels you'll be encountering, it might be a good idea to have different size jets on hand, and take a plug read when you ride into an environment that's new.

 

[shirazdrum]

Hey guys,

Thanks for the replies. the GSR doesn't load here well in B.A and i have to follow links in my emails to get to it.

You are right about the needle in the slide. it only has one groove but raising it a good idea. we can definitely try that. about 3 soda can washers sounds about right or go higher? it was hell to take out the c-clip last night as its deep into the hole.

The diaphragms are fine, all plugs read the same (except the #3 plug which i don't remove because of bad threads on the head, i'm assuming it's the same)

The mechanic is making a tube thing to measure the float levels so will get back to you on that.

I have internet here for another hour so if anything else comes to mind, shoot away.

 

[shirazdrum]

I have to try to pst replies 10 time for it to go through, so if you see a duplicate, that's why. My skpye is on and my username chris.sorbi if anyone has skyp btw.

 

[rustybronco]

about 3 soda can washers sounds about right or go higher? it was hell to take out the c-clip last night as its deep into the hole.

Chris, whatever half the height of the plastic spacer works out to be in soda cans or washers.

you're right about getting that clip out.

what's the elevation above sea level around there?

 

[shirazdrum]

Half the size of the plastic washer. Got it. Thanks.

B.A sits about 50 or so feet above sea level. Uruguay, Paraguay and Brazil will be the same as well. Bolivia will be problematic as i'll climb to almost 17000 feet, but it won't do any harm to the engine as it will just run very rich. i can take out the air filter for high passes to give it more boost.

 

[Dogma]

...
The mechanic is making a tube thing to measure the float levels so will get back to you on that.
...

I forgot to comment on the float heights. I don't know if you or your mechanic are aware, but direct measurement of the float heights is a little odd on these carbs. Most carbs you measure to the bottom of the float (top when the carb is upside-down). On these, there is a step near where you want to measure. Measure to the bottom of the step, not the top. As usual, Cliff has a good illustration on his site, along with other good 850 carb data, including float height and fuel level.

It sounds like your mechanic is getting ready to measure fuel level, which is the superior troubleshooting method, I'd say. I'd say to check both methods against each other to, just to be sure.

 

[BassCliff]

I have been told that the K&N filters require a jet kit on the 1000G. I would imagine the same is true for the 850. Your plugs trump whatever I've heard though. Stock jetting with the UNI filter should have been right. Perhaps gasoline is formulated a little differently in SA.

Hi,

FWIW, I go back and forth between my UNI air filter and my K&N filter (depending on which one is clean) without changing any carb jetting. I don't really notice any difference. But as Mr. Dogma states, the plugs are the determining factor.


Thank you for your indulgence,

BassCliff

 

[Guest]

White on the ceramic is ok as long as the heat is ok. Look for spots of aluminum on the ceramic. Count the threads on the plugs. If there is color more thab 2.5 threads I'd worry.

 

[Skateguy50]

Based on the previous engine melting holes in 3 of the pistons and the world of effort it took to get him that engine I think it is a very serious concern

I got nothing constructive to add to this conversation... just saying Chris please stay put and get this worked out, does Z1 stock jets and could he send them direct if needed?

 

[shirazdrum]

Ok, here's the update:

I bit the bullet and took the carbs off. We measured the float height and they are perfect. Main Jets are stock so are all the other ones. The Pepsi can idea didn't work, since the shims are going to be only 3mm wide with a 1 milimeter hole in them, and that would take all year to make that many tiny shims. we settled on small thin washers and will try that tomorrow as soon as i can locate some.

What size is the OD of the fuel hose? Inside is 8mm i think but i what's the OD? i need it to go inside the spring and the spring is not here. Anyone has a caliper handy?

Thanks,

Chris

P.S. I found Wi-Fi so internet problem is solved.

 

[Guest]

If you want to bump up the main jet I have some jets. I also have some shim washers I can send you. You can richen the idle mixture with the screws. Take them out a half turn.
The plug pictures I saw had soot on the bottom ring (good) a half to one thread of heat (good) and a clean ceramic (no particles).
Could it be the carb jetting didn't cause the melt down?

 

[Skateguy50]

For what its worth my initial thought was cracked old intake boots caused the melt down, but want to be sure nothing remains that will cause a similar ending.

 

[shirazdrum]

Well, somehow these carbs started to go lean and mean on their own, George Foreman style. We'll put an end it to it tomorrow though. Bill, thanks for the jets and shims offer, i'll see what we can do here locally and if not i'll take you up on that.

It's just hotter than hell down here. 97 degrees with 55% humidity. Wearing riding gear is like waking into an oven.

 

[waterman]

For what its worth my initial thought was cracked old intake boots caused the melt down, but want to be sure nothing remains that will cause a similar ending.

Another poster suggested that the alcohol content of gas could be the culprit. A quick wikipedia check states that Brazil uses 25% ethanol in gasoline. I am thinking that can't be too good for our motors. I have posted in a couple different forum areas trying to get some ideas on how to jet for that much alcohol, hopefully we can find some useful info to prevent engine failure 2.0.

 

[rustybronco]

Chris,

Is there any place around where you are now that sells aviation fuels? if there is, check to see what percentage of ethanol is in that fuel. if you can (do) carry additional fuel on board, you can blend it with the locally available fuels. that might be a better option than re-jetting for the area you presently in, then having to un-jet for a different country at a later date.

100LL ??? possibly one of our members who fly aircraft will offer up an opinion.

 

[Skateguy50]

the more I read the more I see the extremely high ethanol content as a big suspect here... I guess the solution is the go up the jetting and if it becomes problematic with other fuels bring it back down later. Not sure what else you can do as he has to take what he can get for fuel.

I know products like stabil and seafoam help with preventing the ethanol gas from gelling as quick for storage, do they help with preventing it from burning so hot as well?