83 Suzuki GS850GLD carb sync/adjustments

[auddyb]

We rebuilt this bike along with a different exhaust (still 4 to 2 just cut with no baffle)

The bike will run but it really likes the choke. With the pilot screws completely closed it will run on choke only and will die as soon as you try to shut the choke off. We assume it was getting to much air so I went to buy oversized main jets but was told at the shop that this wasn't my issue. He suggested we count the pilot screws out and screw them in half way(12 total turns so we put it to 6). We did so and the bike managed to start without the choke and idled just fine. However, we still had no throttle control, would die if we did so. We backed out the pilot screws a couple turns to see where our mixture was at but didn't get much of a difference idle wise. We figured we'd take apart to check and adjust the jet needle with the circlip placement, turns out there is only one setting on these jet needles.

I'm getting the feeling that this is a more rare bike due to the minor adjustments available including the automatic timing unit to the carbs. Seems like everything needs to be perfect for this bike to run. We're lost right now and any knowledge on this particular bike will help. Thank you for your time.

[Steve]

First of all, , now let's tackle the SEVERAL problems you are talking about.

We rebuilt this bike along with a different exhaust (still 4 to 2 just cut with no baffle)

I really don't want to preach, but you will be doing yourself, your bike and the motorcycling community in general a big favor if you get some mufflers on there.

The bike will run but it really likes the choke.

This is quite common, at least until you strip the carbs down, soak each one for about 24 hours in carb cleaner dip (Berryman's or GUNK are the favorites) and put them back together with a new set of o-rings from cycleorings.com. Do NOT get "carb rebuild kits" for them.

With the pilot screws completely closed it will run on choke only and will die as soon as you try to shut the choke off. .

That's because they are not "pilot screws", they are MIXTURE screws. By turning them IN all the way, you were turning off the fuel that was needed by the engine. A properly-running set of carbs will have them set to 2 to 2 1/2 turns out, but we usually start about 3 turns out for easier starting before we start tweaking mixtures.

We assume it was getting to much air so I went to buy oversized main jets but was told at the shop that this wasn't my issue.

You need to find a new "shop". By altering the air flow capabilities (cutting the exhaust), you also need to alter the fuel flow capabilities. Are you running the stock airbox on the intake side? If not, you need to adjust for that, too.

He suggested we count the pilot screws out and screw them in half way(12 total turns so we put it to 6). We did so and the bike managed to start without the choke and idled just fine.

As mentnioned above, 6 would be WAY too much. The mixture screws actually don't have much adjustment past about 4 turns out, so it would not matter if you had them at 4 turns or 12 turns out, it would run the same, ... too rich.

However, we still had no throttle control, would die if we did so. We backed out the pilot screws a couple turns to see where our mixture was at but didn't get much of a difference idle wise.

I will ask again, do you have the stock airbox on the intake? Did you have anything on the intake when you tried this? Unless you are perfectly-jetted to run with no airbox, you WILL have problems getting above idle speed.

We figured we'd take apart to check and adjust the jet needle with the circlip placement, turns out there is only one setting on these jet needles.

You can thank the Feds for that. When these carbs started to show up here in 1980, they were jetted a bit lean, there were NO adjustments available (other than idle speed) and the mixture screws were even sealed with tamper-resistant covers.

I'm getting the feeling that this is a more rare bike due to the minor adjustments available including the automatic timing unit to the carbs.

I have worked on dozens of these bikes and even have five of them in the stable right now (three of those are 850s, too), but I have no idea what the "automatic timing unit" is on the carbs. Please elaborate.

Seems like everything needs to be perfect for this bike to run. We're lost right now and any knowledge on this particular bike will help. Thank you for your time.

No, things can actually be rather "sloppy", but it's SO much nicer when they are right.

.

[auddyb]

Thank you for the response.

"I will ask again, do you have the stock airbox on the intake? Did you have anything on the intake when you tried this? Unless you are perfectly-jetted to run with no airbox, you WILL have problems getting above idle speed."

We've tried with and without the airbox and got pretty much the same results. I currently have four cheap individual air filters which we've used for the most previous tests (between 5-8 turns on the pilot mixture screws). I noticed the filters have very little resistance to air flow, probably because they were so cheap, this might be a concern...

"You need to find a new "shop"."

Agreed.

"but I have no idea what the "automatic timing unit" is on the carbs. Please elaborate."

I should have proof read better. Sorry for the confusion. I was just referring to the bike as a whole, we had some major issues trying to get the timing just right, not necessarily with the 20 notch counting but whether or not the "T" mark is directly in line with the "T" or its the line to the right of the "T"... After about 5 or 6 attempts removing and installing (we got pretty good at it) the timing is dead on. This unit is what they refer to as the "automatic timing unit" (there is no adjustments for the "atu" where as older bikes have the springs you can adjust). So, with all of the headaches from this unit, to trying to get the carbs adjusted, there has been some demoralizing long nights.

In regards to the bike needing to be perfectly jetted with the changes to the exhaust and air flow, they refer to changing the main jets as "step ups" or "downs"... I initially was going to jump up three steps when the gentleman at the shop told me this isn't my issue. Is three a lot? Is it more of a trial and error process? Mine are the stock sized #115, any idea on a number or range to start at?


"I really don't want to preach, but you will be doing yourself, your bike and the motorcycling community in general a big favor if you get some mufflers on there."

I'm assuming I'll be losing some respect if I plan on this bike being a bobber.

Thank you again for your time.

[Steve]

OK, your "automatic timing unit" is actually the "automatic cam chain tensioner" and has nothing to do with the carbs.

The hardest part of that timing is realizing that the pin that is over the #2 mark on the exhaust cam is not #0, it is #1.


With "cheap" pods on there (you would really be happier if you splurged for K&N or APE pods) and basically open pipes, your main jets should be around 130. You will also need to "shim" your needles to raise them. After removing the needles from the slides, you will see that there is a thick nylon spacer above the clip. It is the thickness of that spacer that determines needle position. Replace that spacer with a couple of washers that are about half as thick, the needle will be raised about the equivalent of one notch on the older, adjustable needles.

In spite of your air flow "enhancements" (pods and cut pipes), your pilot mixture will not need much tweaking, so the mixture screws will probably end up in the 2 to 2 1/2 turn out range. Of course, this assumes that the carbs are CLEAN and have new o-rings. Please note that a visual check for "clean" will not suffice, as the parts that get clogged can not be seen.


Oh, you mentioned "sync" in your thread title, that has not even been addressed yet, but it will need to be done after the carbs are cleaned and rebuilt.


What part of this big blue marble do you call "home"? One of us might be close enough to stop by and help, if needed.

.

[spyug]

As I read it you are trying to deal with several things at once and actually making things harder for yourself. Guru Mr. Steve has done his usual commendable job of pointing out the areas of concern and some changes you should consider. I'll chime in too.

As he says, to get any bike running properly, the carbs first have to as clean as you can get them and need to be free of airleaks. The intake boots too should be in good shape and devoid of airleaks. A common issue with them can be the o-rings that seal the boots to the head. You need to check that they are not cracked or split as air will get in and you'll be chasing your tail. Looking at them is not enough, pull them apart slightly to see if they are cracked. Obviously replace them if cracked or have gone flat.

Once the carbs are clean you need to have the right jets installed to compensate for the airbox or pods you intend on running and the exhaust pipes and mufflers you are using. This is where the balancing comes in and it can be a nightmare to sort out if you try and do everything at once.

These bikes are designed to run with a stock airbox and mufflers. If your carbs are also stock, you should start with these in place. Once running and idling properly, then you can start to fiddle, but again one thing at a time.

With pods, be aware that cheap ones like Emgos offer no air restriction or filtering and are esssentially useless so before you go to changing jets find good pods first K&N, Ape or even UniFilters are best. Once you have them running right with pods then go to your exhausts.

All of this takes some studying, time and trial to get right so don't expect to bang it off on a Saturday afternoon. Trying to do it in one fell swoop will only lead to frustration, trust me on that.

Good luck with the project.

Spyug

[auddyb]

Thanks again for the responses.

I will check for leaks/tears around the intake. Along with a thorough carb dip, and new o-rings.

We've spent countless hours working on this bike and hearing it start made me extremely ambitious to ride it right now!! I understand that I still have a lot of work to do and will focus on the carbs for now and will take it step by step. Thanks again for chiming in, and I will keep you posted on the progress.

Steve, I currently live in Greeley, CO.

[Steve]

Steve, I currently live in Greeley, CO.

OK, that means that you are far enough that I won't be stopping by, but it also means that my eardrums are that much safer.

Please reconsider your exhaust choice, bobbers can have mufflers, too.

.