Slight hesitation w/ throttle above 3000rpms Q.

[andmoon]

83 850g
Carbs are clean.
Jets are stock.
Float level is correct.
Intake is stock.
Exhaust is a 2 into 1 for each side of unknown make.

From steady state cruise above 3000rpms when I apply throttle she hesitates (smooth hesitation, no stumbling) for 1/2 a second and then pours on the power. I also feel the bike may be slightly surging at steady state speeds above 3000rpms but it may also be my imagination.

I am guessing this is where the pilot jet and needle are controlling things. I am also guessing I am running lean in this range. Do I raise the needle or raise the float level or both?
Any other things?


History...
I replaced the main jets from dynojet 165s to 160s to 155s to the current stock jets to cure a stumbling issue at full throttle.

The air screws were out 7 turns when I got the bike, I started at 2 turns out and now am at 3 1/3 turns out. The 3.5 turns sounds like it is 1.5 turns more than the norm but that's what it took to get rid of most of the popping on deceleration.

The floats were all even but set above the limit in the manual so I brought them down to spec.


This GS is starting to act like my CB!

 

[rustybronco]

stock needles or, dyno jet?
air box sealed?
air filter properly oiled?
fuel levels are at? mm.
spark plugs look like?
valves adjusted?

does adding a little choke @ 3,000 help or hinder the hesitation/surging.

This GS is starting to act like my CB!

Only if your CB was also hacked on, by a previous owner.

 

[andmoon]

stock needles or, dyno jet?
air box sealed?
air filter properly oiled?
fuel levels are at? mm.
spark plugs look like?
valves adjusted?

does adding a little choke @ 3,000 help or hinder the hesitation/surging.


Only if your CB was also hacked on, by a previous owner.

Stock needles
airbox check
air filter check
floats set to 0.95 in.
plugs are a nice tan
valves check
carbs were synced as well.


CB came in some cardboard boxes ...parts were hacked on by many people!

 

[rustybronco]

floats set to 0.95 in.

Not the float height measurement, the external fuel levels as measured with something like this...http://cgi.ebay.com/ebaymotors/Carb...X&its=C%2BS&itu=SI%2BUA%2BLM%2BLA&otn=7&ps=63

 

[Rudeman]

Did you check for leaky manifold boots? You might need an O-ring replacement. It's sucking more air than it should at idle. How does it run at 5K?

 

[TheCafeKid]

Not the float height measurement, the external fuel levels as measured with something like this...http://cgi.ebay.com/ebaymotors/Carb...X&its=C%2BS&itu=SI%2BUA%2BLM%2BLA&otn=7&ps=63

Im not trying to start an argument or anything Rusty, you know your stuff as well as I do, But this is yet another thread where ive seen people talk about these "fuel level" measurements... Im not trying to say that such a thing is useless, but *I* have NEVER used one of these tools, never had a problem related to that, and really, if the float levels are set, the carbs are clean (as well as the fuel tubes cleared) I dont see why there is a necessity to measure with this....thing. Yes, the CV carbs are touchy, but I dont think they're THAT touchy.

Lets review here..
OP, you say the plugs are a nice tan colour..is this from doing chops in various ranges of throttle or just an overall full range reading?

Generally, the stagger you are experiencing, from MY knowlege, is a fairly COMMON problem, and seems to show up more in the shaftie bikes. I dunno if its an 8V thing, or a shaftie thing or what, but I TOO have found both my 1100G, and a couple of the STOCK 850Gs to have this problem. Many people have. The common fix seems to be "shimming" the stock needle position. As a rule, the GSs were set pretty lean from the factory, and it seemed to show up MOST in the pilot/needle transition. My guess is that this is where they were likely having the most problem keeping the bikes inside the new EPA regs, and therefore attempted to run them leaner here. Or it simply could be a by product of trying to comply EVERYWHERE.. not sure, Im no tuning guru. BUT, I have tried the "shimming the needle" process, and found it to solve the stated problem, as well as solve some of the "wall" you may hit at around 6k. Now, again, Im not discounting other ideas here, so you may want to investigate them all, but shimming the needle is pretty quick and easy, and you dont even have to pull the carbs to do it, as you can get the slides out of them with them still on the bike.

You'll need some small washers, about the same size as the washers that are in the slides already. Probably need 4 or 8, depending, but i wouldnt shim the needle more than that, or your gas mileage may suffer quite badly as i found out. It will also make the bike *jump* when you grab the throttle. Feels FUN as hell, but its not good for the drive line, as its quite the shock to the splines and drive gears. Give it a try, it may solve your problem, but again, everyone so far has given good advice as to other posibilities too..

 

[Bert Patterson]

It seems to me ? correct me if I?m wrong (and it?s irrelevant to the post) that the greatest thing one can do to keep carbs in good order is to ride regularly???am I right?

 

[tkent02]

It seems to me – correct me if I’m wrong (and it’s irrelevant to the post) that the greatest thing one can do to keep carbs in good order is to ride regularly………am I right?

Bert, Absolutely correct.

Josh, I have had troubles with a VM carb that would not play well with the others, float heights set all the same, everything identical.

I made up one of those fuel level devices and found that one carb was different than the rest, and they were all just a little bit off.

I don't always use it but when something is not right I pull it out.

Andmoon, it seems to me a slight hesitation is pretty much normal for these early CV carbs, it just takes a little time for the slides to lift up.
I think shimming the needles too high lets it run better during the half second or so the slides are lifting, but at the expense of being too rich all the time while at that partial throttle setting. This is one thing that kills fuel mileage, as these low throttle settings are where most of us ride most of the time.

On the other hand some bikes need a slight needle shim adjustment just to not be too lean.

 

[andmoon]

Me, the hot stud that was trying to fix my original stutter issue w/out removing the carbs ended up removing the damn things 5 times today!


Stuttering at last 1/3 throttle....waay to large main jet. (DJ 165-160-155 to stock)

Popping under deceleration....air screws out 3 1/2 turns fixed...mostly.

1/3 second hesitation from steady state ~3K rpms...fixed by shimming the needle (shims from dynojet jet kit, no idea on thickness) but may learn to live w/ if gas mileage drops too much.

I do not know about the float settings via height vs the poor man's fuel guage tool. I had to grind down one of my pliers to make a circlip plier for the carbs...that and the carb sync vac adaptor nipples are the only special tools this GS is getting!


Thanks all for the advise. I have become quite proficient at removing the carbs now.



Now...I need a tutorial/pointers/tricks on clutch spring replacement.


Don

 

[andmoon]

Did you check for leaky manifold boots? You might need an O-ring replacement. It's sucking more air than it should at idle. How does it run at 5K?

Which O ring are we talking about?

I did the spray wd40 thing and there was no sign of leaks.

Besides the slight hesitation when applying throttle, she ran great everywhere....maybe an imaginations worth of surging ~ 4500rpms??

Don

 

[Dogma]

Bert, Absolutely correct.

Josh, I have had troubles with a VM carb that would play well with the others, float heights set all the same, everything identical.

I made up one of those fuel level devices and found that one carb was different than the rest, and they were all just a little bit off.

I don't always use it but when something is not right I pull it out.
...

Perhaps if a float been repaired and was heavier than the others (or maybe it's leaky), it would result in such a variation?

 

[rustybronco]

Im not trying to start an argument or anything Rusty, you know your stuff as well as I do...

TCK, you will never have a argument out of me over a difference in opinions.

all that matters is the bike gets running correctly.

but, with that said, I've been burn more than a few times over setting float levels and that is why I'm suggested to check fuel levels. the short answer is to raise the needles, but what is the true reason for the hesitation. the only way is to double check all items and that includes the fuel levels.
another thing to consider is the fact we are not dealing with all new parts, like it came from the factory.

is his idea of tan the same as your's or mine?

Willowgreen is going through the same thing over setting float heights and this was the result...

#1 looks too rich but having trouble getting it leaner/ ]#1 fuel level with mating line

#2 not sure, maybe a little lean?/ #2 fuel level was ~2mm below mating line

#3 too lean I think/ #3 fuel level was ~5mm below mating line

#4 like 2, not sure maybe a little lean/ #4 fuel level was ~4mm below mating line

 

[TheCafeKid]

Well, I will honestly say, that after worrying my brains out for the last couple of years over plug chops and the like, Number one is Rich for sure, but the other three..Id honestly call them "OK" for an everyday rider. There is one thing I have learned, and it has taken 3 years of the OLD guys on here beating it into my brain:

WORRY LESS, RIDE MORE...

LOL!

I have to say, I have on more than one occassion been call a "neurotic tuner" and actually i wear that badge with some pride, because, for the most part, If I work on someones bike, I will fret about it untill *I* think its right, simply because my name is attached to it. Now, there will be a point where, if someone doesnt want to spend more money, or *I* simply dont have the knowhow to repair whatever is wrong, where I will conceed the point. But, for the most part, i try to help and make it right. Having said that, there have been more than a couple of MONTHS of the last two seasons where I have spent more time wrenching than riding. I enjoy wrenching, but I like riding more...LOL. At some point, I just have to say "Its running well enough, its time to quit obsessing over it" You'll never get an argument out of me either Rusty, as i said, you know your stuff, and I have PLEANTY to learn myself, I am far from an expert on these bikes. Every time I work on one, i learn something new, or a faster/better way of doing something...etc. I guess my point is, Ive tried to adopt the philosophy that Im not building a race bike, so i try to quit tuning it like its one and just ENJOY the damn thing...LOL

Oh, ONE OTHER point I could make... Those plug readings could ALSO have alot to do with mix screws... There are so many variables with carbs, You could HONESTLY go insane trying to make them run perfectly. I suppose thats why everything now days is FI

 

[rustybronco]

Well, I will honestly say, that after worrying my brains out for the last couple of years over plug chops and the like, Number one is Rich for sure, but the other three..Id honestly call them "OK" for an everyday rider.

Now I think they are all to rich for optimum power and fuel economy; because there is an excess of carbon on the outer shell(s)... (except for #3 of course)

I have to say, I have on more than one occassion been call a "neurotic tuner" and actually i wear that badge with some pride, because, for the most part, If I work on someones bike, I will fret about it untill *I* think its right, simply because my name is attached to it.

You and I are very much alike...