I finally decided to make the ol' rejet leap, though the mildest common version for ye olde style GS5: stock exhaust, stock air box, vanilla Filtro air filter, 40 pilot, 125 main, 1 washer. I started with 3 turns out on mix screws, currently at 3 turns and a one-sixth turns of a flat head hex bit.

Starting/low RPM:

Warm seems to spring to 4k a bit more quickly and reliably, but the bike still isn't really warmed up until riding for 15-20 minutes, preferably at a constant speed. It seems to be more finicky now about idling now until really warmed up. Until then it bogs until above 3k, doesn't like sudden WOT. Sound is definitely deeper now, a bit Harley-like uneven burbly idle.

Warm/above 3K RPM:

This sucker SCOOTS. MUCH more vibey now...to the point I'm with getting a pad/lambskin cover of some sort to put between my lower portions and the tank. More torque, but seems like it may come at the sacrifice of horsepower (?).  Noticed yesterday that it seemed to starve set to reserve...wondering if I reinstalled the tank filter backward when I had it off to clean (hoses should be correct). [edit: the family pet chicken is being replaced with a new one]


There are times when I miss the more sedate nature of the original settings. There are other times when I go "WEEEEEEEEEEEEEEEEEE". The fiddly idle is disappointing...wondering if others only changed the main jet.

That said, I also wonder if having the additional performance has just highlighted the conditions I was experiencing before the change....like careful clutch application from stopped, having to downshift to get over 85mph, really being able to tell the difference in character between cold, warm and really warmed up.

At current settings, 59 MPG in mixed driving including 60-70mph cruising, some WOT acceleration, and trundling around neighborhoods. May open up mix a bit more tonight. I definitely felt a difference between current settings and when I had the screws at 3.5 turns or more.

Wondering....how much is to be gained by only opening mix screws instead of re-jetting..?

It's funny. I rejetted a long time ago and the only major change I noticed was that it idled and started much better.  I recently did a valve adjustment and started noticing the symptoms you're talking about.  It idles fine, but then from idle until about 4k, it bogs and doesn't make any real power.  It didnt' used to be that way.  I might have had to slip the clutch *a little* but I used to just slowly and smoothly rev out of idle and it would make power the whole way.  I just did a carb sync, and it was a little off.  When I had my tank off and was syncing the carbs, I did notice one of my fuel lines was starting to crack near the nipple.  Also, when revving the throttle out of idle I hear kind of a hissing or whistling sound.  I sprayed some wd40 around the area where the carbs connect to the engine and nothing happened.  I disconnected and reseated the air filter (lunchbox), but it didn't seem to make a difference.

Not really sure what it is.

cWj:- You may have a slide rising too fast. The not liking WOT before it got warm is a sign of that. Now the 15-20 min to warm up and issues with acting like its too rich after rejet = you either have air screws open too much, or float is too high. More vibes post 3k ... I'm stumped, but is that under load or at idle. Jetting is related to throttle position, so rpm is a bit irrelevant. 3k @ idle is under 1/8 th throttle = pilot jet. 3K in 3rd is about 1/4-1/3 throttle = float level. 3k in 6th = you need your head examined, and buy a Harley or something.

007Brendan:- You gave your bike a bog after a valve adj Did you check just before the adjustment maybe it has a high float. It progressively gets high as it wears ... 1-2 years and its off far enough to be super rich ...

Cool.
Buddha.

Quote from: 007brendan on June 27, 2015, 03:55:09 PM
It's funny. I rejetted a long time ago and the only major change I noticed was that it idled and started much better.  I recently did a valve adjustment and started noticing the symptoms you're talking about.

I believe I forgot to mention that I adjusted the valves and set the exhaust valves to wider spec for longer service intervals....also rebuilt the whole top-end and I suppose timing could be a bit off in my case, but I very certain I set it back to what it was before (notches very close, but not perfectly facing each other - I simply could not get them to match perfectly as shown in illustrations).

the reference to vibration is while under load.

I decided to take a look at my jet needles today, thinking that I might remove the washers to see if how it would affect my current imperfect tuning....and discovered that they weren't added when I had him rejet/rebuild the carbs.

SO, I'll put those on and see what it does.

And...anothre re-jet disaster...


Cookie

Quote from: cWj on June 27, 2015, 10:49:59 AM
I finally decided to make the ol' rejet leap, though the mildest common version for ye olde style GS5: stock exhaust, stock air box, vanilla Filtro air filter, 40 pilot, 125 main, 1 washer. I started with 3 turns out on mix screws, currently at 3 turns and a one-sixth turns of a flat head hex bit.

Starting/low RPM:

Warm seems to spring to 4k a bit more quickly and reliably, but the bike still isn't really warmed up until riding for 15-20 minutes, preferably at a constant speed. It seems to be more finicky now about idling now until really warmed up. Until then it bogs until above 3k, doesn't like sudden WOT. Sound is definitely deeper now, a bit Harley-like uneven burbly idle.

Warm/above 3K RPM:

This sucker SCOOTS. MUCH more vibey now...to the point I'm with getting a pad/lambskin cover of some sort to put between my lower portions and the tank. More torque, but seems like it may come at the sacrifice of horsepower (?).  Noticed yesterday that it seemed to starve set to reserve...wondering if I reinstalled the tank filter backward when I had it off to clean (hoses should be correct). [edit: the family pet chicken is being replaced with a new one]


There are times when I miss the more sedate nature of the original settings. There are other times when I go "WEEEEEEEEEEEEEEEEEE". The fiddly idle is disappointing...wondering if others only changed the main jet.

That said, I also wonder if having the additional performance has just highlighted the conditions I was experiencing before the change....like careful clutch application from stopped, having to downshift to get over 85mph, really being able to tell the difference in character between cold, warm and really warmed up.

At current settings, 59 MPG in mixed driving including 60-70mph cruising, some WOT acceleration, and trundling around neighborhoods. May open up mix a bit more tonight. I definitely felt a difference between current settings and when I had the screws at 3.5 turns or more.

Wondering....how much is to be gained by only opening mix screws instead of re-jetting..?

It is by no means a disaster, and what I'm experiencing could be related to many things. As I discovered, mine wasn't even complete. Furthermore, trying to the rejet has caused me to get even more intimately aware of the function of the carbs. I was originally one of those that said I'd never bother with rejetting. After riding the bike for two years, I decided to try. I will put the washers on and see how that affects the performance. If I decide to return to stock, I still have the original jets and will likely just try to do it myself this time (sent off to bike mech brother this time).

I understand seeing people do something that doesn't make sense to me. At some point, however (assuming it is not something that presents an actual danger to one's or anybody else's self), you just let people do what they want to do. 

I held no assumptions about guaranteed success.

If it isn't something you are interested in, just don't click.

Update:

SURPRISE! Adding the washers to needles appears to have solved my problems. Pokey started up with choke after one quick push of the starter after sitting for a week then almost immediately shot to 3K...running more smoothly everywhere in the rev range...no more Harley-Davidson Tractor sound.

Happy with it for now.

..kinda wondering what happens with another washer on each needle and another half-turn out on the mixture screws.

Quote from: cWj on July 10, 2015, 07:14:30 PM
Update:

SURPRISE! Adding the washer to the needle appears to have solved my problems. Pokey started up with choke after one quick push of the starter after sitting for a week then almost immediately shot to 3K...running more smoothly everywhere in the rev range...no more Harley-Davidson Tractor sound.

Happy with it for now.

..kinda wondering what happens with another washer on each needle and another half-turn out on the mixture screws.

Nice! 

Did you find this helped even out your idle, your overall band across the revs, or both?

Quote from: Al Capwn on July 10, 2015, 07:30:56 PM


Nice! 

Did you find this helped even out your idle, your overall band across the revs, or both?

I'd say both.

The only problem I notice now is what appears to be the dreaded fuel starvation at WOT (6-7k in 6th). I guess this is why the racers switch to gravity feed. My solution is to switch to reserve.

Decided to add a second washer to the needles. Even smoother now.  Take off from stopped still seems slow/finicky...stalls if too aggressive. Will experiment with idle speed.

Quote from: cWj on October 12, 2015, 08:47:08 PM
Decided to add a second washer to the needles. Even smoother now.  Take off from stopped still seems slow/finicky (stalls if too, aggressive. Will experiment with idle speed.

You have 40/125 and 3 turns Stock airbox and filter ? good clean filter without some nasty rip in it ? Airbox hoses intact ? the drain on the bottom and the Crank vent on top - both good ?

Then you may have to set the floats right. The 89-00 bikes wear the floats high, and that is with or without rejet. They also do that with or without much riding. If you drain the bowls, they don't, but you ride every month 1 day, it will be like you rode every day for this aspect. Set the floats to the top of the bowl.

I'll check the floats every year on the 89-00's. And every 3rd yr on the 01+'s. Regardless of your setup.

Cool.
Buddha.

air filter looks clean, about 6k miles on it. may replace with slightly larger OEM anyway.

floats reported to be in good condition by gentleman that serviced/rejet them. about 3k more ago.

no air leaks that I can tell.

noticed slide springs are both bent a bit when I took needles out, if that has potential effect.

cleaned grey gunk off of slides... wondering if gunk was actually lube.

Quote from: cWj on October 12, 2015, 08:47:08 PM
Decided to add a second washer to the needles. Even smoother now.  Take off from stopped still seems slow/finicky (stalls if too, aggressive. Will experiment with idle speed.

If you let the clutch out too fast you mean ? that sounds rich. Try checking the floats again.
Cool.
Buddha.

Looks ok to me 

Too close to call - 1mm can make a difference ... actually 1mm is a fair minimum measurable amount in this ... if there is no parallax or other error, you're on the nose on both.
Cool.
Buddha.

Noticing that I don't seem to be able to pop the teenie-tiny wheelies that I did before modding the carbs, I decided to remove the washers from the slide needles to see if it made some difference in the performance from stop.

Having done it, still no wheelies. And I now definitely feel a difference in the performance. I did miss the relaxed nature from 3-5k from before the rejet. Now I miss the ability to buzz traffic above 5k. The acceleration doesn't feel as immediate. The bogs from 3-7k are apparent. Though I haven't checked the MPGs, I am now conflicted as someone who likes to mitigate his contributions to the atmosphere and the pockets of the oil companies.

(because buzzing traffic feels so guuuuuuuuud)


Also noticed during the spacer removal where the kinked slide springs. When I put the washers in I noticed that both springs were kinked just past the middle. I would just try to straighten them as much as possible and re-install. The last time with the carb tops off, the right carb spring had managed to flip itself into complete loop.....now wondering about the effects on system performance of kinky springs...


As to the wheelies - it suddenly occurred to me last week:

me: "Hey, Genius, remember how you put that larger tire on the back...for the sake of dropping revs a bit at higher speeds?"

me: "Oh. Yeah. That did happen. That could make a difference."



(note that the above are not complaints, just observations)