'82 GS 650 glz - Carburation issue (probly)

[mmattockx]

Next step would seem to me to raise the needle some more...

That sounds right. If you get it working OK to a bit more than 1/4 throttle and find it is still lean then I would go to a larger main jet just to be safe as you get transitioning onto the mains. Where are your mixture screws at now?


Mark

[upb4dawn]

"Where are your mixture screws at now?"
About 3 1/4 turns out..seems to be plenty, but it's not very happy w/ less.

FWIW- the stock 'brown' nylon space that sets above the needle clip is 2.54mm thick. The white one provided by 6 Sigma is 1.38mm. I'm now using a thin steel spacer and a thinner brass spacer, which is 1.11mm combined. So, 1.43mm lift on the needle now. Am reassembling them, & leaving the mains at 125 for now.

Thanks-
Doug

[upb4dawn]

A test ride shows a wee bit of improvement, but it still requires choke at 1/4+ throttle, and falls flat w/o it as you twist on. Low speed response past 1/8 to 1/4 throttle is really good, a torment as it's a taste of how well this thing should be running.
I tried it with the mixture screws out 2.5 and it had barely enough power to climb my driveway. Remarkable that 1/2 turn made that much difference. Put it back to 3+ to get it where it is. I've read that if it needs more than that it's time to go one up on the pilot, which I do have, and that will be another time.
So, I'll remove a washer from the needle and the spacer height will be about .61 mm. Not much of a change from the last time, but if it's an improvement I'll have some more clue that I'm on the right path. Guess bigger mains will be the next step if that's not getting the job done.

[Steve]

Have you read the spark plugs with any of these runs or are you still just guessing?

.

[upb4dawn]

Plugs are black, not sooty. If I rub the electrode there's insufficient carbon/soot to come off on my finger.

[mmattockx]

"Where are your mixture screws at now?"
About 3 1/4 turns out..seems to be plenty, but it's not very happy w/ less.

There is nothing wrong with 3.25 turns, that is where I am at with my 1100E. Much over 3.5 turns is getting to be maxed out and indicates it is time for a jump in pilot jet size.

FWIW- the stock 'brown' nylon space that sets above the needle clip is 2.54mm thick. The white one provided by 6 Sigma is 1.38mm. I'm now using a thin steel spacer and a thinner brass spacer, which is 1.11mm combined. So, 1.43mm lift on the needle now. Am reassembling them, & leaving the mains at 125 for now.

Thanks-
Doug

1.43mm is about one notch on my Suzuki OEM needles (Canadian model with adjustable OEM needles), so you haven't jumped a massive amount overall.


Mark

[upb4dawn]

Thanks, Mark. Good to know I'm not way out of line on these bits anyway.

[upb4dawn]

So, while I'm away from the shop and bike for a few days, I've been wondering (dangerous I know) ... since I seem to consistently lose power at about 4K, and evidently that's when the spark advance is supposed to begin, is there any chance this is the signal advance/governor acting up? From what I can tell, the ignitor pretty much either works or it doesn't, but I can't find much info on the advancing unit. Or, am I just imagining this to get out of tearing down the carbs a few more times....?
Feel free to impune what little savvy I have in this regard..

[tom203]

The advancer starts advancing at just above idle and maxes out at about 40 degrees BTDC by 4000 rpms. Make sure it moves freely and returns when you twist it.

[upb4dawn]

Thanks. Will check it when I return. But meanwhile, I'm thinking that since it runs really pretty well up to 4-4500 then the advancer must be working Ok...

[upb4dawn]

I checked the advancer, it looks fine. Cleaned it up a bit. All looks fine, things move with ease. So, seems this is not an issue.

[RayC]

Hi
Just putting my 2 cents in here the fuel screw on the bottoms correct - only matter on idle to just a bit off idle Same for the pilot jets sounds like just a thought 3 &1/2 turns seems like alot and it appears its reflecting on you plugs.
Just start over -pull the carbs -clean all the jets and passages- ck your air cleaner-timing etc. etc.
Maybe I missed the begining of this conversation

[upb4dawn]

Thanks.
I'm going over everything each time I've taken the carbs down. Floats are set to spec - 22.4mm. Little screens in there are clean. Passages are clean. Float needles seem to function just fine.
As for timing.. I thought w/ the electronic ignition there was no adjustment for timing. Am I wrong here?
And as for the beginning of the conversation, I've got K&N dual pods, and essentially everything else is stock (mufflers drilled out somewhat). I got a jet kit from 6 Sigma, and am trying all the various possibilities. The jets they sent seem extraordinarily big (but their numbering convention is different than Mikuni). So, I've gotten 120 Mikuni's because that's what seems it should like based on all the conventional wisdom. It starts and idles and runs fine up to about 1/4-1/2 throttle and falls flat at 4000rpm, but likes the choke there and then. Can be coached up to maybe 6-7K, but no more.
Tomorrow it will go back to as close to stock as possible (w/o the airbox), and then I'll work from there. May throw in the big jets again just for the hell of it if that doesn't work or seems to go in the wrong direction.
I see that DynoJet kits have a tapered needle w/ clip settings (the Sigma kit uses the stock needles w/ various spacers), and also a fitting for the air orifice on the right side of the carb (facint the intake side). The Sigma kit does not address this at all. I'm wondering whether this may have something to do w/ it falling flat..
I've also got some hotter plugs coming, since these look dark.

[upb4dawn]

Much improved.. but not quite there

OK, it's running much much better. I'd say I'm 85% there.
Rev's and pulls happily to about 8K now, and then acts like it's starving...& responds to choke to get up top. 1/8, 1/4, 1/2+ throttle response seems just fine - almost roll-on wheelie territory.
To get here, I've gone up one size on the pilot (45), & removed all spacers above the needle clips, and following the 6-Sigma Kit instructions put the nylon spacer and one steel washer below the clip (just ads spring pressure I know). There's no spacer above the clip, so this is effectively as high as I can raise the needle.
And, for jets I used the biggest ones they sent. #142.5 on the outside cylinders and #145 on the center two. The jets are marked AB and evidently they (6 Sigma) use the same sizing convention numbers as Keihin, so that translates to 122.5+ and 125 in Mikuni numbers according to the chart at Jetsrus. Seems a bit big, but not as big as the ones in a DynoJet Kit, from what I can tell. (I had tried this setup when I first got the kit, and it ran miserably, then I found I had cracked intake tubes, and they've been replaced).

The plugs look tan.

In addition to the 'starving' feeling at high rpms, it basically 'runs out of gas' unless I switch to 'prime' on the petcock (which is new). My floats are set correctly, and the vacuum hose is on correctly.
So, it wants more gas up top, and likes prime vs regular setting on the petcock. I don't mind that part so much except that it's dangerous to go off and leave it parked in prime... and it just ain't right.
In addition to going up yet one more size in jets, I'm wondering if I should set the floats differently to address that starving sensation.

Thoughts and comments?

[tom203]

Run petcock on "RES" and see if more fuel gets delivered. The "ON" spot is a couple inches up into gas.