Jetting my 78 GS1000

[KEITH KRAUSE]

OK. I'll try. Do you know what brand of pipe? 4-1? Baffled? K&N pods or cheaper brand? Any other mods you know of? Will you buy a DJ kit or separate jets? DJ suggested.

[80GS750]

ok, no idea on the pipes, they are a 4-2 with a short muffler that turns out.... heres a pic




i looked inside and there is some type of baffle in them...

i have some very old k&n pods that came with the bike, i will try to clean them up and use them, they look pretty dusty though.... i put a DJ in my 750 and am very pleased with the results.... so i would like to stick with the kits...

itll probably take the DJ stage III, your thoughts?

[KEITH KRAUSE]

I'd get the DJ kit then. I would usually use the K&N pods anyday but I hope they're in good enough condition. A simple thing like washing/rinsing them wrong (from the outside-in) can compromise their flow characteristics. Of course, you wouldn't know if they've been serviced right I suppose. I'm guessing those pipes flow a little better than the stockers but not as well as a quality 4-1?? Yes, you'd need stage 3 but remember that the kit was designed for a quality pipe and K&N pods. Any other parts used or in questionable condition may make the re-jet more difficult, but we can do it.
Remember to tune before jetting. Clean carbs, inner o-rings, manifold o-rings, valve clearances, good timing/clean electrical, etc. If all is good, then you're ready to jet.

[80GS750]

the engine is pretty much all torn apart right now... i will reassemble with new piston rings, and make sure timing is good, and that the valves are within tolerance...

it has 30k on it, and everything i have for it appears to be in good condition... if not, i have 2 more engines for donors.....

[80GS750]

i have a k&n filtercharger cleaner kit, i will use it to refurbish the pods for now, and make sure they supply ample flow for this application

[vwdoctor3]

this is the man to ask...

http://www.wgcarbs.com/

[KEITH KRAUSE]

this is the man to ask...

http://www.wgcarbs.com/

About what? Jetting? Go ahead and pay for it. He typically suggests proven lean jetting.
I got into with this guy before. He came around and did offer some good advice on various subjects but he was just trying to drum up business. I have no doubt he can repair carbs with his eyes closed, but he comes up with some BS now and then tying to get your business and making it sound so simple. He has a lot to learn too.

[80GS750]

i will stick with your advice keith. your right here where i need you....

this forum makes it easy to troubleshoot over the net

[KEITH KRAUSE]

OK. I understand you're going to get the stage 3 DJ kit.
Only thing that could be a problem is that pipe and how it flows. You'll want to use the 138 main jet that comes in the kit. Only possible problem I see is the 138 could be too rich if that pipe is too restrictive for the flow the kit was designed for. Hopefully it will work. If not, it wouldn't be too hard to figure out, either a 136 or 134 DJ would work. The new jet needles will work fine. There shouldn't be a need to change pilot jets.
I only see two possibilities regarding jet needle position, either the clip in the 4th position, or with the clip in the 4th position with a jetting spacer (supplied) directly on top the e-clip (equalling position 3 1/2). It's generally best to jet on the richer side if you just don't know for sure. Of course I'm trying to get it right the first try. So I'd go with position 4. Be sure both factory plastic jet needle spacers are re-installed in factory order. Thicker above the e-clip (and above any jetting spacer, if used), and thinner under the clip.
Use the stock 15 pilots and set the pilot fuel screws underneath to 1 1/2 turns initially. Set the side air screws to 1 3/4 initially. REMOVE the two floatbowl vent lines and leave the ports open.
Bench synch the slides for fully closed and then fully open positions.
Warm up completely, set idle at 1,000 rpm, then set the side air screws using the highest rpm method. Now vacuum synch. Timing/valve clearances must be spot on before the vacuum synch. I suggest new gaskets for the pipe so you don't confuse decel popping for an overly lean condition. Also, new manifold o-rings are a must. Also, don't over oil the K&N's and use K&N oil only. One quick pass for each 2 or 3 pleats works well. Oiling "each pleat" as K&N says makes it easy to over oil in my opinion.
Test performance/get plug chop reads at full throttle for the mains, 1/3 throttle for the jet needles and minimal/steady throttle for the pilot circuit.
Anyone who wants to go with Wiredgeorge is certainly welcome. It's just the manner of how he was placed into this thread that irritates me. I'm trying to help and then "this is the man to ask" pops up. Like I don't know these carbs. I know them as well as anyone and I have a much better understanding of how to jet them than George does, based on past posts here and replies from many owners who used my suggestions. You don't leave a factory jet needle in the factory position for pod/pipe mods but he'd have you do that. He also comes up with BS like saying he'll vacuum synch your rebuilt carbs on his test bike and that means you won't have to vacuum synch when they go on your bike. Ridiculous.
Like I said, he's trying to make it sound simple and thinks he can BS you into thinking you won't need to buy a vacuum tool if you have him clean/rebuild your carbs. He'll "do it all". You WILL need to vacuum synch
for best performance and any accurate re-jet. As for the jetting, his past suggestions are very lean. Of course, he'll try to use his carb repair knowledge to impress you and make you think his jetting set up will be correct and needs no testing. To tell you the truth, since he BS's about other stuff, I seriously doubt you get EVERY inner o-ring replaced with new in his rebuilds. I think he just replaces the hard/brittle ones in many cases. Same for components.
I don't doubt his repair knowledge. It's too easy to be impressed by a website. I just want others to make intelligent decisions and try to work on their bikes themselves and be sure the job is done right.

[80GS750]

sounds great! when i get to the carb rebuild i will set exactly as you say, i need to get a vacuum tool so i can synch correctly... as i have not done any of that yet

[80GS750]

hey keith you mean the 4th position down the needle right?

the way i understand it, they count positions down the needle..

[jknappsax]

Keith, you've shown your real knowledge of these carbs and setting them up a million times, and as far as I (and a whole lot of other folks here at the GSR) am concerned, YOU'RE the man! Thanks for all the help and advice you've given to MANY of us through the years!

[jknappsax]

Now that I've buttered you up (all true, all true), I have a 1979 GS 1000 with a Two Brothers 4-1 with a D&D can, and K&N pods. The bike came to me running rich, according to the PO, fouling the plug in cyl #3. He had installed a Dyna S, and told me that that he had installed a Dynojet Stage 3 kit. The pipes have dents on the #2 and #3 cylinders from hitting. I pulled the carbs apart, and they all have 112.5 Mikuni mains (have a little box-within -a box marked on them), 15 pilots. It appears that he never installed the Dynojet kit. I believe the needles are still the Mikuni; they are a sort-of light brass color, but they do have 5 grooves for adjustment, and are marked 5DL36, IIRC. The needles in the box with the other Dynojet stuff are a silver color, and also have the adjustment grooves, but seem slimmer than the current ones. He also had never set the valve clearances; the shims were all like 2.75 to 2.85; I've got them set properly now, and will bench-sync and then vacuum-sync the carbs and set ignition timing before proceeding with carb tuning.
The mains in the box are 138s and 142s (DJ).
I'm planning on keeping the pipes, and running a K&N replacement with the airbox, and either using the stock filterbox with the lid off, or just the K&N attached to the airbox., as I'm planning on using the bike as a sport-tourer, and I think the airbox with the crankcase vent dumping into it will help mitigate the effects of temp, humidity, etc. I know that the stock mains were 95s, so the mains were changed out. I talked to the support folks at Dyno, and they recommended using the 138s and installing their needles with the clip in groove#2. Does this sound like a likely starting point for the setup? The difference in Mikuni and Dynojet jets makes it hard to tell if the 138s might be too rich, but with this setup, it seems like it might be. If you want to PM me rather than clogging up the thread, please feel free. Thanks very much for all that you do.

[salty_monk]

If the carbs are synched on a test bike, why would you need to synch again? It this VM's only or with CV's too?

With CV's I think you are only equalising the butterflies????

Just a thought....

Cheers,

Dan

[tkent02]

If the carbs are synched on a test bike, why would you need to synch again? It this VM's only or with CV's too?

With CV's I think you are only equalising the butterflies????

Just a thought....

Cheers,

Dan

Because each cylinder is different, slightly different compression, slightly different airflow characteristics, everything.
As the engines age the differences get bigger.
Carbs can only be synched and adjusted on the engine they will be run on.