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4-1, K&N in stock box VM jetting stuff

J

jknappsax

Forum Mentor
Past Site Supporter
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 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. The needles in the box with the other Dynojet stuff are a silver color.
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. 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.
 
jknappsax said:
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 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. The needles in the box with the other Dynojet stuff are a silver color.
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. 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.
Click to expand...

If it's only rich on #3, check the petcock, it can leak fuel down the vacuum line to that carb.

My 1000 ran well with 112.5 main jet, but there is high elevations involved, I live at over 5,000 ft.
Maybe 115 would be about right? Maybe bigger.
Just a guess.
Don't know about Djet, never used them.
 
It's weird, because the needles in the carbs now have the 5 grooves for height adjustment, but so do the ones with all the other DJ parts. The current needles, marked 5DL36 (IIRC), seem stubbier than the ones I believe are the uninstalled DJ needles.
 
I ran a V&H pipe with the stock airbox, lid removed & KN drop-in. I used 117.5 main jets and the stock needles in the 3rd position with stock spacers. It worked fine.
 
Thanks, Robert. That's just the kind of information I was looking for. Anyone out there have any idea what the 117.5 Mikuni's would roughly equate to a Dynojet 138? I know trhe Mikuni's are flow-rated, whereas the DJ jets are actual diameter of the hole in the jet.
 
I don't know the conversion factor, but aftermarket Mikuni 117.5s are only about $2.00 each at most bike shops.
 
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