1981 Gs1000g CV main and primary jet size

[Guest]

I have an '81 GS1000G running CV carbs with pod filters and an aftermarket 4 into 1 exhaust. Can someone please confirm from their experience what size main and primary jets should be used?

[JTGS850GL]

You can try various stock jet combinations but the easiest way to get it working is to go with the Dyno-Jet kit. They problem you run into using the stock jets is that the middle ground (needle and needle jet) aren't great. The DJ kit replaces the needle and provides a method to replace the main air jet as well. DJ spent a lot of time and research on developing the combination for stage 1 and stage 3 (yours). It's a tried and true combination that works.

[Miff]

Thanks for the comment, I have used DJ kits on other bikes and been pleased with the results but I was hoping someone had a good setup on the GS1000 by swapping jets, I'm trying to keep the cost down.

[Nessism]

Not all pods nor 4:1's are the same, thus the jetting requirements are different between them. Hopefully you have some proper pods like K&N's instead of junky Emgo's or similar. Typically, assuming a good quality exhaust and K&N's you can expect to bump the mains at least 3 sizes, shim the needles, and maybe even one size up on the pilots. This is just a wild a$$ guess though.

[JTGS850GL]

Wild a$$ guesses are all that anyone's going to be able to do. If you have luck with the DJ kits in the past then that may still be your best solution. When you consider the time spent changing jets out, frustration and the number of jets you'd have to pick up it may very well turn out to be the least expensive option.

Do update us as to what pods and exhaust you have currently.

[Miff]

DSC05494.jpg
This is the exhaust......
The pods are Pipercross, I also have a set of Chinese K&N's.

[Miff]

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This is the bike in question...

[Miff]

20160808_134859.jpg
The carbs are like new!

[JTGS850GL]

Carbs can look new but still be clogged. Have you done a thorough cleaning? Those fuel enrichment screws look pretty backed out. How many turns do you have them set at?

[Miff]

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I've had them apart, completely stripped, float levels set and balanced...several times. The air screws have been down as much as 1 1/2 turns but are currently 2 turns out.

[JTGS850GL]

If that's two turns out then they were never seated at the start. The screw heads would not be flush with the tower.

The jets may look good but if you haven't disassembled, dipped, poked and sprayed the carbs properly then it's not done. It's the small passages in the carb body that's more of a concern as they are the usual area of trouble. Even the float bowls have a passage that's critical to proper operation. It's hard to tell but the pilot air jet looks like it wasn't removed and cleaned from the pic. Why did you do the rebuild "several times"? Should only need to be done once.

Not trying to be a pr!ck but just pointing out that there is a lot of detail to doing a carb rebuild job right the first time.

[Miff]

Your not a Prick! That's why I'm here asking for advice and experiences..... Seafoam has been used as a cleaner and fuel additive, I have stripped them a few times whilst changing jets, primary's have been removed and are cleaned whilst scratching my head for reasons it wont take full throttle. Currently running 127.5 main jets and stock primary. A friend tells me he had 110 mains and 37.5 primary's, does that sound right?

[Miff]

Oh and I'm not sure what the air screw was set at in the photos?

[JTGS850GL]

A friend tells me he had 110 mains and 37.5 primary's, does that sound right?

Those are even small then the stock mains and pilots assuming that you meant pilots instead of "primary's". I still say go with the DJ kit. Save yourself a lot of grief.

Just in case you haven't seen it, here is the CV carb rebuild tutorial that may help.:

CV Carburetor rebuild tutorial

[Miff]

Had a think and I'm saving up for a DJ Kit...lol
One thing though, I had another look just to confirm, the air screws at 2 turns out has the head level with the tube? Both sets of carbs are the same.....