Jets for pods and 4 to 1 exhaust

[Guest]

Whats up guys.. I have asked this question before but I can't for the life of me find the response.. anyway.. I have a gs750 done in a cafe style.. this is the way I got the bike. It has cheap air pods and a 4 to 1 exhaust. I have the carb apart and in some dip.. I ordered the orings kit for the carb and the intake seals.. I want to jet the carb for the exhaust and pods. I don't know what size to get for this set up.. I am gonna put quality pods on the carbs before they go on the bike.. help.. I realize everyones bike is different but if someone could suggest a starting point for jets with this set up it would be greatly appreciated. thanks!

[hjfisk]

Not sure what model carbs 750 your has VM or CV's but with pipe, and pods you should probably get a jet kit. Also if you have cheap pods throw them away and get K&N's because you will have a hard time getting it tuned. If you have VM's they are a little more tunable, and you my not need the jet kit. Not sure where to start with the jetting maybe 5-6 sizes larger than stock on your mains.

[ATNasty]

Not sure what model carbs 750 your has VM or CV's but with pipe, and pods you should probably get a jet kit. Also if you have cheap pods throw them away and get K&N's because you will have a hard time getting it tuned. If you have VM's they are a little more tunable, and you my not need the jet kit. Not sure where to start with the jetting maybe 5-6 sizes larger than stock on your mains.

The carbs are VM's.. I plan on getting K&N filters. Would I only need to do the main jets? not the slow jets? My GS is a 78 btw

[koolaid_kid]

http://www.mikuni.com/pdf/vmmanual.pdf

[btbarb]

pipe pod thread

This pipe/pod thread will give you some guidance:

http://www.thegsresources.com/_forum...d.php?t=199275

[ATNasty]

http://www.mikuni.com/pdf/vmmanual.pdf

Thanks for the info.. It says for selecting the size of the main jet to do a test riding the bike.. my bike isn't working enough to do the test.. Im going through all the stuff I need to to get it going well.. carb, intake seals, Im gonna check valve clearances, electric, ect.. so I was just asking for a starting point.. it has 100 in for the main jet.. Im gonna order some bigger ones.

[ATNasty]

This pipe/pod thread will give you some guidance:

http://www.thegsresources.com/_forum...d.php?t=199275

DOPE!! thanks!

[Steve]

... so I was just asking for a starting point.. it has 100 in for the main jet.. Im gonna order some bigger ones.

Looking at the chart that I have, 100 was the stock main jet for the '78 750. That tells me that your 'previous owner' did not care about re-jetting.

As a rule, you need to add about 3-5 sizes for an exhaust system (depending on how restrictive (quiet) it is) and about 4-6 sizes for switching from stock airbox to pods. At least with the K&N pods, you will have a good starting point.

Since you have pods and a pipe, you will need to add those figures, giving you a range from 7 to 11 sizes up, or 117.5 to 127.5. My guess is that you will end up around 122.5, but that is just a guess.

You will also need to lift the needles. You do that by lowering the position of the clip. Probably two notches, but testing will tell you for sure.

To richen the pilot mixture, set the fuel screws (the ones on the bottom) about 1 1/8 to 1 1/4 turns out from lightly-seated and set the air screws (the ones on the side) to double that, or 2 1/4 to 2 1/2 turns out as a starting point. After the bike warms up, slowly adjust the air screws, listening for best idle. I would slowly turn them out until the bike starts to stumble a bit, then turn them back in about 1/8 to 1/4 turn.

.

[ATNasty]

Looking at the chart that I have, 100 was the stock main jet for the '78 750. That tells me that your 'previous owner' did not care about re-jetting.

As a rule, you need to add about 3-5 sizes for an exhaust system (depending on how restrictive (quiet) it is) and about 4-6 sizes for switching from stock airbox to pods. At least with the K&N pods, you will have a good starting point.

Since you have pods and a pipe, you will need to add those figures, giving you a range from 7 to 11 sizes up, or 117.5 to 127.5. My guess is that you will end up around 122.5, but that is just a guess.

You will also need to lift the needles. You do that by lowering the position of the clip. Probably two notches, but testing will tell you for sure.

To richen the pilot mixture, set the fuel screws (the ones on the bottom) about 1 1/8 to 1 1/4 turns out from lightly-seated and set the air screws (the ones on the side) to double that, or 2 1/4 to 2 1/2 turns out as a starting point. After the bike warms up, slowly adjust the air screws, listening for best idle. I would slowly turn them out until the bike starts to stumble a bit, then turn them back in about 1/8 to 1/4 turn.

.

Thank you for the info.. it is greatly appreciated!!