1980 GS 750 Jetting with Pods and V&H

[EricEder141]

Hey all I picked up a nice vance and hines exhaust for my 1980 GS 750 and once I started reading the directions for jetting I got kind of lost. On the vance and hines spec sheet it gives 3 different GS750 models all with different Jetting Specs. The link for the spec sheet is below. I took out a 112.5 main and swapped it for a 122.5 (all my local dealer had) the pilots that were in it were 17.5's I am guessing some one upped them before I got bike. Is anyone out there running this exhaust on this year bike with Pod filter, and can you give me some hints. Sorry if I have been rambling I have been in garage sniffing gas and carbon monoxide fumes all day trying to get her to run right I have 54mm pod filters on bike.

http://static.chaparral-racing.com/Resources/documents/pdf%5CV12001-P.pdf

thank you

[Guest]

Hey all I picked up a nice vance and hines exhaust for my 1980 GS 750 and once I started reading the directions for jetting I got kind of lost. On the vance and hines spec sheet it gives 3 different GS750 models all with different Jetting Specs. The link for the spec sheet is below. I took out a 112.5 main and swapped it for a 122.5 (all my local dealer had) the pilots that were in it were 17.5's I am guessing some one upped them before I got bike. Is anyone out there running this exhaust on this year bike with Pod filter, and can you give me some hints. Sorry if I have been rambling I have been in garage sniffing gas and carbon monoxide fumes all day trying to get her to run right I have 54mm pod filters on bike.

http://static.chaparral-racing.com/Resources/documents/pdf%5CV12001-P.pdf

thank

I've seen 80 750s withg CV carbs with 40 pilot jets but not 17.5s. I'd go with a 42.5 pilot jet.
This may be a 79 which means you have VM carbs.
I'm not sure how to advice.

[Agemax]

you need to establish whether you have the 2 valve or the 4 valve engine. then follow the instructions. your bike is a 1980 so ignoring the 83 onwards, that only leaves you 2 options.

[EricEder141]

you need to establish whether you have the 2 valve or the 4 valve engine. then follow the instructions. your bike is a 1980 so ignoring the 83 onwards, that only leaves you 2 options.

What is the best way to decipher between the two?? the vin or some type of stamp on engine??


I can also tell you that when I swapped out the mains there were 4 screws holding the bottom of the bowl, and 4 screws on the top of the carb (I tried to take the needles to lower the clip but the pliers I had were not long enough to get down there and take the c-clips out in order to get to the needle)

[Guest]

Round cam covers on the side of the engine (79 and eight valve)
Rectangular cam covers (80 and sixteen valve)
CV carbs (80) have round tops
VM carbs (79) have a three screw tower type cover

[Agemax]

the 2 valve engine has round end caps on the cam cover and the 4v has square/rectangular caps

[EricEder141]

the 2 valve engine has round end caps on the cam cover and the 4v has square/rectangular caps

That's simplifies things a lot thank you,

I also took a look in service book and according to the pictures I have BS carbs... I am going to get the right tool this week and drop the needle hopefully that gets me into the ballpark of where I need to be.

PS Vance and Hines makes a great system and saved me about 15 lbs

[gearhead13]

PS Vance and Hines makes a great system and saved me about 15 lbs

Just wait a few years until it starts rusting out from the inside. My baffle rusted and broke in half along with big holes in the megaphone