gs850 re-jetting

[robbo]

1986 gs 850 i have just purchased a motad 4-1 and am also thinking of a k&n filter can anybody give me some advice on re-jetting please

[Guest]

Are you going with K&N individual pod filters or one in the airbox.

[robbo]

just one in the airbox

[Guest]

Most websites for the exhaust will give jetting suggestions. I know that the Kerker and V&H are usually spot on.
You will have to bump up your main jet and raise your needle a notch or two. Some even have to bump up the pilot jet one.
Mikuni jets run in 2.5 increments. I was going to help you with jet sizes but I can't seem to find an 86 850.
You really don't have to rejet for an airbox K&N filter but a 4-1 you will.

[Roy]

1986 gs 850 i have just purchased a motad 4-1 and am also thinking of a k&n filter can anybody give me some advice on re-jetting please

I have a 82 GS 850 gz with a 4-1 transac system, should be the same carbs as yours. 32 mm cv:s . Standard jets are 115 my GS is running fine with 120 jets fitted I didnt fined it nessasary to raise the needles at all . I also have the standard air box .

[dardoonk]

Per a discussion I had with a factory rep, it seems as though the Motad will breath only slightly better than a factory setup. Based on decible levels, the stock bike should have been around 80 max while the Motad is rated at 84 decibels. I could be wrong, but thats probably a good indication that jetting would be similar to having the stock pipes along with whatever airbox mods you have.

[KEITH KRAUSE]

I have a 82 GS 850 gz with a 4-1 transac system, should be the same carbs as yours. 32 mm cv:s . Standard jets are 115 my GS is running fine with 120 jets fitted I didnt fined it nessasary to raise the needles at all . I also have the standard air box .

I was thinking one full size up too would be enough for that exhaust. 120's.
Do throttle chop/plug test at 1/3 throttle to see if the jet needles need to be richer.
A little richer (additional 1/2 turn?) out on the mixture screws should be enough for any pilot circuit issues.