4 to 1 Exhaust and Rejetting

Hello all,

1982 XJ650

I am sure this has been covered plenty, but I cannot remember where I saw the information. I remember a thread talking about how these bikes are under jetted to begin with. With a 4 to 1 exhaust, and OEM box air filter, what size should the main and pilot jets be? I will be drilling out the jets that I have. Thanks.

 

I'm searching for the same info. I'm sure I read it here somewhere. I just broke down and bought a Mac 4-1 for my XJ550. Just installed today - it fit better than I thought it would, but I will need to fabricate something better for the rear bracket.

Anyway, tomorrow I hope I have time to work on tuning but I'm thinking resetting might be needed. Although I may first try a glass wrap on the insert to calm the noise down a bit.

 

for the 550
just up the pilot jet 1 size . main jet fine
I have the mac 4 to 1

I just use a bar from original mount location to muffler bracket.

you could shorten the front of the muffler aa bit to get closer or remove the bracket on muffler and reweld it.
i am going back to oem exhaust as the mac is a screamer sometimes i forget my ear plugs.. does sound nice with out muffler.

another issue with the mack is oil filter housing will not come out between the headers so you have to rotate it to change filter out