Can exhaust cause richness?

[Take Warning15]

The previous owner replaced the stock exhaust on my seventy five with an after market exhaust. The bike runs very rich and I've been through everything suggested to me here by you guys to correct it, still to no avail. So my question is, could it be the exhaust modification? If I put the stock exhaust on it, would 130 mains be too big?

 

[jd750ace]

Exhaust has an effect on flow for sure. Typically, there is nothing as restrictive as stock exhaust, as it goes under the scrutiny of the government for emissions, gaseous and noise. The typical aftermarket exhaust weighs less, is less restrictive to noise and in some cases gaseous emissions as well, although the latter is not a big concern with the XS. I doubt very seriously that returning to stock exhaust will fix your problem. If you have a stock air box, I'd suggest a return to stock jetting, regardless of where you are with it currently, and work from there.

 

[Jack]

The previous owner replaced the stock exhaust on my seventy five with an after market exhaust. The bike runs very rich and I've been through everything suggested to me here by you guys to correct it, still to no avail. So my question is, could it be the exhaust modification? If I put the stock exhaust on it, would 130 mains be too big?

The "75" mufflers while heavy, weren't that restrictive and has a nice exhaust tone. What mufflers are on the bike now? Some of those cheap muffler place a small hole diffuser in the middle of the baffle,not good flow or performance,probably to much back pressure building up causing the rich condition.

 

[5twins]

If you're contemplating new mufflers, I highly recommend the Commando mufflers from MikesXS. They look nice, sound great, and flow better than stock. And they happen to be on sale too.