4-1 Kerker q's

I recently switched out the stock exhaust on my 81 xj550 Seca for an old Kerker 4 into 1 and since then it's been acting a little differently. I'm getting a little clanging/rattling sound in the engine that wasn't happening before and I also feel like I might have lost a little power. I didn't change the jets in the carbs and I'm wondering if there might be a difference in pressure causing the rattling sound. The old exhaust was junk and wasn't even the original mufflers. The PO had welded the mufflers to the swing arm rendering the shocks useless and it was also producing an exhaust leak. I already adjusted the cam chain tensioner and that didn't change anything. I'm going to check the valve clearances pretty soon. I guess what I would like to know is generally speaking what kind of mods must you do to compensate for a 4 into 1 exhaust?

 

I have a Motad four into one on my 900f and it was designed to work with the standard carburettor and airbox setup. I don't know if the Kerker was designed for a standard setup so that is the first thing I would try and find out. It might not have been as you notice changes from the stock system?

 

It does say XJ on the actual muffler but that can just be purely a coincidence. This is the early eighties and I'm sure many advances were made since then.

 

Most times a change in exhaust you need to go up 2 sizes in jets . The noise may have been there all along you just did not hear it before , the tone and pitch changes with the exhaust change. Unless it is a knocking sound , it could be in the muffler , many after market exhaust have removable baffles could be packing is deteriarated .

 

I have a Kerker 4:1 from the early 80's and I had my carbs re-built by Dave and AFAIK, it has stock jetting.
I will say, when I replaced my badly rusted muffler with a new (old) Kerker that wasn't rusted out, I started hearing a lot more engine and gear noises. It is amazing how much quieter the bike is and I like that!

 

could be primary chain slap increase rpm to 1200 rpm from spec of 1050 rpm

also make sure your oil is full with just a little air bubble in the sight.

do you have a center stand? could be chain hitting center stand or center stand hitting muffler