Exhaust Selection Question

Greetings - I have a Canadian 1982 XJ 750 Seca now running in So CA. It has 11k miles but as we all know...is 27 year old metal.

The situation
Low speed occasion exhaust rattling noise and constant high speed noise caused me to remove entire system. Presto, 1/2" hole on underside of right muffler and rattling rust inside. Muffler is not coming off collector easily and currently soaking with Kroil oil. Additionally, the PO laid my bike on the left side so the left muffler has a few minor dents and a surface rust spot almost identical to the right muffler hole. The collector has a fair amount of exterior rust.

I don't see any stock mufflers for sale on ebay or xjbikes. I have seen XJ posts about aftermarket mufflers but fit to existing brackets will not be correct.

Can I get some practical comments back from those who have dealt with exhaust:
Used mufflers may have rusted/rusting baffles as well.
New mufflers (chacal) will work till the collector rusts out!
A 4-2 sytem from MAC appears to be close to stock & costs $360.
I do not want to re-jet.
Any advice for another system?
Greg

 

Ok guys...out of 30some views nobody has a MAC or other aftermarket system that can give me feedback!!! Ok, I'm rattlin the cages. Actually, I have my exhaust system down on the floor and I need to buy or rebuild so looking for a few other experienced views. Thanks, greg.

 

I have the MAC 4-1. It's cheap but OK. Sounds funny but works fine.

The only thing I can say about the 4-2 is that I don't believe it has a collector box like the stock systems do, so it would really be 2x 2-1, rather than a 4-2. I don't think you'd need to rejet for that, but I can't be sure... it will still change the resonance of the exhaust system.

PS: If your collector box and headers are OK, a better bet might to just replace mufflers, either with MACs or with the Sportster mufflers a lot of people seem to like.

 

Well,let me chime in with my little knowledge base. Chacal has a great description of the needs for when u go to a 4-1. basically it requires upsizin the main jet to a 124 which isnt that hard,(yea easy to say i know), and if u leave the stock airbox on this is adequate but understanding the backpressure requirements of that arrangment is key. with a 4-1 or any straight pipe mod u lose the backpressure from the collector which increases teh draw out of the exhaust,which in turn cause a bit o loss of fuel on the momentary ex-intake valves being open at same time thus requiring the larger size jet as compensation i guess. To go from a 4-2 to a 2x2-1 causes this basic same principle but may not require more than a 122 jet,unsure really. never did that. If it was ME and i had to do an exhaust mod due to unavailability of stock set-up i would think i want a 4-1 for several reasons. but the drawback of that is the additional weith to one side versus a balanced weight set-up overall. The souond of it is quite awesome,but then again gotta weigh all concerns and make the best OVERALL decision. Collector boxes are very rare finds on ebay and be careful to ask questions before u get stuck with one that is ready to pop from rust. i had a hole in my collector last year and found one that the seller said was in good condition and completely usable,so i took a shot and it was jsut as he had said,and is on my bike now.

 

i had a hole in one that by the time i found good metal you could put your fist in
i'am by no means a welder but i have a gas setup so a half hour later it was sealed up, then a half a can of green gas grill paint and all was well
that was a few years ago and it's still holding
try finding a welder that rides, he'll fix ya up

 

hmmmm didnt think o that one,and it was before i found this site. see all the useful ideas aorund,i so love this forum!!!

 

hey gregu, i have a 85 maxim 700 center collector if your interested. this is a arizona bike, the po crashed the bike and the muffs were beat up. there is little damage to the chrome area and exit pipe. pm me if you want it'....

 

Holy Gas Man Fasthoe...that's the best lookin collector I've seen to date. (Put my hand on my collector while still cool and I can feel the baffle banging!)

I will continue looking for some stock mufflers but not having good luck. Most are dented. If I can find 2 muffs, I'll PM about the collector.

Otherwise, I may go with the MAC 2x2-1 system. Sounds like most owners have not had serious jetting issues. (1 XJer and 1 Dennis Kirk opinion)

The collector is a mystery to me. It certainly must increase backpressure. Why is it there? Does it alter or sync the flow somehow that achieves better gas removal than equal length pipes (as in the 4-1 systems)?