Exhaust question

I have an 81 maxim 550 and I have removed the mufflers and collector box.(too rotten to salvage) Is there an exhaust I can use that will incorperate the existing headers?I want to stay with the 4 into 2 setup.

 

I understand that 550 exhausts are hard to come by. BigFitz is your best shot for some ideas for the 550's.

 

I think if you get some stock collectors, you can really go with most mufflers. But I could be wrong.

I believe most of the backpressure needed to keep stock jetting is accomplished by the collector box.

 

pretty sure you can run straight pipes on these without a rejet.

 

Hrm. Ideas you give me, cubed...

How do you think that would sound?

 

The best place to find an exhaust is eBay; collectors and head pipes aren't too hard to find at all. I just saw a 550 system (pipes and box) last week. If you leave the collector in place you can run pretty much any mufflers you want that will fit.

I got both my collector boxes and a whole assortment of head pipes from eBay. I got TWO sets of stock Seca 550 mufflers from salvage yards.

My '81 came with a Kerker 4-1 with an open megaphone. It was unrideably loud (at least for me.)

 

I did start it with just the headers (I couldn't resist!) I will call around today to see what I can come up with for a collector box. BTW You can download the oem manuals for several models from pdftown.com
It is a very good reference and covers a complete breakdown of the carbs and has all the pics and because its in pdf format you can magnify the wiring diagrams.!! Thanks for the Ideas guys I love this site!!!!

 

Found this on ebay.

http://cgi.ebay.com/ebaymotors/ws/eBayI ... MEWAX%3AIT

 

I don't think that is the stock pipes he's looking for, especially because they don't have a collector.

Also, I think there's a difference between the 650/750 exhaust and the 550, from what I've seen on this site

 

My Bad, I just noticed he has a 550.

 

Hunh, I can't here you over my pipes man... 8O

 

Collector box (with slightly raggedy mufflers http://cgi.ebay.com/ebaymotors/81-YAMAH ... ccessories

 

Thanks,I looked at those pipes but unfortunately I live in southern ontario and the shipping and especailly duty would kill me.I called a local salvage yard and he's gonna look for a cllector box for me.Appearently Kawis and honda can get away without this box without affecting jetting (according to him)

 

Please add your bike info to your signature and your location to your profile. It saves confusion and mis-communication.

The collector box for the 550s is unique but common to both the 550 Seca and Maxim. It shouldn't be too difficult to locate one.

I can tell you this much: the 550 WILL run "ok" on a 4-1 open pipe without rejetting in terms of not running so lean as to burn up the motor or anything; HOWEVER it simply doesn't gain RPMs as quickly as one in completely stock trim; especially in 2nd-4th gears.

 

Well according to Chacals in the rejetting predictor...

Typical Exhaust Changes:

+2 main fuel jet size for custom 4-into-2 exhaust
or
+4 main fuel jet sizes for 4-into-1 exhaust
or
+4 main jet sizes for no muffler (open headers)

Typical Intake Changes:
+2 main fuel jet sizes for single K&N filter (inside a stock airbox)
or
+2 main fuel jet size for drilling holes in the airbox with stock filter
or
+4 main fuel jet sizes for individual pod filters (no airbox)

Additional changes:
- Add up all the main fuel jet size increases and subtract 2 sizes.
- Decrease main fuel jet size by 2 sizes per every 2000' above sea level.
- Under a mis-match condition, such as when using pod filters with a 100% stock exhaust, or 4-into-1 header with stock filter and air box, then subtract 2 main fuel jet sizes.

By my reading its a plus four (+4) for straight pipes, then with stock intake add nothing, then a minus two (-2) just because you always take off two, and a minus two (-2) for the mismatch of stock intake/non-stock exhaust.

+4 - 2 - 2 = 0 change. (i.e. your starting point would apparently be where you are! Unless your above 2000 feet MSL then thats a -2 also).


Think that the stock filter/box combination is the choke point right now. Opening up on the back end won't change how much you can get in the front end much.

 

That doesn't sound right, have a completely open exhaust and need no jet change??

 

I would just go to a muffler shop and have them make two 2-ino-1 collectors and mount a muffler on each side of the bike. Or if you want to get fancy, have them bend pipes so you can mount both mufflers on the right side of the bike. It's worth a shot.
If you have access to the raw materials (tubing the correct size) and are handy with a welder, you can make the collectors yourself. I've done it for truck exhaust when I ran dual mufflers and switched back to a single muffler.