Aftermarket Exhaust Suggestions - No re-jetting Required

I have no idea LOL i just went to a second hand Harley shop and he had hundreds laying around i just picked up the best one i could see.

 

In the US, pretty much your only option is Mac or Kerker. If you shop on eBay UK or look on Webike your options will multiply greatly. Be ready to pay a bit for shipping.

 

I used a pair of slash-but Dyna shorties on my 4-into-2, but there are a couple of mods needed.
The reducer needed was simply cut off the front of the old previous mufflers (not OEM, but they were a replacement system that were near enough identical to the stock set) and used as a packing piece on the inlet of the Dyna mufflers.
When the mufflers were on the Dyna, to suit the differing characteristics of each cylinder and the unequal lengths of pipe on the Harley, the internal baffle plate on each muffler is placed differently. I solved this by removing them and rigging up a temporary spacer equally set on each side to match them in for my use. Said spacer holds back a stainless steel pot scourer internally, and forces the gases through the silencing slots and into the deadening material. Some also goes right through the pot scrubber and exits in a free-flowing manner, but as it's doing so down a tube lined with baffling holes backed with more deadening material, it does so quite quietly.
Fastening the mufflers was quick and dirty - I just used car exhaust clamps at the front *ugly but effective* and I'll try a different solution some other time.
The mounting of the muffler bodies was easy - a pair of stainless steel hose clamps round the muffler bodies and locating over the lower portion of the alloy footpeg bracket there. This is on an XJ900F, so other models probably don't have that handy feature.
The overall result is quite pleasing - the bike pulls as well as it ever did, and is nearly as quiet as stock. If I want to make it a bit noisier I can unbolt the scouring pad retainers and move them back or even reduce the size of stainless pad.

The best part is; the mufflers cost about two bucks.

 

I've been looking for mufflers off and on... anyone know the outlet diameter of my 75o Seca collector?
I'm too lazy to take it off and measure myself.
Besides, there are newer gaskets there so why disturb them I'm thinking....

 

From reading this and living in Phoenix, AZ at 1080' elevation.
On the 83 Maxim 750, if I put a MAC 4-1 and K&N filter into the stock box I should need
Main Fuel +4
Pilot Fuel +1
Main Air- unchanged
Pilot Air- unchanged

Would this be correct?

I currently have stock air and just stock headers on it, (that's the way I bought it) it would have the occasional "popping" sound while riding it home but rode very well!

 

stick with the oem style filter

 

on my 750 seca, i run a mac 4/1, a filter with two layers of uni foam and a supertrapp muffler
122 main, everything else original. things didn't come together till the supertrapp happened
i didn't try real hard with the mac muffler because i didn't like how it sounded

 

^^^+1 Do NOT waste your money on the K&N filter . The PO of my bike had put one of these bike struggled over 75 , swapped to paper filter WOW bike would bury the 85 mile an hour speedo . Later went through my carbs church of clean , as experiment I put in bigger jets 124 main and tried the K&N results bike popped and did not run right , put paper back in and problem solved.

 

Hi Guys,
Been away for a while,but I came across this exhaust article and it triggered a couple questions. I think for my 1981 Seca, the exhaust is a little noisy, and moreso on one side. Valves in spec, stock jets, stock air filter, Balanced carbs, Colortuned( need to rebalance 2nd time after colortune), idles fine at 1000rpms, and it sounds roughly like a sewing machine(a lower DB range sewing machine). The stock bike videos I watch, have a higher pitch whine at idle and thru acceleration(like moms old Singer).

-From my pic does it appear to be the stock exhaust?
-I see some models around, that have a chrome conical part at the tail, is that stock?
-Should I look for exhaust leaks (replace the header gaskets, ck other joints along the way)? I am not sure if a baffle ever existed on these exhausts(I still see the black insert at tail exit,which appears to be welded in there, so I couldn't really get a look inside.
-I was also considering a pair of small silencers which 'snap in'
Any suggestions are appreciated

Patrick

 

MAC makes a nice 4 into 1 and a 4 into 2 set up have a nice exhaust note , not cheap but in my opion a good set up. I had this on my seca till I scored a stock system that is mint. So for now the MAC system sits in my storage.

 

Thanks JF. Am hoping not to have to replace(has 9k orig miles) it. It runs great, no backfiring, no sputtering, and is much quieter upon returning from a ride. I will prob start with simple things ,gaskets, tail pipe connections etc, I am sure they are crap. I have a new back tire,bearings and rear drum that have priority.
I am not a purist, but lean toward keeping what I can original. As you know we can find parts for the bike.(Except of course for the dreaded 'right side cover'. )
Did you end up rebuilding your rear springs or replace?

 

Not to hijack a thread but what's the deal about the right side cover? Do they all fall off on the road?
Cheers, 50gary

 

The battery is on that side,so cover is removed and often lost, I had to buy one for my Seca 750 and bought another as a spare.

 

50 Gary,
here in the US for some reason 1981 Seca 750, right side cover is hard to find.
In fact if I ever sell my bike I will sell it to the next person exactly like I got it, no right side cover. Maybe it'll go from $100 to 2000 and then I can go find another used xj750. I do have an extra left side cover which I'd be happy to sell of 30 bucks.

 

I think what happened is the bike sat for a while with the last owner because I did find Bike in a leaf pile. He didn't want his wife to know you owned a motorcycle haha.
water collected in base of headerpipes sat there so I'm thinking it rotted through pipes , explaining Muffler noise. We have weep holes in window sills why we can't come up with an ingenious way to drain moisture out of our Muffler pipes is a mystery motorcycle Engineers need to solve, especially since on these bikes pipes pitch back towards the front.Duh.

 

I hunt ebay for right side covers then buy a bike to put it on.
right side is lost because someone removes it sets it on the ground and steps on it .
take cover off for battery to go to winter nap and lose or forget where tgey put it

I have heard that most bike accidents hapen with bike falling to right side and destroying cover , I do not think this is a big factor but coud be another reason.

 

Some of them do, but mild steel pipes will rot out eventually no matter what you do.

 

Pipe wrap baby and some JBWeld

 

Stainless is a better long-term solution. Once a mild steel pipe starts to rot away, it's time to start looking for a decent replacement.
Given the price of motorcycle-specific mufflers, I've been using Hardly mufflers, which are pretty well built and seem to last a long time.
Right now I'm seriously looking at a car resonator final muffler, built entirely from stainless, 4" or 5" in diam, 2" or 2.5" inlet/outlet and say 20" long (length can be specified). All this for around 40 or 50 quid and a lifetime's use out of it.
Once I get my AFR settings properly dialled in, I will either fit the genuine Delkovic muffler or a car muffler.

 

Can you post some photos Dave if you fit the car muffler? Interested to see how it will look.