Topic: 550 4/1 exhaust

[tommy54]

I have a 78 550K with rotten stock exhaust on the left side of the bike.  I need to figure out an exhaust so I can tune it.  I'm guessing there's no point in trying to tune it when the left side is pretty much straight piped and the right has proper mufflers.  I know a guy that has a 4/1 exhaust system that he'll let go for $75, should I pick it up?  What is there to know about 4/1 exhausts?  I like the idea of a 4 into 1 exhaust on this bike, but were there any 4/1's made for a 550 that I should watch out for?  I don't know what brand this guy has, does it really matter?  I need an exhaust and money's tight. Thanks for any input

[Triffecpa]

4-1 pipes for the 500/550's are not extremely common.  Your options with a rusted out stock system is to either replace it with a 4-1 system, or buy a 4-2 slip on kit that uses the stock head pipes and puts a "Y" onto them with a single muffer on each side.

If the pipe that is available for $75 is in decent condition, then you are probably money ahead to buy it.  Shipping on any otehr pipe options are likely to run half of the $75.

TR

[73hutch]

i have a stock 550 4 into 4 left side. it's in good shape, if you want to go that route. PM me if you're interested.

[TwoTired]

I'm pretty confident that the carb will need a rejet going from the stock 4into4 to a 4 into 1.
Absolutely confident that adding pods filters will demand a carb rejet.

The 77-78 Cb550 4 into 4 is more restrictive than the earlier 4 into 4 style.  So, they are not interchangeable.

The 4 into 1 will reduce your low and mid range torque vs. the 4 into 4.  It may not matter to you, though.

[tommy54]

well, while we're on the subject of rejetting, I might as well bring this up.  the boots that go from the airbox to the carbs weren't on the bike when I got it.  They were yet another part of the bike that was supposed to be there, but aren't.  I had been planning on keeping the stock airbox, but I'm not sure now since I'd have to buy the boots.  I'm not really concerned about horsepower.  I wish I could tune it with the stock airbox and exhaust, then start messing with things like exhaust, pods and rejetting.  The bike is not going to be original, and it's not going to be a cafe racer.  I'd like to get it running as cheap as possible and then figure out what direction to take the bike as far as styling.  Will a 4 to 1 really hurt torque down low that much?  I'm mainly concerned with driveability, not top end speed, but $75 seems like a pretty cheap fix for my exhaust problem.

[TwoTired]

Sorry.  If you want to tune the engine (carbs) correctly you will have to determine what you want for filter and exhaust.  Or, you will have to redo the "tune/rejetting" for each change you make.

With the changes you have described, it's not the peak power in any range that you must be concerned about.  It is the way-lean mixture the PD style carbs will provide without the stock air filter and exhaust restriction, making the engine run hot and possibly melting pistons.

Anyway with the stock configuration, there is very little "tuning", just setting things per the manual.  It's when you change engine breathing parameters that you need tuning skills in order to keep the engine from destruction.

So, is it "cheaper" to get the proper components or rebuild the engine after it destructs?

[tommy54]

Well, i'm in wisconsin, and it's the middle of winter so I've got a little time to figure this out.  The bike doesn't run properly right now, it keeps picking up and dropping cylinders.  I've been fiddling with it in my shop, even though I know it's kind of pointless.  I'm just trying to figure out the cheapest way to get some sort of proper intake and exhaust systems.  I know right now it will run extremely lean, so running it as-is is not an option.  The exhaust will end up being whatever is cheapest, since it doesn't seem to make much of a difference other than moving the torque curve around.  I could either buy the intake boots or buy pod filters, do rejetted PD carbs respond well to pods or am I safer going with the boots?  I don't mind rejetting the carbs.

[TwoTired]

Depending on which pods you buy, you will likely have to open the pilot screws, raise the slide needles and go to larger main jets.  What adjustments//settings you end up with will be more or less unique for what components you chose.

You will need a Dyno or a test track and several sets of clean spark plugs to determine the correct jetting/carb adjustments.

[the technological J]

I have a 78 550K with rotten stock exhaust on the left side of the bike.  I need to figure out an exhaust so I can tune it.  I'm guessing there's no point in trying to tune it when the left side is pretty much straight piped and the right has proper mufflers.  I know a guy that has a 4/1 exhaust system that he'll let go for $75, should I pick it up?  What is there to know about 4/1 exhausts?  I like the idea of a 4 into 1 exhaust on this bike, but were there any 4/1's made for a 550 that I should watch out for?  I don't know what brand this guy has, does it really matter?  I need an exhaust and money's tight. Thanks for any input

my buddy put a mac 4 into1 on his 78 550k  and the only change that  we did was on the set screws it runs better than ever

[TwoTired]

my buddy put a mac 4 into1 on his 78 550k  and the only change that  we did was on the set screws it runs better than ever

That is not the same as saying it runs with the correct A/F ratio, or the best power it could have.

...Just saying....

In the same vein. I have a couple of bikes that I have never even made run (I haven't tried).  If I get them started, whatever i did, will make it run better than ever (even if only three cylinders are firing).   

[jph550]

I plan on re-jetting my MAC 4into1 this spring and want to quiet it up some too. Thought about stock pipes but hope I CAN do it cheaper with a baffle, some jets, and time.

found this thread,
http://forums.sohc4.net/index.php?topic=7952.0
and wondered if anyone has had success with anything like this and what jetting they ended up with? (mine's a 76 CB550)
Jason

[Lars]

If you go from 4-4 to 4-1 you have to raise the needle by one on the circlip. Did it the other way around on one bike I had, replaced a 4-1 to original 4-4. It would not run properly, so I checked the needles and they were not at standard setting. Changed the circlip to standard (middle) setting and it ran perfectly ever after.

[turboguzzi]

http://www.marving.com/faces/detprodotti.jsp?prodotto_id=209685

[the technological J]

my buddy put a mac 4 into1 on his 78 550k  and the only change that  we did was on the set screws it runs better than ever

That is not the same as saying it runs with the correct A/F ratio, or the best power it could have.

...Just saying....

In the same vein. I have a couple of bikes that I have never even made run (I haven't tried).  If I get them started, whatever i did, will make it run better than ever (even if only three cylinders are firing).   

according to MAC there was no jetting necesarry and not too much riding has been done yet  it was late in the season... but i'll have to look into it a little closer in the spring... definate power difference though

[the technological J]

better is always good a step in the right direction.... is there ever a best?

my buddy put a mac 4 into1 on his 78 550k  and the only change that  we did was on the set screws it runs better than ever

That is not the same as saying it runs with the correct A/F ratio, or the best power it could have.

...Just saying....

In the same vein. I have a couple of bikes that I have never even made run (I haven't tried).  If I get them started, whatever i did, will make it run better than ever (even if only three cylinders are firing).   

according to MAC there was no jetting necesarry and not too much riding has been done yet  it was late in the season... but i'll have to look into it a little closer in the spring... definate power difference though

[TwoTired]

my buddy put a mac 4 into1 on his 78 550k  and the only change that  we did was on the set screws it runs better than ever

That is not the same as saying it runs with the correct A/F ratio, or the best power it could have.

...Just saying....

In the same vein. I have a couple of bikes that I have never even made run (I haven't tried).  If I get them started, whatever i did, will make it run better than ever (even if only three cylinders are firing).   

according to MAC there was no jetting necesarry and not too much riding has been done yet  it was late in the season... but i'll have to look into it a little closer in the spring... definate power difference though

And how much research do you think MAC made to the cheapest exhaust system on the market to differentiate needs between the old rich burning CB550s with the newer and less available lean burn 77/78 CB550k model/carbs?

I've had a MAC 4 into 1 on a 75 CB550 with 022a carbs.  I used stock jetting, too.
I would in no way expect the same jetting with the EPA lean burn carbs and a MAC.

Since you are pressing the point, I will question your "power difference" statement, as well.
Mac has less weight than the 4 into 4.  So, that changes the power to weight ratio. (Perceived power increase?)
The MAC is louder than the stock 4 into 4.  (More noise means more power, right?)
Show me the dyno or track time improvements.
Show me the spark plug deposit color change.

Perhaps this thread will be of interest:
http://forums.sohc4.net/index.php?topic=20869.msg258435#msg258435

[jph550]

I'll be reading that tonight. looks interesting and helpfull

[OldSchool_IsCool]

If it is the muffler that is rotten, what about cutting it off and using a slip-on muffler?  You'll keep the 4-4 configuration although matching the back pressure may be problematic.

[jph550]

I already have a 4-1 installed. its not rotten, except for the sound and I need to re-jet cause I have some rich running symptoms.
hoping to swap out its existing baffle for one that reduces the noise and gives a little more back pressure for low and mid rpm power.
I'm running a stock airbox with paper filter now, and have a mild megacycle cam installed by PO. I may put a foam filter in to open up the intake since I'm re-jetting anyhow. then i can stop buying new paper filters when the old get cruddy.
Jason