Topic: Cycle X (Mac) Drag Pipes (short ones)

[Stoli]

Anyone have or had a set of these:

http://www.ebay.com/itm/Cycle-X-BLACK-Drag-Pipes-Honda-CB750-Chopper-Bobber-Cafe-Hot-Rod-/200844013122

They look very similar to the Mac drag pipes. Anyone know if they are the same?

If anyone has a set, I am interested in a few things, like:

- Do the the rear bracket(s) hang from the main foot peg(s)?
- What is the Inner and/or Outer diameter of the pipes?
- Do the pipes hang in the same horizontal plane or is one higher than the other?
- Ground clearance - In relation to the foot peg bolt (exhaust bracket mounting hole):
            how much lower is the center of the inner pipe?
            how much lower is the center of the outer pipe?

[Stoli]

OK - So I got confirmation that they are in fact Mac pipes.

So if anyone has a set of the Mac Slash Cut TT Drag pipes (69-76), can you help me out with my questions?

Thanks.

[Powderman]

Can't answer those questions. Are you not interested in how they perform? I see only negatives for those pipes unless used in a high RPM application.

[Lostboy Steve]

I think those are going to be uncomfortably loud, also without heavy engine mods will probably reduce performance.

[seanbarney41]

I have a couple sets of those hangin' around the shop...definately not a performance improvement in any rpm range and sound like noisy crap imo.  I could get the tube measurements for you but I am not gonna mount 'em up on anything any time soon.  Yes 1 and 4 are mounted kind of diagonally higher and more outside than 2 and 3.  Ground clearance sucks.  They mount off the main footpeg.

[leaderbean]

I was really disappointed that when Cycle X finally introduced pipes for the 550 - it was just the MAC ones.  I'm still hoping for pipes similar to their 750 stuff

[Stoli]

I'm no expert but I have familiarized myself with the intricacies of resonance, scavenging, back pressure, etc. and their effects on power production and loss in different throttle ranges. I have read all the opinions regarding the quality of the Mac exhaust systems. I'm just interested in some low cost headers for a bike that I have lowered a bit and, as such, has some ground clearance issues with certain header configurations. Just having some fun with it and am not looking to win any races. I will probably modify them with some inserts or possibly extend them a bit with some type of baffle. One step at a time.

For now, I just want to find the answers to the above questions. There also seems to be a few guys who have had difficulty with side stand clearance using the Mac drag pipes. I'd like to hear more from someone who experienced that as well. Some of the pictures I have found (that appear to be bikes with the Mac pipes) are perched on side stands so it would seem that is something that can be overcome fairly easily if it is a problem at all.

[Stoli]

I have a couple sets of those hangin' around the shop...definately not a performance improvement in any rpm range and sound like noisy crap imo.  I could get the tube measurements for you but I am not gonna mount 'em up on anything any time soon.  Yes 1 and 4 are mounted kind of diagonally higher and more outside than 2 and 3.  Ground clearance sucks.  They mount off the main footpeg.

Your comment regarding ground clearance is surprising to me.  The pictures I have seen look like they are higher off the ground than any aftermarket 4-1 and even higher than the stock 4-4 for that matter!

I think all of my questions can be answered with the pipes off of a bike if you are willing to spend a few minutes with a ruler. It looks like each side has a clamp arrangement where 1 and 4 are attached to the footpeg and 2 and 3 are attached to 1 and 4 respectively. With the pipes bolted together, if you could measure (doesn't have to be exact) the horizontal and vertical distance from the center of the hole (that the footpeg bolt goes through) to the center of each pipe, that would be awesome.

If you don't know what I mean, please let me know and I'll post a picture.

[Ewan 500K1]

no probs with ground clearance here , yeah they make a racket but can be baffled. Outside diameter on mine (which look idential to cyle X , but dunno where they atually came from) is one and a half inch. Has standard side stand (which hits off the bottom exhaust in the raised position .. but no big deal)

[seanbarney41]

I will try and get those measurements for you in the next couple days.  Yes, ground clearance is really bad with them, even though it doesn't look like it.  The only reason I have them is because they came on a couple running parts bikes I have purchased over the years.  I would ground them just making low speed turns on to side streets and stuff like that.  Sidestand will work but interferes with pipes.  You are going to burn rubber on your boots everytime you kick the side stand.  I found some pics of them mounted here...
http://forums.sohc4.net/index.php?topic=80592.175    ...about halfway down the page.

[Stoli]

no probs with ground clearance here , yeah they make a racket but can be baffled. Outside diameter on mine (which look idential to cyle X , but dunno where they atually come from is one and a half inch.

Thanks! I forgot to mention that the bike is a CB750. The pics from your build are a big help to see where the pipes sit in relation to one another. I just read that the glas-pak inserts that Mac sells for their 69-76 CB750 drags are 1-5/8" so they are a little larger in diameter than the pipes on your 500 but the bend geometry looks to be the same.

[Stoli]

I will try and get those measurements for you in the next couple days.  Yes, ground clearance is really bad with them, even though it doesn't look like it.  The only reason I have them is because they came on a couple running parts bikes I have purchased over the years.  I would ground them just making low speed turns on to side streets and stuff like that.  Sidestand will work but interferes with pipes.  You are going to burn rubber on your boots everytime you kick the side stand.  I found some pics of them mounted here...
http://forums.sohc4.net/index.php?topic=80592.175    ...about halfway down the page.

The 2 and 3 pipes on that bike look to be sitting a lot lower than other pictures I have seen. That would account for the ground clearance problem. Are the brackets bent?

I guess this is going to be harder than I thought because there seems to be a lot of variation in the geometry of these things. For instance, here is a pic of the chromed Mac drags from the cycle x site:



To look at it, you'd think the 2 and 3 pipes sit higher than the 1 and 4

[Stoli]

I don't know if my bracket depiction or pipe relationship in this drawing is accurate, but here are the measurements I was hoping to find from a:

CB750K 69-76 4-4 Drag TT Pipes Slash Cut Exhaust System

[Retro Rocket]

I will try and get those measurements for you in the next couple days.  Yes, ground clearance is really bad with them, even though it doesn't look like it.  The only reason I have them is because they came on a couple running parts bikes I have purchased over the years.  I would ground them just making low speed turns on to side streets and stuff like that.  Sidestand will work but interferes with pipes.  You are going to burn rubber on your boots everytime you kick the side stand.  I found some pics of them mounted here...
http://forums.sohc4.net/index.php?topic=80592.175    ...about halfway down the page.

The 2 and 3 pipes on that bike look to be sitting a lot lower than other pictures I have seen. That would account for the ground clearance problem. Are the brackets bent?

I guess this is going to be harder than I thought because there seems to be a lot of variation in the geometry of these things. For instance, here is a pic of the chromed Mac drags from the cycle x site:



To look at it, you'd think the 2 and 3 pipes sit higher than the 1 and 4

Look at the pipes on the 500, Ewans bike, they sit the same, it looks like they are only sitting straight side by side in the unmounted pic because they are sitting on a flat surface, the pipes on Ewans bike would scrape easily, especially under a competent rider....

[Stoli]

Point taken. Look at the vertical bracket though. If one were to imagine that as perfectly vertical when mounted on a bike, it looks like the outside pipes would actually be higher. I'm sure they are not though. I was just trying to point out one of the reasons for my confusion here. Also, the pic of the chrome pipes is from a 77-78 set. I didn't think that would make a difference at the peg mount but maybe I am wrong.

[jamesb]

Here's the diameter of my pipes outside is 41.3mm inside is 41.2mm. Mine are mounted like your picture. And here is two pictures of mine.  Hope this helps.

[Ewan 500K1]

  the pipes on Ewans bike would scrape easily, especially under a competent rider....

hands up to being fully incompetent rocket, but never bottomed them out in 17 years .. how low can ya go ... . Here's another picture of the 500 / 550 mac ones from CycleX .. all fittings etc look identical to mine. Also a picture of the baffles.

[Stoli]

Thanks Ewan. I enjoyed reading through your build thread. Really nice job with the bike and the documentation. Do you have those baffles installed in your pipes? Didn't see any mention of them in your thread.

I would think that the rider who scrapes his pipes is the incompetent one. Don't you think?   

[Stoli]

Here's the diameter of my pipes outside is 41.3mm inside is 41.2mm. Mine are mounted like your picture. And here is two pictures of mine.  Hope this helps.

Thanks for taking the time to measure and post the pics james. You must have made one of the measurements on a slightly oval spot though. Either that or your pipes are paper thin (.05mm). I would think there would be an 1/8" (3.1mm) difference between the ID and OD. I'm not positive but I think they are 1 5/8" inner and 1 3/4" outer  which would make your inside measurement (41.2mm) accurate.

[thelowmax]

I realize I'm posting months later but I was curious how those drag pipes worked out for you. Did you end up using them? Have you tried the baffles?

[Stoli]

I wound up making my own out of some old K8 headers and some stainless steel tubing:



They are probably very similar in performance to the Macs. I never tried them without baffles. I fitted them up with short baffles like the one pictured in Ewan's post earlier in the thread. They are about what you would expect. A bit loud even with the baffles but it's a nice throaty sound none the less. Tuning wasn't too bad. I don't notice any power loss in the mid range but I haven't put it on a dyno or anything. There is a bit of popping during decel/downshifting which I attribute to the pipes. Popping can also be caused by a lean mixture but my plugs are a nice tan color so I think the mixture is good. The bike idles really well and throttle response is great throughout the range with the exception of a very slight hesitation (sometimes) just off idle when the bike is at speed. It isn't there when accelerating from a stop so I attribute that to the lack of an air box (takes a moment for the carbs to overcome the turbulent air). It is very slight and doesn't bother me but worth mentioning. I have plenty of ground clearance and could drop the bike even lower with no problem. My frame mods lowered the bike 2.5" but the Firestone tires raised it back up an 1" or so compared to Avon Roadriders or something comparable.

My thoughts - I like them on this bike. They have the look I was going for and are "good enough" performance wise. I'd like them more if they were a little quieter. I wouldn't recommend them unless you were putting form ahead of function. I don't think you can beat a good 4-1 system for all around performance.

[thelowmax]

I wound up making my own out of some old K8 headers and some stainless steel tubing:



They are probably very similar in performance to the Macs. I never tried them without baffles. I fitted them up with short baffles like the one pictured in Ewan's post earlier in the thread. They are about what you would expect. A bit loud even with the baffles but it's a nice throaty sound none the less. Tuning wasn't too bad. I don't notice any power loss in the mid range but I haven't put it on a dyno or anything. There is a bit of popping during decel/downshifting which I attribute to the pipes. Popping can also be caused by a lean mixture but my plugs are a nice tan color so I think the mixture is good. The bike idles really well and throttle response is great throughout the range with the exception of a very slight hesitation (sometimes) just off idle when the bike is at speed. It isn't there when accelerating from a stop so I attribute that to the lack of an air box (takes a moment for the carbs to overcome the turbulent air). It is very slight and doesn't bother me but worth mentioning. I have plenty of ground clearance and could drop the bike even lower with no problem. My frame mods lowered the bike 2.5" but the Firestone tires raised it back up an 1" or so compared to Avon Roadriders or something comparable.

My thoughts - I like them on this bike. They have the look I was going for and are "good enough" performance wise. I'd like them more if they were a little quieter. I wouldn't recommend them unless you were putting form ahead of function. I don't think you can beat a good 4-1 system for all around performance.

Did you have to rejet with the baffled drag pipes? (or was that due to the velocity stacks?)

[Stoli]

Did you have to rejet with the baffled drag pipes? (or was that due to the velocity stacks?)

Both. The velocity stacks more so than the pipes, but I can tell from the sound that the drag pipes with the baffles I used are less restrictive than the stock exhaust. I noticed your other post today inquiring about the need to rejet with baffled drags and I would say that it depends on the baffles as some would be more restrictive than others. In the case of the baffles that I used, and probably in most cases, there would be a need for slightly larger main jets and possibly a needle adjustment.  Free flow intake or air cleaners tend to affect everything from idle to wide open throttle where open headers or exhaust with only mild baffling affect the throttle from about 1/3 to wide open throttle. That would mean that if you just changed the exhaust, you shouldn't have to change your slow jets but might consider going up a size or two on the mains. The year/model would also affect things since the later SOHC (77 & 78) were tuned lean from the factory to begin with, so those bikes might benefit from an even bigger jump in size.

[thelowmax]

Did you have to rejet with the baffled drag pipes? (or was that due to the velocity stacks?)

Both. The velocity stacks more so than the pipes, but I can tell from the sound that the drag pipes with the baffles I used are less restrictive than the stock exhaust. I noticed your other post today inquiring about the need to rejet with baffled drags and I would say that it depends on the baffles as some would be more restrictive than others. In the case of the baffles that I used, and probably in most cases, there would be a need for slightly larger main jets and possibly a needle adjustment.  Free flow intake or air cleaners tend to affect everything from idle to wide open throttle where open headers or exhaust with only mild baffling affect the throttle from about 1/3 to wide open throttle. That would mean that if you just changed the exhaust, you shouldn't have to change your slow jets but might consider going up a size or two on the mains. The year/model would also affect things since the later SOHC (77 & 78) were tuned lean from the factory to begin with, so those bikes might benefit from an even bigger jump in size.

I see they also make several size baffles. I just sent a note to MAC, asking what the comparative compression rates are for the drag pipes, with the various baffles. I'll post any info they give me.

[Retro Rocket]

Did you have to rejet with the baffled drag pipes? (or was that due to the velocity stacks?)

Both. The velocity stacks more so than the pipes, but I can tell from the sound that the drag pipes with the baffles I used are less restrictive than the stock exhaust. I noticed your other post today inquiring about the need to rejet with baffled drags and I would say that it depends on the baffles as some would be more restrictive than others. In the case of the baffles that I used, and probably in most cases, there would be a need for slightly larger main jets and possibly a needle adjustment.  Free flow intake or air cleaners tend to affect everything from idle to wide open throttle where open headers or exhaust with only mild baffling affect the throttle from about 1/3 to wide open throttle. That would mean that if you just changed the exhaust, you shouldn't have to change your slow jets but might consider going up a size or two on the mains. The year/model would also affect things since the later SOHC (77 & 78) were tuned lean from the factory to begin with, so those bikes might benefit from an even bigger jump in size.

I see they also make several size baffles. I just sent a note to MAC, asking what the comparative compression rates are for the drag pipes, with the various baffles. I'll post any info they give me.

Mac isn't a performance pipe builder, I seriously doubt they would have any info like that at all...