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

[Stoli]

Retro is right. I doubt you will get anything useful from Mac but doesn't hurt to ask. Even if they did give you something, the conclusion would be that you need to up your main jet size but the exact amount can only be determined by trial and error, plug chops, etc.

[SOHC]

Sorry I have to point this out it has been bothering me for awhile.

Why is it when people ask about a non-stock-ish part, people post just about every reason why u shouldnt use them or buy them, oh they scrape, oh they are loud, oh they need etc etc etc.
i understand you are trying to inform the person....but as u read on, it seems like if he bought these pipes, his wife will leave him for a harley guy, the dog will shoot himself, and the neighbors will turn into zombies.....

It just seems like informing someone, of the negatives of parts could be more constructive.
I understand the purists view, but these are mass produced japanese bikes, besides certain model bikes, these arent pulling down retire early money, most are purchased for far under and around $2K, and they are a great platform for cheap, cool, and practical builds to make the bike fit your style, not u fitting the bikes style.

[Retro Rocket]

Sorry I have to point this out it has been bothering me for awhile.

Why is it when people ask about a non-stock-ish part, people post just about every reason why u shouldnt use them or buy them, oh they scrape, oh they are loud, oh they need etc etc etc.
i understand you are trying to inform the person....but as u read on, it seems like if he bought these pipes, his wife will leave him for a harley guy, the dog will shoot himself, and the neighbors will turn into zombies.....

It just seems like informing someone, of the negatives of parts could be more constructive.

I don't understand your post, you just completely contradicted yourself...?  I would suggest that if i were told that they scrape easily, will give problems tuning or are too loud that that would be negatives to a lot of people...?  Don't you think informing someone of their negatives or potential problems is exactly whats been done...?   Some people will obviously benefit from constructive criticism as well don't you think..  I'm far from a purist mate...

[seanbarney41]

Sorry I have to point this out it has been bothering me for awhile.

Why is it when people ask about a non-stock-ish part, people post just about every reason why u shouldnt use them or buy them, oh they scrape, oh they are loud, oh they need etc etc etc.
i understand you are trying to inform the person....but as u read on, it seems like if he bought these pipes, his wife will leave him for a harley guy, the dog will shoot himself, and the neighbors will turn into zombies.....

It just seems like informing someone, of the negatives of parts could be more constructive.
I understand the purists view, but these are mass produced japanese bikes, besides certain model bikes, these arent pulling down retire early money, most are purchased for far under and around $2K, and they are a great platform for cheap, cool, and practical builds to make the bike fit your style, not u fitting the bikes style.

Dude, I like to modify stuff just as much as anyone else.  The thing is though, I don't really care what my bike "looks" like.  I try to modify my stuff to work better.  Why?...cuz I actually enjoy riding these old bikes and actually put tens of thousands of miles on them a season.  It seems logical that the great enjoyment I get from them, might be available to others?  So when someone here asks about a part that I know is less effective than the stock part, or even another aftermarket alternative, why would I not tell them about it?  Remember when you asked your dad something and you didn't like the answer?  Like didn't get ya very far, did it...

[Retro Rocket]

The problem is Sean, some people take any advice as criticism, then get all defensive or worse, remember Fenders, he was a victim of his own stupidity...

[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.

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

Maybe they aren't performance oriented, but they have good customer service. Here's my letter and their reply.

Hi, I am thinking of replacing the stock 4 into 4 pipes on my 78 Honda CB750K with these drag pipes.

http://shop.macperformance.com/MAC-Honda-CB-750-K-77-78-Chrome-Slash-Cut-TT-Drag-pipes-001-1506.htm?categoryId=-1

My concern is their effect on performance and requirements of rejetting, tuning, etc.. Can you tell me anything about the glass pac inserts in regard to comparative compression? What length would you recommend to replicate, as closely as possible, the stock pipes? Your input is greatly appreciated.

A

Hi A,

If you are not looking at doing any jetting and trying to stay at the stock Back Pressure levels, "Do not order the Drags". In order to keep the stock compression as you stated it you would need to run like 5-6 glass pak in each tube and there is not that much room in the head pipe for that. If you are looking at trying to stay with the stock jets it would be better off with a 4 into 2 and not the Drags. Other qise with the Drags installed you will need to ReJet the Carbs. If you have any other questions feel free to let me know.

Mac


I certainly listen a little more intently when a company tries to dissuade you from buying one thing and points you in the direction of a cheaper item.

[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...

Maybe they aren't performance oriented, but they have good customer service. Here's my letter and their reply.

Hi, I am thinking of replacing the stock 4 into 4 pipes on my 78 Honda CB750K with these drag pipes.

http://shop.macperformance.com/MAC-Honda-CB-750-K-77-78-Chrome-Slash-Cut-TT-Drag-pipes-001-1506.htm?categoryId=-1

My concern is their effect on performance and requirements of rejetting, tuning, etc.. Can you tell me anything about the glass pac inserts in regard to comparative compression? What length would you recommend to replicate, as closely as possible, the stock pipes? Your input is greatly appreciated.

A

Hi A,

If you are not looking at doing any jetting and trying to stay at the stock Back Pressure levels, "Do not order the Drags". In order to keep the stock compression as you stated it you would need to run like 5-6 glass pak in each tube and there is not that much room in the head pipe for that. If you are looking at trying to stay with the stock jets it would be better off with a 4 into 2 and not the Drags. Other qise with the Drags installed you will need to ReJet the Carbs. If you have any other questions feel free to let me know.

Mac


I certainly listen a little more intently when a company tries to dissuade you from buying one thing and points you in the direction of a cheaper item.

 They didn't necessarily point you to a cheaper item, they pointed you to an item that gave you more chance of getting the result you are after, the fact that it may be cheaper is an added bonus. I knew with absolute certainty they wouldn't be able to answer your question, actually, after seeing your question, its virtually impossible to answer without a dyno and a lot of testing and the results would still be no where near stock. Exhaust theory tells you that those pipes aren't a performance add on, in fact the complete opposite, the length of the header pipes is critical to performance, as is every other part of a good pipe . I didn't dispute their customer service,  their advice was good . This is why I get annoyed when people post things like

"people post just about every reason why u shouldn't use them or buy them, oh they scrape, oh they are loud, oh they need etc etc etc."

,  Some of this is the very information you needed,  I find it funny, these forums are a wealth of information, i'd rather weigh up everything said and make up my own mind, or if i didn't know, do what you did and call the manufacturer, screw wasting time and money  making stupid mistakes I'm to old for that sh1t...

[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.

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

Maybe they aren't performance oriented, but they have good customer service. Here's my letter and their reply.

Hi, I am thinking of replacing the stock 4 into 4 pipes on my 78 Honda CB750K with these drag pipes.

http://shop.macperformance.com/MAC-Honda-CB-750-K-77-78-Chrome-Slash-Cut-TT-Drag-pipes-001-1506.htm?categoryId=-1

My concern is their effect on performance and requirements of rejetting, tuning, etc.. Can you tell me anything about the glass pac inserts in regard to comparative compression? What length would you recommend to replicate, as closely as possible, the stock pipes? Your input is greatly appreciated.

A

Hi A,

If you are not looking at doing any jetting and trying to stay at the stock Back Pressure levels, "Do not order the Drags". In order to keep the stock compression as you stated it you would need to run like 5-6 glass pak in each tube and there is not that much room in the head pipe for that. If you are looking at trying to stay with the stock jets it would be better off with a 4 into 2 and not the Drags. Other qise with the Drags installed you will need to ReJet the Carbs. If you have any other questions feel free to let me know.

Mac


I certainly listen a little more intently when a company tries to dissuade you from buying one thing and points you in the direction of a cheaper item.

 They didn't necessarily point you to a cheaper item, they pointed you to an item that gave you more chance of getting the result you are after, the fact that it may be cheaper is an added bonus. I knew with absolute certainty they wouldn't be able to answer your question, actually, after seeing your question, its virtually impossible to answer without a dyno and a lot of testing and the results would still be no where near stock. Exhaust theory tells you that those pipes aren't a performance add on, in fact the complete opposite, the length of the header pipes is critical to performance, as is every other part of a good pipe . I didn't dispute their customer service,  their advice was good . This is why I get annoyed when people post things like

"people post just about every reason why u shouldn't use them or buy them, oh they scrape, oh they are loud, oh they need etc etc etc."

,  Some of this is the very information you needed,  I find it funny, these forums are a wealth of information, i'd rather weigh up everything said and make up my own mind, or if i didn't know, do what you did and call the manufacturer, screw wasting time and money  making stupid mistakes I'm to old for that sh1t...

Even with all the pertinent information, there's no guarantee I won't screw it up.

[bcscotty]

I have them on my bike now. Loud and pop a lot. Thinking about going 4-1 or 4-2. Only plus side is I can tell when a carb gets dirty or plug is bad

[thelowmax]

I have them on my bike now. Loud and pop a lot. Thinking about going 4-1 or 4-2. Only plus side is I can tell when a carb gets dirty or plug is bad

Do you have the baffles? What size? Air box/pods/velocity stacks? And the big one, did you rejet?

Ultimately, this is for an Amen savior/cb750 chopper, so I'm leaning more on the style versus performance. I just hate the whole jetting process.

[seanbarney41]

I have them on my bike now. Loud and pop a lot. Thinking about going 4-1 or 4-2. Only plus side is I can tell when a carb gets dirty or plug is bad

Do you have the baffles? What size? Air box/pods/velocity stacks? And the big one, did you rejet?

Ultimately, this is for an Amen savior/cb750 chopper, so I'm leaning more on the style versus performance. There's such a fine line between cool and stupid. I just hate the whole jetting process.

on a chopper? what's the big deal?  it's gonna be loud stupid fun.  Not that hard to swap main jets until it runs ok at full throttle.  Sputters some on the over run?  Just adds to the appeal.