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Discussion Starter · #1 ·
Hi,

My first post; my first bike. :)

I have a 1981 cx500d and I just replaced the stock exhaust system with the Mac 2 into 1, in black. I did not rejet the carbs and am using the stock air filter (not pods).

Everything seems to be running normally with the new system - no leaks, no black smoke. However I noticed after I took the bike out for a short ride, the finish on the headers had dulled and the right header had some very mild raised bumps at the bend.

My question is - is this normal? Or is it a symptom of not rejetting the carbs? (Or something else?)

Any advice would be appreciated.

David
 

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I've been running a Mac on my 500C since I got it {7 years or so, it was on it when I got it}

The bike also has the stock airbox.

I rebuild carbs and often run them on this bike. It tolerates all jetting from standard up to about 85/118. Above this it gets too rich. Stock jets seem fine though. The bike is happiest on 80/118.
 

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Discussion Starter · #4 ·
If it's gold, you should be fine.
If it's blue, you are running too lean.

Mac's almost always require a re jet.
Hi Timothy -

The finish on this Mac exhaust is black - I can't tell if the discoloration is gold or blue.

See pictures below for reference.

David

Auto part Automotive exhaust Exhaust system Muffler Suspension part
Auto part Automotive exhaust Vehicle Exhaust system Tire
 

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Did you buy that directly from Mac or a business, or is this a private party transaction?
That looks like paint bubbling to me.
 

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Discussion Starter · #6 ·
Did you buy that directly from Mac or a business, or is this a private party transaction?
That looks like paint bubbling to me.
That's a good call. I purchased it from Niche Cycles, which appears to be a reputable supplier, but maybe a follow up call to Mac is in order.

David
 

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Discussion Starter · #7 ·
Did you buy that directly from Mac or a business, or is this a private party transaction?
That looks like paint bubbling to me.
Timothy - you're spot on. Talked to Mac and it's likely contamination in the paint. Thanks for the help!

David
 

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Hi,

My first post; my first bike. :)

I have a 1981 cx500d and I just replaced the stock exhaust system with the Mac 2 into 1, in black. I did not rejet the carbs and am using the stock air filter (not pods).

Everything seems to be running normally with the new system - no leaks, no black smoke. However I noticed after I took the bike out for a short ride, the finish on the headers had dulled and the right header had some very mild raised bumps at the bend.

My question is - is this normal? Or is it a symptom of not rejetting the carbs? (Or something else?)

Any advice would be appreciated.

David
I installed the chrome Mac on my 80C with stock airbox and factory jetting (78/112) Top 8 inches of pipes turned blue immediately within the first 50 miles.

I re-jetted to 85/118, the blue is still there but with a golden hue. Its now been close to 2 years and plugs look great. I would recommend that anyone running a Mac 2-1 use the 85/118 jets.

BTW. My 80c "Blue thing" is by far the quickest/fastest of all 3 of my cx/gl bikes. It's pull through the 6000-8000 RPM range puts a smile on my face every time I ride it.
 

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I installed the chrome Mac on my 80C with stock airbox and factory jetting (78/112) Top 8 inches of pipes turned blue immediately within the first 50 miles.

I re-jetted to 85/118, the blue is still there but with a golden hue. Its now been close to 2 years and plugs look great. I would recommend that anyone running a Mac 2-1 use the 85/115 jets.

BTW. My 80c "Blue thing" is by far the quickest/fastest of all 3 of my cx/gl bikes. It's pull through the 6000-8000 RPM range puts a smile on my face every time I ride it.
Considering rejet, are you using 85/115 or 85/118? thinking there is a typo going on there.
 

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yes there was a typo ... fixed
 
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