Topic: Mac Exhaust Header Fitting Question

[cshanek]

So I got my new MAC 4 into 1 sidewinder exhaust (#901-1401) in, and spend the day polishing, cleaning, and painting so I could install them tonight. Everything was ready and good to go and when I got the headers and gaskets positioned and in place, I notice that the flange fittings are about 3/4" longer than my OEM flanges (see pic). The bolts they sent to install the headers are sufficiently long, so I can install them but the flanges will not be flush to the block. This can't be right ... right? I am assuming they sent me the wrong pipes. I was also surprised that I could not possibly get the old heat sink collars on since the header was one piece.

[Medyo Bastos]

Do the stock flanges slide inside the headers?


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[cshanek]

They slide over a header sleeve, and under the outer header rim, which is tightened by the collars. Here are a couple of pics of the OEM setup.

[Medyo Bastos]

Do they fit inside the Mac headers?


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[cshanek]

They do not, and if they did I would have two flanges per pipe because the header I bought are all one piece (flanges are not removable).

[ekpent]

 The flanges on the MAC  won't fit tight to the cylinder block, they will stand off a distance from it as I have seen on some other aftermarket headers. Look for some pictures of them mounted on other bikes or contact the company to be sure but I think that is just how they are.

[cshanek]

Interesting ... I suppose they do that for cost and compatibility. I did just see a couple of pics with flanges mounted with 1/2"+ gaps.

[curtisound]

I just installed a set of these on my 750K4 because the buckets of parts that came with my basket case didn't include the OEM flanges and I didn't want to spend the money to buy a new set of flanges on top of a full exhaust system. I recommend test running all the bolts into the head before installing to insure the tension you are feeling as you draw the pipes against that gaskets are you actually crushing the gaskets and not stripping out your heads. Also, the pipes are not likely to line up perfectly and will require some inward compression to get them to center on the gaskets. I used a couple of carpentry clamps to squeeze 1&2 and 3&4 together a little while tightening down.

[cshanek]

Thanks for the pointers, I got them on a few days ago, have not tested for exhaust leaks.

[curtisound]

Same ones I installed. Looks great! I made the mistake when attaching the muffler clamp of not aligning the adjuster bolt on the clamp with one of the slits on the muffler. I ended up buckling the muffler flange instead of compressing it which caused a leak. I pulled the muffler, tapped out the buckle, and aligned it all properly before re tightening the clamp and now it's all good. 

[cshanek]

Yeah I would be money I am going to have a leak, though kind of cool that this system is just 2 pieces. Even the exhaust flanges are part of the headers. I found it for %30 off so had to pull the trigger.