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Discussion Starter · #1 ·
Hello everyone,

I own a 1970 cb350 twin and the previous owner fit it with a 2-1 exhaust that unfortunately covers the oil drain plug. When I was disassembling the exhaust manifold/collar assembly to access the drain plug, I must have not been paying close enough attention (I know, rookie mistake) and now as I'm reassembling it, I'm noticing that the pipe joint collars (#2 on diagram below) are different sizes. I have four collars in total - two for each pipe - and two of them are shorter than the other two, so I have a pair of longer collars and a pair of shorter collars. The difference is about 1/8th of an inch.
Gesture Art Font Auto part Circle


The collars within each pair are the exact same size, so it seems like something that would come stock...?? If so, which cylinder do the shorter ones go on and which do the longer ones go on, or are they each supposed to have a long one and a short one?

I can upload pictures of my actual collars tomorrow once I disassemble the exhaust again.

Any input helps!
 

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The two per cylinder should absolutely be the same size, no doubt. Don't mix sizes.

As to which tube gets the longer vs shorter, you'll just have to play around with them. Hell, it may not make any difference, to tell you the truth. You'll probably just wind up screwing the nuts down that 1/8" more on the short ones.
 

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Discussion Starter · #3 ·
The two per cylinder should absolutely be the same size, no doubt. Don't mix sizes.

As to which tube gets the longer vs shorter, you'll just have to play around with them. Hell, it may not make any difference, to tell you the truth. You'll probably just wind up screwing the nuts down that 1/8" more on the short ones.
Thank you
 

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If the header pipe has a thin flange on the end, you use the long collars. If the header pipe has a thick ring on the end, you use the short collars. If the pipe you have was installed with two different length collars, something has been rigged. Both header pipes should use the same length collars. Stock 350 headers used longer collars the first few years, and shorter ones the last few years, due to the change in the end flange to keep it from breaking.
 

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There are indeed two types. One is the long early type and the other newer shorter type. First type mufflers had a more narrow formed lip on the exhaust. Late type has a fat ring welded on.
 
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