Topic: Which Exhaust Number is Stock?

[HowardRoark]

This sounds like an easy/common question that would have 2000 posts on it, but I can't seem to find them.  Perhaps the answer could be put into the exhaust FAQ?

Just wondering what's up with with the numbers on the exhausts.  The previous owner included a beautiful set of pristine HM405's with my bike which he said were the stock ones, but my bike is a K5 and I think I've heard that the 405's were stock for the K7 and K8 or something.  I believe I heard that on an ebay posting.  Anyway, I was thinking about either putting them on my bike because they look awesome or selling them on ebay (in which case I have no idea what they're worth).  I like my exhaust OK, but it's incredibly loud and it's going to piss off my neighbors this summer...

So, anyone want to give a little quick history with the numbers?  Are mine worthless?

[jsaab2748]

Correct code for the 750 k5 pipes is 341. Not sure if the others will fit or not. Anyone?....

[Clyde]

The 405 is the model number for the 77 and 78 k CB750.
I have seen a set of 77K pipes on a 76K bike, but did not pay much attention to them.
Problems I see are that, firstly you would have to remove the exhaust spigots that bolt into the head on the 69-76 K models. The heads are the same but you will need to find the later exhaust clamps and half pieces that hold the pipes in. Unless your bike, having a non-standard exhaust, has been changed already.
The early mufflers (stock) slip on over a spigot and use a clamp to hold them in place. The F/F1 and later SOHC 750 models (also the DOHC 750 and 900) use a clamp that bolts the exhaust direct to the head. The parts are not hard to find.
The other problem is that I do not know whether the bracket fits to the early frame. You may have to make something up to support the exhausts at the rear.
Others may be able to help more
Regds Clyde

[SteveD CB500F]

Sell the 405's on eBay and see if you can get some 3412s.  A bit of research should give the values.

If you don't need/want 4-4 and just want "quieter", then look for a Motad 4-1 or similar.

[HowardRoark]

Thanks for the info, guys.  I do like my exhaust, but it's loud and backfires a bunch - which makes it hard for me to sneak up on unsuspecting women.  Amazing how fast they can run away when they see me coming 

[GroovieGhoulie]

Reportedly, Honda stopped making factory replacements for the 77-78K 4-into-4.  If they're in good shape, they could fetch a pretty penny!

I'd get some 341s from David Silver.  Factory correct for your year.

[SteveD CB500F]

Well you certainly can't get the 404s any more (they are the 550K3 variant) - even DSS doesn't have a set.

If they are in good nick they may be worth a lot to a rebuilder.