Topic: Exhaust 4into 2 and 4 into 4 Which years will fit my 76 CB750K-6?

[Aerobhoy]

As above i would like to find a good used exhaust for my 76 750K-6  And looking on e,bay there seems to be a lot of choices, will a HMH25 Fit my bike? can someone tell me which years are interchangable i want to stick to the 4x2 or even 4x4

thanx in advance
jimmy O

[jaknight]

Well Aerobhoy,

If you want the factory 4 into 4, the HM341-900 series was used for quite a few years, yours had those as standard issue, if you will.

You can even use the original HM300 series, which was on the first 1969 models.  The only difference was the way they were baffled internally and the "muffler" material used at the very end of the exhaust pipe.  The '69's were given a deeper, "throatier" sound by their baffle system and final fiberglass wrap at the end of the pipe (Honda knew the public would go for that sound).

The thing is, you will pay a lot more for the HM300 series than what you will pay for the HM341 series.  And, theoretically, you would have to replace the fiberglass wrap in the HM300 series a lot more often.

If you like the deep throat (ha ha) sound of the 300 series better, you can do modifications to the HM341 series and change its tone to suit you better.  Believe me, the HM341 series is expensive enough........ never mind the HM300 series.

Bottom line, from '69 up to yours, they can all be made to fit......
will fit without doing anything, just bolt up.....

~ ~ ~ jaknight ~ ~ ~

[cookindaddy]

Hi there.
I don't need a new exhaust for my 78 750 K8 yet, but I am interested in your message.
What/whose model/part numbers are you quoting (HM341-900, HM300)?
Thanks
George

[Mach-5(50)]

I would presume it is the numbers stamped on the exhaust itself. This is from one of the 4 on my 76 Cb550. I just happened to take this yesterday, as I am trying to trade mine off.

[cookindaddy]

OK thanks. I don't have the original 4 on mine but some sort of after market 4 into 1 so I haven't seen those numbers on mine.

I haven't asked at Honda: are new sets of the original pipes still available? They must be expensive.

George

[jaknight]

Hi there cookindaddy,

The new pipes for your bike are still available.  And, yes, they are expensive, all the Honda series pipes are.

From what I see the pipe series for your bike are 18300-405, 18350-405, 18400-405, and 18450-405.  Then of course, there is an additional number on the end of each pipe's number, like say (this is just an example, I don't know the actual number) 18300-405-009*........ the -009 bit could be whatever.

But, the 18300-405 and 18350-405 and the other samples are correct designations for your pipes........ I just don't know the final number designations.

From what I understand, your bike has a wheel base length that is one and a half inches longer than the earlier K model 750 series.  One half inch is in where the front wheel axle is located, the other inch is in where the rear axle is located (this is in relation to the swingarm, more or less just behind your front foot peg).  In order to deal with this greater length, Honda had to change the exhaust/muffler design.  Hence, different mufflers, different part numbers.

There are several OEM suppliers on the internet that have exploded parts diagrams so that you can look these things up.  In the FAQ section here they have listings for some of them.  One is at ServiceHonda.com....... but you may have to install a plug-in from them so that you can view the drawings.  I hope this helps you out, looking at the drawings is great for just "browsing" things.

~ ~ ~ jaknight ~ ~ ~

[GammaFlat]

Here's what you'll find on a 77 or 78.  They mount differently in the rear than an HM341 or HM300.  The way they attach to the head is different but they are interchangeable by switching studs for spigots or vice versa. 

[jaknight]

Yes,

The original poster, aerobhoy has a '76 and either the HM300 series or the HM341 series will fit, with the proper gaskets and all the proper retainers at the cylinder head..... the rest for you aerobhoy is a simple bolt up match.

And for you cookindaddy, having a '78, the HM300 series and the HM341 series will not match up to bolt holes in the bike's frame.  I thought I had made it clear that you will have to use the 405 series of pipes.  The actual numbers and the prices listed at ServiceHonda are:

18300-405-777 --------> $180.03
18350-405-777 --------> $169.89
18400-405-777 --------> $130.01
18450-405-777 --------> $131.96

I originally posted the almost full numbers to give you cookindaddy a heads up start if you wanted to look up the pipes to see what it would cost you.

For the factory Honda pipes you are going to pay about $611 smackers.  Plus, you will need new gaskets and then whatever retaining hardware for attaching to the cylinder head.  That all depends on what you want to do there.

In a manner of speaking, feel fortunate;...... guys like me who want to use the 341 series or even the 300 series are going to fork out $850 to over $1,000 smackers for new Honda stock pipes.

I would rather have Honda factory pipes over anything on the market, it doesn't have to do with performance, it's a cosmetics thing....... nothing looks right to me on a Honda 750 except its factory pipes, but then, I like "classic" motorcycle appearance........

~ ~ ~ jaknight ~ ~ ~