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Author Topic: HM300 on a K4?  (Read 1134 times)

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stretch

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HM300 on a K4?
« on: February 12, 2009, 01:37:42 PM »
I've got a CB750K4 which currently has the original HM341 exhaust system, and the exhaust is due for replacement soon.  I had planned to save up and buy a new HM341 replacement system, but I'm wondering how practical it would be to instead put on a HM300.

Is this something that would just fit on without any modifications, and would it be worthwhile?  I'm assuming it would sound better, and maybe give a bit more performance.

(Post edited to reflect that I meant to say HM300, not HM340!)
« Last Edit: February 12, 2009, 03:25:44 PM by stretch »
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Offline Duke McDukiedook

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Re: HM340 on a K4?
« Reply #1 on: February 12, 2009, 02:07:54 PM »
If you are spending the money why not go for the HM300's? You can still get them when I checked last, they are expensive though  :o
I would like to when I hit the lotto  :D
I think they should fit fine, with no problems.

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stretch

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Re: HM340 on a K4?
« Reply #2 on: February 12, 2009, 03:25:00 PM »
Quote from: Dukiedook on February 12, 2009, 02:07:54 PM
If you are spending the money why not go for the HM300's?

D'oh!  That's what I meant, HM300.  I think I need more coffee!
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Offline hoodellyhoo

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Re: HM300 on a K4?
« Reply #3 on: February 12, 2009, 05:44:00 PM »
I think a fellow named "Jonsey" did it on his later 750 just fine.
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Offline dpender836

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Re: HM300 on a K4?
« Reply #4 on: February 12, 2009, 06:01:03 PM »
I'm glad you asked this question, I was actually thinking of putting the HM300 pipes on a K2, We need all you CB750 experts to voice your opinion, is this politically incorrect or a big NO-NO or is it done all the time?  I also have been told they sound and perform better,is that true? looking forward to your answers. Thanks
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Offline Johnie

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Re: HM300 on a K4?
« Reply #5 on: February 12, 2009, 06:16:19 PM »
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stretch

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Re: HM300 on a K4?
« Reply #6 on: February 12, 2009, 07:16:23 PM »
Quote from: Johnie on February 12, 2009, 06:16:19 PM
Check this out...
http://forums.sohc4.net/index.php?topic=45301.msg473654#msg473654
Good info for you..

Thanks for that.  Sounds like it was a straightforward swapover on his K3, so I assume it'd be the same for my K4.

I'm trying to keep my K4 nice and original, so putting HM300's on it would be a bit of a departure from that theme.  But the idea of a throatier exhaust has an irresistable appeal.  If I ever won the lottery I'd buy both sets NOS and change between them as the mood takes me :)
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Offline Jonesy

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Re: HM300 on a K4?
« Reply #7 on: February 12, 2009, 07:23:00 PM »
Quote from: hoodellyhoo on February 12, 2009, 05:44:00 PM
I think a fellow named "Jonsey" did it on his later 750 just fine.

Why, yes.. I did!  ;D

Quote from: stretch on February 12, 2009, 01:37:42 PM
Is this something that would just fit on without any modifications, and would it be worthwhile?  I'm assuming it would sound better, and maybe give a bit more performance.

The only mod is you'll have to re-jet. My K3 with the stock 341's was running the specified 105 mains. Now with the 300's I had to install 115 mains. I left the jet needle in the 3rd position and the bike runs great. The sparkplugs (NipponDenso X24ES-U) have a nice tan color to them.

The 300's flow better (the small glass-pack baffle is the only thing in the way of it being an open megaphone) and have a throatier tone. Still civilized at idle and cruising speeds, but make a pleasant growl when the throttle is opened!

As for worthwhile, I would say so. Granted, my bike also has a 17-tooth front sprocket, baffles removed from the airbox, etc. so the setup is more like an earlier CB750. But, they sure sound nice!
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stretch

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Re: HM300 on a K4?
« Reply #8 on: February 12, 2009, 08:16:39 PM »
Thanks for that Jonesy, that's excellent info.
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Offline cafe750

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Re: HM300 on a K4?
« Reply #9 on: February 13, 2009, 06:19:52 AM »
If you're going to spring for new pipes, buy the HM300's. The sound makes 'em worth every penny. They sound awesome on my K3.
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