Topic: Will diffusers from HM300 pipes fit in HM341 pipes (CB750)??

[markb]

I've got a decent set of HM341 pipes that I'd like to run on my K0 until I can afford to buy a set of new HM300's.  Anyone know if the K0 diffusers will fit the 341 pipes??  What differences are there in the pipes?
Thanks,
Mark

[JLeather]

Nope, the HM300 diffusers are larger (and so is the opening in the end of the pipe).  That's why they sound so cool.  The HM341s are a smaller diffuser and are quieter.

[736cc]

  If you are very brave and like to hop things-up, remove the 341 caps, get a loooong 3/8" drill bit and drill a bunch of holes inside the pipes. Leave the caps off or hacksaw them to open-up the tiny outlet. They will sound and breath like 300 pipes. And you will be officially a hack.

[markb]

What if I run the 341's without the diffusers, would they breath about the same as the 300's with diffusers.  I'm wanting to run standard plugs and carb setup until I can get the real thing.

[Jonesy]

Removing the diffusers from HM341's might improve the sound a little, but the HEm341's have baffling welded in place inside. The HM300's were open expansion chambers with glass-packed tips- quite a difference in construction (and performance!).

[Terry in Australia]

I love my HM300's............... 

[cafe750]

What if I run the 341's without the diffusers, would they breath about the same as the 300's with diffusers.  I'm wanting to run standard plugs and carb setup until I can get the real thing.

You can run the 341's without diffusers, and its loud, with a sound similar to the 300's, but much "tinnier". The 300's that I have replaced my diffuser-less 341's with, perform better, and have a much "tighter" sound, and thats with the 300's diffuser in. I too Love my HM300's... . Hope this helps a bit...

[andy750]

I love my HM300's............... 

+1  (and I also have HM341s - completely different sound)

I just replaced the baffles on the HM300s (well 2 of them at least) and wow what a difference in sound! Is this normal? Do new baffles really make that much difference? Should I replace the other 2!? Sounds much throatier now, love it! Of course I did change the pipes from the CB750K4 to the K2 but didnt think this should affect the sound......

good luck in getting the HM300s....

Cheers
Andy

[736cc]

  Remove the HM300 baffles and hacksaw-off the inboard-ends and chuck the cloth while you're at it. Replace the baffles (diffusers). Now we're making the perfect tone, something between HM300 w/ and w/o baffles.

[Jonesy]

I just installed brand-new HM-300's on my 750... Now I REALLY have spring fever!!!

[markb]

Thanks for all the great replies.  Looks like I might have to bite the bullet and by the 300's.  It's the right thing to do.

[Jonesy]

  Remove the HM300 baffles and hacksaw-off the inboard-ends and chuck the cloth while you're at it. Replace the baffles (diffusers). Now we're making the perfect tone, something between HM300 w/ and w/o baffles.

I finally got to take mine for a very brief and chilly ride today, and I see what you mean. The 341's sound "tinny" as someone described, while the 300's sound sort of "nasal" (best word I can describe it with). I might try your approach...

[andy750]

  Remove the HM300 baffles and hacksaw-off the inboard-ends and chuck the cloth while you're at it. Replace the baffles (diffusers). Now we're making the perfect tone, something between HM300 w/ and w/o baffles.

I finally got to take mine for a very brief and chilly ride today, and I see what you mean. The 341's sound "tinny" as someone described, while the 300's sound sort of "nasal" (best word I can describe it with). I might try your approach...

Agree Jonesy! Im going to try and get some video of the HM300s this weekend.....and post it on here...my HM341/K4 bike is not re-assembled yet so comparison for me at least will have to wait.

[andy750]

Here is a movie I took yesterday after riding home...little bit of camchain noise that needs to be adjusted but you get the idea with the pipes when throttle is turned...sorry i was doing to myself so filming/throttle is a bit off....upper 2 baffles are new....

http://s141.photobucket.com/albums/r58/andy750/?action=view&current=P1090240.flv


cheers
Andy