Topic: Cb750 K6 4into4 to K7

[xhevi]

CB750
I have a usable complete set of HM341 that I want to install on a K7.

I need the spigots, countersink screws, header clamps.
I have posted on "wanted" section but no luck so far. Likely not much traffic there.

Any of you that swapped from 4into4 to 4into1 and has no use of spigots and clamps and wants to sell?

I know I would also need to make a bracket to hang the pipes from the rear foot pegs.

Thanks.

[PeWe]

Why not sell or trade for K7 pipes?

[xhevi]

Why not sell or trade for K7 pipes?

Rather keep the K6 pipes.

I also have a K6 that's needs a total tear down and rebuilt. But that's not gonna happen for a while.

The K7 it's almost complete and initially I was going to install F header on but I am missing the muffler and like the 4 into 4.
 

[PeWe]

https://www.cmsnl.com/products/muffler-assy-cb750k7-non-oe-alternative_01800405781/?locale=en-se&utm_source=shopping&utm_medium=organic&gclid=EAIaIQobChMI-b22puPL-QIVLe7mCh2ePgiyEAQYAiABEgL0a_D_BwE

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_308344/

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_42964/

[xhevi]

https://www.cmsnl.com/products/muffler-assy-cb750k7-non-oe-alternative_01800405781/?locale=en-se&utm_source=shopping&utm_medium=organic&gclid=EAIaIQobChMI-b22puPL-QIVLe7mCh2ePgiyEAQYAiABEgL0a_D_BwE

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_308344/

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_42964/

Appreciate the links.

New pipes are not within my budget.

[PeWe]

https://www.cmsnl.com/products/muffler-assy-cb750k7-non-oe-alternative_01800405781/?locale=en-se&utm_source=shopping&utm_medium=organic&gclid=EAIaIQobChMI-b22puPL-QIVLe7mCh2ePgiyEAQYAiABEgL0a_D_BwE

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_308344/

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_42964/

Appreciate the links.

New pipes are not within my budget.

Exactly what I told myself about Yamiya750's no numbers 4-4 and their new tank sets some years ago.

I suddenly changed my mind and I could squeeze some money. Yen currency rate OK too.

Restore these CB's can make us to open the wallet a little bit too much.

[bryanj]

Not so much open it as empty it and throw it away

[xhevi]

Not so much open it as empty it and throw it away

Digging into the coin jar.
And I am not even trying to restore it to stock.

[beemerbum]

Why not sell or trade for K7 pipes?

The K7-8 pipes are super heavy and ugly as well

[xhevi]

What are the differences between K5 and K6 HM341?

Parts fiche has different part numbers for each and shows those are not compatible.

Additionally the diffusers at end of each pipe are shown to be removable for K5 but not K6. That's part # 18311341300 on K5 fiche.
 
I removed the rusted diffuser on the K6 mufflers and looks like  I can use the K5 diffusers.

Anyone has first hand experience on these? Better/cheaper options out the there?


https://www.cmsnl.com/honda-cb750k5-four-1975-usa_model483/pipeexhaust_18311341300/

[PeWe]

Hondaman has explained how the 4-4 developed during the years becoming more restrictive due to EPA.

There is a thread about it somewhere.

[MauiK3]

The no number pipes are pretty heavy, I can imagine the baffle packed 341's are even heavier.
I love my Yamiya No-number pipes.

Best sound on the planet. (for a motorcycle)

[PeWe]

I fully agree!
Yamiya no numbers have a really nice sound. Work well too.
Remove the "wool" around the diffursers.

[xhevi]

Ok I got convinced, I will get Yamiya no numbers.... (when I hit the jackpot

Until then ..How do I bring this old pipes back to life?

[Don R]

https://www.davidsilverspares.com/CB750K7-FOUR-1977/part_308344/

 Why can't any no number pipes be this cheap? Even seconds.

[xhevi]

Here we go again with new pipes. Lol.🤔

I haven't hit the jackpot yet!!

I need advice on parts.

[PeWe]

Check how much Yamiya's Lotus Root 4-4 costed when they had them. The No Numbers are cheap when comparing.
New Kerker is not cheap either. Dynoman's homepage if still there.

A good priced new exhaust is Delkevic 4-1.

If your HM341 looks good, make sure to not damage them.
That system is worth some for stock builders when the original printed HM341 on pipes is part of the exact stock build.

The No Numbers is just a much better exhaust, but not for exact stock builds.

If your HM341 pipes are in very good condition, you might trade it for a new No Numbers if finding a stock restorer.

Modify your frame bolting brackets that fits the HM341 will take efforts and money.
Maybe not hidden behind the exhaust either. 

See your K6 rear triangle part of the frame. K7 much shorter.
Passenger footpegs sit in the rear bolt holding the pipes.
Should cope with a passenger standing on them.

Better if you focus on your K6 with those pipes.

[xhevi]

All very good points.

However. The K6 is likely the one I wanna keep, if and when I find the time and money to work on it. But with the new home and other things it will take a couple of years. The HM341s are usable, not showroom condition. There is some decent pitting of the chrome, but no holes or dents. The diffusers were rusted through so I need to replace. I still need to get my boroscope out and try to look into the pipes.

Meanwhile the K7 is almost done, engine, carbs, frame, controls, wheels, electric etc. What's missing on the K7 is the exhaust, chain and other little bits and pieces. Oh and tuning.

So I am thinking to enjoy the K7 then swap the pipes back to K6 if and when done.

K7 is not a full resto and is a solo bike, no passenger to need the  foot pegs. I dislike the tank and the seat shapes of the K7. So I am also looking into swapping the tank with K6 and modify a K7 fiberglass seat pan that I already have to move the seat forward to avoid the gap where it meets the seat.

At the same time I also have a 4-1 F header that only needs a muffler. The only muffler that I might be interested is the 18" Cone quiet core, but don't like the looks of it and I think the K6 pipes install would cost me half the price.

Sorry. Got off track here. So back to original questions plus one more:

1) anyone has and wants to sell the K6 (or earlier) spigots and clamps?
2) would K5 diffusers fit K6 HM341?
3) how about a muffler to fit the CB750 F OEM 4-1?

My Budget roughly 100$. (Till I hit the jackpot, but then I might just get a time machine, travel back in 1969 and pick up 1000 K0 and gift to distinguished members on here)

[Stev-o]

I need advice on parts.

Your asking advice on a parts swap that is not common!   

[Don R]

 I want a set of these,
https://japan.webike.net/products/21363386.html

[PeWe]

One guy that wrote a review of his buy of those pipes:
".....this actually was fitted to a 1977 CB750 with only muffler hangers needing to be fabricated... so even though it says K0-K1, it will fit all SOHC CB750's."

[xhevi]

What are the differences between K5 and K6 HM341?

Parts fiche has different part numbers for each and shows those are not compatible.

Additionally the diffusers at end of each pipe are shown to be removable for K5 but not K6. That's part # 18311341300 on K5 fiche.
 
I removed the rusted diffuser on the K6 mufflers and looks like  I can use the K5 diffusers.

Anyone has first hand experience on these? Better/cheaper options out the there?


https://www.cmsnl.com/honda-cb750k5-four-1975-usa_model483/pipeexhaust_18311341300/

Following up on this,

The K5 diffusers fit the K6 pipes. Link above

I got a set from CMSNL, (the cheaper ones about 14$ each) and they fit fine. They are matt finish, the more expensive ones looks to be glossy.

For the price I am happy with the purchase.