Topic: Italian made 4-4 exhaust performance, fact or fiction? cmsnl 341 report also

[Don R]

  I promised I'd never again say the B word. If you know you know.
  I resisted using my Italian 4-4 pipes for a long time but I'm over being mad at some pipe and chrome.
  Early in the advertising, it was posted that they sound awesome and may even call for re-jetting since they flow so well. Has this actually been verified by someone in the know, or was it wishful thinking to promote a group buy?
  I did install a set as a test fit, but that motor wasn't ready to run. 
 

[69cb750]

https://www.bussostore.com/collections/honda/products/senza-titolo-15lug_12-49
Stil available, amazing.
Did your pipes fit?
Most need the outer header pipe shortened to fit properly.

[Don R]

   Tugging on them with a ratchet strap helped get the peg bolt in, trimming the front connector would also work. The reason I ask is I'm deciding what exhaust to put on the 997cc engine we're working on. Once I only dreamed of 4-4's and cool headers, now 20 years later, I have options.
 
  I'm only going to ask about the actual pipes, talking about the deal I was involved in makes my blood pressure rise.

[PeWe]

How do the look like inside?
Open like Yamiya no numbers as I think is a HM300 version, see photos below.
These No numbers need more main jet than HM341.

K6 carbs (086A) must have needles at 4:th notch from top on my K2 with these pipes below.
(Later on my almost stock K2) 064A 3rd, 120 main K&N filter in K6 air box.

Same carbs had 3:rd when my K6 was stock and less main

 

Or even more open as the Lotus Root pipes.
Baffle/Diffuser. Yamiya No numbers without "wool" vs Lotus Root bomb style

[69cb750]

Tugging on them with a ratchet strap helped get the peg bolt in

Mine need trimming, need to make a jig.
This was the biggest fiasco I have seen since 1980.
My 30 second experience pipes sound the same as Yamiya.
What is bore and stroke?

[Don R]

 Stock stroke and 71mm bore, ported big valves and cammed.  I'm a big fan of Yamiya 4-4's and David Silver had a fair price and the lowest shipping for them.
 
  I honestly tried to pull a baffle out of the Italian pipes and wasn't able to get it out. It appears to bolt in like stock, but I didn't want to make wrench marks on the diffuser ring so I quit. My thought was maybe the packing glue smeared as it went in. I wonder if John ever pulled a baffle on his?

 Twice, I bought brand X 4-4's because of availability concerns and found out later I should have waited. I even sold a set of Yamiya pipes back to David Silver on a K5. I should have traded the bike for more Yamiya pipes.

[Don R]

 My Covid era purchase, CMSNL 341 pipes had a rattle on the right side, it sounded like a miss or a knock in the motor except it goes away when the diffusers are removed. I've heard the same complaint from others that own a set. The last time I had it on the lift I cut out the inner most tube in the diffusers, it seems to relieve some back pressure and minimize the rattle.
 I was hoping that the Eastwoood inside the pipe exhaust coating that I applied when new might glue something in place but that didn't happen. I considered using a long 3/8" bit and punching some holes through the baffles like we did in the 70's but haven't resorted to that yet. I'll likely move these pipes to my brothers K4 where 341's would have been found new.

[MauiK3]

Be nice to see a set of "B"'s installed and hear them running.

[Don R]

Be nice to see a set of "B"'s installed and hear them running.

I did get a response on facebook, he was comparing B's to 341's so we would expect them to sound better and he normally re-jets up a step to allow for modern fuels.

[PeWe]

Be nice to see a set of "B"'s installed and hear them running.

I did get a response on facebook, he was comparing B's to 341's so we would expect them to sound better and he normally re-jets up a step to allow for modern fuels.

Hopefully not E10 or worse fuel. 98RON here is E5 which is a max number if I have got it right.
I wish less than 5% ethanol.

E10 must need richer pilot, needle and main jet, right?

[Don R]

Be nice to see a set of "B"'s installed and hear them running.

I did get a response on facebook, he was comparing B's to 341's so we would expect them to sound better and he normally re-jets up a step to allow for modern fuels.

Hopefully not E10 or worse fuel. 98RON here is E5 which is a max number if I have got it right.
I wish less than 5% ethanol.

E10 must need richer pilot, needle and main jet, right?

He did mention gas with alcohol so I would assume that to be the case, but a switch from 341's to 300's alone would require a re-jet if we followed what Honda did.
  I actually have a set of B's on a K0, I wasn't really wanting to make it run yet because it is a "for sale" bike and would be another set of fueled carbs and gas tank to worry about.

[HondaMan]

I wish less than 5% ethanol.

Per, can you 'get away' with adding an ounce or 2 of oil into the gas tank there? This neutralizes the ethanol here quite well. It also helps with the butanol (butane) recently added to our fuel, pairing with it chemically and making it burn a little slower.

[PeWe]

Hi Mark,
My bikes get 98 RON E5. They work fine with that.
Shell V-Power is no longer available here.
The stations bought by ST-1 that still were branded Shell used another really bad fuel.
This was done many years ago, fuel quality degraded all the time until I noticed always wrong jetting despite my jetting changes.

My K6 and car run much better with another brand of 98 RON E5.
OK Q8  (Q8 former Gulf)

[Don R]

 I'd like to have a VP gas station nearby, they sell pump gas and also race fuel.