Hello,
For those who are interested in my bike's pipes this is the story...
The pipes came with the bike when I bought it as they are, but they have become a real nightmare until last weekend. The bike seemed to run ok but when speeding over 6.000 rpm suddenly the bike went down. What could it be? First I checked the gasoline intake. Petcock, fuel strainer... It was right. Air filter. Ok. Then carbs. Ok too. Electrical? No. Decided to open the heart of the bike... and that was it! a burnt valve. Changed two valve's guides and the burnt valve (ex. one). Sync carbs again, compression tested... everything ok. To the road again. First gear, second... over 6.000 rpm and damn it, again!!!! Desperate as I was I got to the conclusion it had to be the exhausts... and it were! I drilled a hole in the center of the silencers (front and back), placed a 15mm diameter tube and.... magic!! the bike run as a bullet, speeding like an arrow and what's more surprising, with a fantastic sound!! The problem was that the fumes didn´t exit properly returning to the cilynders and maybe burning my valve and making the motor go-down.
What I have done is connecting directly with the exit in a way that the fumes go directly outside without trespassing the silencer labyrinth. Obviously some fumes get to the labyrinth due to the pression and thats why the sound is smooth and not loud.
Here you are a picture of the botched job... ;-)
I also upload a drawing of a CB750 exhaust where you can see pictured in red how the exhaust is working right now. I have placed two tubes in each silencer to let the fumes exit.
Maybe this exhaust are for a different bike (a CB350 maybe?) less powerful. I don´t know, I will try to find out where they came from calling the previous owner. Anyway this model was sold only with 4-4 (which I'm in the search of right now...) or 4-1 exhausts and no with 4-2, so...
Hope you enjoy the story!
