Wrapped baffles

[slosher]

Noise reduction in Walsall during the 70's was Dunstall Mega's on my Beazer and no bafffle's in the Suzuki

[itsnotateapot]

Noise reduction in Walsall during the 70's was Dunstall Mega's on my Beazer and no bafffle's in the Suzuki

or when scotch is on holiday

[slosher]

Noise reduction in Walsall during the 70's was Dunstall Mega's on my Beazer and no bafffle's in the Suzuki

or when scotch is on holiday

Late 60's early 70's began to see a lot of changes on both British and Japanese motorbikes for fuel,emissions and also noise level reduction and the United States insisting on those changes.The rest of the world had to take heed and because of the massive import of Japanese and Bitbikes into the States cross over/joining pipes began to appear on big Thumping Twins and also the big Suzuki Triples,some claim the cross over pipe were also introduced as a noise reduction measure any thoughts on this theory guys What was the reason for the cross over pipes

[teazer]

Cross over pipes can have a beneficial effect on power and are used in H and X configurations on many muscle car exhausts. Roger Slater had an X pipe arrangement on the Laverdas that supposedly helped power as well.

As I understand it, the idea behind cross overs is essentially that it allows all cylinders to vent through all pipes and so reduces back pressure as it also reduces noise. Honda did that on the 400 twins and plastic maggot IIRC and probably on others.

[slosher]

Cross over pipes can have a beneficial effect on power and are used in H and X configurations on many muscle car exhausts. Roger Slater had an X pipe arrangement on the Laverdas that supposedly helped power as well.

As I understand it, the idea behind cross overs is essentially that it allows all cylinders to vent through all pipes and so reduces back pressure as it also reduces noise. Honda did that on the 400 twins and plastic maggot IIRC and probably on others.

Interesting that Teazer makes a lot of sense with increase of power,do you think the distance the cross over pipe is applied from the exhaust outlet makes a difference It certainly made a difference with noise reduction on the Bonnie but my thoughts are it being too close to the exhaust outlets Iv'e replaced my down pipes without the cross over pipes on the Triumph and it's a lot more responsive.

[barney01]

I'm no expert by my understanding that the crossflow pipes produce more low down torque but at the expense of top speed. It was also claimed to make the engine smoother.

[teazer]

The other way that a cross over pipe can work is that as one pulse passes the cross over it tends to "pull" gas from the other pipe giving more complete evacuation. How much and at what revs I don't know.
Yoshimura used small cross link pipes part way down the headers on some of their GSXR performance pipes but what part of the power curve that was supposed to boost I don't know.

It's interesting that 4 strokes often use stepped headers with multiple steps which act like a simple convergent cone of an expansion chamber but the steps create a barrier to reversion, where we want that reversion wave to push fresh mixture back into the port just before it closes.

On a T140 it would be interesting to test one back to back with and without the link pipe to see what difference it makes to torque , fueling and noise. Someone that worked on the design would know.

[slosher]

Strange as to why Suzuki ceased using cross over pipes on M,A,B models perhaps thought noise reduction had no effect on the earlier models Strange set up with the carbs on the Bonnie you set each carb individually but then has a joining pipe prior to inlets on the barrels then the cross over pipe comes immediately at the exhaust outlet of gasses.With the Suzuki's any joining pipes on the carbs are further back and cross over on exhausts well away from barrels.That said the T140 is on the naughty step tooth sheared on 3rd gear mainshaft

[barney01]

When i bought my 550 the exhaust crossovers had been blanked off with engine block plugs welded in. This apparently was quite common as it saved you faffing about with o rings and gave you more top end power.