Forum

[Bullet Whisperer]

Oh dear, a sad internet troll calling itself Gibbons has seen right through it all and left a comment on you tube. Both Hitchcocks and I am done for now ...
'It's a make-believe carb conversion, with dummy plugs ans such, nor real and not a full conversion. Pathetic.
And, why would yo take a client's bike on a test drive in rain ...?! '
'

[windmill john]

I think only you and I ride in the rain BW

[Cranky]

Oh thats a shame --why cant we carry on. I was going to ask why you don't increase compression ratio or bore out to 88mm with a Honda piston with better rings like I did.

[Presto]

'Reversion is a horrible thing...'

Reversion is the event of exhaust gases being drawn back into the cylinder by the vacuum created in the cylinder by the downward stroke of the piston while the exhaust valve is still open.

Not sure how a step at the port would alleviate this phenomenon. If the gases can flow out of the port they can flow back through it. A 'step' at that point in the system would offer no effective obstacle to the force generated by the vacuum the piston creates in its downward stroke. I'd have thought a narrowing of the tract would make the gases drawn to fill the cylinder vacuum to flow faster at that point. Nor do I understand how the length of the exhaust pipe would alleviate this problem.

But anyway...

[Haggis]

Its all to do with reflected pressure waves arriving back at the exhaust port at the wrong time. A step or restriction at the port may help in reflecting the pressure wave.?
Its much more than just gas flow. Apparently.?

[Presto]

I think Haggis that's 'back-pressure'. I believe reversion is different - and is as I explained.
But who knows??? (Yes I know he does!!)

[Wheaters]

A “wrong way” step will definitely affect gas flow in either port. I first came across this subject many years ago, possibly fifty years.

What I still I don’t understand is how a wrong way step in the inlet can be claimed not to have any effect on gas flow. Suddenly the discussion changed from inlet to exhaust flow.

[Cranky]

Reversion is a shock wave , it can be sonic and thermal. If you get it wrong it will pass the shock through the combustion chamber right through and into the air filter.

There is some you tubes of very wrong set ups where reversion is throwing fuel out of the carb.

Messing with an exhaust down pipe diam is trespassing on very dangerous ground and yet very body does it.

[Cranky]

Reversion is a shock wave , it can be sonic and thermal. If you get it wrong it will pass the shock through the combustion chamber right through and into the air filter.

There is some you tubes of very wrong set ups where reversion is throwing fuel out of the carb.

Messing with an exhaust down pipe diam is trespassing on very dangerous ground and yet very body does it.

'Reversion is a horrible thing...'

Reversion is the event of exhaust gases being drawn back into the cylinder by the vacuum created in the cylinder by the downward stroke of the piston while the exhaust valve is still open.

Not sure how a step at the port would alleviate this phenomenon. If the gases can flow out of the port they can flow back through it. A 'step' at that point in the system would offer no effective obstacle to the force generated by the vacuum the piston creates in its downward stroke. I'd have thought a narrowing of the tract would make the gases drawn to fill the cylinder vacuum to flow faster at that point. Nor do I understand how the length of the exhaust pipe would alleviate this problem.

But anyway...

That is very wrong the exhaust is not open as the piston is going down--that would be the induction stroke and the exhaust is shut.

[Bullet Whisperer]

Oh thats a shame --why cant we carry on. I was going to ask why you don't increase compression ratio or bore out to 88mm with a Honda piston with better rings like I did.

OK, Mr Troll, I had my suspicions and for your information, the exhaust valves will be open in most four stroke engines for anything up to nearly half of the down stroke, after firing. Get your facts right, or wind your neck in. Oh, and I will ride in whatever the weather is doing, if I have to. Look out for another fast 535 CGT coming soon, whether you like it or not.
B.W.