1976A Dyno Run

[tz375]

Ian, very nice results. Thanks for sharing.

It is interesting that raising the ports by 3.5mm ( spacer plus extra gasket) did not tun it into a rev mad race bike with no bottom end. It simply raised the curve at all revs but more at the top and gives a pretty good idea of what happens when a motor is freshened up. I suspect that raising the intakes also helped to bring back some of the bottom end that might have been lost if the transfer and exhaust ports were raised by that amount by porting alone.

The speed at which it peaks was raised but with no downside at all.

The pipes added some at the top end but are clearly street pipes because they did not raise peak revs at all. Yes they lost a little HP below mid revs and gained a lot at the top end but overall they were a nice improvement and much lighter than stock pipes too.

If you would like more top end, try raising the exhaust port roof to increase blowdown time and exhaust duration a little.

[oldjapanesebikes]

If you would like more top end, try raising the exhaust port roof to increase blowdown time and exhaust duration a little.

Thanks Richard - appreciated. All I've done so far is what you have suggested in many previous posts over the years. And I'm happy to say it worked 'as advertised'.

I have another dyno day tentatively planned for next week to run some other pipes I have - I'll post results here when I have them. We can perhaps talk off line about future changes, but nothing will be happening soon. It's a toy, not a vocation !

[tz375]

If you would like more top end, try raising the exhaust port roof to increase blowdown time and exhaust duration a little.

...... It's a toy, not a vocation !

And how many bikes do you have?

It's an obsession.

If you run out of pipes to test, let me know and I'll ship you a few more to try.