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Dukedesmo · 11-07-2020, 10:12 AM

My take on it is that the crossover is not great and that it 'allows' more gases to go out of one pipe than the other due to the way that both pipes tend to favour one exit.

Originally I had a standard crossover but I opened it up as much as possible, however it still gave more 'flow' from one pipe than the other, at least at idle and this made that pipe run hotter if left just idling.

I'm certain it balances out at speed and can only assume that the pipe routing (rear cylinder having to go around more corners) and variations in back pressure from the crossover design cause it?

The Spaghetti pipes I have are made in such a way that the rear cylinder has a smoother run than the OEM pipework and this certainly helps.

But it's even more pronounced on 916 type bikes and the exhaust on that has a much more extreme bend/routing for the rear cylinder, IIRC later model supebikes; 999 etc. used larger bore rear pipework of shorter, unequal length to the front to get a better balance?

11-07-2020, 10:12 AM	#7
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,844	My take on it is that the crossover is not great and that it 'allows' more gases to go out of one pipe than the other due to the way that both pipes tend to favour one exit. Originally I had a standard crossover but I opened it up as much as possible, however it still gave more 'flow' from one pipe than the other, at least at idle and this made that pipe run hotter if left just idling. I'm certain it balances out at speed and can only assume that the pipe routing (rear cylinder having to go around more corners) and variations in back pressure from the crossover design cause it? The Spaghetti pipes I have are made in such a way that the rear cylinder has a smoother run than the OEM pipework and this certainly helps. But it's even more pronounced on 916 type bikes and the exhaust on that has a much more extreme bend/routing for the rear cylinder, IIRC later model supebikes; 999 etc. used larger bore rear pipework of shorter, unequal length to the front to get a better balance? __________________ M900, 916, LeMans II.