Exhaust Pipe Tuned Length

[fastharry]

Yes indeed. i spent a small fortune in my road racing days looking for more power, Ended up with 72 bhp at the back wheel with a 630 rotax single. But i was actually faster round my favourite track when i had 64bhp and more in the midrange.

[smotorboy]

Yes Yes Yes on that midrange….back when I was crewing on circle track cars,,,,FIRST thing I did was tho change the camshaft from the peaky max hp possible camshaft that were always in the motors to a Torquer grind that would pull really hard out of the turns but not fade too much on the straight chutes….

The cars usually moved up ten or more place in the race field…

Robert

[fastharry]

I will be paying attention to the cam area, Im about to get the 501 case machined so i can take the cam out without a full strip down, i have not stripped the bottom half on my 400 so im guessing its got the Sport cam as it started as a 350 sport, The 501 has a J cam have you had any experience with these? i also have some sort of L5 copy done by Paul some years ago but he has not told me what numbers it has in the profile. i have read that the M cam is a good mid range cam maybe i will have to look out for one of those. im thinking of sending them all to Phil Joy to have them measured as im not to well up on cam profiles. Regards, Harry.

[solviken]

Made an equal length system with an electrical conduit bender at work for my 350 engined 2C around 20 years ago. Front pipe crossed under to exit from the left and rear went down, followed the front but forwards and then turned back under the engine to exit on the right, included a balance pipe too. Front silencer exited at a funny angle but it was the only way I could do it to make it equal in length to the millimetre... Didn't make a blind bit of difference so went in the scrap bin!

A mate had a 350 with the usual rusted in half Lanfranconi on the rear cylinder so took it off and hammered a torch battery into the header so effectively made a 2 -1 system and that went like the clappers!
Till the battery shot out when I was trying to catch him, bounced on the road and nearly took my head off! Later found out why his bike went so fast but that's another story.

[Steve Brown]

Made an equal length system with an electrical conduit bender at work for my 350 engined 2C around 20 years ago. Front pipe crossed under to exit from the left and rear went down, followed the front but forwards and then turned back under the engine to exit on the right, included a balance pipe too. Front silencer exited at a funny angle but it was the only way I could do it to make it equal in length to the millimetre... Didn't make a blind bit of difference so went in the scrap bin!

A mate had a 350 with the usual rusted in half Lanfranconi on the rear cylinder so took it off and hammered a torch battery into the header so effectively made a 2 -1 system and that went like the clappers!
Till the battery shot out when I was trying to catch him, bounced on the road and nearly took my head off! Later found out why his bike went so fast but that's another story.

[img][IMG]http://i937.photobucket.com/albums/ad213/solviken/005_zpszl1mo8rr.jpg[/img][/img]

Cadwell short circuit hairpin? If that was an MRC do it was a while back!

[solviken]

Yes MRC Cadwell mid 1990s? Did a few, first in 1983, brilliant fun and led on to some 'proper' short circuit racing.
After 6 Morinis I've been clear of my addiction for many years now lol.

[Steve Brown]

After 6 Morinis I've been clear of my addiction for many years now lol.

That's what I thought after a 15 year break...it never quite leaves you

[solviken]

Stop encouraging me to get into bad habits!

To be honest I wouldn't mind another 2C, better handling than the 350 but all a bit pricey nowadays now it's a classic and and not a poor relation to a Ducati anymore! The 2C in the pic cost me nothing, rescued it from a skip!

Nick

[fastharry]

Good info on the pipes Nick, Don't leave us hanging. What were the reasons for the fast motor? regards, Harry.

[solviken]

Eventually bought my mates 'fast' Morini when he defected to Honda. Initially I thought his extra speed came from his engine having the all roller crank (76) and mine the later plain crank (78) model Sport so decided to strip to see any other differences. Didn't find any apart from a previous rebuild had got the crank timing pinion slightly out (advanced) so corrected it, big mistake! Never went as fast again! By advancing the cam a few degrees his top end was faster then mine and conversely his midrange weaker, you don't get owt for nowt!

[EVguru]

By advancing the cam a few degrees his top end was faster then mine and conversely his midrange weaker, you don't get owt for nowt!

Advancing the cam timing lowers the rpm at which peak torque is generated and vice versa.

[solviken]

This has got me thinking now, difficult going back 30 years but think I've realised what was going on?

The crankshaft cam pinion mark (dot) was slightly to the left of the crankcase dot (looking at the offside with the cam lined up) so assumed (wrongly) that the crank was advanced in relation to the cam timing as the camshaft would be if the camshaft pinion dot was before the case dot. So of course my mates 'fast' Morini had in fact a retarded camshaft.

I was young and daft then, now I'm just old and daft!

[fastharry]

Ah Yes cam timing, Something i have not studied a lot. Time is the killer.