What type of exhaust for power. (2019)

Fast Eddie said:

Wudda loved to have watched that race !

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Yep, they passed each other about 4 times a lap, was neck and neck up to the last lap, Lee Hodge threw the TZ away on the same slippy patch that Cormac had hit the previous lap and that was that

Spike is a terrific rider.
I'm in luck though John, they are only allowed 350TZs. I'm looking forward to it.
Still think it should by 501 unlimited but I think it's all restricted due to lack k of run off.
What meetings do you think you & Cormac will get to? I want to do Tandagree

Schwany said:

Nothing and without a rider on it? That is impressive.

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I brake into the corner without reverse steering to tip in, then get straight back onto the gas. The bike does the rest. It over-steers a lot if gassed when on a lean.. I have to be careful if there are other guys in front of me in the corner. My mind has to always be where I am coming out of the corner. Self steering is dangerous until you become accustomed to it. It depends on squat at the back of the bike which changes the rake on the steering head. All bikes do it to some extent, but mine has much more trail. The last time I raced, I rode under the three leaders at turn 2 on Winton. They were all out on the ripple strip. I was well ahead when my motor stopped. I had the race won, there was no way they would ever get back in front. There were four more tight corners before the next straights.

Hi Chris
I don't think I'll be doing any meetings this year....bikes are 500 miles away in storage !

Cormac is only interested in the Endurance stuff, and as Brendan is retired now I can't see anyone else throwing bikes at him

storm42 said:

I am hoping to do Pembrey so will see you there but , those Welsh politicians are a bit unpredictable.

How do you get to race at Goodwood?

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You get invited! Which may be more about who you know than what you know. I would loved to have seen Lloyd and Cormac there. I actually figured what was wanted was a few 750cc bikes that weren't triples, 2 stroke or 4 stroke, and I am just glad there aren't (as far as I know) TZ750s.

Back in the '70s I rode many races that Lloyd was in at Cadwell, I think his exhausts made my ears bleed once! The only time I remember beating him with my 850 was when he was riding a GS1000 he was developing! Not a very successful venture! Mostly I never saw where he and Bob Smith went.

(For those who don't know the name Lloyd Dickinson you will see the profile of the cam he designed and made around somewhere, it made power, and noise!)

You need a 750 motor, or a 350 TZ.....It was supposed to be F750 one year, TZs the next. This would be a TZ year but, on the original Goodwood date the TZ had a clash with GP Originals at Donington, so they decided to invite F750s as well. Then they changed the date! Covid eh!

I only want to do it because I lived 20 miles away from Goodwood for 35 years and have driven car track days and rallied around it, but I never rode a motorcycle there. And I am thinking of hanging up my leathers before there will be another opportunity.

Neither F750 nor TZs are really a good fit for Goodwood since racing stopped in 1966, but, they already run two periods of Manx Nortons and such at the Revival and wanted something different, so here we are.

Watching the live timing from Mallory I will have to ask what happened on the start line that added 45 seconds to your first lap?

acotrel said:

I brake into the corner without reverse steering to tip in, then get straight back onto the gas. The bike does the rest. It over-steers a lot if gassed when on a lean.. I have to be careful if there are other guys in front of me in the corner. My mind has to always be where I am coming out of the corner. Self steering is dangerous until you become accustomed to it. It depends on squat at the back of the bike which changes the rake on the steering head. All bikes do it to some extent, but mine has much more trail. The last time I raced, I rode under the three leaders at turn 2 on Winton. They were all out on the ripple strip. I was well ahead when my motor stopped. I had the race won, there was no way they would ever get back in front. There were four more tight corners before the next straights.

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Always enjoy the war stories al, and I was just ribbing you. I know you like your Seeley.

It's been so long since I actually went fast on a motorcycle I can't remember what I did technically. All I do remember is I felt like I was part of the motorcycle and physically pulling it through the corners with my upper body and steering it with my ass, pressure of my outside thigh against the tank, and foot pressure on the outside peg. That was on a liter Ducati. I may have gone fast enough to stay in front of mid-pack at least twice in my life, but it was on the street, and I barely got the rubber to soften up and get gooey near the sidewall edge. My eyes and reaction times are so bad now all I can do is pretend once in a while when there are no cars around and a nice curve is in front of me.

I never got the racing bug. I got the motorcycle owner/tuner/spectator/photographer bug instead.

One thing you will notice about MotoGP - is these days , they all play the same game. If you have excessive horsepower, you are probably committed to it. Self-steering with over 100 horsepower would probably crash you very easily. John Kocinsky seemed to be using it with the VFR750R in 1993. But that was a long time ago, when power outputs were lower. When I ride my Seeley 850, I always feel I am doing in corners what I should not be doing. It is counter intuitive. If you are running wide in a corner, it is not natural to wind on more throttle. The first time you do it, you take your life in your hands. After that, it is easy. But you need smooth power delivery - no bumps.

I would never intentionally put anybody on the wrong tram. When I see other guys racing Nortons, I am always for them, never against. What I have said is quite simple. To race really fast you need smooth power delivery and that means more torque rather than top end power. On every race circuit there is usually a slow corner which has plenty of run-off. If you get into it at moderate speed and halfway through it apply full power - when the rear end of your bike squats, the bike should self-steer. Which way it turns determines how much throttle you can use in the corner and when accelerating out. With my bike I brake one third of the way in when going into any corner, then gas it as hard as I can. The bike does the rest.
The Dunstall 2 into 1 into 2 exhaust is probably a good answer to the noise problem. If there is any restriction where the pipes converge, you lose too much power off the top of the rev range. My 2 into 1 has no restriction and makes it difficult to avoid over-revving. But it is extremely loud. With the Dunstall exhaust you have it opening out into two mufflers. You would still get smooth power delivery without losing top end.

yep, those guys these days are nuts ( but super fast).

With the steering geometry I use, the bike seems to stay more upright in corners, so I get more power down than I could if it leaned more. It is quite strange and not something I would ever predict.

Extreme angles of lean only happened when we got better tyres and most guys went to 18 inch wheels. The only riders who had decent rubber on 19 inch wheels, were probably those who raced in Europe. I noticed that the McIntosh Manx which was raced at Phillip Island by Cameron Donald in recent years, has 19 inch wheels.. 18 inch wheels reduce the trail when they replace 19 inch wheels with the same rake steering head and yoke offset.. Most modern Manxs use 26 degree rake with 18 inch wheels instead of 24.5.degree rake with 19 inch wheels. With less trail, you probably get more lean.
If you put 18 inch wheels on an original Manx to get better rubber, it stuffs the handling completely.

OK, we turned it into a general racing thread....Ho Hum!

SteveA said:

OK, we turned it into a general racing thread....Ho Hum!

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Yep - thinking the same thing!
Where is there anything about best performing exhaust systems in the last XX posts.
....boring guys!!

If you want to talk about racing, have a perpetual thread on it and stick to that - don't contaminate other threads!

...oh, and talking about frilly knickers - did I tell you how much changing my steering geometry improved my cornering speed?

robs ss said:

Yep - thinking the same thing!
Where is there anything about best performing exhaust systems in the last XX posts.
....boring guys!!

If you want to talk about racing, have a perpetual thread on it and stick to that - don't contaminate other threads!

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You could probably count on 1 finger how many threads stay on topic on this site. Just saying

Could we retitled this thread "frilly knickers" it caught my attention, as we have veered a long way from the question.

This might interest you guys. These bikes dominate the class in which Commandos are eligible. The last time I raced, I rode under three of them at turn two on Winton, and did it easily. They were all out on the ripple strip on full lean as I passed under them. I had forgotten to tighten the clip under the tank and my motor stopped. But it proved the bike.

Chris said:

Could we retitled this thread "frilly knickers" it caught my attention, as we have veered a long way from the question.

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I don't think this thread has veered far from the question. It is what exhaust is best for getting power. There are two kinds of power and you have a choice about which one you use. On most circuits with Commando motors, smooth strong power delivery from a 2 into 1 exhaust, is better than what you get with separate pipes, and particularly if the separate pipes have megaphones. With separate pipes you get more top end, power but you usually go slower. For a road bike, the Dunstall 2 into 1 into 2 would probably be best. You would get the benefit with half the noise. In fact with the Dunstall pipe, you could fit an Exup system into the bit where the pipes converge

Just some comments on the 350 Manx power band. It's completely empty below 4000. Useful power band is between 5000 and 8200 (maybe some 500 more on short circuits). Compared to my CB250 with a power band from 5000 to 12500. Though on most tracks I've raced no need to go under 8000. Back in the days when fairings became a must for serious racers, the increased top speed and subsequent taller overall gearing, you had to either slip clutch in the hairpins or get a 5 speed gearbox.

Sorry. Back on track. Pun intended.

There are many paths up the mountain, Grasshopper.