Track day feedback

Status
Not open for further replies.
I tried racing with the standard Commando gearbox. It is impossible to do a really smooth downshift without using a heap of revs. And coming up through the box, the acceleration of the bike is too slow. The four-speed close ratio American box is perfect everywhere except first gear is too high for a clutch-start race , but it is cheap.
 
Good point ref the log book Dances. I keep one anyway, but have laspsed in discipline!

Ref the fork oil, I have discovered that I did not use cheapo no brand stuff. I used 160cc of 10wt Putoline race fork oil. Which should be more than man enough for the task.

I shall keep looking for more mundane answers (tyre run out, bearings, ISOs, etc) but I gotta be honest, my gut feel here is that perhaps we’re seeing the design limitations of the dampers and that they are (a little too) sensitive to viscosity change.

And before I’m lynched for heresy, I will also say that I have been nothing but pleased with the Lansdownes on the road, which is where the bike sees most use. I’m only seeing this issue on certain bends on the track. But when it does happen, it is disconcerting enough to warrant a solution.
 
Last edited:
The logbook approach is surely correct. Without data you are going nowhere. Reading the list over the years points out the way forward is the scientific method. Even hobot come to conclusions based on observation despite reaching the wrong answer at times. Jim Comstock puts all in the shade as he
has the tools the know how and the discipline to approach problem solving.
Im learning the hard way to follow my own advise! :-(
 


If you are not a Brit you might not know who the legend Murray Walker is.
 
Fast One,

Chatter is something every (classic) racer fights. When it's bad it will scare the hell out of you, and can pitch you off the edge. There's not enough space or time to write all about it here, but just as Dances says, take a very systematic approach, changing one thing at a time, and you'll zero in on it. We keep meticulous worksheets on every race weekend and document all the changes made, including tire pressures, preload adjustments, damping adjustments, etc. Much of the time it can be regulated by changing one thing to get the harmonic in place. Often that's as simple as raising or lowering tire pressures. And also, never discount the importance of the rear. If your rear shocks are not setup properly your front will fight itself trying to overcome. And setting up the rear is important based on your riding/body position, as it really affects how much load is put to the front. One thing to try is adding or subtracting preload on the rear, also changing damping on the rear (if your shocks allow). And it goes without saying - the "Roadholder" design of the front end is not great, and if there is stiction you will negate benefits of any damping (Landsdown, Cosentino, Ohlins, Maxton). Having the front move freely on its own is paramount before you can begin tuning the front. Generally we begin a weekend damping more on rebound than compression, but that's a very loose rule.

We have also found that different tires do different things. I have always done very well on Dunlops at the track because they let go sooner than Avons, and that slide actually helps with the chatter. Avons are very sticky and grip so well it can stick then skip, and that is the patter that gets spooky. I'm not sure what compound Avons you are running, but consider this. Then again, Dunlops are gone here in the US, so this past weekend I ran Avons front and rear and won the 500 Premier race on my Seeley G50 by a country mile, with absolutely no chatter (I have had chatter at this circuit before). So... it's all about the setup, the minor changes, and a little magic that you will have to stumble upon simply by trial and error. This is where the documentation comes in. If you like I'll send you a copy of the NYC Norton track worksheet we use at every meeting (it's what Dances is referring to). Email me at info@nycnorton.com

-Kenny
 
What Kenny at NYCNorton says.

Switched Commando Seeley front end (Marzzochi) to the Nourish Seeley after a long hiatus a few years back and the Nourish was a nightmare of a front wheel pattering monster. Kenny tore down and blue printed the front forks, new rear shocks and Dunlop tires transformed the Nourish Seeley into a rock steady racer.
 
Kenny,
Thanks for taking the time to share your learned thought sir. It is MUCH appreciated.
PM sent !
 
gortnipper said:
Nigel - the viscosity index and centiStoke measurements on this page might be interesting for you to look at. After all, not all 10w is created equal! I note that Putoline is not on the list.

http://mahonkin.com/~milktree/motorcycles/fork-oil.html
Click to expand...

Interesting, but I fear tis more complex. The Putoline performed perfectly, until it didn’t. It went off with, I suspect, temperature.

As much as I’d like to claim to be Rossi, there’s no way I was out doing the oil! I’m thinking the damping design is putting the oil under more stress than other forks, especially in a repetitive use and high speed situation.

Unless I find something else, I’m reaching the point where I’ve convinced myself it’s the dampers...
 
Keeping a logbook with records of settings is like reading instruction manuals - artists don't do that. I commit everything to memory and measure nothing, that way I get a better picture - like abstract art, it doesn't mean much.
 
Fast Eddie said:
Interesting, but I fear tis more complex. The Putoline performed perfectly, until it didn’t. It went off with, I suspect, temperature.

As much as I’d like to claim to be Rossi, there’s no way I was out doing the oil! I’m thinking the damping design is putting the oil under more stress than other forks, especially in a repetitive use and high speed situation.

Unless I find something else, I’m reaching the point where I’ve convinced myself it’s the dampers...
Click to expand...

"The other interesting number is the Viscosity Index (VI), which is how stable the viscosity is over a wide temperature range. Bigger numbers are better. It doesn't just mean hot-day vs. cold day, it means begining of race vs. end."

Look at something like the Bel Ray HVI or Silkoline Pro oils - they have a much higher VI than others.
 
Hi Eddie

Go with the rear shocks.
With the front end, I have run Maxton, Landsdowne & standard. They all work to a point.
I did a new build & all was good for a couple of seasons, until the front end chatter started. I blamed it on tyre wear.
Worked my way round until I ended up at the shocks. Replaced them with an old set of Konis & the handling was back.
I run Dunlops & they have been brilliant but I cant buy them anymore. Waiting for Conti to bring in thier rumoured classic race tyre in our sizes.

chris
 
Fast Eddie said:
Thanks Chris.

BTW, what yer got against Avons?
Click to expand...
Nothing against Avons Eddie, just was lucky & brought some IOM soft compound 124s & the project came with dunlops & a set of wheels came with Dunlops. Have a friend who was fast, told me he preffered the Contis over Avons. Me I like the price!!! They dont really cover our size tyres yet! Keep being told they are coming.

Chris
 
Status
Not open for further replies.
Back
Top