Author Topic: Preparing for trackday (Read 6953 times)

voxonda · « **Reply #25 on:** June 13, 2008, 08:11:02 AM »

Quote from: turboguzzi on June 13, 2008, 06:11:38 AM

I am running a 90/90-18 Avon AM20 in front, and a 130/70-18 AM23 in the back.

Might try Dunlop KR124 / KR164 for next season

But first of all you should consider the rim widths you have, useless putting a race compound tire if the rim is too narrow and it squishes it to a worng profile.

Check here:

http://www.avonracing.com/club_page.asp

http://www.avonracing.com/motorcycle_page.asp

Dunlop (scroll down for the "classic range"

http://www.dunloptyres.co.uk/ourTyres/motorsport/motorcycle/

Hey TG, thanks for the info. I am running the same sizes as you do, but I do not want to go to wider rims. Want the bike to be '70's like. Second I do not intend to go "all out racing". If that will come in the future, although with these oil prices nobody will be able to afford, maybe will grow in rim width. Seen racers back in the day, who performed miracles with Dunlop TT100's, so with a bit more modern rubber.....................

Cheers mate

Sam Green Racing · « **Reply #26 on:** June 18, 2008, 01:30:15 PM »

bill440cars · « **Reply #27 on:** June 18, 2008, 07:32:08 PM »

Gotta tell you all that I could sit and listen to (er.... read) what you all (Sam, T.G. and Rob) talk the racing stuff all day (or night). You all make this a heck of an interesting read!

Just realized that Tracy had some input concerning HIS racer and I apologize for not initially including him with the others. I find it really interesting, to hear (and see) the mods done to the bikes to make them more efficient racers and to also hear how the outings go.

You all keep up the good work!

voxonda · « **Reply #28 on:** June 19, 2008, 02:35:58 PM »

So "her maiden voyage is done". Today I had my very first outing with the replica on the circuit of Zolder in the north of Belgium. I enjoyed the day and met a lot of interesting people. The bike did reasonable well. The sound on, and according to spectators, off the bike was awesome!! From around 4000rpm even my ear protection did not help all that much! What a joy to ride with a open megga. In september there is a new outing, so I can work on a few minor problems, oil leakage on the, original, oil line. Have to alter the front fork. Waiting on the adjusters and have to put in some harder linear springs an some heavier oil. Carb's need some re-adjustment. So there is some work to do, but I can tell you, I love it!!!
Will show some more picture's tomorrow.

Go to bed now and hope to re-live this day in my dreams.

cheers, Rob

turboguzzi · « **Reply #29 on:** June 19, 2008, 02:59:28 PM »

nice to hear all went well rob!

Already did some 7 races by now but the excitment of taking the bike out to her first track outing is also something I'll never forget.

Stock fork were always soft and lightly damped. What I did in my racer was to shut off totally the little holes at the top of the damper pistons and simply shorten the springs (it makes them stiffer) and compensate for the shortening with a simple tubular spacer.

Just installed new barnett clutch plates on my bike for sunday's race, let's see how it goes

Cheers

TG

voxonda · « **Reply #30 on:** June 20, 2008, 01:23:43 AM »

Hi TG,

Hope everything goes well on your next efford. Am impressed by the Dyno reading of your bike. After solving some of the minor problems with the bike it will get the Dyno-treatment also to fine tune the carb's. Here some pic's, will put some more on today.

Cheers

Rob

Terry in Australia · « **Reply #31 on:** June 20, 2008, 05:02:01 AM »

That's a beautiful bike rob, well done, I love that pipe, it looks like a fancy musical instrument, so it's no wonder you're impressed with it's "note"! Cheers, Terry.

voxonda · « **Reply #32 on:** June 20, 2008, 05:55:57 AM »

Quote from: turboguzzi on June 19, 2008, 02:59:28 PM

nice to hear all went well rob!
Already did some 7 races by now but the excitment of taking the bike out to her first track outing is also something I'll never forget.
Stock fork were always soft and lightly damped. What I did in my racer was to shut off totally the little holes at the top of the damper pistons and simply shorten the springs (it makes them stiffer) and compensate for the shortening with a simple tubular spacer.
Just installed new barnett clutch plates on my bike for sunday's race, let's see how it goes

Cheers
TG

Hi TG,

Just wondering about your damping solutions, how do these little holes work? When does the oil go through these passages? Looks to me that it will pass through the centerbore, so by reducing the bottom holes the damping would be effected. The small holes may work at a nearly compressed fork. Do I miss something?
I have taken out the spring, it is a linear one not a progressive one. So shortening won't make them any stiffer. Am I seeing things wrong?

PLEASE HELP.

Cheers, Rob

voxonda · « **Reply #33 on:** June 20, 2008, 05:58:33 AM »

Quote from: Terry in Australia on June 20, 2008, 05:02:01 AM

That's a beautiful bike rob, well done, I love that pipe, it looks like a fancy musical instrument, so it's no wonder you're impressed with it's "note"! Cheers, Terry.

Thanks Terry,

Am very happy with the bike, now trying to put everything in order for the next outing. The shape of the pipe was just a wild quess, but what a good one!

There will be a sound check on You Tube.

Cheers, Rob

Terry in Australia · « **Reply #34 on:** June 20, 2008, 06:04:43 AM »

Make sure you post a link Rob, I'm looking forward to hearing that "music", ha ha!

voxonda · « **Reply #35 on:** June 20, 2008, 07:57:58 AM »

Quote from: bill440cars on June 18, 2008, 07:32:08 PM

Gotta tell you all that I could sit and listen to (er.... read) what you all (Sam, T.G. and Rob) talk the racing stuff all day (or night). You all make this a heck of an interesting read! Just realized that Tracy had some input concerning HIS racer and I apologize for not initially including him with the others. I find it really interesting, to hear (and see) the mods done to the bikes to make them more efficient racers and to also hear how the outings go. You all keep up the good work!

Hi Bill,

Think I can speak for the rest of the guys, thanks for your kind words. We are all here because of our mutual hobby, so it is nice to hear that there are folks enjoying it when we talk about it. You're very much welcome.

Cheers, Rob

voxonda · « **Reply #36 on:** June 20, 2008, 12:34:30 PM »

Quote from: Terry in Australia on June 20, 2008, 06:04:43 AM

Make sure you post a link Rob, I'm looking forward to hearing that "music", ha ha!

Here's that link:

As you can obvious here the gearing is, much, too tall. And I am, much, too heavy! But I love it.
Hope you like it.

Cheers, Rob

Terry in Australia · « **Reply #37 on:** June 20, 2008, 06:07:49 PM »

Beautiful!

voxonda · « **Reply #38 on:** June 23, 2008, 02:30:12 PM »

Well worked on the bike tonight, and have altered the forks with some heavier damping, TG's solution for the damperrod's with some slightly heavier oil seems to work fine. Think that when the preload adjusters arrive the fork will be fine. Changing the oiltank is a somewhat bigger 'challenge', during some cornering seems the pump doesn't get sufficient oil. See what I can do about that. Also changed the mainjet's from 134 to 125. According to the spark plugs the mixture is too rich. Maybe the needles have to drop? Have to put it on a dyno before long. Feld like the gearing was too tall but when I calculated, it's somewhat shorter then original. Run 16x44(2.75:1) instead of the 18x48(2.667:1), perhaps I need to really lose some weight?

Cheers.

scondon · « **Reply #39 on:** June 23, 2008, 03:24:11 PM »

Nice thread, beautiful bike voxonda

Does anyone race with a stock 19" front rim? Or are racing tyres only found in 18" for front wheel?

I've been very happy with Pirelli's Sport Demon tyres for the road but am thinking that

a) I will have to get "tubeless" rims in order to get max speed rating

and

b) I will have to find a 18" front in order to try racing tyres. I can find none in 19" size.

Sorry to stick this in your thread voxonda, but this is the highest viewed area of vintage racers I could find

ralt12 · « **Reply #40 on:** June 23, 2008, 05:00:22 PM »

Nice Joey Dunlop as well...

Sam Green Racing · « **Reply #41 on:** June 23, 2008, 05:09:42 PM »

to late ralt

Re: The 1970 Daytona CR750s.
« Reply #256 on: June 17, 2008, 07:12:34 pm »

--------------------------------------------------------------------------------
Well done Rob, I hope it goes as well as it looks for you.

Nice helmet as well RIP JD

Sam.

Report to moderator 62.24.129.68

Sam.

voxonda · « **Reply #42 on:** June 23, 2008, 10:57:19 PM »

Am very happy with the real Joey Dunlop ARAI lid. Am one of the lucky ones who could get hold of one.
JD will always have a special place in my heart.

Joey4ever.

Cheers.

turboguzzi · « **Reply #43 on:** June 25, 2008, 04:24:23 AM »

Hi rob

Yep, bike looks good! Now you need to work on your own posture :-)

Was busy with my own racing this weekend, but am planning to open the forks in the long break I have till next race and will send you some pics.

shortening of the spring will stiffen the rate regardless if it's progressive or not. I shortended mine by 20%. Maybe start at 10% and see if it improves. Just put the cut end at the top where it will not rub with anything and dont forget to re adjust the height with spacers. Normal threaded height adjusters will not have enough range to compensate for so much spring shortening.

Gearing depends on how long the straights in the circuit are, slowest turn, your riding level and more. In general you need to drop BIG time from stock unless it is a very very fast road circuit. for short-medium tracks i am up to to 2.375, original was only 2.00 ! , that's a good 15% shorter.

Scondon. Look up at my earlier link to avon race tires in this tread, they do make the AM20 like I use also in 19" in race compund.

Cheers

TG

voxonda · « **Reply #44 on:** June 25, 2008, 07:24:32 AM »

Hi TG,

Hope everything went allright during your raceweekend? Any results?

Very interested in your front suspension solutions. Have followed you in adjusting the damping. Had some linear springs, almost same length think from a F2, lying around. Made some height adjusters (5 - 25m/m) and put in some 15W oil with a 150m/m airchamber. Feels much more firmer now, and damping 'feels' better. Have to wait until the next trackday to see what the real effect is.

Brazed the tiny holes shut.

The height adjusters.

First will check the carb's and then take a closer look at the gearing.

Am working on the weight 'problem' but it seems that gaining is much easier then losing it.

Cheers, rob

MRieck · « **Reply #45 on:** June 25, 2008, 07:40:38 AM »

Quote from: voxonda on June 25, 2008, 07:24:32 AM

Hi TG,

Hope everything went allright during your raceweekend? Any results?

Very interested in your front suspension solutions. Have followed you in adjusting the damping. Had some linear springs, almost same length think from a F2, lying around. Made some height adjusters (5 - 25m/m) and put in some 15W oil with a 150m/m airchamber. Feels much more firmer now, and damping 'feels' better. Have to wait until the next trackday to see what the real effect is.

Brazed the tiny holes shut.

The height adjusters.

First will check the carb's and then take a closer look at the gearing.

Am working on the weight 'problem' but it seems that gaining is much easier then losing it.

Cheers, rob

I welded one of the rebound holes on my damper rods....I'd leave one open. How about the Race Tech Emulator kit. It would be great for your application. I hear you about the weight too.

voxonda · « **Reply #46 on:** June 25, 2008, 08:58:22 AM »

Quote from: MRieck on June 25, 2008, 07:40:38 AM

I welded one of the rebound holes on my damper rods....I'd leave one open. How about the Race Tech Emulator kit. It would be great for your application. I hear you about the weight too.

[/quote]

Hi MRieck,

Thanks for the Racetech tip, looks neat and for sure think I will try this if the 'tests' show not enough improvement. Seems they have distributors in England and Germany too.
Though both the rebound holes are shut the rebound damping seems OK now. Let's wait and see what it all brings. thanks to you all for keeping me from making to much mistakes. Never too old to learn.
Problem with the weight is that I enjoy life alot!

Cheers, Rob

turboguzzi · « **Reply #47 on:** June 25, 2008, 11:14:05 AM »

Hi rob

Hard to say wether you need one or two holes shut. If the white plastic seal is a bit worn, then two shut might be better.

You can always play a bit with oil weight, 5W 10W, etc. + the nice thing is that if it's still too firm, you can always drill back the hole for less damping. 150 mm (without springs, forks legs fully up) sounds a good starting point. Changing the oil height is the easiest way to avoid bottoming. The best way to know quickly if you have OK damping/springing is to lightly tie a zip tie around one fork tube and see how far up it goes after a track session. You should still have some fork travel left for safety, if it bottoms or doesnt use enough frok travel then you know you are too soft or too hard.

Had a strange race. In qualifying I had very good times, but the race was held with a 35 degrees heat (100 F) and my head was about to explode, Then I had a moment on the main straight, almost touching handlebars with another guy at 160 kph and that threw me off a bit...so didnt do really well, was slower by 2 secs than in practice, 15th out of 24, my worst result since starting racing....

there's always the next one!

TG

611 is the guy I almost crashed with, also on a 500 SOHC

scondon · « **Reply #48 on:** June 25, 2008, 12:39:34 PM »

Quote from: turboguzzi on June 25, 2008, 04:24:23 AM

Scondon. Look up at my earlier link to avon race tires in this tread, they do make the AM20 like I use also in 19" in race compund.

Cheers

TG

Thanks TG

Tried to find speed ratings in those charts but couldn't, any idea? I'll look up Avon here in the 'states and see what I can come up with.

EDIT: All I can find from Avon here in the US are the RoadRiders. Tubeless rating is 240km/149mph. They don't mention anything about being a special race compound though they are "sticky".

EDIT #2: This is the reply from Pirelli when I asked about the Sport Demon tyres(my favorite) and whether they offered a race specific tire for 19(F) and 18(R) rims...

Hello

Typically installing a tube in a street tire drops the speed rating to 130 mph. The track pressures for this type of tire is 32 front and 36 rear. We do not offer any racing tires for vintage racing and we have no plans to do so. Sorry to say the vintage Roadracing scene is shrinking and requests from the market are smaller every year. Thanks for the e-mail.

US Pirelli Moto

turboguzzi · « **Reply #49 on:** June 26, 2008, 10:30:37 AM »

well.... that does explain the outrageous prices (200$ a piece and up) that Avon and Dunlop charge for vintage race rubber!

I posted it once on another tread, Conti (continental) have very sporty vintage stuff (not race compund ) they are TKV11/22 if I am not mistaken. pretty cheap too.

If you aren't going full out racing, true race compund are a waste of money....

Try of course vintage racing guys in your local track ( I am i italy) where they get their covers.

Another option are the tires that Avon makes for the Triumph Thruxton cup. The AM22/ AM23

TG

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Author Topic: Preparing for trackday (Read 6953 times)