Lightweight Roadrace Digest #21-30


LtWtRR-digest           Monday, May 26 1997           Volume 01 : Number 021




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Date: Sun, 25 May 1997 13:29:40 -0800
From: "Michael Moore" 
Subject: LtWtRR Posts to the list

I see that some of the list members are making LWRR list-appropriate
posts to the race and 2smoke lists, but not to the LWRR list.  Feel
free to post the message here too, as there are probably some people
here that aren't on the other lists who may have info that you need, 
or can benefit from your info.

It just seems odd that when you've got a list specific to the 
lightweight roadracer topic (and there seemed a lot of interest in it 
when I proposed starting the list) that you'll post to the other 
lists and not to this one.

With puzzlement,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

Date: Sun, 25 May 1997 16:53:49 -0800
From: "Michael Moore" 
Subject: LtWtRR Oh No!  Another vintage road race project

Hello, 

My name is Michael, and I'm a projectaholic.

While at Craig's shop the last two days I did a deal with his friend
Marc to buy his MotoBi (also known as Benelli) horizontal-cylinder
250cc four stroke stuff.  This is a fairly complete chassis with
presumably running engine and 2 additional engines.  It appears that
all the bikes are 4 speed transmission models.  In the spares is a new
race kit head (with "RR" lettering stamped below the exhaust port on
the underside of the head) that looks to have much bigger ports than
the standard head.  There is also a new camshaft with "S" designation,
but we don't know if that stands for Sport, Speziale, or Standard
(maybe spatzle? - probably not since it is an Italian engine).

Craig and I spent about 40 minutes looking at the parts and scheming
on what to change.  The crankshaft is not a real impressive looking
item.  It has the same stroke as an XR200 Honda single (and is about
the same width), and the mainshafts on the Honda crank are enough
bigger that they could be turned down and modified to work in the
MotoBi.  This would also give a bigger crank pin.  

The 4(!) ring piston isn't very impressive either, but it is the
same bore as an XL250, and they are both flat top pistons so that is
solved too.  The Honda piston uses a 1mm bigger wrist pin, but since
the deck height is a little lower that would probably be taken care of
by ordering a slightly longer Carrillo rod to the appropriate
length/ID dimensions. 

Megacycle is supposed to have a master for the factory race kit cam,
so I'll contact them for timing specs on that to see what cam I've
got, or if the race kit cam will be at all suitable.  Craig looked
through some catalogs and found some 5.5mm stem titanium valve blanks
in appropriate sizes, and I'm sure that R/D Spring will either have a
suitable valve spring set or can come up with one once I send them a
head.  This time I won't worry about trying to come up with
replacements for the OEM parts as I did for the Laverda - whatever
retainers they've got on the shelf are what will be used.

Craig said the intake port didn't look too bad, but the exhaust is one
of the wretched flat ports that the Italians seemed to love to put in
their engines.  I see a bit of TIG welding in the exhuast ports
future.

Ivar very kindly took some time send me some MotoBi information.  He
told me that the factory bikes had trouble with the side thrust from
the helical primary gears (much as do Ducatis - Nova sells a straight
cut primary set for the Ducs) so this is going to have to be
addressed.  

The transmission is the other sticking point.  All of the engines I
got appear to be 4 speed boxes, which strikes me as less than optimum
for a 250 race bike.  5 speed models were also sold in the States, but
Ivar tells me that all the factory racers used 4 speed transmissions. 
The standard 5 speed has a wider overall spread than a Ducati 5 speed
(and we won't even mention how it compares to an Aermacchi race
gearbox!), and the top gears aren't very close together.

The immediate conclusion was to find another transmission to install
(since I know of another Italian 250 racing bike that is running a
CR125 6 speed).  But wait - the MotoBi uses an English-style
transmission with a mainshaft/layshaft setup (power comes in and goes
out from the mainshaft), not a typical Italian/Japanese indirect
crossover type box where the power comes in on the main shaft and
leaves via the countershaft.  The 4 speed cases are fairly narrow
inside as well.  Hmmmm,  this is going to require more thought.  

I've been emailing with a fellow in Australia who has some of the 5
speed engines, but even there new gears would have to be made, though
this might be less trouble in the long run than finding a different
transmission to swap into the engine.  Then again, most of the tracks
over here don't have (m)any first gear corners, so if I could build a
dry clutch that would tolerate a lot of slipping on the start a close
ratio 4 speed might be tolerable.

I don't know yet if Zanzani or others made straight-cut gear
conversions or different transmission ratios, but I'll find out.  I
now have a (presumably) good address for Werner Maltry, who developed
a lot of the factory racers and his own LinTo-type 500 twin based on
the MotoBi single, so I'll drop him a line and see if he recalls any
helpful information.

I'll build a new chassis for it.  Ivar told me that Zanzani made a
space frame for sale for the bikes, and I see no problem doing a
replica of that or a LinTo 500.  The lower rear motor mount appears to
be usefully wide, but the top mounts are only 30mm wide and about
60-70mm apart.  Hmmmm, maybe a bit more TIG welding will be called for
here.

The engine has a pretty narrow chain line with about 10-15mm 
clearance to a 3.00x18 Avon tire, so it may need to be slightly 
offset in the frame to allow a 90 or 100 section tire.

I think that a set of late model external-damper Guzzi GP pattern
leading link forks are likely, or maybe some Reynolds type LL forks,
whichever seem to be more appropriate for the link geometry that I
decide upon.

Before you know it (well, maybe late next year) I may have a perfect
replica of the MotoBi racer that everyone wished they were riding in
1965.

As you might guess, any bits of MotoBi lore, legend or engine 
components are desired - you know where to find me.  I guess I need to
see if the Benelli club caters to MotoBi - or maybe I'll have to start
a MotoBi club myself (in my copious spare time - right).

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

Date: Mon, 26 May 1997 20:49:09 -0800
From: "Michael Moore" 
Subject: LtWtRR SS1 Dell'Orto Manual

Moto Italia has a couple of pages from an SS series (remote float 
smooth bore) Dell'Orto manual on their website at:

http://www.aa.net/~garage/motoital/dellorto.html

This is some good information that I hadn't seen before.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #21
***************************
LtWtRR-digest         Wednesday, May 28 1997         Volume 01 : Number 022




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Date: Tue, 27 May 1997 14:58:06 -0700
From: Jason Van Slyke 
Subject: LtWtRR SRX250

To Bill:
Your nospam system didn't like my original message, so this message is
now for everyone:
I, too, have an SRX250 that I have been trying to make faster and handle
better.  KEEP the recommended tire sizes---DO NOT CHANGE SIZES UP!  It
makes the turn-in a lot slower.
I used to have a somewhat restrictive filter and I actually saw 105 (the
speedometer needle buried against the stop and rpms rose), then I put in
a Uni filter
and it suffered severe stumble from 2-5K, then seemed to come on
stronger at higher rpms.  I put in two 3mm spacers on each needle jet to
raise them and it cured the stumble.  Got more induction noise and a
little louder exhaust (now probably to 89dB from 88) but would only wind
out to
perhaps 102.
There are no exhausts available, as you may well know.  Michael
has given me information on new carbs, and I'm very interested. 
What would really help is a brace going from the head to the swingarm
mount to give it a lot more stability.  
I saw a guy who had a solo seat conversion which is really cool.  I have
the manual and bought it last October---it is a reprinted copy from a
Yamaha dealer which looks like a Kinko's special.
But the point Michael brought up is where do you stop with something
like this bike?  Putting on good rubber may be about the best thing you
can do, because the general consensus seems to be there is severely
diminished returns from doing any modifications on this bike.

Good luck,
Jason

------------------------------

Date: Tue, 27 May 1997 10:24:17 -0400
From: Bill 
Subject: Re: LtWtRR SRX250

Jason Van Slyke wrote:
> 
> To Bill:

> I, too, have an SRX250 that I have been trying to make faster and handle
> better.  KEEP the recommended tire sizes---DO NOT CHANGE SIZES UP!  It
> makes the turn-in a lot slower.
> I used to have a somewhat restrictive filter and I actually saw 105 (the
> speedometer needle buried against the stop and rpms rose), then I put in
> a Uni filter
> and it suffered severe stumble from 2-5K, then seemed to come on
> stronger at higher rpms.  I put in two 3mm spacers on each needle jet to
> raise them and it cured the stumble.  Got more induction noise and a
> little louder exhaust (now probably to 89dB from 88) but would only wind
> out to perhaps 102.

So the uni filter HURT performance? 

> There are no exhausts available, as you may well know.  

I have considered making one from tubing, I've done this before
but it's a lot of work....

> Michael has given me information on new carbs, and I'm very interested.

I am interested in better carburation, but only if it's worth the $$$,
without a cam and exhaust, I think it may be a lost cause.

> What would really help is a brace going from the head to the swingarm
> mount to give it a lot more stability.
> I saw a guy who had a solo seat conversion which is really cool.  I have
> the manual and bought it last October---it is a reprinted copy from a
> Yamaha dealer which looks like a Kinko's special.

I'll ask at the other Yamaha ha ha dealer if I can get a manual. 

> But the point Michael brought up is where do you stop with something
> like this bike?  Putting on good rubber may be about the best thing you
> can do, because the general consensus seems to be there is severely
> diminished returns from doing any modifications on this bike.

Do you mean that this bike is pretty close to the best it can be or
that it is too limited to be worth spending money on it?

> Good luck,
> Jason

I heard rumors that the motor in this bike is the same as the off road
250 4 strokes, can anyone confirm or deny this?

I have to change the clutch soon but I don't recall where to 
put the bolts to keep the clutch pack together on a yamaha, I haven't
seen one in a while. Anybody remember the procedure?

Bill

*  If everything is going well, you don't know what the hell is   
   going on.

------------------------------

Date: Wed, 28 May 1997 16:52:52 -0800
From: "Michael Moore" 
Subject: Re: LtWtRR SRX250

> > But the point Michael brought up is where do you stop with something
> > like this bike?  Putting on good rubber may be about the best thing you
> > can do, because the general consensus seems to be there is severely
> > diminished returns from doing any modifications on this bike.
> 
> Do you mean that this bike is pretty close to the best it can be or
> that it is too limited to be worth spending money on it?
> 
> I heard rumors that the motor in this bike is the same as the off road
> 250 4 strokes, can anyone confirm or deny this?

Hello Bill,

The off-road engines are basically the same, and my friend Craig says 
that it looks like the TT350 is a pumped up 250 since the valves are 
a bit small. 

An SRX250 would be a fun project to drop a grand or two into. . . 
Unfortunately, project bikes often seem to cost the same for the same 
results, no matter what the original bike was.  You might find that 
after coaxing a relatively big amount of bhp out of the engine that 
the chassis is now not as adept as it was with less bhp, and then you 
start spending money on the chassis, wider wheels, better brakes, 
modified chassis, etc.

You might look to see if you could swap a 350 motor into your bike.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #22
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LtWtRR-digest           Friday, May 30 1997           Volume 01 : Number 023




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Date: Thu, 29 May 1997 20:26:51 -0800
From: "Michael Moore" 
Subject: LtWtRR Kicking people off the list

> By the way...did you throw me off all of your new lists ... I
> haven't gotten any mail for awhile.

I checked and you aren't currently subscribed.  Some ISPs seem to
bounce up and down, disappear for awhile (as far as the mailing
process goes), can't recognize their own subscribers, people go away
on vacation and their mailboxes get full, etc.  I think this is a
fairly widespread problem.  I'll let a subscriber go for 2-3 days of
bounces, but after that I presume that the email address is terminal
(usually after trying a direct message that gets bounced) and
unsubscribe the person.  If you are in digest mode on my lists you
should be getting a couple of digests a week minimum, so if you don't
get anything after a bit you might drop me a direct email to check.
I've had my ISP contact me to have people unsubscribed when the
bounces get very heavy (ie lots of list traffic).

Sorry for the inconvenience, but MY mailbox starts getting filled up
with bounce messages, and I have to look at each one to see if they
are different people or just one.

I now have instructions on subscribing for all five lists on their own
page on the web site.  I'll see if I can come up with an easy way to
get the digests on the web site, but you can always mail me and let me
know the last digest/message you got and I'll send you the digests you
missed.

Cheers,
Michael 
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

Date: Fri, 30 May 1997 21:59:24 -0800
From: "Michael Moore" 
Subject: LtWtRR Lots more pictures on the web site

The latest addition is an entire section devoted to some of the 2, 3
and 4 wheeled racing vehicles (and a 120 mph race-vehicle transporter)
constructed by former GP sidecar racer/constructor Rudi Kurth.

There are Kurth CAT sidecar outfits with BMW twin Rennsport four
stroke and Crescent and Yamaha 3 cylinder (yes, Yamaha) two stroke
engines.  The solos are Yamaha and Crescent triple powered
semi-kneelers, and the four wheelers include Alfa and Fiat racers, as
well as the CATVAN and several solar-powered racing vehicles.

I've also set up a separate page for the line of composite chassised
bicycles that Rudi makes.

Cool stuff - check it out.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #23
***************************
LtWtRR-digest           Sunday, June 1 1997           Volume 01 : Number 024




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Date: Fri, 30 May 1997 21:59:25 -0800
From: "Michael Moore" 
Subject: LtWtRR Eat your hearts out!

I've excerpted a section from a message sent to me by Ivar.  Not only
did he do this last weekend, but he should be at the Isle of Man now!

Enjoy reading it - I did.
Cheers,
Michael

**********************************************************
Ivar wrote:

Last weekend I went to the CRT races. They ride in 6 classes,
50/125/250/350/500 and sidecars. Each class, but especially the 50,
has very interesting racing bikes, all classes have production racers
in them, some have factory racers competing. 

In the 50cc class some old G.P. riders from the seventies ride their
bikes, like Aalt Toersen on his 50cc Kreidler. He rides like a rocket
and the Kreidler is really extremely fast. Three or four other van
Veen Kreidler's compete, together with a batch of sixties Kreidler's,
Jamathi's (!!), FB Minarelli's, Sachses, and some home-made racing
bikes like a Hercules (with very intersting light-weight leading link
fork), Garelli, Moto Guzzi and Gilera. 

The bigger classes are interesting as well, seen can be a extremely
nice and fast 125cc Villa racing bike, ex. factory, who competes in
the 250 since it is so bloody fast. He competes often with a Yamaha
250 factory racer, which once belonged to Phil Read. It's nice to see
the rider makes a difference as well. Many Aermacchi Ala d'Oro's can
be witnessed, many carry a Metisse frame, in the 350 an ex. Sid Lawton
Aermachi competes, with it's distinctive light green colour. These
bikes are real fast and very well handling as I could judge myself
during a test spin. The 500 is very interesting. 

Some Crooks-Suzuki's, Yamaha 500's, and a bunch of hopped up
Goldstar's, 50's Gilera Saturno's, a Vincent Comet (Grey Flash
replica), Ducati single's compete enthousiastically against each
other. Most times the battle is against a Yam. 500, a Crooks Suzuki
and a hopped up Duc. 450 (non desmo). The Ducati rider sweeps with the
bike in a way which is not to be expressed in words, FAST!  On
straights he loses, but he makes it more then well in corners, and
just after corner's torquey accelaration.  Indeed, the rider makes the
difference.  He carries still stock brakes, naturally with non stock
linings.  "It's a hobby", he always says when someone asks him why he
doesn't ditch the old brakes.  The CRT races are always fun, and
atract a crowd as well. 

------------------------------

Date: Sun, 1 Jun 1997 10:40:07 -0800
From: "Michael Moore" 
Subject: LtWtRR Determining rear damper length

I initially wrote this to send to Alec Millet in Australia, who is
trying to decide what dampers to buy for his Ducati 350 road racer.  I
thought that it might be of use to someone else.  This is a pretty
basic treatment, and if you are running a 100 bhp bike this procedure
may require a bit of modification on the final setup.
********************************************

Before buying your rear dampers do this:

Pull off the dampers and let the tire rest inside the rear fender.
Measure the center-center distance on the damper mounts, then add 1/2"
to that for fender clearance and record this dimension.  Be aware that
fender clearance can vary with chain adjuster position so to check
that out move the adjusters full forward and full aft to see if the
minimum clearance changes.  

Now put the bike back on the stand (still without dampers) and let the
rear wheel droop.  I don't know if you still have the passenger peg
mounts, as they are often used as an exhaust mount on the Ducati
singles, but let the wheel go down until you start to see the chain
interfering with the top of the swing arm pivot or other parts of the
bike.  Measure the damper mounts again.

Now align the c/s sprocket, swing arm pivot and rear axle on the
same line.  Measure the damper mounts again.  This should be the
tightest point on the chain, and the chain will loosen as the rear
axle moves up or down.  This is a good time to set your chain tension.
 When you get a final setting on the damper lengths you can measure
the chain slack at full extension of the rear suspension and record
that figure for later use.  This is much easier than pulling the
dampers off every time you want to adjust the chain!

You now know the potential maximum and minimum lengths of the
dampers. 

Try to get a 4" travel damper, as the Ducati dampers are not heavily
leveraged on the swing arm and 4-5" of travel is pretty nice to have
on a road racer, especially on a bumpy course.  I think that both my
Laverda and the Honda run close to 5" of travel in the rear
suspension.  The longer travel lets you run a little more sag,
allowing the rear wheel to move down into dips in the road instead of
leaving the ground when encountering the dip.  The longer travel will
also let you run a lighter spring.  Sometimes the dampers come with
shorter travel done by adding spacers on the shaft, and I've
successfully cut these off of Girlings/Hagons (the Hagons are plastic)
to increase travel. Don't confuse these spacers with the rubber bump
stop.  Always presume the bump stop will compress to zero when
figuring the actual shaft travel of the damper.

Consider making the travel symmetric about the "3 points in a line"
figure, as that will keep the chain tension most constant.  Record the
max/min damper lengths that this gives you, and compare with the
potential max/min lengths you measured earlier.

I'd recommend biasing the length a bit towards the long side, as that
will steepen the front end a bit and give some more ground clearance.
As long as you aren't having massive chain rub on the swing arm pivot
you probably don't need to worry much about excessive anti-squat in
the rear end (besides, it doesn't seem to make a great deal of
difference in our small displacement low-powered vintage bikes). 

You now have a good idea of what damper length you need for your bike,
which may well be different than the length of the OEM damper, or what
your local "never seen one of these bikes, mate" parts guy will
recommend for your bike.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #24
***************************
LtWtRR-digest          Saturday, June 7 1997          Volume 01 : Number 025




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Date: Sun, 25 May 1997 16:38:39 -0400
From: Bill 
Subject: LtWtRR Tires?

Hey, I am looking for an appropriate tire for my SRX250.

I am thinking about the Bridgestone BT39SS or BT90
but I can't seem to find these.

Thanks,
Bill

------------------------------

Date: Sat, 7 Jun 1997 16:48:53 -0800
From: "Michael Moore" 
Subject: LtWtRR MotoBi pictures

I've added several photos of the MotoBi 250 team at Daytona in 1962
(thanks to Michael Green for making them available) and a photo of
Kurt Liebmann winning a 200cc race in the early 1960s.

They are on the graphics page on the website - the MotoBi photos now
have their own section instead of being in with the other vintage
roadracers.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #25
***************************
LtWtRR-digest          Tuesday, June 10 1997          Volume 01 : Number 026




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Date: Sat, 7 Jun 1997 20:57:15 -0800
From: "Michael Moore" 
Subject: LtWtRR Another photo

I've just added an action shot of a 50cc Honda CR110 road racer at
Brands Hatch in 1966.  It is located at the top of the "vintage
Japanese" section on the graphics page.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

Date: Tue, 10 Jun 1997 11:37:11 -0400 (EDT)
From: "Mark J. Andy" 
Subject: LtWtRR '94 RS-125 stuff for sale

Howdy,

Got some extra parts left from my '94 RS-125 that I need to sell:
(ML == MotoLiberty price)

new  head 	 (ML$135)	$70
new  CDI  	 (ML$165)   	$100
used peg hangers (ML$60 & $58) 	$50 (both) (excellent condition)

Package deal $200 for all.

Mark

  -------------------------------------------------------------
                  The 1997 M and N Racing Team
    Team Owners:  Laura Maynard-Nelson, Paul Hoyt Nelson
         Riders:  Paul Hoyt Nelson (WERA/CCS/NASB Expert #81)
                  Mark Andy (WERA Expert #3)
          Tuner:  Connie S. Brooks
        Manager:  Laura Maynard-Nelson
  -------------------------------------------------------------

------------------------------

End of LtWtRR-digest V1 #26
***************************
LtWtRR-digest          Monday, June 16 1997          Volume 01 : Number 027




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Date: Wed, 11 Jun 1997 17:13:25 -0800
From: "Michael Moore" 
Subject: LtWtRR Aermacchi Transmissions

If anyone out there has an Aermacchi 4 stroke single I'd be very
interested to hear how the clutch and countershaft sprockets are
located in the engine.  

The pictures (all of which have the side cover on) that I have make it
look like the clutch and c/s sprocket are both mounted on the same
shaft (at opposite ends of the shaft).  If so, this would be the same
set up as my MotoBi, and means I need to start looking at Aermacchi
transmissions for possible use in the MotoBi racer project.

Thanks,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

Date: Mon, 09 Jun 1997 19:22:31 -0400
From: Bill 
Subject: LtWtRR Race Tires for small bikes

Hi all, I am looking for appropriate tires for my bike.

It is an SRX250 and I slide it around alot ( tires are rocks )

I have decided that I would like the Bridgestone BT39SS or BT90
tires but I cannot find them.

Sizes are F= 90/90-16  R= 100/90-18

Min speed rating required is S (105 mph)

If you have another good suggestion for a light bike like this,
please tell me about it.

Thanks, 
Bill
1987 Yam SRX250 race toy
1994 BMW R100M  new streeter
1975 BMW R90/6  old faithful

------------------------------

End of LtWtRR-digest V1 #27
***************************
LtWtRR-digest         Thursday, June 19 1997         Volume 01 : Number 028




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Date: Tue, 17 Jun 1997 16:54:56 -0400 (EDT)
From: SCOTTA336@aol.com
Subject: LtWtRR Reed calculations

Folks, 

I found some interesting info on the Boyesen web page, in particular an
article by
Kevin Cameron on reed theory.  He says Yamaha figures that for best power the

natural frequency of the reed ought to be 80% of the engine's speed in RPM.
 He
goes on to give the equation for the fundamental frequency

F=(3.52/2pi)* (Eb^2g/12DL^4)^.5

where E is Young's modulus, b is the thickness, g gravity, D the density of
reed
material, and L the free length of the reed.

Then he goes on to simplify for steel material, 

F = 32900B/L^2

Here's where it falls apart for me.  I plug in Young's modulus and the
density of steel, 
change the units just like they taught me in engineer's school, and I get
nothing like
his simplification.

Anybody else want to take a crack at this?  

------------------------------

Date: Tue, 17 Jun 1997 16:58:31 -0500 (CDT)
From: "Paul C. Kurth" 
Subject: Re: LtWtRR Reed calculations

On Tue, 17 Jun 1997 SCOTTA336@aol.com wrote:

> 
> F=(3.52/2pi)* (Eb^2g/12DL^4)^.5
> 
> where E is Young's modulus, b is the thickness, g gravity, D the density of
> reed
> material, and L the free length of the reed.
> 
> Then he goes on to simplify for steel material, 
> 
> F = 32900B/L^2
> 

I don't know why that gravity term is in there, but if you use B^2 
instead of B^2g you will get Cameron's reduced frequency calculation.

I got F = 32781B/L^2  by using D = .73E-3 and E and 30E6.

Make sure that your units are correct. E is usually given in inches and 
pounds, while density varies from pounds per cubic foot to pounds per 
cubic inch, depending on your reference.


Cameron

PS I just derived the natural frequency equation, I sure would like to 
know why he stuck that gravitational term in there.  

------------------------------

Date: Fri, 20 Jun 1997 09:52:56 +0800
From: Matthew Carter 
Subject: LtWtRR RS125 Tyres Sizes

Hi,

Still looking for some info on '91-'93 RS125 tyre sizes.

I've got an '89 but with 17" wheels. 3.15x17 and 3.00x17

What tyre sizes would be suitable?

I've currently got 90/575 and 105/585 Bridgestones. I think I can go wider
on the rear (115)as it wears to the edge while the front is nowhere near.

Ta,
Matt

- ---------------------------------------------------------------------------
Matthew Carter		 			mjcarter@cyllene.uwa.edu.au  
Robotics Laboratory,			  	     Ph (09) 328 7740  (Hm)    
Dept of Mechanical & Materials Engineering,	        (09) 380 3051 (Lab)
University of Western Australia
- ---------------------------------------------------------------------------
YOU WANT INTERNET INTERACTIVITY?   	  http://telerobot.mech.uwa.edu.au/

------------------------------

End of LtWtRR-digest V1 #28
***************************
LtWtRR-digest         Saturday, June 21 1997         Volume 01 : Number 029




----------------------------------------------------------------------

Date: Fri, 20 Jun 1997 10:11:57 +0800
From: Matthew Carter 
Subject: Re: LtWtRR RS125 Tyres Sizes

Whoops!

Should be 2.15x17 and 3.00x17

>I've got an '89 but with 17" wheels. 3.15x17 and 3.00x17

Doh!
Matt

------------------------------

Date: Fri, 20 Jun 1997 13:35:09 +1100
From: Daniel_Builth-Snoad@wlgore.com
Subject: Re: LtWtRR RS125 Tyres Sizes

Hi Matt,

I'm running a 92 with Machesini 3.25 & 3.00 x 17 over in Sydney and I've
tried a few tyre combos. Currently I'm running a 120 Michelin rear but it
would be a little too big for your 3.15 I would say (which is a shame
because the Mich's are great but have limited sizes). Prior to that I had a
115 Yokie which worked well for the rim size and would be the size for you
to go for.

Hpe this helps, Danny

>Still looking for some info on '91-'93 RS125 tyre sizes.
>
>I've got an '89 but with 17" wheels. 3.15x17 and 3.00x17
>
>What tyre sizes would be suitable?
>
>I've currently got 90/575 and 105/585 Bridgestones. I think I can go wider
on the rear >(115)as it wears to the edge while the front is nowhere near.
>
>Ta,
>Matt

------------------------------

Date: Fri, 20 Jun 1997 13:34:49 +1100
From: Daniel_Builth-Snoad@wlgore.com
Subject: Re: LtWtRR RS125 Tyres Sizes

Hi Matt,

I'm running a 92 with Machesini 3.25 & 3.00 x 17 over in Sydney and I've
tried a few tyre combos. Currently I'm running a 120 Michelin rear but it
would be a little too big for your 3.15 I would say (which is a shame
because the Mich's are great but have limited sizes). Prior to that I had a
115 Yokie which worked well for the rim size and would be the size for you
to go for.

Hpe this helps, Danny

>Still looking for some info on '91-'93 RS125 tyre sizes.
>
>I've got an '89 but with 17" wheels. 3.15x17 and 3.00x17
>
>What tyre sizes would be suitable?
>
>I've currently got 90/575 and 105/585 Bridgestones. I think I can go wider
on the rear >(115)as it wears to the edge while the front is nowhere near.
>
>Ta,
>Matt

------------------------------

Date: Sat, 21 Jun 1997 20:43:21 -0800
From: "Michael Moore" 
Subject: LtWtRR Another photo

I've just uploaded a picture of some modern girder forks that Tony
Foale made for a customer.  Tony was surprised at how well they
worked, and thought they had some advantages over telescopics.

It's at the top of the "Tony Foale" section on the graphics page of my
web site.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #29
***************************
LtWtRR-digest          Friday, June 27 1997          Volume 01 : Number 030




----------------------------------------------------------------------

Date: Sun, 22 Jun 1997 12:04:59 -0800
From: "Michael Moore" 
Subject: LtWtRR Vintage Japanese site URL

This looks pretty interesting - a fellow in the Netherlands passed the
url to me.

>>Perhaps you've found it already, but there is a Japanese site,
with a huge picture gallery on Japanese classic racers up to 125cc. I
found it amazing (never seen 23 Honda CR110 racers in one picture):
http://lump-proof.com

Paul Kellner>>

Check it out if you haven't already.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

Date: Fri, 27 Jun 1997 10:17:39 -0800
From: "Michael Moore" 
Subject: LtWtRR Lots more photos

I've just added a number of photos to my web site's graphics page.

Included are shots of one of Tony Foale's racing sidecars, details of
the Q2 rear axle setup, and shots of a FF bike to which Tony assisted
the owner in fitting one of his QL front ends.

There are some new photos of Ollie McKagen's alternative front end
dirt bikes, and one of his projects with a space frame and
old-fashioned telescopic fork.

I've also (over the last few days) added pictures of various small
Italian ISDT bikes, a page for my Laverda 150 vintage MX project, and
some other stuff that escapes me at the moment.

Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Distributor of Lucas RITA and Powerbase products
Sole North American source of "The Racing Motorcycle: a technical guide for constructors"
http://www.eurospares.com
AFM/AHRMA #364

------------------------------

End of LtWtRR-digest V1 #30
***************************



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