Topic: Turbo Charged CB550 Landspeed Attempt

[madmtnmotors]

Subscribed in order to live vicariously through y'alls endeavors on the salt! 

[Old Scrambler]

We breezed through tech after waiting in line for a while...........754 MPS CG 750

We set up in the pits about 10 spots down in the second row..........just past the Honey Buckets.

Leading-link front suspension and a somewhat flat tire-tread is best for stability.   You may want to experiment with an off-set tank to get your head lower and bend your handlebars downward with grips as low as possible.

[BomberMann650]

Just scrolled through scramblers class 750 racer thread.  That bike didn't stop at my paddock for inspection.
But...
If you're the man with the white hrc pants, than yeah, we totally did chat for a minute at the impound yard!

I did consider a leading link front.  But after reviewing my list of spare parts.  The shock springs i have in surplus are not well suited to the application.
Acquiring a gsxr front end is likely the route i will go.  Tuning the valves should make it a straight shooter.  Along with the steering damper!

The sidecar class rule 5b states

Standard  motorcycle  handlebars  are  required.

Not sure how to officially interpret that.  I could assume clip on's are a standard.  But it would suck to find out they want a solid bar that is clamp mounted. On the top triple.
No such statement in the purpose built A-class rules.  Albeit there is a limit to how much lower a bar grip can be.

The market for z-rated tires isn't looking so hot right now.  Low aspect ratio r17's are harder to source.  Hiro runs on a dunlop Q so maybe its not that big of a problem.

For the tank, might F-around and just make a coffin to lay in.

[Old Scrambler]

Yep........HRC leathers were inspected by the AMA steward.

Special Purpose is just that............no other class rules carry over

I tend to be very focused on my job until after the last run............so I don't remember BMST names and faces until Wednesday PM

[BomberMann650]

My Man!  I remember the hat
You were totally sharing secrets of how to sneak modified heads past ol' drew 😆

If you're wondering what i look like.  Im in the flat out 200 video.  Ep7@2:12
The sponsor bike failed tech twice before getting sorted to race

[Alan F.]

I just found something in another search that might be useful, have a look online for Aircraft Wheel Pants
a r.h.side pant might be the ticket for your hack, and I'll bet the wheel would be pretty damn low & light too.

Food for thought with dimensions: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.skyshop.com.au/pdf/2009-2010_catalog%2520198.pdf&ved=2ahUKEwjF24z1mrX1AhUjheAKHSo5Cj04ChAWegQIBBAB&usg=AOvVaw1P2HrRq2QENCuXCl5lllAF

[BomberMann650]

I just found something in another search that might be useful, have a look online for Aircraft Wheel Pants
a r.h.side pant might be the ticket for your hack, and I'll bet the wheel would be pretty damn low & light too.

Food for thought with dimensions: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.skyshop.com.au/pdf/2009-2010_catalog%2520198.pdf&ved=2ahUKEwjF24z1mrX1AhUjheAKHSo5Cj04ChAWegQIBBAB&usg=AOvVaw1P2HrRq2QENCuXCl5lllAF

Some of those are quite shapely - though im not sure what size tire cessnas use.  Will definitely reference the FAA approved pant should i get around to making my own plug mold

[Alan F.]

I think they're pretty small like a big scooter tire but probably rated for more speed.

[Old Scrambler]

Some tires weigh a bit more than others

[BomberMann650]

Having flashbacks to wheel changes on the farmall now.
Calcium filled.
Took some rigging to get em swapped.

[Old Scrambler]

Our 1925 Allis-Chalmers was converted from steel to rubber with calcium-liquid for added traction.

At your projected speed, modern m/c-tires will do................a front wheel and tire from a Super 90 would do on the chair.

[BomberMann650]

To think, how many kids complain about having to do chores like cleaning their room and putting the dishes away.
While some have to avoid getting crushed by agricultural equipment.  No belly-aching about it either!

Been digging around for sprockets.  Found one source for a 19t front.  The rear wheel and sprocket however.  Gah!
People are asking an arm and a leg for crusty old 550 wheels.  And 34t sprocket is the smallest i've come across.
19/34 gearing puts the 155mph target deep into the redline.

Meanwhile, a 250 rebel rear hub can be bought cheap.  Allowing a 30t rear sprocket
 puts the target speed closer to the engines happy place.

The custom spokes to lace a rebel wheel out to 17" though.  🤑🤑🤑

[Alan F.]

Prices aren't that bad if you don't mind import parts. Do you know the spoke lengths?

I'd recommended these spokes, eBay item number: 292653284788 to a guy on the Rebel Forum. He's in Okinawa and needed stainless for the salt air... His Vintage Japanese mechanic laced them up for him, so I guess quality was good enough for him.

I've got a set of complete 250 Nighthawk front and rear hubs to donate just hit me with a pm. I've got their measurements too so you can calculate spoke length once you have the hoops you want to use. These are both drum hubs, finding aluminum rims drilled for drum hubs is so easy.

Edit: these are 36 spoke hubs.

250 Nighthawk uses 520 sprocket & chain btw.

Spoke length calculator, I've used it a few times: http://earlymotor.com/leon/misc/html/spoke.htm

[BomberMann650]

Well its hard to say no to that!
Thanks Alan.  I'll get an address out to ya soon.

In the meantime, can you post up those dimensions?

[Alan F.]

I'll have to locate the hubs and brake plates first since everything's in storage, I've got 2 pair so shouldn't be all that bad to find. I'll post the measurements later tonight. Hey if it helps get you there I'm happy.

JTSprockets part number is jtr279.30 for 30t on eBay it's under $25 shipped.

Looks like Michelin Road 5 comes in a 140-17 Z rated.
https://www.jpcycles.com/product/48159/michelin-road-5-motorcycle-tires

[BomberMann650]

Yep, finding the 18 and 19t front sprockets for 520 conversion will be interesting.

Unless its possible to turn down a 530 sprocket to fit 520 chain.  Someone tell me if thats a bad idea

[Alan F.]

It's a good idea. 530, 525 and 520 are all the same pitch but different widths.

[Old Scrambler]

Your motor must have a LOT of power for those sprocket combos. Cast wheels have less flex and tend to be lighter.

[Alan F.]

Hub measurements 91-08 CB250 Nighthawk
Front
Hub diameter - 180.7mm
Flange spacing - 48mm
Dia of spoke hole - 5.08mm (10ga.)
Cross - 2
Number of spokes - 36
Stock Front spoke length calculates to 161mm
ERD = 441mm for stock 18" front rim

Rear
Hub diameter - 167.8mm
Flange spacing - 44mm
Dia of spoke hole - 5.3mm (9ga.)
Cross - 2
Number of spokes - 36
Stock Rear spoke length calculates to 133mm
ERD = 400mm for stock 16" rear rim.

If you find a pair of 17" aluminum rear rims from some rear drum brake equipped dirtbike you'll be in business.
With a 3.00 rim width you should be able to mount as narrow as a 110 and as wide as a 150, which is great because I find Z rated tires only as narrow as 120 front and 140 rear, so win/win. I'll keep an eye out for rims.

[BomberMann650]

Your motor must have a LOT of power for those sprocket combos. Cast wheels have less flex and tend to be lighter.

19/30 won't be the only sprockets in the supply box.
Not sure about a cast rear wheel that can mount such a small sprocket.  with spokes it seems simpler to get the center line wheel offset and chain alignment right.  In my head at least.

Im eager to get in the workshop.  Get out of the planning phase and into some real action.

Not gonna boast until rubber meets the halite

[BomberMann650]

Looks like Michelin Road 5 comes in a 140-17 Z rated.

Wish i could say nice things about my michelin road 5 experience.  It was a tire i had to think about too much while on tour.  Especially off pavement and even in the rain.  Which is where they claim to shine.

Hopefully supply chain issues improve later in the year.

[Alan F.]

Oops!

[BomberMann650]

Taking a roundabout first step towards the race bike. 
Since im having a terrible experience with college math. 
Signed up for the schools tig-welding class.  Stopped at the harbor freight for class supplies.
Paid a little extra for the paint job.  Vanity, sure - like that it matches my other helmets 😎

Dc tig welding in essence isn't difficult.  Of the various welding previously attempted.  Seems like a most relaxing way to melt steel.  Doing it well, on the other hand - thats gonna take some time.  Will see how i feel about it in 15 weeks.

If things went well on the dad's side of the country.  He should be muttering curses about now.  Figuring out how to unload a combination mill/lathe into the shop.  Something to the effect of "what kind of kid asks for a lathe for his feckin birthday ?- oh my feckin kid thats who! - this gurram thing weighs a bloddy ton - feck is this 220v?!"


 

[Alan F.]

Welding class should take the math edge off, good choice. Combo machine eh? Good capacity? Happy birthday.

[BomberMann650]

Yeah, the way they teach mathematics in a classroom is kinda lame.
Heck, i even got a little chuffed today in chemistry. 
Something about not needing to measure everything to the 3rd decimal point (course of habit 😆)

So the old man had a brush with an engine hoist trying to get the combo lathe hoisted around.  No damage to him or the tool.
It's not the fanciest machine shop tool out there.  Heck, everything on it is manual aside from the belt driven chucks.
But the seller was a tool repair guy and included a box full of cutting tips and milling bits.  So what he made on the sale was a fair rate.
Central Machine MM-LH-007

Looks like im on my own from here.  Any accessories or special tips will come out of my pocket.
Next tool on the order - Multi process welder