Thumper SportBike? e.g. CBR600 Frame, XR650L engine?

I'm a big thumper fan, and would like to have a sporty, good handling
street bike. Seems there hasn't been such a beast since the Honda FT500
Ascot.

How hard would it be to build a custom hibred? I've read about a guy in
Florida who stuffed a XR650L engine into an imposable to get Honda
NSR250 frame. I can't find the link now, and parts availability sounds
to be a chore. Are there any easier transplants?

I was thinking about what it would take to stuff a liquid cooled Honda
XR650L Thumper engine into a CBR600 frame, then rewrap it with CBR600
body work. Or maybe stuffing a Yamaha WR450F engine into a YZF or FZR
600 frame?

Basically, I want a "cool custom" bike, with the big thumper torque and
engine feel, in a "crotch rocket" looking body. I could deal with
"crotch rocket" seating, but would prefer "touring" upright seating.
And, I definitely don't want a cruiser!

Considering all the trashed donor bikes out there right now, and having
some friends willing to do custom part fabrication, I would think there
might a real cool project in this. Anybody out there have some solid
advice about what engine/frame/body combos that would require the least
work?

Thanks in advance.

 

Lots of people have done it. I've seen a old Harley side-valve engine in
a BSA frame (OK, so not a thumper) and it looked as if it were made for
it.

I've seen an SR500 engine in, I think, an RD frame. The trouble is that
with thumpers, the quality of the chassis is rarely the problem - it
doesn't take much of a frame to contain 40-odd bhp, for God's sake. And
some of the frames you suggest may weigh more than an original thumper
frame anyway, bearing in mind they're designed to handle 100+ bhp (OK,
so they use lighter materials, but....)

No the thumper problem is that they just aren't powerful enough unless
you spend lot and lots of money and they aren't always that light.
Probably the best thumper, out of the crate, was Honda's XBR500. But
Yamaha's SR500 has a cult following and can be persuaded to go quite
well for not much money.

I'd be tempted to buy something like an SR500, slim it down, strip it to
near-nakedness, and then breathe on the engine, to build an anorexic
little street racer. I've seen a few of these as well, and they've all
been brilliant.

 

Here's what you want:

http://www.yamaha-motor.co.uk/products/motorcycles/street/xt660x.jsp

As the ad copy says:

"Yamaha's name is synonymous with challenging and innovative designs,
and the radical new XT660X is the first production supermotard to be
offered by a non-European manufacturer.

Tuned to kick out massive low to mid-range torque, this 660cc liquid-
cooled fuel-injected single is equipped with lightweight 17-inch
spoked
wheels running with extra-wide rubber for outstanding roadholding -
while the large diameter floating front disc generates plenty of
stopping power."

Yamaha also still makes the venerable SR500 from 1978, but in a 400
cc size called the "SR400". They sell it in the Japanese market.

See: http://www.yamaha-motor.jp/mc/lineup/sportsbike/sr400/index.html

Now if only they would import these bikes to North America...

:<

 

I have easy access to a EX250R (Kaw baby Ninja). HP wise, it's a match.
Original, it's 300lbs (give or take 5 pounds?). Size wise, how far
off is that from modern liquid cooled thumper engines?

I live in the desert, 120°F or higher temps are common. As solid as the
SR500 engine is, I'd like to stick to a liquid cooled engine.

 

Sorry, 120°F is a bit of an exageration. But 110°F+ would be very true.

 

WOW... The SR500 can be sexy...
http://sr500.cyberrunner.de/25-jahretreffen/bilder/00443.jpg
Looks so Norton...

 

....they'd probably lose money on it, because they wouldn't sell enough
of them to cover their fixed costs.

No matter how fanatical the devotees of a certain model or type of bike
may be, it all comes down to how many units the maker can sell. Cruisers
sell far better than cafe racers, so there are plenty of cruisers on
the market and fewer cafe racers.

 

How about one of these, an Mz "Traveller":

http://www.motorradna.com/MODEL-TRAVELLER.htm

Mz's seem to be awfully rare, but this was a pretty interesting bike.
This one had a Yamaha 660 (5-valve?) thumper. It was dropped after
2002, but I wouldn't be suprised if you could find a left-over new one
at a dealer someplace.

Regards,
Hugh
83 Honda Ascot VT500FT

 

isn't there a street or supermoto version of BMW 's big single?

 

That is utterly *gorgeous*. (x-posted to ukrmc where the old boys will
dribble into their pints of bitter)

Much better aiming for that sort of look than trying to stuff the thing
into an alloy frame, IMHO.

 

True, but the SR was only discontinued in Europe in 1998 after a
production run of 20 years!

It was dropped in the UK in the early 1980s, but the French and Germans
carried on buying it for another 15 years.

 

GB500 lookalike. They lurve SR500s on the Contingnent, tune the bollock off
them, race them, the whole bit. Over here, we whinge because they're only
as powerful as genuine Gold Stars, and merely ordinarily reliable.

 

Didn't know that, but I am not surprised that the SR500 lived on
in Europe. I should have explicitly stated I was talking about the
US market- mea culpa.

I have a friend with a '78 (I think) SR500, and I'd quite like to
'have a go' on it. First, I have to convince him to bring it back from
hibernation, as I doubt he's ridden it even once in the last 10 years.

 

Not quite as retro, but I think this one is more sexy:
http://www.pe-we.de/SR14_1.JPG

 

whassat vent hose thingie attached to the fuel tank filler do? i kinda
remember older gixxers having em too. whats it for? whys it there? why dont
other bikes have em?

 

Try tracking down an MZ Skorpion, Yamaha XTZ660 engine in a modern road
frame and suspension. They were brought in from the late 90s up until
last year http://www.motorradna.com/MODEL-TRAVELLER.htm. I sam them at
my no sadly defunct BMW dealer around 99-2000 and they seemed like a
nice little bike and you would only have to tweak the engine and
suspension instead of reengineering

Ed
1978 BMW R100s

 

I know 2 people in the UK who own these bikes - one has the stock
Skorpion and the other has the Traveller (fairing and fitted panniers).

Yes, they are nice. Too much money, new, for what they were (and
slightly iffy build quality) but nice bikes.

 

They did.

Allows air into the tank (to replace the petrol that's going out)

All bikes have some version, but often they're built into the filler
cap or sometimes run internally, so they're not obvious.