Topic: 1975 Supersport, performance cafe

[Doctor_D]

I think the anodized ends on the oil lines look great.

Thanks.  In the end, I wound up tapping both the engine and oil tank spigots with a 3/8" npt tap drill and simply threading in npt to AN fittings.  Took a few different tries at fittings, but it worked.  I'll go into more detail here soon if others want to give it a go.  The setup will also make my life easier when I go to put on the oil cooler, as a sandwich adapter won't fit behind my oil-filter housing with the CR pipes.

I spy a Fan-KEWLED ducati behind it looks lika a cadet model.. neat.

Good eyes.  It is a fan-cooled Duc 100cc 2-stroke.

420 lbs sounds pretty good.

Thanks.  Not sure how accurate I was with the bathroom scale technique, but that's the number I arrived at.  I'll get it on a proper scale when I get the chance.

[Doctor_D]

I went back to revisit the Mikuni RS34's over the last couple of days and am pleased to report that they're working fine.

I ordered new carb boots from Mike Rieck AND soaked them in Thor Oil Wintergreen  Tire Prep (http://www.thoroil.com/tirepreps.html).  Much easier to install.  I also removed the o-ring-like lip from the inside of the boot, which allowed the carbs to be fully seated.  Finally, I found some nice stainless clamps that look better than the stockers, are strong, and fit the groove in the boot perfectly. http://www.amazon.com/gp/product/B0036R4UDC/ref=oh_o00_s00_i00_details



The manual says the fuel screw should be 1/4 to 1/2 turn out, and is completely wrong.  Two and a half turns got me good mixture numbers on the AFR sniffer at the shop.  No, there are no vacuum leaks, in case you're wondering.  After figuring that out, it was just a matter of vacuum synching,  some fine tuning of the accelerator pump, resetting the idle, and one more go at the mixture screws -- and off to the races.

Went out for a shakedown spin, and was very impressed.  The bike is a lot more tractable down low than it was with the CR's.  Plus, you can send the front wheel skyward with a quick whack of the throttle - no bog whatsoever.  I could be wrong, but it seems quieter, sounding more like a modern sport bike. (I can actually hear the valve gear at idle - something that wasn't possible before.)

I want to increase the pilots from 17.5s to 20s this week, and hope to get it on the dyno before we ship it off to "The One" motorcycle show in Portland next weekend.  If I didn't have to detail it before the show, I would have filled up the tank and just kept going.

[Retro Rocket]

Thanks for the carb details Doc, bike looks great.....

[Doctor_D]

Tige was nice enough to nominate me for BOTM, which he's also up for.  Maybe it's time for a recap of the project.

The goal of this project was two-fold; respect the underlying motorcycle as much as possible, while improving the handling, braking, and acceleration.

It started with this, a forlorn 1975 Supersport that sat in the rain for a few years.



After which was two years of this...



And this...



And this...



And a little of this...



Culminating in this...



And this...



And finally, this...



For the record, it sounds like this:

www.youtube.com/watch?v=2kH7jKOSR00
Video courtesy of Tige Eakin, aka Tweakin.

Some of the parts and work include:

ENGINE
JMR "stage 4" ported cylinder head, oversized 5mm-stem Kibblewhite valves, titanium retainers, bronze valve guides
Wiseco 836cc, 10.25:1 big-bore kit
Megacycle 127-75 camshaft
APE lightened and balanced crankshaft
Polished and shot-peened stock rods with F2 rod bolts
APE cro-mo cylinder and case studs
Cycle-X back-cut transmission
Dynoman HD extra plate clutch kit
Dyna 2000 ignition, 3.0ohm coils, Dyna 8mm plug wire, Denso iridium plugs
31mm Keihin CR-Special carburetors (now Mikuni RS34's)
Replica CR750 exhaust

FRAME & SUSPENSION
Gusseted stock frame
Tapered steering head bearings
Steering damper
Bronze swingarm bushings
Works Performance alloy-tracker shocks, extended 1"
Works Performance fork springs
Racetech cartridge emulators
Redline 10wt suspension fluid (175cc's)

BRAKES, WHEELS & TIRES
Bridgestone BT45 tires
SKF sealed wheel bearings
Sun alloy rims, butted, polished stainless spokes
Speigler braided stainless brake lines
Ferodo Platinum brake pads
Drilled and thinned rotors

Special thanks to Jeff Tower, master fabricator and new owner of Twinline Motorcycles in Seattle WA, Mike Rieck, Simon Tappin, Frank (aka 754), and a slew of other people I might have missed.

The "finished" photos are by Todd Blubaugh.  More info here: http://www.toddblubaugh.com/test/index.php

[Blitzburgh207]

That is one incredible machine.  Gorgeous, and sounds fierce.  Something to aspire to for sure     Now ride the hell out of it!  Congratulations!  It must feel nice  Hopefully I'll see a power band like that someday...

[Doctor_D]

Thanks for the kind words.

You've got no idea how much I'd love to spend some quality time on this bike.  Sadly, I'm going to have to be patient a little bit longer.  It's going to a few more shows before I put a bunch of miles on it. In any case, the nice weather doesn't show up  in Seattle until mid-July.  Until then, I'm on my rain-bike, the CX500 (aka gutless wonder).

Hopefully I'll see a power band like that someday...

You know the old saying, "speed's just a question of money. How fast you wanna go?" 

[Retro Rocket]

Gday Doc, was that dyno run on the CR's or Mikuni's mate..?

[brandEn]

David the bike looks killer! I look forward to riding with you when it finally warms up and dries out.

So Ian sold Twinline?

[Industrial Rat400f Killer]

David the bike looks killer! I look forward to riding with you when it finally warms up and dries out.

So Ian sold Twinline?

I heard Isaac is the top dog now. Just a rumor I don't know if it's true.

[Doctor_D]

Gday Doc, was that dyno run on the CR's or Mikuni's mate..?

This run was with the CR's last year.  Trying to get a run in with the RS's tonight.  If not tonight, then it'll have to wait until early March.

[Doctor_D]

David the bike looks killer! I look forward to riding with you when it finally warms up and dries out.

So Ian sold Twinline?

I heard Isaac is the top dog now. Just a rumor I don't know if it's true.

No, Ians head mechanic and fabricator, Jeff Tower, took over the shop.  Isaac still stops in pretty regularly and does some CNC work for the shop.

[jaguar]

beautiful build

[Cheffish]

Where has this been hiding? Damn its nice! Jus found some new wallpaper for the pc. Well done

[tweakin]

Looks great David, love the new photo's.  All is good but you forgot to mention the video credit, lol. 

[Retro Rocket]

Gday Doc, was that dyno run on the CR's or Mikuni's mate..?

This run was with the CR's last year.  Trying to get a run in with the RS's tonight.  If not tonight, then it'll have to wait until early March.

Thanks mate, very interested in the comparison....

[Doctor_D]

Looks great David, love the new photo's.  All is good but you forgot to mention the video credit, lol. 

Edited original post to correct the oversight.

[Tews19]

SICK BUILD! Video was awesome. Where did you get the CR replica 4-4 exhaust?

[Doctor_D]

Thanks for the compliment and for stopping in.

Where did you get the CR replica 4-4 exhaust?

I got it from Simon Tappin, aka Lord Moonpie.  Lots of work needed to set them up and install them, including relocating the sidestand (they're for a race bike after all).  More info here: http://www.moonpie.co.uk/html/cr750_resource_page.html

[Tews19]

Thanks for the compliment and for stopping in.

Where did you get the CR replica 4-4 exhaust?

I got it from Simon Tappin, aka Lord Moonpie.  Lots of work needed to set them up and install them, including relocating the sidestand (they're for a race bike after all).  More info here: http://www.moonpie.co.uk/html/cr750_resource_page.html

Thanks Doc, OH JEEZE those aren't cheap!!!! Almost double my bike....Anyway, once again great build. Bike really screams.

[Doctor_D]

Thanks Doc, OH JEEZE those aren't cheap!!!!

Tell me about it.  Add to that the time we spent mocking them up, welding them, getting the mounting bracketry set up, then sending them off for ceramic coating and they were a bonafide extravagance.

[HonderCB]

I loves me a good F build, i cant believe i am seeing this for the first time.  Nice bike!  You guys up there in Washington sure know how to do up a supersport right!

[cbstevef]

Just read through your entire thread! amazing work! I have a 77 cb750f and want to do something similar! Just wondering about your rear sets set up and if your buddy that made you that seat has any left or would be willing to make one. I am very interested!

[FunJimmy]

This is one of the coolest pictures.
Great framing.

Cheers
FJ

[Doctor_D]

Just wondering about your rear sets set up and if your buddy that made you that seat has any left or would be willing to make one. I am very interested!

Fun Jimmy is making some awesome rearsets for folks. Mine work and look good, but I wouldn't want to put you through the exercise of welding on the CR rearset brackets.  My suggestion is that you PM Jimmy and see what he might be interested in doing.

As for the seat, I think Jeff has one that isn't spoken for.  Email tower@twinlinemotorcycles.com for details.  Not cheap, but hand made in steel and bomb-proof.  The shop now has a local upholsterer.  He does great work and turns projects around quickly.

[Doctor_D]

This is one of the coolest pictures.
Great framing.

Cheers
FJ

Coming from you that means a lot.  Thanks.