Topic: 1975 Supersport, performance cafe

[Old Scrambler]

This is one of the BEST reads to a great project!  Well Done! 

[Doctor_D]

This is one of the BEST reads to a great project!  Well Done! 

I'm very flattered.  Thank you 750, Ivanhoew, an Scrambler for the kind words.  Welcome to the thread.

Big day tomorrow, around 1pm PST we'll start the next set of dyno runs.  Finger's crossed (I took the "over" for $20 on 84 rwhp in the shop pool).

[ivanhoew]

so the change is just the cam D? what are the old and new cam specs ? just so i can join in on the predictions lol.

[Doctor_D]

I changed the cam from the previous runs and spent a little more time making certain it was degree'd in exactly.  Also, 3 head studs came loose first go around, so I was getting a little oil in cylinders 1 and 2. Finally, I went from 40mm to 70mm long velocity stacks.

Cam 1 Megacycle 125-65: intake .375 lift, 257deg duration, exhaust .354 lift, 253deg duration.
Cam 2 Megacycle 125-75: intake .400 lift, 262deg duration, exhaust .375 lift, 257deg duration.
(Duration at 0.050 lift)

First version put down 79rwhp. I'd love to hit mid/high 80's before all is said and done, but maintaining a broad torque curve and some semblance of streetability is equally important.

[ivanhoew]

if the lobe seperation is the same and they are both timed in the same ,that should relate to a 250 to 500  rpm higher pk power, but the longer stacks will vary things . very interesting INDEED 

[tweakin]

Here is some video today from up at Twinline in Seattle.  A couple of dyno pulls with Davids (DoctorD's) bike.  All I can say is that this build amazes me.  I had to leave before the tune was done.  I do know that I will be taking my bike to Ian when it's ready to be tuned.


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Dave can supply the final info.  Great day Dave!

[Doctor_D]

Interesting day on the dyno, which can be described by four words: "advanced cam" and "under carbed." A good dozen runs with Ian from Twinline Motorcycles, and the results are that we have a fantastic street motor. Blue is today's result, while green was the previous best.



While less than I wanted, the motor gained 2 rwhp, and 5 lb/ft of torque - and the hp and torque peaks moved DOWN the rpm scale and not up. (evidence that the cam is slightly advanced)  We also had to dial ignition advance out of the motor and are down to 30 degrees of total timing. Tried all of the different advance curves on the Dyna2000 - and it turns out 4 is still the king.  Plug chops looked great, but the timing mark on the electrode was a mystery... it was all the way down by the plug threads, which would normally indicate an over advanced condition.

We were clearly under-carbed, and could pick up some peak power by going with CR31's or 32mm flatslides. We could also pull the motor and retard the cam a few degrees, but there's no real reason. At 5k rpm it's making 50rwhp and 50lb/ft of torque and it only loses out to its previous setup above 9k rpms.  Just how much time am I going to spend above 9,000 revs? From 4k-9k we walk all over the previous setup and that's good enough for me.

Shout out to Tige, aka Tweakin, for stopping by to spend some quality time and get some high-def footage.

[MCRider]

That's really cool! What carbs are you running? (I'll skim back in the thread to see)

I found them, CR29s? I'll be running VM29s and a milder cam. But with more cc's hope to get to 80 and 50 +/-.

[Doctor_D]

Tige, thank for editing and posting the video (although it's a 1975 and not a 1977  ).  Glad you could hang out.  Good times.

[tweakin]

I just have 77f on the mind.  Not too much editing but it will do.  It was great to see Ian work, he will be seeing my bike if I ever get it done.

Tige, thank for editing and posting the video (although it's a 1975 and not a 1977  ).  Glad you could hang out.  Good times.

[brandEn]

That video is pretty sweet. Looks like they got a good setup at Twinline. Your tins look red in the video.

[Doctorlumen]

Heya Dave:

Imagine browsing the SOHC forums for 400f mods, and up pops "Hot Street 750". And there I see Twinline's garage...and I think "Ahhh....Dave's million dollar baby." Dude, I caught a glimpse of the paint last weekend and it looks fantastic. And, obviously, she's still racking up the points in the motor build department. I also caught a glimpse of your Norton...what a great looking bike that is. Hopefully, I'll get a chance to catch up at the shop sometime soon.
-Zack

PS, for the readers who haven't seen this beast up close, those pipes almost put a hole in your chest with the air they move. It really is a sweet-as build. 

[tweakin]

Dave, I made a DVD of the short video I shot of your tune yesterday.  I put it on the big screen with surround sound so I could re experience the magic, lol.  Scared the crap out of my wife and little girls...

[mk2jettavr6]

mabey I missed It , but what tank are you using on this bike?

[Doctor_D]

Dave, I made a DVD of the short video I shot of your tune yesterday.  I put it on the big screen with surround sound so I could re experience the magic, lol.  Scared the crap out of my wife and little girls...

Must have been a hoot.  Annoyed my wife as well, and that was just the compressed You Tube version.

mabey I missed It , but what tank are you using on this bike?

Welcome.  The tank's nothing special, just the stock "F" tank repainted in the stock flake sunrise orange color.

[Doctor_D]

Got some small, but satisfying work done this weekend.  Without further adieu, the ever-shrinking punch-list...

Need:
-clutch cover
-stainless fasteners
-turn signals
-seat-pan with upholstery
-oil lines (Need to do them AGAIN as the fittings were crimped in in the wrong orientation)
-oil cooler lines (still looking at options)
-rear brake line
-rear fender
-mirrors

To do:
-pinstriping and clearcoat (pinstriper finally has tank, seat and oil tank in his posession, delivery date is late next week-then they go back to the painter for clear)
-complete and tape wiring harness (not sure why, but I'm avoiding this project)
-mount tail light and turn signals
-weld closed rebound damper holes in forks Feels much better, also realized (Doh!) that I had the top out springs improperly installed.
-make front wheel spacers
-make aluminum rear brake torque-link
-turn and polish stainless bolt heads
-make bracket for Vapor speedo/tach, and install/wire
-install rear brake line and bleed brakes

[Doctor_D]

My pinstriper has begun taping the tank.  Should really break it up nicely.  He'll be at the shop tonight to trace outlines of the "Honda" badge and the "Super Sport" logo.



Photo-shopped the Honda wing on to the oil tank.  I feel like it may be a bit too stark and should possibly be a bit more subdued.  Thoughts?

[tweakin]

Not feeling the wing Dave.  IMO, this build has so much already going on, less is more..

[brandEn]

+1 
The wing looks out of place IMO. The pinstripes look killer though.

[Doctor_D]

I hear ya, guys.  So, what should I do with the oil tank?

[brandEn]

I think it would be ok to just leave it as is. However some suttle pinstripes outlining the shape of the tank would look good too.

[tweakin]

leave it..  Gets my vote.

[brandEn]

Dave, are you going to have New Church make your seat?

[fastbroshi]

Maybe just take down the size on the wing a bit, maybe 50%?

[754]

 Paint the 710 cover/dipstick the same as tank.. make it disappear instead of stand out..
 Those metal wing emlems they used on 350 2wins would look good on the oiltank, if you could mount with double side tape.