Topic: CB 836cc f1 turbo - spoked kickstart street turbo

[Ilja]

Hi guys,

I'm new over here so let me introduce myself first.
I'm Ilja, 28 yrs old and from the Netherlands.. I love to modify old classic bikes and make them handle better as well as modify engines...
I studied mechanical engineering and I worked as a design engineer for a while, but I did build things before I went to university. The engineering background and companys I work come in handy now and then..

So this project will be about my '77 cb750 f1 supersport.  I wanted to leave it as I bought it, but somehow I just can't help myself, the bike had to be changed..

BTW, here's another project I did (for those that also like Kaws ) http://www.750turbo.com/forum/viewtopic.php?f=17&t=10748

So far we got:

-Blackbird swingarm
-CBR900 front and rear wheel.
-CBR900 front fork
-XJR1300 shocks
-CB750 k2 fuel tank
-CB750 k2 oil tank
-CV carbs from a gpz600 with dynojet kit (will need to modify the middle two intake ports to line up with the carbs)
-Mx handlebar.. 
-Garret TB19 turbo (T2 sized)
-K1 style seat.

This bike won't be a huge hp number bike, the engine isn't very suitable for that. Besides, I got the Kaw to do that job.. ;-) So I decided to work with a smaller turbo that will spool fast up to a max of 1BAR / 14PSI. Should be more than enough for a lot of fun! (especially at the traffic lights with the newer bikes!)
No intercooler, external wastegate, DFI, PC3, High impendance injectors, Walbro 350HP fuell pumps, sensors etc...
Just a simple carb turbo setup.

I'll keep you posted.

[Harald F]

turbo's are always cool. 

[Ilja]

Stainless steel exhaust header is finally done. I accidently welded it partly with steel rod... thats what you get for working on motorcycles in the middle of the night I guess. 

Grinded it out and rewelded with stainless steel filler rod. Glad it's done, now I can start on the rest of the exhaust system and the plenum stuff... 

[MOONDOGNYC]

WOW !  Need to see this once completed.

[754]

Nice bike. Does the header fit in OK?. With pipes that short, there is no springing to help line your pipes to head,has to be very close fit.
 My pipe in the pic go in a bit hard, and dont always seat well.. (not using a turbo).

[brandEn]

Great project! I like seeing stuff like this. I am wondering about the steep angle of the rear shocks? Keep in mind I know nothing about frame geometry just wondering out loud.
 

[Mugen_Stumpo]

wow... i really like the before pics... great fairing

[Ilja]

It's been a long time, but recently a lot has happened on the bike... 

[SOHC4 Cafe Racer Fan]

You mentioned a Blackbird swing arm. Can you be more specific on the year and specific model used and what was required for fitment?

[70CB750]

Following.

[Ilja]

Almost ready to fire the bike up!
Got the whole fuel system rigged and set at 3psi base pressure.
All vacuum hoses and pitot tube connected..

Mounting up a innovative MTX-l wideband atm.
Just waiting for a weld-connector for the 10AN oil return line... which takes ages to arrive..

Hopefully I get this thing running before winter! Because since last year you can't drive classic bikes here for 3 months in wintertime..

[eddiebpool]

That project is wild ... I love it! 

[Ilja]

HELLL YEAHHH!!!! After half a year of intense building and one year of waiting for money&parts the moment arrived!

Bike started instantly and doesnt puff smoke! Idles and revs great!
Couldnt be more happy!! 

[hotdog]

Awesome bike - house rockers style is very nice....saw this on FB a while ago and messaged  you about your wheel/fork setup. Didn't know you were a forum member. Good work.

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[SOHC4 Cafe Racer Fan]

Bodaciously bad-a$$!!!

[70CB750]

Excellent, Ilja, simply excellent.

Did not see the pictures before, great job on the bender too!

[Jerilee]

Congratulations! Have you gotten to take it for a ride yet?

[Ilja]

Thanks guys!

No not yet.. I need to do some small stuff to make it road worthy.. getting the chain aligned, blocking the rear caliper, wiring, mounting wideband and boost gauges and thats pretty much it!

Still have to check if the carbs keep dry up to 8psi or something... only had them up to 3psi now... ;-)

But this starting milestone was very motivating. Can't wait to get it riding now! 

[Jerry Rxman Griffin aka MuthaF'er]

We're tuned in now she needs to get tuned up. We always look forward to the dyno runs and graphs.

[hotdog]

Can you post some photos of the swingarm and how you modded it to fit.?
Also chain alignment - do you intend to run an offset front sprocket..?

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[SOHC4 Cafe Racer Fan]

Can you post some photos of the swingarm and how you modded it to fit.?
Also chain alignment - do you intend to run an offset front sprocket..?

Yes, please!

I think your video has been getting a lot of Facebook hits.

[Ilja]

Ahhh the swingarm. I need to find some pics of the modification but in principle:

It's a CB1100 Blackbird swingarm with a length of 53.5cm from center of frame-axle to center of rear wheel axle in middle position of the adjustment range.
It's quite a wide swingarm! If I fit a 160 wheel instead of a 180 wheel it looks funny with lots of space between the wheel and swingarm.. Also quite a long swingarm.
Wheel-axle size is 20mm if I remember correctly, same as the fireblade rear wheel I'm using.

I cut a small part, like 5mm, of the swingarm at the frame-pivot point to make it fit because you need around 225mm width.
Then I installed a new needle bearing which is less wide and removed 1 ball bearing I think (theres 2).I also ground a new groove in the swingarm with a dremel and a small disc for the bearing retaining clip, because it was in the part I had to cut off.
I also made some spacers to fit the 17mm(?) cb750 swingarm axle in the 25mm(?) CB1100 swingarm.
And then welded on the mounting points for the rear shocks offcourse.
It was not a very difficult job, but not easy either!

ALTERNATIVE: 
Yesterday I received a TL1000S swingarm for my z1000 project.. which is possibly a good alternative!
The TL1000S swingarm looks alsmost the same, is 1.5cm shorter, 2cm less wide and most important of all.... it's 225mm at the pivoting point! So you only need to make some bushings to fit the cb750 swingarm axle! And weld on the shock mounts offcourse...
The TL1000S rear wheel and therefore also the swingarm uses a 30mm rear axle... so you need to keep that in mind. ;-)


As for chain alignment, I used a 10mm offset sprocket ordered somewhere in Germany, company called Krüger & Junginger GmbH.. quite expensive at 100 euros... In Germany apperently they call it a "Versatzritzel".

Old ebay ad... http://www.ebay.de/itm/-/321041283215?ssPageName=ADME:L:OC:NL:3160

I am a little worried that it might #$%* up the outgoing shaft since it is only held with the small two-bolt honda sprocket retaining clip....... I might fit a support bearing later.
Next to the offset sprocket, I'm removing around 6mm from the rear wheel sprocket carrier and then its pretty much inline..'

[70CB750]

I may be wrong, but isn't the original swingarm width at the frame bolt something like 242mm?

[SOHC4 Cafe Racer Fan]

Thanks for the details, Ilja.

[Ilja]

I may be wrong, but isn't the original swingarm width at the frame bolt something like 242mm?

I'm quite sure its 225.. same as Kz650 and kz1000..