Author Topic: Copenhagen cb 750 Cafe racer  (Read 9642 times)

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deuce_454

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Copenhagen cb 750 Cafe racer
« on: September 09, 2009, 12:02:28 PM »
Hi Gang after lurking for quite a while I've decided to post some pics and a little description of my project... The bike is a 78 CB 750 f2 that I'm resto-modding into a cafe'ish bike...

The Bike is stripped down to bare frame, all tabs etc has been cut off and I'm building a single seat-er with battery and oiltank in the seat.. The engine has gotten its fair share of Hi po parts and will once its back together displace 1073cc (i found a used 73mm bore cylinder at cyclex that i just had to have... he also had some pistons, carbs, a cam, an ignition system and so on... )

The front fork is a k6 with dual discs and the wheels ate stock 19 inch wirewheel up front (with red rim) and a HD 16 inch rim in the back... I'm keeping the rear disc even if it doesn't look cafe*ish... but i like good brakes...

The pics below is of me shaping the tank in Styrofoam (in 2 attempts, where the first cam eout looking much too laverda like for my taste and the second one is my best stab at making a CR750 tank....) ill be covering it in epoxy and glass-rowing and pouring thinner into it to dissolve the mold when to make room for gas ;-) ..






and the last one is me testing that the thinner actually works (on the laverda-ish tank...)
« Last Edit: September 12, 2009, 09:08:19 AM by deuce_454 »

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #1 on: September 09, 2009, 12:08:10 PM »
the rest of the ingrediences include: clipons, ebay-rearsets, single gauge(tach), 140mm bottommounted headlight, short 4into 1 wrapped exhaust... black paint, red rims and whitewall tires.... i know somone will scream NO... but i think it will look cool, and if you guys are right ill swap to some 18 inch front and rear hoops with blackwalls....

Offline sangyo soichiro

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Re: Copenhagen cb 750 Cafe racer
« Reply #2 on: September 09, 2009, 12:26:38 PM »
I don't think I've seen anyone make a tank in this way.  Should be interesting.

You can also use acetone to dissolve the styrofoam (I think they used styrofoam and acetone in those Alien movies to make it look like the Alien's 'acid blood' was eating through floors and such).

Sounds like you'll have one horse of an engine too!
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Offline Bonafide

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Re: Copenhagen cb 750 Cafe racer
« Reply #3 on: September 09, 2009, 01:06:56 PM »
You can also use acetone to dissolve the styrofoam (I think they used styrofoam and acetone in those Alien movies to make it look like the Alien's 'acid blood' was eating through floors and such).

acetone is a named solvent/paint thinner. pretty sure he was just using the term 'thinner' to be any ol kind of paint thinner.

interesting approach deuce - looking forward to seeing more on your build.

Offline Laminar

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Re: Copenhagen cb 750 Cafe racer
« Reply #4 on: September 09, 2009, 01:36:49 PM »
Yeah, can't wait to see how this tank turns out.

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #5 on: September 09, 2009, 11:24:58 PM »
im also stoked to see if it can be done this way.... ill probably pour in a tank sealer just to be sure that it doesnt de-laminate.. even though the epoxy is low solvent permeable and supposedly good enough to make marine tanks from...

alittle update... the tires arrived and turned out to be blackwalls... which is kinda ok since i was really worried that the whitewalls would look "out of period"  also ill propably make a seat in the same fashion... somthing akin to the wrenchmonkees cb 750 cafe racer.... it will allow room enough for the battery and an oiltank... and if i make it sturdy enough one could even have a removable "saddle"/passenger seat.... not sure where the pegs would go... but its the plan for now

update.... the fibreglassdealer also has carbonfibre rowing.... so im thinking that if i did the outer lay-up in CF and only clearcoated it... it would give the bike somthing extra... or am i "out of period" again?
« Last Edit: September 10, 2009, 06:28:53 AM by deuce_454 »

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #6 on: September 10, 2009, 12:26:36 PM »
Ok so the glass is ordered allong with the CF and epoxy... the dealer was very clear about not recomending it and stressed over and over that the lamination had to be perfect and the sealer should cover the entire inner surface...

The CF will be the last layer and is only for looks.... it will be covered with PU clearcoat that ill sand and buff so it will look like somone put a great deal of effort into it... also i found a petcock on egay its off a kawa R6 and mounts with two bolts so ill laminate two stainless bolts into the bottos so all ill have to do is drill 2 holes and secure it with nuts

im still searching for an aircraft style filler cap that will bolt on and not cost a fortune...

Offline Laminar

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Re: Copenhagen cb 750 Cafe racer
« Reply #7 on: September 10, 2009, 01:54:48 PM »
I'm under the impression that it might be difficult to get the CF weave to lay correctly but if you can pull it off, it will look incredible.

Offline beta1042

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Re: Copenhagen cb 750 Cafe racer
« Reply #8 on: September 10, 2009, 05:59:26 PM »
Awesome, I always wanted to make a tank.  When I made my fairing I used the blue foam from Lowes.  Before you go and apply your resin and plies, test the resin on the styrofoam, I have a feeling that it will eat it as well.  Since you are making a male mold and laying up plies around it, you will get a rough surface on the outside since it isn't tooled.  Are you planning on vacuum bagging the part?  Might help with compaction of the laminate and possibly the outer surface finish.  Also, is the clear coat a UV protectant?  If so, what are you using, I plan on heading to the boat place and see if they have something.  I just made a dashboard for mine out of CF.  Trimmed and drilled it today on the mill.  Needing to prep and clear it sometime.

As far as laying the fiber down, if it is a plain weave it might make it without darting.  Twill would lay down nicely as well.  In my opinion, I don't see why fiberglass or carbon fiber should be different when laying down.  The thing that really dictates how the fiber will lay is the weave of it.

Sorry, just thought of one more thing, you might have to use 2 plies of CF on the outside.  Reason is that you might be able to see the fiberglass show through the edges of the weave.

I'll be following, so please update progress when you can.  Good luck.

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #9 on: September 11, 2009, 09:43:28 AM »
i talked to the fibreglass/epoxy supplier and i ended up ordering a half pound of microbaloons... I'm not going to bag it for the first layup as i don't want the air in the Styrofoam displacing the epoxy trying to escape.... so first layup is 4 layers of GF 220G/sqm rowing... then follows a couple layers of filler made from epoxy and microbaloons... with a sanding in between till i'm satisfied with the shape... then a layer of black epoxy etch primer... and then the CF "beauty layup" ... decals and then clearcoat galore to give it the right finish....

There is a clearcoat available for the new corvette ZR-1 roof.. that us UV protectant but it is stupidly expensive so ill pass on that

i made a seat shape that I'm relatively content with and it allows both for a 12Ah sealed batt and leaves room for an oil tank... i have posted pics below what do you think??
o
 oh yeah i almost forgot i welded in a pan below the seat that will accommodate the battery. and ill be extending it forward under the seat to make room for the electrics.. sort of an 1 inch tall santee box...





above you also see the "CR750" inspired chin cutout

and ill be laying up the seat on the tape base...
« Last Edit: September 15, 2009, 12:38:23 AM by deuce_454 »

Offline beta1042

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Re: Copenhagen cb 750 Cafe racer
« Reply #10 on: September 11, 2009, 12:19:48 PM »
Hmm... That's a pretty good idea splitting up the layup.  Wish I would have thought of that when I did my fairing.  Would have saved me time on adding all that fiberglass filler and sanding.  I used a latex paint over my foam to protect it from getting eaten by the resin.  Again, nifty idea.  I'll put that one away in the ol' noggin.  ;D

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #11 on: September 13, 2009, 03:23:53 AM »
just alittle update... recieved the fuel valve i planned to install, its off an r6 and bolts on so i will need to mould in a pair of nuts or alternativelt bolts so it will be a bolt on deal once the sueface is flat.....

Im considdering two options carburation wise, one is a set of CR´s or doing the EFI conversion with a cbr600f4 injector and a microsquirt... im still not set on either.... but the CR option seems alittle easier.... input?


Offline Retro Rocket

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Re: Copenhagen cb 750 Cafe racer
« Reply #12 on: September 13, 2009, 05:22:35 PM »
I just posted a link for you to look at in the "fuel injection" thread. I was going to use CR's but after reading the thread in that link and just the lure of having an injected CB is too much to resist... ;D

http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=13119&postdays=0&postorder=asc&start=0

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deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #13 on: September 13, 2009, 10:27:39 PM »
wow........... that just changed my mind....

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #14 on: September 14, 2009, 09:35:30 AM »
Now Ive gone and done it! i went ahead and dove right in head first and ordered a GSXR600k7 '07 injector along with a a VFR800 in tank fuelpump and fuelfiller cap... on eBay.. so now i guess it just turned into a fuelie-build.... ill post pics as soon as it turns up
« Last Edit: September 15, 2009, 12:32:33 AM by deuce_454 »

Offline Retro Rocket

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Re: Copenhagen cb 750 Cafe racer
« Reply #15 on: September 14, 2009, 04:08:59 PM »
Excellent.... ;D

Mick
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If You can't fix it with a hammer, You've got an electrical problem.

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #16 on: September 15, 2009, 12:36:40 PM »
while i impatiently await the guy in the brown van with my fuelie stuff i decided to lay out the pattern for my rotordrilling endeavour.... the holes are spaced 5 degrees appart in rows circles that are 9 mm different in radius, first row of holes is 9mm from the inner edge of the brakesurface.... the rows are staggered so each 3 hole row is 10 deg separated from the next.. and there is a 2 hole row in between... make sense?? if not see picture... it all works out to 180 holes, that will be drilled 8mm in dia...

they will be drilled on my cousind Deckel FP3 mill on a round table...



deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #17 on: September 17, 2009, 12:20:44 AM »
Hurray... more stuff arrived... found some Decals in ebay that i think will look kewl on the tank... and the Fibreglass, epoxy  and CF arrived from MrBoat.nl

The tires are 100/90-19 & 150/80-16... the bike is originally an F2 with the offset sprockets, so there should be room for the 150 rear (i hope LOL)

Does anyone know what to use to seal the rims so i can the Pirelli Route tubeless ?? there must be some sealant/tape outthere !






Offline Laminar

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Re: Copenhagen cb 750 Cafe racer
« Reply #18 on: September 17, 2009, 05:59:19 AM »
Hurray... more stuff arrived... found some Decals in ebay that i think will look kewl on the tank... and the Fibreglass, epoxy  and CF arrived from MrBoat.nl

The tires are 100/90-19 & 150/80-16... the bike is originally an F2 with the offset sprockets, so there should be room for the 150 rear (i hope LOL)

Does anyone know what to use to seal the rims so i can the Pirelli Route tubeless ?? there must be some sealant/tape outthere !

If your rims were designed to be used with a tube, then use a tube even if you're running tubeless tires. Tires aren't something you want to gamble with.

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #19 on: September 17, 2009, 09:02:25 AM »
point taken on the tubes....

some stuff showed up tioday.. and i fear that the EFI is on the edge of whats possible... my advice to anyone would be not to get the Gixxr TB's ill need to either make new intake rubbers or weld an angled extension on the heads and use straight rubber hose to mount the TB's... im looking into making the steel bucks that are used as tools for making custom hoses and having some intake rummers made so i wont have to modify the TB other that removing the secondary butterflies and plugging the holes for the secondary injectors and secondary throttleshafts

i got some rearsets from thailand.. il moint them and i fthey look too modern ill sand and paint them...

also here is a mock up of the distance ill need to space them to get decent flow in the manifolds....

The vfr800 fuelpump that screws into (or will screw into) the fueltank...

it also has return.. it feeds into that stainless sponge so it doesnt froth in the tank

deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #20 on: September 17, 2009, 09:10:40 AM »
the TB vas a bit of a pain to disassemble but it worked out.. After reading more on the manual on the microsquirt i shoulde be able to run the injectors staged.. so i wont have to modify anything but jb-welding the hole for the secondary shaft.. and i can retain the big/small injectors on the gixxr.. that way i have injectors that are small enough to idle without running too small a pulsewidth .. and still have enough injector to fuel 130+ horses... now if i could only find a source for the connectors for the injectors.. the TPS and the MAP sensor...

and where and how do you mount an engine temp sensor on an aircooled engine... a head fin? in the oil return?


« Last Edit: September 17, 2009, 09:31:54 AM by deuce_454 »

Offline Ecosse

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Re: Copenhagen cb 750 Cafe racer
« Reply #21 on: September 17, 2009, 10:28:46 AM »
fascinating project! intake rubbers seems to be a common obstacle; figure it out and you'll make lots of people happy i think.

sorry if i missed it but will you line the tank?
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deuce_454

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Re: Copenhagen cb 750 Cafe racer
« Reply #22 on: September 17, 2009, 02:53:13 PM »
fascinating project! intake rubbers seems to be a common obstacle; figure it out and you'll make lots of people happy i think.

sorry if i missed it but will you line the tank?

I will seal it with a pour in sealer... the epoxy vendor didnt have any experience but quoted somthing about a coast guard regulation about epoxy fuel tanks in boats.. and they are aproved for diesel, but not gasoline so re highly recomended that i was very carefull and not get any voids in the layup.. and used a sealer...

Im figuring somthing out with the intake rubbers,, i have talked to an engineer in Samco (a hose maker) and they could make the rubbers in a viton or PU rubber that was fuel and heat resistant if i supplied the male moulds... so i need to do an inner and an outer..... what is the potential market for such an item?

Offline Laminar

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Re: Copenhagen cb 750 Cafe racer
« Reply #23 on: September 17, 2009, 02:58:01 PM »
Small.

Offline Ecosse

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Re: Copenhagen cb 750 Cafe racer
« Reply #24 on: September 17, 2009, 03:59:23 PM »
im figuring somthing out with the intake rubbers,, i have talked to an engineer in Samco (a hose maker) and they could make the rubbers in a viton or PU rubber that was fuel and heat resistant if i supplied the male moulds... so i need to do an inner and an outer..... what is the potential market for such an item?

yeah, likely limited but i'd talk with some of the big brain racer types on this forum. maybe a quick thread hijack on the high performance/racing forum could solicit feedback as there are engine builder/racer types chatting there. http://forums.sohc4.net/index.php?topic=58479.new;topicseen#new
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