FRANKENHONDA II the 1982 DOHC CB 750F2 Build

99b6eeb9cd8982ee07c3844afb55e796.jpg
so I'm mucking around with the tail part of the bike trying to get a rough idea of how it's all going to come together.
I've decided to add small side fairings to kind of finish it off... you're going to have to imagine it connects with the tail section and covers over the rear hoop...
d9adc46170b4dda01d7c16af090032e4.jpg

It just looks kind of unfinished without the side fairing.

Although I've got all the gear to fibreglass it up I think I need to do a little more r & d on how best to incorporate the side fairings and also how the fairing is going to marry to the frame.




Sent from my iPhone using DO THE TON
 
Really cool build! Following along for sure. I have a 900F that I plan on giving a similar treatment, although on a bit more of a budget so will be using CBR wheels instead of spoked ones and a 919 RWU fork. Nice to see the Delkevic exhaust on an F build, I've been eyeing that same one and it looks good! I like the way you're going with the rear!

Ground clearance seems like it could be a problem? Have you done the rake/trail calculations? From what I understand one drawback of the GSXR front end is the small offset in those triples that could lead to really low trail numbers. I'm no suspension expert, but that's what I've been able to gather. You might be able to kill two birds with one stone and get custom triples from Cognito that are raised/winged (to gain some ground clearance) and with something like a 45mm offset?

Btw, what is the total length of those forks?

Good luck with the build!
 
Hey Lights out

GSXR forks are 720mm with 17" rim the originals are 780mm with 19" rims, when I was looking into it i noted that CM offer a triple converion stem and bearing set, it ended up being a lot cheaper to turn one up on the lathe and grab the required bearings from a bearing shop. because CM offered the conversion stem i assumed (making an ASS out of U and Me) that it was all good and didnt check (rookie error).

I do intend to put a steering dampner on after a friend from MCR came unstuck on his tricked out cb 750. Im actullay only really concerned with the clearance or lack thereof :/ the Delvic pipes look sick but Im worried on a sweeping right hand corner it will be ground away. If worse comes to worse Dad just purchased a mill so maybe try to turn up an new triple if required

At the moment im trying to prepare the mould for the tail section I'm nearly happy with the shape I'll lay mesh over the mould before I pour the resin hopefully give it some more strength

see how we go, unfortunately my breaks nearly over :/ so the build will go on hold for 6 weeks booo
 

Attachments

  • IMG_4919.JPG
    IMG_4919.JPG
    1.3 MB · Views: 586
The CBR900RR forks I'll be using are 732mm and I'll be using a 17" CBR/VFR front wheel (the Fireblade had a 16" but that's way too small). My 900F had the 18" front, but I assume frame geometry wasn't changed when they went to 18" from earlier years 19" so that probably wont't help me, I'll be in just 12mm better situation than you ;D
With the CBR forks the original stem can be used, since Honda has been kind enough to use identical stems for a long time - so no conversion stem/lathe work or special bearings needed. Doesn't help the height or offset issue though :)

Darren Beggs (who built these beasts) uses winged top triples to regain some ground clearance when using shorter forks. Here are some pics of what they look like.

Looking forward to progress on the seat/tail. Where will you be putting the battery? Will a small one fit under the hump?
 
LightsOut said:
Really cool build! Following along for sure. I have a 900F that I plan on giving a similar treatment, although on a bit more of a budget so will be using CBR wheels instead of spoked ones and a 919 RWU fork. Nice to see the Delkevic exhaust on an F build, I've been eyeing that same one and it looks good! I like the way you're going with the rear!

Ground clearance seems like it could be a problem? Have you done the rake/trail calculations? From what I understand one drawback of the GSXR front end is the small offset in those triples that could lead to really low trail numbers. I'm no suspension expert, but that's what I've been able to gather. You might be able to kill two birds with one stone and get custom triples from Cognito that are raised/winged (to gain some ground clearance) and with something like a 45mm offset?

Btw, what is the total length of those forks?

Good luck with the build!

The forks are about 720mm long with 17" rim as opposed to the original 780mm with a 19" rim that was on it.

I'm not too sure of how the numbers work out, we fabricated a new triple stem and pressed it into the original GSXR triple, cognito moto also offer a replacement triple stem also but it was a lot cheaper to turn it up on the lathe ourselves.

I'll have to see what she rides like definitely need a steering dampener after talking to a mate from MCR who came off his cb750 from tank slapping, although his was a monster bored out and Dyno tuned.

If worse comes to worse Dad just got a mill
1bf5c55b88e76d849ed35efa6d3191fd.jpg

Which I reckon he is dying to use, will definitely be fabricating the rear set brackets with that.

Managed to snap up a few more goodies on line
3740af7986df27fa5dfca59d4b96537a.png


So now Frankenhonda II will have some lungs

Today I've been trying to mould the seat pan up ready to

Those are some trick beasts.

I think once I put the fibreglass on the tail section and get that sorted I will make up a seat pan also. I was unable to put the resin and glass on because I had nothing to use as a release agent...poorly prepared.

There's some kick ass small batteries but I'm unsure which ones are best.

Just got some of these too
283ea4b4e16b3b2812dea1a77af6cb80.png
but I don't think they will arrive before I leave.

You'll have to show us some shots of your build


Sent from my iPhone using DO THE TON
 
Today I fibreglassed the tail section.

First I made a mould basically I used some foam for the tail section and cardboard for the seat pan
4ac580705a3a85b58bb8949eb1a9cf8e.jpg


Then i taped the lot up so it wouldn't stick and also the tape give a much smoother finish than my bread knife made cuts.
42acfc23923f4c135d2572892227eaf6.jpg


I then put mesh over my mould to give the fibreglass a little more rigidity, but unfortunately I did not put wax on the tape as a releasing agent. So after getting it all nice and tied into place I removed it,waxed it up,then reinstalling the mesh
b6f7cc7154b70c28b4e5837d6f90047a.jpg


Then I cut out my sheets of fibreglass I used two different kinds one that is a cloth and the other a fibreglass matting. I think the matting is stronger but the cloth gives a nicer finish
25b09e11e01944f8cc1874bd0d3e1a67.jpg


Then I used a plastic sheet to cover the rest of the bike
4d14df9a8c6b93431f363b10bb2312de.jpg


Then lay the resin on and fibreglass
89d78121df9ff9e61eee590a36652efc.jpg
a0265acf3322c8b577368630ad1c294a.jpg


Now to wait for it to dry



Sent from my iPhone using DO THE TON
 
Damn, those CRs are sexy! Fibreglass work looks good, giving me lots of good ideas here :)

I will start a thread once my build is properly underway. At the moment I'm planning and gathering parts... and (slowly) working on a GS550 build.
 
We'll progress was slow and I'm all out of filler

121219f5aa0ec62ecb9140c890ff8f56.jpg


I think I have the shape right tomorrow I'll go and get more filler and some more sand paper

47a1bd2bddce905fafbe64a33b2c78a3.jpg

a5eb8e7140ec889c94f046bc91426d04.jpg
f511790ec2758ab9b6328775b74c4cac.jpg
faf831ace46667364f5ddd6aca3e2f62.jpg

fa8cabf5ed1d00b96f7ff8b277ebd529.jpg
110829dc5d8d9436179bee36434aeb6f.jpg


Let's see how many runs I can get on the board tomorrow


Sent from my iPhone using DO THE TON
 
Ok so I cut it out and she's a little rough (glass half full optimism)

She still needs a lot of work and I need to get a contour gauge to help me get the shaping spot on
bd60ed25afc35a18e2524b3f158b432a.png
hopefully this tool allows me to get the clean finish I want as paint only highlights your imperfections.

e5bc4f3d9ec3a24b58890e809db44294.jpg
03dbcdd1fdccb9a4647ab650d5d80427.jpg


You can see where I cut too much off on the front left near the tank I'm not happy with that line and need to fix it up
9aea7705859087e9232d8f628c80e051.jpg


bd0e0610ba53c08a4bbb713ef8564686.jpg
0f6bbd982fc73f16f1325036df5a4b15.jpg
1a6f9b8cbed3d6a18735d8cbb711bc80.jpg
69e2e18d7b298720a65771b9893a7fbe.jpg


So that's where I'm at it's a long way from where I want to be but hopefully I can make it work


Sent from my iPhone using DO THE TON
 
cb250nproject said:
I agree the disc does look odd, would it be cheaper to get it drilled? or just buy a brand new disc?

Also im trying to work out exactly what model of cb 750 had the 6 stud bolt pattern for mounting that disc, the other ones I had were all a 5 stud bolt pattern, that was off the original wheel that came off. dont want to oreder the wrong one.. again

Given how little the rear brake does i dont think I will go to the trouble of putting a nissin caliper on, I have ordered a kit and was going to strip down and refurbish the original caliper. I think the brake upgrade that came with the GSXR fork conversion will still make it like night and day.. thats wat I'm hoping anyway

you could ask max at planet discs.
 
So I'm trying to take a more measured approach.

So I drew up a centre line and a few other points of reference
ca6117caa643ed022b98d3219cdbe2a3.jpg


As you can see it took me a couple of attempts to get it where I wanted to
092debff9f39b99729012e389c1a9ec4.jpg
14db4b82f11ebc3b25f5fdf038420506.jpg


Once the lines were drawn I cut it all as close to the desired shape as I could
b35233b7e0c5d43f59ef08f854b47f7f.jpg


Next thing I did was go to work on the left hand side of the seat pan didn't mould to the chassis rail it was bowing out a little in two spots and was doing my head in so I cut them out the redid the left side
467c8f755dea1e75d98af0f46da4c78d.jpg

3ba5a8744cc9b23dbe1dd98d7df163a1.jpg


You probably can't see the difference in the before and after but it follows the contour of the tail around much better.

Once the resin dries I may have to build it up wit a few more pieces of fibreglass just to get it sweet.

In addition there are a few spots that will need to be filled in and levelled out then I'll look at cutting the slot in for the rear tail light LEd strip and I'll have to weld a support bracket for the hump in the tail




Sent from my iPhone using DO THE TON
 
Great bike! The joy of fiberglass is you can keep adding or removing it until you get the shape you want. You just need time and motivation!!!!! For me that rear disc is spoiling the good looks, drilling some holes to match the front ones might help.
 
Popeye SXM said:
Great bike! The joy of fiberglass is you can keep adding or removing it until you get the shape you want. You just need time and motivation!!!!! For me that rear disc is spoiling the good looks, drilling some holes to match the front ones might help.
I agree wholeheartedly the disc needs to be drilled. I'm away at work now for the next six weeks but once i return ill look at going somewhere to get someone to drill it out, my seal kit for the rear caliper came in the mail today
017edb31e3ccd3aba47be1faeb0c8d4c.jpg
so i will strip it down repaint it and refurbish it will be a good opportunity to take the disc of and sent it away.

Still have a few other things to nut out now also kike the speedo i had a cable one left over from a previous build but i just realised with the CM hub and spacers i used there is no room for a speedo, so ill have to find some other option with the guages less is more for me small and unobtrusive. Guess ill be scouring the net for options while im at work.

The fiberglass depending on how the ocd is could take longer than anticipated but it was never meant to be easy, honestly i wish i was an accomplished welder steel seat pans and tails look trick, but unfortunately thats a skill im yet to master so fiberglass it is

Sent from my GT-I9305 using DO THE TON mobile app
 
Fiberglass work looks really good in the pictures at least!

Don't recall where that rear disc was from, but some (old Hondas) are apparently really hardened so get some good drill bits :)

Re speedo, aftermarket ones like Koso use a magnetic sensor you mount to the one of the brake caliper nuts. That's a clean and minimal solution. Believe they read the tach from the coils as well so that would eliminate the tach cable from the valve cover as a bonus.

...or I've seen some get a sensor from e.g an F3 CBR which reads from the front sprocket. That would require a custom machined or at least modified sprocket cover for mounting though. Google 'dons cup of gold' for a build with that solution.


Sent from my iPhone using DO THE TON
 
Lol good from a far but far from good, it will need some TLC when im home next.
Those koso speedos look pretty trick have you used them?

Today the CR carbs arrived in the post today pretty happy about that, now im just waiting on some shims so i can finish the valve clearances, reseal the engine and give it a good glean up... then onto wiring not ny Forte at all.

Sent from my GT-I9305 using DO THE TON mobile app
 
Haven't used the Kosos myself, but only heard good things. Will probably be going with them when I get going with my build. Seems like a quality brand. I believe Acewell uses similar setup too.

Remember to set the valve clearances to .005-.006, not down to .002 as the FSM says. At least that seems to be the collective wisdom of the 1100f.net forum :) Too tight especially on the exhaust side risks burning the valves.


Sent from my iPhone using DO THE TON
 
i had max make me a disc recently, i think it was all water cut, even the holes in it. not sure how thick the original is, but you could get it made thinner too from stainless, 4mm is fine. and a bit smaller, to take a smaller caliper.
 
LightsOut said:
Haven't used the Kosos myself, but only heard good things. Will probably be going with them when I get going with my build. Seems like a quality brand. I believe Acewell uses similar setup too.

Remember to set the valve clearances to .005-.006, not down to .002 as the FSM says. At least that seems to be the collective wisdom of the 1100f.net forum :) Too tight especially on the exhaust side risks burning the valves.


Sent from my iPhone using DO THE TON
Ill have to check out Acewell also, yea i too scoured over the forums and came to the same conclusion as you and left min .006 i think better to have too much than not enough may sound shit but wont fuck the valves.

Hopefully all the shims are ready would be cool to put them in fit the carbs and see if i can fire her up (very wishful thinking) i really want to hear the Delvic pipes.

Sent from my GT-I9305 using DO THE TON mobile app
 
LightsOut said:
Haven't used the Kosos myself, but only heard good things. Will probably be going with them when I get going with my build. Seems like a quality brand. I believe Acewell uses similar setup too.

Remember to set the valve clearances to .005-.006, not down to .002 as the FSM says. At least that seems to be the collective wisdom of the 1100f.net forum :) Too tight especially on the exhaust side risks burning the valves.


Sent from my iPhone using DO THE TON
Ill have to check out Acewell also, yea i too scoured over the forums and came to the same conclusion as you and left min .006 i think better to have too much than not enough may sound shit but wont fuck the valves.

Hopefully all the shims are ready would be cool to put them in fit the carbs and see if i can fire her up (very wishful thinking) i really want to hear the Delvic pipes.

Sent from my GT-I9305 using DO THE TON mobile app
 
Back
Top Bottom