The Nazgul 740cc cafe , motor on board

[emokid]

Well riding season is over up here in the cold north , so its time to start tearing into my 76 550f , been riding it for a few months now , just to get to know it ( and of course enjoy the riding ) .

So whats the plan you might ask
In brief my main goal is to get a good looking well performing vintage/racing/cafe style bike .
I will be tearing it to atoms , and start from there

Engine - keep the 550 bottom , add 650 crank cylinders and head , try to keep the 550 valve cover for the looks , machine in a cycle x 915 cc overbore piston and sleeve kit , i hope by machining down the outer diameter of the sleeves from 74 to 72 mm i will be able to fit them in the 650 cylinder (fingers xxxxx)

Body - keep it light , will build my own seat and tank in epoxyresin and fiberglass , leave out all things not essential to performance and looks , so no practical stuff like fenders, chaincover , centerstand -------

Suspension and brakes - 2005 R6 forks and caliper , custom tripple trees with 550 stem , cbr 600 brakedisc


Weight - figure its easier ,and cheaper to loose weight than to add hp , so i have a goal of getting the dryweight below 160 kgs /352 lbs , so i will loose all non essential weight like starter ,fenders,instruments, battery will be a lit/ion 2,4ah

so i hope you all will aid me in my quest to finish this project by mid April , all suggestions and input is highly welcome , and i hope i wont bore you to death

I have three major inspiration threads for this project , two on this forum and one over at sohc4 , i hope you guys are ok with me using some of your ideas for my build even though i will put my own twist on things

first up is Ringo and the lemans special : http://www.dotheton.com/forum/index.php?topic=19771.0
second is Funjimmy and his Interceptor : http://www.dotheton.com/forum/index.php?topic=21648.0
third i have Paulagues over at sohc4 : http://forums.sohc4.net/index.php?topic=40414.msg648043#msg648043

All of these are well worth the time to read through , and all fantastic builds

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

strip time
Thats what it looked like a few hours ago , and a little later with a mockup of what i imagine the rear part of the frame should look like , and some brackets removed

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

I left the engine in the frame , so i can see what it will look like while i make the plugs for the tank and seat .
Started off with a few pieces of Styrofoam and glued the together with spray on glue .
The seat part dried first so i started with that one
I'm tying to make the lines of the frame tubing flow into the bodyparts , so the back of the seat padding is going to look like an extension of the rear tube in the triangle , the frame tubing will also be visible under the seatpan and cauling( i just have to do something to that ugly upper attachments of the rear shocks to make the frame lines flow more naturally)

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

So , if you first don't succeed ...
after one failed attempt i decided to start over on the tank after measuring a bit , and findig everything a bit out of line
I took some inspiration from Ringos lemans special build , and cut the bottom out of the old tank and used as a template for the bottom of the new one .
But i thought it was to flat in the bottom so i cut that away also , to get i lower in the front and higher in the middle over the valvecover .
Then i cut a template for the shape of the new bottom in cardboard and traced that over to a piece of Styrofoam and formed the new bottom from that .
covered the styro in clear tape , and clingfilm , witch i hope will let the epoxy separate from the Styrofoam .
Keeping the lightweight theme i had to cut some speedholes ,right

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Then for the first try with epoxy ........
Bought all the stuff i needed today , epoxy, fiberglass weave , cups , brushes ...........
So the tank went back to the styro mold , on witch i also made a extension in the front and back , so i can adjust the final length when i sculpt the top of the tank later .
I taped up the speedholes from the back to keep the fiberglass from sagging into the holes , and mixed the first cup of epoxy
Not at all hard to work with, did to layers in roughly 90 minutes , and I'm quite pleased with the result

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

First thing was to shape the bottom of the tank to the shape i wanted , i wanted a much narrower tank than the stock one , so i shaved off a few centimeters on each side , then put the tank to be on the frame to determine the since of the inndents for my knees .
A laser level is a very handy tool if you want to get stuff straight and level

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

A little trick i figured out to get the tank even on both sides , was to use a piece of clear tape .
first i cut one side , then put a strip of tape along the centerline, draw the shape i just cut on the tape .
After that just flip the tape upside down and tape it on the other side of the center line ....... easy . i guess this is called learning by failing

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

skipping further description of the shaping of the tank , i have arrived at this point now , its technically a fiberglass tank now i guess, even if its full of styrofoam
the whole thing is now covered with two layers of epoxy and fiberglass strips , and this is what it looks like :

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

In other news , the frontend is going , it will be replaced by 06 yamaha R6 forks and calipers, and a custom triple tree with 550 stem , mfd by Durgam here on the forum , its the same style as the upper triple ringo has on his fantastic lemans special .
The yamaha frontend i got on ebay and it should be delivered in Michigan tomorrow , cant wait to see how this turns out

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

It seemed like the time to get the styrofoam out of the tank , so i drilled out the hole for the fillerneck , and pried it off the styro .
Then according to my plan it should be just to poor in the acetone And let it do its work right ? WRONG !!!!
The acetone eats into the styro pretty quick , but not into all of it , and it doesn't dissolve it completely , it turns it into the stickiest goooooooo you can imagine , if you do a picture search on google for goo, you should get right to a pic of styrofoam dissolved in acetone
So any thought of just washing the tank out with acetone vanished after a few minutes , maybe it could be done if you had a bath big en ought to submerge the tank fully in acetone , but really i dont think so .

Anglegrinder- cut the top of and spoon the goo out , what a mess , but after an hour of dirty work , most of it is out , the rest starts to dry and can be sanded of, and all in all it dint look bad
Now i will put a couple of layers of fiberglass on the inside while i have the chance , actually that will help strengthening the bottom corners that i was a bit concerned about being to thin , and also let me get a smooth surface on the innside .

NOTE TO SELF ( and advise to anyone doing the same ) : next time cover the Styrofoam with plastic film or clear plastic tape that will make it possible to cut the tank open and pick the foam out without it sticking to the fiberglass, forget acetone .

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Last layer of fiberglass is on the tank
I have been sanding down the bumps every two layers ( i now have six ) to avoid getting a major problem in the end , seems to work quite well , before the last layer the tank felt reasonably smooth , so i don't think i will need very much bondo , fingers crossed .
The petcock bunge is in place , i used the old one witch i cut out , sanded down the metal left around the pipe , drilled some holes in it and sandwiched it in between some layers of fiberglass .
On the first pic the filler neck is in for a test fit , it is approx 3,5cm high , and approx 1 cm will be visible over the tankbody .
in the lower 2.5 cm i cut some grooves with an angle grinder to increase ( at least in my mind ) the bond to the epoxy , then i put it upside down in a hole i cut for it in some styrofoam ,with the bottom part protruding and made a collar with fiberglass , it will be something like 1,5 cm wide , and tomorrow i will fuse it to the tank with epoxy .
And BTW sanding fiberglass is some itchy sh..

 

[SONICJK]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Looks awesome!
I really like the tank, could have told you about the acetone though :

 

[BigBSBusa]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Skills!

 

[john83]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Wow, that's a lot of fiberglass work. I have a carbon fiber/kevlar tank that started leaking gas because of a bad liner so make sure you use a quality liner. Caswell or something. I was gonna trash that thing but reading threads like this make me think I might be able to make a copy of it.

 

[two-smoker]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

I did a tank that way for my Honda CB450 hardtail, and I just used gasoline to eat the styro out... I never considered acetone. Of course, the shop I worked at was a little "country".

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Welded the frame back together , got the rear hoops on , and new mounts for my rearsets .
The hoop going up over the frame will be visible with the seat tucking in underneath it , and the cauling as a separate piece behind it , don't know if that made any sense though , in my head its clear at least .
i wanted to put the rearsets on the old passenger peg mounts , but i think the original ones didn't look to good , so i cut them of , leaving the tubing , and then welded in two pieces of roundbar witch i had machined to fit the bolt of the new pegs .

And as a comment to the last picture ,Yes i am that anal , i really smoothed out the kickstand , i need to get my head checked ,i know

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe

Managed to squeeze in a couple of hours again today .
Put some fiberglass bondo on the tank and caulig , and sanded it down , starting to get close to smooth now , so i put on a coat of primer to have a look at the tank while the primer was glossy and get an idea of where i needed to do more work (plus its nice to see it all in one colour to get an impression of the final look).
laid some padding on the seatpan , and got it ready for the upholsterer , it will be made up in black vinyl with black stitching (i think ).

Any comments on the lines and look are welcome , i really would appriciate ideas now before i start painting and upholsteing , and its all to late

 

[mercuno]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe , primed now

that a great idea on the rear cowling. I have been so wrapped up with final exams and christmas I havent even seen my bike. next weekend Imma gonna get it all set and then welded. Then on to my gas tank. I got that caswells in the other day and I am so excited.

About how much wider do you think your tank is??? I was thinking of going about 2 inches wider at its widest point??
I also like your knee dents. looking good man

 

[john83]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe , primed now

I was a bit dubious about that extra frame loop but after seeing the picture with the cowl on I'm sold. That looks really good, very unique.

The only thing I don't like about the tank is how the front edge is so vertical and comes to such a corner. Does that make sense? The knee dents and general shape are great and that hard right angle just doesn't seem to mesh with how curvy an fluid the rest of the shape is.

 

[emokid]

Re: The transformation of the -76 cb 550f into the Nazgul 798cc cafe , primed now

that a great idea on the rear cowling. I have been so wrapped up with final exams and christmas I havent even seen my bike. next weekend Imma gonna get it all set and then welded. Then on to my gas tank. I got that caswells in the other day and I am so excited.

About how much wider do you think your tank is??? I was thinking of going about 2 inches wider at its widest point??
I also like your knee dents. looking good man

Thanks , im looking forward to seeing your tankbuild .
My tank is actually quite a bit narrower than the stock tank , maybe as much as three inches , i can check