Author Topic: CB750F2 .... silk purse from a sows ear.  (Read 18025 times)

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #270 on: September 07, 2021, 04:11:59 PM »
Well now ..... that is a decent looking pipe!

It's added to my 'watch and ponder' list. The Dekovic pipe is broadly similr....but this seems to keep a flat run under the sump, where the Delkevic has an odd shape to it that spoils the look.

Much appreciated with regard to the suggestions on both welding tips ... and how to get mockups done for piperation by a proper pipist. I am sure they have a real name.....but like you...I have no clue what it is!

I would love to learn proper TIG welding...but the cost of the kit and the consumables is one I can't justify with the use I would get from it. I bought my MIG and taught myself after we bought an old VW Beetle...and I got a shock with the cost of welding simple patches. Plus the quality was not good. When the next bit of work needed doing, it was cheaper to DIY it, as plenty of repair panels with swaged edges were available but while I can get the penetration, and produce welds good enough to pass muster at MOT....it's a lot of work to clean up....and welding pipes, I know the inside will be ugly.

Still...I will just have to make do with re-watching Alan Millyard just 'bashing up' a petrol tank in 1.5mm ally for his replica 6 and tig welding it in his shed, and pretend I will live long enough to learn to do that
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #271 on: September 21, 2021, 12:40:36 PM »
So....decided to sort out the seat arrangements while I wait for brake parts and some other odds and ends.

I picked up a fibreglass single seat, basically a wide CR one for not a lot of pennies. The seat the bike came with was a non-standard wreck, being a US king and Queen thing, complete with buttons...torn cover and a base so rotten the foam was tougher than the metal. The 'buttons' having been shoved through the foam, and pop rivetted to the base. Great...so water poools in the buttons recess, wicks down the string...and rotted the base out. The only parts of the seat that were worth saving were the hinge...and the catch.

My philosophy remains to use what I have that is 'right' and ruin nothing of what Mr Honda made.

Now, I have used race seats before, and found them a PITA to get on and off when needed, so I wanted to retain the original seat mounting and lock....which required a bit of thought!

The stock hinge was too tall...and if I had use it, the seat would sit about40mm above the frame rails, so out came the thinking cap. The lock was also too long...so I started there:



An 8mm bolt was found, and a sleeve made to fit over the end. The bolt head was almost removed, and the tip shaped to a dome to mirror the shape of hte stock lock core. A slot was cut, and it was then shortened by the required amount. The RC Car parts bin provided what was a 1/8 scale shock spring which I cut down to fit and provide the right spring rate. This lot went together to make a lock piece that was quite a bit shorter than stock. The threaded part of the bolt was cut down once the thing was all fitted and the exact length known.

The hinge on the other side gave more problems. Putting the seat where I wanted it....the hinge was half under the seat pan, half in fresh air under the hump. No good....so as I needed a much flatter profile hinge..I started from scratch. Found some steel of the right thickness...cleaned it up...and made a hinge plate that was beefier than stock....but basically reversed the way the hinge worked. It also stepped the hinge forward so the mounting to the seat was all on the flat pan part. An ally spacer shim was needed to lift the hinge a fraction, as the seat would foul on the mounting studs otherwise, stopping it sitting level.



The bottom part of the stock hinge was then used to attach to the seat itself....the stock pin slots through sweetly, with a spring clip to hold it in rather than the dog earted old split pin. The flat surface of the hinge that used to sit against the frame now sits against the seat pan.



Bolting the hinge to the seat required another ally shim, just to get the spacing perfect and to ensure the seat sat flat, and everything sat where it should without stressing the seat. Big washers went on top to spread load. I may glass in the shims later to hold them in place.



The lock part was fixed to another ally plate, and that was bolted too the seat pan. The catch needed to sit slightly outside the seat, hence the plate to step it out. This will be covered up with a bit of fibreglass and blended so you can;t see the fixings. It will look a bit neater after this. Stainless bolts and nyloc nuts were used for all fixings.



The seat opens and loses nicely, and the latch engaes securely, opened with the key as before. The front part of the seat sits on 2 3D printed blocks that clamp around the frame and give a flat platform for the seat to sit on. If I need to...I will put a pair of nylon rods into the blocks, with clips to go through. This would stop any wobble at the front, but I haven;t had an issue with this so far...but riding over bumps might rattle it. Some rubber pads sit on top of the blocks ( old inner tube currently! )

So, with the lock mounting covered with a bit of GRP and a pad glued onto the seat base....it will look just how I want. The seat opens to clear the battery compartment and a battery will slide in without issues. It also sits high enough over the frame to clear everything...without looking 'detached'

The next job is to cover up the gap between the seat and the rear of hte tank...and I have an idea for a small 'storage' box that might work.... or I end up with a flat piece of ally and a longer bit of seat foam.... will see how that goes


CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #272 on: October 06, 2021, 09:41:39 AM »
This week....I decided to unbreak the broken brakes......

The front calipers weren't bad, but the pistons had the beginnings of rust pitting which I reckon would have made the seals weep. Literally. The rear was a horror. The piston had needed brutal treatment to shift it, and there was corrosion inside. Much polishing and a bit of dressing with fine wet and dry was needed, followed by a bath in the ultrasonic cleaner to make sure they were spotless and free from dust. The wallet was opened with much ceromony ( and moth sprays ) and £100 was spent on stainless pistons, seals, rubber boots, and the like. Half measures were not considered ...and a can of VHT spray ( as recommended on here ) was bought too.



Brake carriers were stripped and painted. Silver up front and satin black at the rear. The calipers were painted.....and hung on the line to dry. The VHT paint impressed me. It went on well, covered nicely, and just felt 'good' to work with. A mist coat followed by a few more proper coats on rubbed down and degreased calipers, and they looked OK. The missus was out....so in the oven they went as per the instructions. 1 hour at 200c ..... balanced to keep the paint clear of the baking tray was what the recipe said. Boy, did it stink! When I opened the oven after the bake, the fumes fair made my eyes water! But after much airing of the kitchen and a clean of the oven....all was well. Dinner tasted OK......so all good!

The calipers had developed a bit more of a 'shine' than they had before, and were more semi gloss than satin....but I was pleased with the finish and it looked OK to me!



Everything bolted up well, with the seals given a smear of lube to help the pistons slide home. Fresh seal gaiters all through finished off the job. I am pleased with the end result. More so than I am with the photography anyway!

« Last Edit: October 06, 2021, 09:45:00 AM by SumpMagnet »
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Spitfire

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #273 on: October 06, 2021, 10:07:03 AM »
That looks great and reminds me of doing the same kind of job on my F1, very satisfying.

Cheers

Dennis
1976 CB750F

1977 CB750F2 In bits

1964 BSA A65R In bits

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #274 on: October 12, 2021, 06:22:04 PM »
Been a busy beaver in the shed again today.

We have a solution for the brake master cylinder problem.....and a nice way to get some footrests that will work with the seat and bars. So....what did we do?



Having decided that a pair of rearset footrests was going to fit with the way the project is evolving and with the riding position my seat and bars required...I looked at prices to see what it was going to cost me. I looked at hte cheap chinese ones the filled most of my search, and discounted them. I have seen how good they aren't when a friend bought a set. What a bargain...until you looked at the build quality, the poorly cut therads that vibrated loose, and the generally poor and sloppy linkages. No...that was out. I then looked at hte prices of the well known branded items. Ouch. So on went the thinking cap.

So, why not find a bike with the right sort of setup, and adapt that to fit. Simple!

So, the search was on. Didn't take me long to find a suitable donor pair. Off a CBR600F3....so it's at least Honda. For £60 I managed to get a somplete left hand footrest assembly with gearchange linkages, complete, AND a complete right hand set with brake lever, master cylinder, even the brake light and wiring and brake pipe.

Mocked up a couple of flat wooden brackets to sit over the swingarm pivot bolt and lower engine mount, where the F2 stock footrest carriers go. That allowed me to get the position right, and made sure I had clearance for the MC and brake light switch etc. It all fitted REALLY well. I even found the splines on the gearchange linkage are the same size as the ones on my F2. Might need to change the length of the linkage rod...but thats just threaded M6 x1.0 both ends, so no problem to make that if I have to.

Now I need to order up some 12mm thick ally plate to carve my actual mounts out of, 12mm so I can use offcuts to make the additional spacers to recreate the 25mm thick stock pieces. As it's all stock proper parts, the controls look neat, and it all fits and works perfectly.



Will need to swap the pipe around, as the curved front banjo is angled which doesn;t work, but the fixings are the same size. So thats all good.
The only potential fly in the ointment is the master cylinder not being right for the brake. My estimated measures say it's about the right bore size....so should work. Time will tell. But as my stock MC was not in good shape, and even with a rebuild kit needed a new linkage and pushrod....which I still haven't been able to find...even if I got a seal with the stocker, I was struggling for parts

edit: looking at it now, I might need to bring the lower mount point forward, to more closely reflect the angle Mr Honda put it at. But I will fine tune that in the mockup before I cut metal
« Last Edit: October 12, 2021, 06:30:59 PM by SumpMagnet »
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline andy120t

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #275 on: October 13, 2021, 06:55:58 AM »
Just looking at your earlier posts about exhausts -Predator motorsports in Welwyn make stainless exhausts for bikes. Might be worth a call there. They've been around for ages but I haven't personally used them.
andy120t

CB650 project
CB400F frame - just missing a few bits...
ZX6R
GSXR 7/11
Triumph 5TA

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #276 on: October 13, 2021, 10:02:55 AM »
thanks for the tip Andy... Predator are on my radar, but the more I think about it, the more I have to conclude I will either have to compromise....or get a more bespoke solution. That will depend on how the finances look when the time comes. I've been out of work for a few months, and am watching the pennies closely. I have a chunk of money from the sale of my old Hornet in the bank for the bike fund....so we will see. The more I can save elsewhere, the more will be there for shinies :)

But I do have a plan B ..... or is it C .... or D ... if I can just get the damn stock headers apart!
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #277 on: November 20, 2021, 01:50:37 PM »
Following the shjocking revelations in Practical Sportsbike that my great idea was absolutely not original, already done...and therefore old-hat, I was not discouraged.

My first attempt was a tragedy of epic proportions, but was enough to convince me the idea was a good one, but my approach was wrong. I tried to build a mould out of the rear section of the tank, and then remove material to narrow it down ..... as it would otherwise be too large. Sadly.....what also became apparant, was that every other curve, slope and angle also appeared wrong. By the time I had chopped it a couple of times, taped the bits back together and offered it up a load of times....I could see the thing was never going to be blending in like I wanted.

So I binned it.

Not to be beaten, however, I had another go. I had bought some expanding foam filler for a job on the house, and had about half a can left...so I made a little polystyrene base, greased up the back of the fuel tank, covered anything likely to get gunk on it ....and sprayed up a big pile of foam to fill the gap between the back of the tank and the seat. Took a copuple of goes to get it all ....as put too much on and its prone to sag...but it was done!

Then I could carve it back once fully set and blend it with the tanks curves, forming the shape I wanted. It sands really easily, and can be chopped to a rough shape with a saw. Card templated helped me to get it symetrical.

I made it undersize.....as my plan was to lay the fibreglass straight on it, tidying up the surface with a thin skim of filler.

The final cutting of hte edges and the surface finish has yet to be done, but I like whats done so far.





The fit at the back isn't perfect, and needs some fettling...which is making it ride up slightly and angle to one side when let go of. Push it into place, and it looks spot on though.
Once I finish trimming the back and getting it square, it will fit. No idea why the first pic has come out blurry....but you get the idea. Next job is to sand it flat, and apply filler to the imperfections.
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Laverdaroo

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #278 on: November 20, 2021, 02:51:42 PM »
 ;)
Now that's coming on a treat, good skills!
I read about your rear-sets and thought straight away, before I'd got to the end of the sentence......."CBR600 of some incarnation will fit". They read that's what you did! Im not that soft then? Winning! ;D

Re the master cylinder, I shared this with Allen on his disc conversion but have you had a look at the HRC M/C option?

Much cheapness, bit racey :o, still Honda but most of all............its only £14 and HRC!!!!    Whoop whoop!


Ebay item...162805847400
I had one on my Ducati 748/853 and was so simple, worked a treat and very unobtrusive but looked great. (if you're an HRC lover as I am) 8)
Mornings are the invention of the devil!
1977 CB550F (new money pit!!)
2002 VFR800 VTEC
1977 CB400F (current money pit!)
1998 Ducati 748\853 conversion
1980 ish CB750KZ in a billion bits (need to get rid!!)

Offline haynes66

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #279 on: November 20, 2021, 04:40:59 PM »
ive had a look on ebay and it doesnt show much. what do you get?

pete
honda DN01
fazer 600
honda britain project
phil read rep project
half a 500 four
yamaha ygs1

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #280 on: November 20, 2021, 04:54:04 PM »
If I have this right....the 'reservoir' ... is not a pot, its the long greenish coloured tube. There is a bung in the top to keep the fluid in and the water out if it rains. Then there is a clip to fasten it at the MC end, and a jubilee clip for the other end? Think thats right.

It's cheap because it's pretty simple...but in my case, I reckon it would tuck up quite neatly behind the side panel which is tight on space due to the oil tank being in there. I will snag one becuase I think it's a neat solution and fits with what I am doing. The tube only needs to hold enough fluid to account for one 'piston' full in the MC to work the brakes, so I guess race teams looked for how to store just enough and no more.

@Laverdaroo ...thanks for the tip, and the nice words :)  I wanted to stick with a Honda solution, and get something affordable. But I definitely wanted rearsets. Cheap imported ones are out there, but I have seen the quality, and often its awful. You want solid dependable pivots and I figured this was a way to get pegs and controls that looked neat, worked well, and were well finished. That and the fact that CBR600 bits were silly cheap, getting a full set of pegs, linkages and M/C for peanuts. Even allowing for the big chunk af alloy I bought..... it's still cheaper than a set of Chinesium rearsets. Winning for sure!
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline haynes66

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #281 on: November 20, 2021, 05:25:36 PM »
splendid, thanks.  nice work by the way.
honda DN01
fazer 600
honda britain project
phil read rep project
half a 500 four
yamaha ygs1

Offline Laverdaroo

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #282 on: November 20, 2021, 10:11:15 PM »
It's a small kit but like you say, it tucks away, looks neat and does exactly what you suggested you needed. Its compatible and to those that know, is cool as hell!
It may be a clip, a tube and a stopper for 14 quid :'(, but..................... its and HRC clip, tube and stopper :o 8) ;D

Pleasure and lovely bike coming on there, the cbr rearsets are cheap as there's billions out there and heaps were raced making standard parts easy to get hold of and the spares market is still really cheap for bits and bobs. You're right to not do the chinese thing, you have to stand and put your weight on those crap things; I wouldn't be trusting any of those at all and I reckon you've done it justice by grabbing those bits.
Mornings are the invention of the devil!
1977 CB550F (new money pit!!)
2002 VFR800 VTEC
1977 CB400F (current money pit!)
1998 Ducati 748\853 conversion
1980 ish CB750KZ in a billion bits (need to get rid!!)

Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #283 on: November 24, 2021, 06:34:13 PM »
hehe heh.... I am now the proud owner of a genuine HRC branded jubilee clip, a similarly branded piece of plastic tube, a bung and another clip.

should tuck in nicely :)
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Laverdaroo

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #284 on: November 24, 2021, 06:37:38 PM »
Whoop, whoop!

You are now a proper cool dude! 8)

whats not to like about anything HRC? ;D ;D
Mornings are the invention of the devil!
1977 CB550F (new money pit!!)
2002 VFR800 VTEC
1977 CB400F (current money pit!)
1998 Ducati 748\853 conversion
1980 ish CB750KZ in a billion bits (need to get rid!!)

 

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