FRANKENHONDA II the 1982 DOHC CB 750F2 Build

jpmobius said:
Very nice project! I'm afraid you will need to do a bit more work on your shift linkage though. The driving and driven links need to be much closer to being parallel to each other. (Red lines in pic) They do not have to be exactly parallel, but much closer than you have them. You can't adjust the driving link without cutting and welding or changing the pedal location, so you have to work around that. Ideally, the angle between the driving and driven crank arms and the connecting link would be 90o, but there is also a bit of leeway here and this likely will be ok. I realize that you have a very nice 90o angle between your crank arms and connecting link, but the 90o needs to be between the crank arms and a straight line between them. This is the theoretical or imaginary dark green line in my pic. Often as you know, this straight link is not possible to fit, but for design purposes, you must think about the link as if it were straight. No matter what the shape of the link (light green line), the function (discounting strength/flexibility issues born from the shape) is as if the link were straight. If you draw a straight line for the link on your existing setup (I didn't make a line for this), you will see that when you push down on the pedal, you won't be rotating the driven link very much. Easy fix though. Just rotate the driven crank to match the driving, and create a new connecting link. Making the bend in it as small as you can (orange line) will make it flex less. And once you are driving the bike, you will find making very small changes to the angles of the components can make a big difference in the shifting quality.

Yea the gear linkage was a tricky set up for a few reasons

First was how much backward travel I had when pushing the lever upwards before I would hit the rear side of the chain guarding.

The next issue was that when you would push the lever down wards causing the linkage to travel forwards the linkage hits on the foot peg housing, this in turn acts as a fulcrum causing the linkage to go up.

There is a very small sweet spot in which the linkage will; A not hit the housing causing it to go up, and B still actually change the gears both up and down.

How you see it in the photos is actually in that sweet spot.

Although I am yet to ride it (for obvious reasons) I will have to wait to see if it impacts on riding comfort. I’m. It particularly concerned about the linkage breaking due to it being under excessive force, give there is so little pressure required to select gears.


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Yes sir. Having built dozen(s) of these things I am well acquainted with the frustration of getting them to work properly. I build most things like this from scratch, and while you have to make a lot more parts, you do have a lot more freedom to have anything you want. I had presumed that you have the pedal where you want it. Don't underestimate how important this is - down the road it will be a constant irritation if it isn't in the right place and likely you will have to make alternative parts to fix it. Really, on my own bikes, I sit on it for quite a while (1/2 hour +) to make sure I have the pegs, seat and bars where they will all work and be comfortable. (make sure you have beers close to hand!) On customer bikes, I get them to pretend to ride similarly, and change things around until the bike fits the rider. (this torture I provide at no extra charge!). Back to the point, if you are in fact happy with the pedal situation as shown in your original pic, it looks like it will be just fine. The driven crank that is on the shift shaft is what needs to be rotated like in the pic below. You will find this to be critical. Then you only need to alter or create new a new connecting link as shown in green. The upward angle from the pedal crank arm should provide more clearance when pressing the pedal down. Also, with bent/curved links with heim joints (spherical bearing, rose joint) on both ends, there is another problem with the link flopping around and potentially rubbing on nearby hardware. The solution usually is to use a clevis on one end. A clevis will rotate only in one plane, which will keep the link from flopping around. Your existing link looks very nice, with it paralleling the mounting bracket, but you can still have this look with an extra bend on the link (light green).
 

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jpmobius said:
Yes sir. Having built dozen(s) of these things I am well acquainted with the frustration of getting them to work properly. I build most things like this from scratch, and while you have to make a lot more parts, you do have a lot more freedom to have anything you want. I had presumed that you have the pedal where you want it. Don't underestimate how important this is - down the road it will be a constant irritation if it isn't in the right place and likely you will have to make alternative parts to fix it. Really, on my own bikes, I sit on it for quite a while (1/2 hour +) to make sure I have the pegs, seat and bars where they will all work and be comfortable. (make sure you have beers close to hand!) On customer bikes, I get them to pretend to ride (this torture I provide at no extra charge!). Back to the point, if you are in fact happy with the pedal situation as shown in your original pic, it looks like it will be just fine. The driven crank that is on the shift shaft is what needs to be rotated like in the pic below. Then you only need to alter or create new a new connecting link as shown in green. The upward angle from the pedal crank arm should provide more clearance when pressing the pedal down. Also, with bent/curved links with heim joints (spherical bearings) on both ends, there is another problem with the link flopping around and potentially rubbing on nearby hardware. The solution usually is to use a clevis on one end. A clevis will rotate only in one plane, which will keep the link from flopping around.

I’m hearing what you’re saying about the Clevis I think I may have one lying around in the shed.

In hind sight we probably could have fabricated up the rear set assembly, but it was a lot easier to get these ones. Worst comes to worst I’ll head down to the old mans place and we can make a linkage to suit on the lathe.

Or I could make a guide to keep the linkage straight and mount it off this bolt.

I’m currently going over the seat cowl with a light in the shed and a grey led just marking out all the slight imperfections. Most of them are so small I’ve been able to hit them with some primer filler.

I think for the rest of the day I’ll be sitting in the drive way with the hose running and the 1200 a 2000 wet dry sand paper.

Still not 100% happy with the tank either so it will need to be sanded back and have a little more filler put in where I sanded the back too far yesterday. Luckily the tank will be predominantly white as opposed to black which is a very unforgiving colour.

I’m going to quickly head to the hardware and pick up some mat black paint and knock this mud guard over, hopefully if I time it right I can go from tank to seat to guard as they are drying


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So I managed to etch prime and get the first coat of Flat black on the front mud guard.

Then I sanded back my original filler job to have another crack at it

And after all that I put some primer on and it’s still not right.

I was hoping to spray it at my old mans tomorrow but that ain’t going to happen, I have to get these small imperfections out or they will look at me every time I hop onto the bike.

Back at it tomorrow I didn’t realise how long the enamel paint took to cure. I’ll probably get another coat on tomorrow then rivet it to the brackets tomorrow.

Need to at least finish something before I fly out to work.


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Nothing but respect man - I'm a bit of a perfectionist too and while it never gets perfect I can always say I gave it my best. You're going all out mate, and it's inspiring to watch.
 
The Jimbonaut said:
Nothing but respect man - I'm a bit of a perfectionist too and while it never gets perfect I can always say I gave it my best. You're going all out mate, and it's inspiring to watch.

Thanks Jimbo, while I know it will be worth it, it’s frustrating at times, knowing that soon I won’t be able to work on it for another 6 weeks .

I’m debating whether or not to take the engine apart and get the cylinders and heads done while I’m at work.

I’ve been quoted 4 - 500 to have the cylinders bored out, and about the same to have the heads cleaned up, new valve stem seals put in and the valve lapped. Then when I get home I can get stuck straight into putting the big bore kit in and getting the motor back together.

although there is still work to do on the frame, steering damper mount lol decisions, decisions... but first I better get this tank and seat in order. Jnr decided he would give me an early wake up call today, so it must be a sign to get stuck into it


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Going big bore man, what would that push the cc up to? Thing's gonna be faster than a fart in a fan factory...
 
The Jimbonaut said:
Going big bore man, what would that push the cc up to? Thing's gonna be faster than a fart in a fan factory...

It’s goes up to a 823 cc, I’m hoping that l, the CB 900f cams, CR 29’s, CB 600 F2 coils and Delvic 4 into 1 will do the trick.

Although I’ve been told by a guy that use to build these to race that with the cams they use to have one of them from a cb 1100 or 1000, not sure if it’s an inlet of exhaust.

Ok see how I go with the 900s first, still such a long way off, all I want to do is get it done so I can go with a bust with the guys from Melbourne Cafe Racers. Plus I want to hear how it sounds with all the mods


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So the wifey did a trade with me while I looked after jnr she made a start on the upholstery for the seat

It’s been a little challenging we used about 3 layers of thin foam with another think layer of high density to put up under the top piece of leather to get that rippled effect.

Then she sewed the side strip on unfortunately the first time she confused the front with the back of the seat and put the seam at the wrong end (insert angry wife face emoji) so after I brought this up and then agreed that I would unpick it she got back to it.

So far it’s coming out alright, we will have to use Velcro to hold the leather on to the seat pan as I believe if I try to staple into the fibreglass it will break it. So we will glue the Velcro to the finer glass and stick it to the leather, then use that to pull it tight then I’ll use another strip of Velcro between the seat cowl and seat pan and upholstery to hold it to the bike.

Maybe tomorrow we may get it done, but jnr can make wifey availability a little unpredictable. Hes not quite ready to do the panel work with dad yet.


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I usually use rivets on the underside of my seat pans to hold the seat covers on. I just go around the perimeter of the pan and drill an 1/8” hole every inch, inch and half. I use small washers on the rivets to help keep the vinyl, leather, or whatever you’re using from ripping.
 
I didn’t even think about that, shattered because the Velcro I got cost nearly $50 .

I don’t think I will achieve much today have some friends popping in for lunch, see how it goes.

Yesterday when I went to put the second coat of black onto the front mud guard I knocked it over totally ruined the paint I had to strip it right back and start again (I’m pretty sure I swore when that happened). Such is life resprayed it and I’ll have to put the second coat on again today, fingers crossed I don’t do a repeat performance.

I managed to get the seat cowl all sanded back and primed up so that’s where I need it to be, and the tank I sanded back and filled in again but this time I let it cure over night.

I will also be using a solid piece of wood for my sanding block instead of a cork one, I think it may have been flexing and that’s why I was able to sand the filler lower that the surrounding panel work.

That’s my theory anyway and I hope it’s correct. If I can get the tank squared away and primed up, I may have an opportunity on Wednesday to spray it up. I’ll be pretty stoked if I have that done along with the mud guard and seat upholstery.

Then I’ll look at trying to fabricate up an electrical tray and getting the motor out, so I can send the cylinder and heads away to get some love.


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Looks like you will end up with a cool seat. On my own seats, I use contact cement to glue the cover to the base. The perimeter really needs to be a single thickness of material with a minimum of seams to get a good bond though, so I tend to have pretty simple upholstery. I spend a fair bit of time getting the foam the way I want it and contact cement that to the base. Before I install the cover, I stretch some car headliner over the so far completed seat and glue it on just like I plan to do the cover. This is super cheap and REALLY helps the end result. If it looks good at this point, it will look good with the cover. Rivits are good, I sometimes use them on trouble spots that the glue doesn't want to hold, but they can be aggravating to get right sometimes. I tend too use some pretty stretchy vinyl most times because it makes easier - leather is much more difficult - but patience and perseverance will get the job done.

Looks like a good portion of your dents are on outside corners, which can indeed be a bit taxing. A stiff flexible sanding block is likely good, but avoid shaping the actual corner until after you have the top/sides cut level with the adjacent flatter areas. Then carefully shape the corner radii. The trouble I see most people having results from using too fine a grit of sandpaper to do the bodywork. If your parts were in my shop, #80 grit would be the finest paper to touch them until I was shooting primer. Get the shape right with course paper, and stay focused on the shape and don't be concerned with how smooth it is. Once you are happy with the shape, shoot some high build primer. I try to get inexperienced people to use a guide coat right away, as it will teach faster than any lesson. In case you don't know, A guide coat is simply a super thin layer of paint you will sand completely off. There are official commercial products, but I just grab an old spray bomb of black quick dry lacquer and dust the whole thing from 3 feet away or so. It can be super thin - barely even visible. It will be very obvious when you start sanding. Block sand with #220 wet. You can use a slightly flexible block, but do use a block until you really know what you are doing (I always do) or you will put finger marks in the surface from the uneven pressure of just using your fingers. You will see low areas, scratches and pin holes will stay black until you sand deep enough to remove them. If you hit metal or epoxy (I recommend always starting with with epoxy to encapsulate the steel or fiberglass base of the part you are painting, but it is common not to do this) and still have visible guide coat, you will have to have another go at filling the surface at those areas. So sand the whole part with #220, fill what you miss, re-prime, re-guide coat, and re-sand. Repeat as many times as required until you can sand the entire part and have no guide coat remaining, and no cut through spots into the steel base (or whatever material the part is constructed from. Another coat of primer, another guide coat, and now #400 sanding again (always) with a block.
If you now have all the guide coat removed, and have not cut through, you are ready for paint. And your bodywork will be absolutely, positively, flawless. Now you just have to get the paint to match!
 
jpmobius said:
Looks like you will end up with a cool seat. On my own seats, I use contact cement to glue the cover to the base. The perimeter really needs to be a single thickness of material with a minimum of seams to get a good bond though, so I tend to have pretty simple upholstery. I spend a fair bit of time getting the foam the way I want it and contact cement that to the base. Before I install the cover, I stretch some car headliner over the so far completed seat and glue it on just like I plan to do the cover. This is super cheap and REALLY helps the end result. If it looks good at this point, it will look good with the cover. Rivits are good, I sometimes use them on trouble spots that the glue doesn't want to hold, but they can be aggravating to get right sometimes. I tend too use some pretty stretchy vinyl most times because it makes easier - leather is much more difficult - but patience and perseverance will get the job done.

Looks like a good portion of your dents are on outside corners, which can indeed be a bit taxing. A stiff flexible sanding block is likely good, but avoid shaping the actual corner until after you have the top/sides cut level with the adjacent flatter areas. Then carefully shape the corner radii. The trouble I see most people having results from using too fine a grit of sandpaper to do the bodywork. If your parts were in my shop, #80 grit would be the finest paper to touch them until I was shooting primer. Get the shape right with course paper, and stay focused on the shape and don't be concerned with how smooth it is. Once you are happy with the shape, shoot some high build primer. I try to get inexperienced people to use a guide coat right away, as it will teach faster than any lesson. In case you don't know, A guide coat is simply a super thin layer of paint you will sand completely off. There are official commercial products, but I just grab an old spray bomb of black quick dry lacquer and dust the whole thing from 3 feet away or so. It can be super thin - barely even visible. It will be very obvious when you start sanding. Block sand with #220 wet. You can use a slightly flexible block, but do use a block until you really know what you are doing (I always do) or you will put finger marks in the surface from the uneven pressure of just using your fingers. You will see low areas, scratches and pin holes will stay black until you sand deep enough to remove them. If you hit metal or epoxy (I recommend always starting with with epoxy to encapsulate the steel or fiberglass base of the part you are painting, but it is common not to do this) and still have visible guide coat, you will have to have another go at filling the surface at those areas. So sand the whole part with #220, fill what you miss, re-prime, re-guide coat, and re-sand. Repeat as many times as required until you can sand the entire part and have no guide coat remaining, and no cut through spots into the steel base (or whatever material the part is constructed from. Another coat of primer, another guide coat, and now #400 sanding again (always) with a block.
If you now have all the guide coat removed, and have not cut through, you are ready for paint. And your bodywork will be absolutely, positively, flawless. Now you just have to get the paint to match!

You are 100% with the guide coat, although I don’t call it that I never really know how good, or bad a job I’ve done till I respray over it once there is a solid colour over the panel the blemishes become obvious.

It’s going to take a few goes yet with the tank, I’ve nailed it with the seat (as long as the paint goes on well) but the tank and it’s angles are quiet a challenge and will require a little perseverance yet.

I’m fairly stubborn/ persistent once I’m set on something, that said it doesn’t get me to the end result any quicker.

My guests for lunch have just left so I reckon I might hit another coat of black onto the mud guard. Then go and put some of your advice to good use on the tank.


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So the paint is touch dry on the mud guard. So I thought I would put it on the bracket to see how she looks.

I still need to drill out the hole for the brake line bracket and the other two rivet holes.

I don’t mind it black I needed to comply to the law relating to guarding but at the same time I really like the no mud guard look (however impractical it may be on a wet day). I guess by having it black you kind of get the best of both worlds.

Last night I put some spray filler on the tank because where the filler was looked a little porous, so I hoped the spray filler would fill in these small imperfections.

This morning I’ve just been out with the wet dry and then hit it with some etch primer again

Once it’s dry I’ll take a few photos so we can inspect my handy work.




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So turns out when we went out the upholstery on, it was too small we tried to pull it but it was just getting ridiculous and after going so far with everything else. We’ve now gone to mark II

I then took a few photos of the tank, you may not be able to see it in the photos, but it’s round 3 now sanded it back.

I’ve just washed it off and wiped it down now. I’ll probably need to put some filler into the one dent that’s got me miffed it’s on top of the rear left curve going down to the back of the tank.

It’s a straight dent that runs east west on the tank, seems every time I sand it back I somehow sand the filler too low, even when I’m using a solid wooden block to sand with I keep going too low.

Although each time I’m doing it, the depression is less and less, so I guess that’s a sign to just keep chipping away at it.

I’m really not that good at panel beating / spraying / fiberglassing ... I have nothing but the upmost respect for people that are masterful in these disciplines.





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So while I think I’ve nailed the angle here, I noticed a small dent that I failed to see earlier :/

Right on the edge and a curve Murphy’s law.

The back ends of the tank seem to have come up alright.

The etch primer is doing something weird it nearly looks like it’s wrinkled here, I know when I sanded it it was smooth.

I’m unsure what would be causing it? Perhaps moisture ? I usually wipe it dry, the wipe it down with wax grease remover then let it sit before I spray.

The last two photos are of the dent I just can’t seem to nail with the filler.


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So the wifey had some more progress with the mark II upholstery,

She’s put some Velcro along the sides but is yet to put some in the ends, we will still have to use rivet in some places.

I just threw the leather over the seat to give us an idea of the direction it was heading, and it’s going where we want it to.

Tomorrow I think we will get the Velcro sewed on to the leather then I’ll glue the other half to the seat pan and hopefully she comes up looking mean. I think I’ll need to spray some contact adhesive to the foam in the seat pan and the foam on the underside of the leather before laying it down it comes out sweet.

Tomorrow I’ll finally finish this front mudguard by putting in the rivets and mounting the brake line bracket.


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